Abbasali Vali; Mahvash Mehrabi
Volume 6, Issue 19 , September 2019, , Pages 125-143
Abstract
Introduction According to some researchers, predeting and preventing water shortages is not possible. However, by fitting the distribution of the probability to the data of a river, it is possible to determine the incident corresponding to the probability of the occurrence or a certain period of return, ...
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Introduction According to some researchers, predeting and preventing water shortages is not possible. However, by fitting the distribution of the probability to the data of a river, it is possible to determine the incident corresponding to the probability of the occurrence or a certain period of return, and with the management and implementation of the drought management programs to reduce its effects and consequences. Hydrological droughts affect vast areas and are detected by reducing lake water storage, lowering groundwater levels, and decreasing river flow flux. This decline in river flow fluctuates from two environmental and management perspectives on water resources. On the other hand, hydrological drought affects the agricultural sector and causes irreparable damages to this sector. Therefore, the importance of studying hydrological droughts is shown in relation to other droughts. Droodzan dam basin is one of the mountainous basins of central plateau of Iran located in the northwest of Fars Province. It provides approximately 760 million cubic meters of water per year, including drinking water, and agricultural and industrial facilities in and around the area. Recently, due to drought, it has faced severe water losses. Therefore, the preservation and maintenance of the reservoir of this dam and the continuity in exploitation of water resources requires attention to its watershed and the potential of water production in the river basin. Therefore, studying the hydrological status of surface waters of the basin can have a special place in the management of drought in the country. Methodology In this study, 5 stations that had appropriate data during a long statistical period were selected. Reconfiguration of the statistical defects was done using the correlation between stations and using the SPSS software. After reconstructing the statistical defects and completing the data, their homogeneity was analyzed using run test and SPSS software. Then, the river flow index was calculated at 3, 6, 9, and 12-month intervals during the statistical period of 28 for each station. In this study, for the frequency analysis, the data from series of limit values were used and fitted with the probabilistic theoretical fit. Chi-Square and Kolmogorov-Smirnov tests were used to determine the appropriate distributions for each time scale using Chi-square fit test. Then, the return period for each of the drought conditions was obtained on the basis of the river flow index at each time period and was extracted from the frequency analysis curve of each station. Results The results of the data homogeneity were studied. The data of all stations were at a level of confidence of at least 99%. In general, the results of the river flow index were very similar at different time scales and indicated the severity of the drought in these years (64-65, 80-78, and 92-87). This increase was observed at 9 and 12-month intervals. Also, the number of years in which mild drought occurred at a time scale of 9 and 12 months, was compared to the 3 and 6-month time scales. In the abundant analysis, the normal distribution of the 3-month river flow index, the distribution of generalized limit values for the river flow index of 9 and 6 months, and the exponential distribution of the 12-month river flow indices were recognized as the best distributions. Discussion and conclusion The results obtained from the calculation of the studied indices showed an increase in the severity of the hydrological drought, especially in the recent decades. River flow index is one of the indicators of the hydrological drought assessment, which can be a good measure for assessing the drought phenomenon in the region. This indicator is also very efficient and has a high sensitivity to other drought indicators. In addition, the zoning maps showed that in the northern and eastern regions of the mild drought, less than the other regions, except for the 6-month period, they were less likely to return to the rest of the period. In the case of the moderate and severe droughts, this was true in the northern parts of the region. In general, with the increase in the return period, the extent and severity of the drought in the area increased. Particularly the northern and eastern areas of the studied watershed were more prone to these natural disasters. Therefore, this area was exposed to economic and social damages and hydrological droughts, so water resources studies require more attention. Thus, the drought risk poses these areas to severe economic, social, environmental, agricultural, and ecological degradation. These areas can serve as short-term and medium-term goals of integrated strategic management and operational plans.
Keyvan Mohammadzadeh; Seiran Bahmani; Mohammad Hossein Fathi
Volume 4, Issue 11 , September 2017, , Pages 127-148
Abstract
Introduction
Iranian territory has the main prerequisites for the occurrence of a wide range of landslides due to its mountainous topography, tectonic activities, high seismicity, and different geological and climatic conditions. Therefore, reducing the effects of natural disasters, particularly landslides, ...
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Introduction
Iranian territory has the main prerequisites for the occurrence of a wide range of landslides due to its mountainous topography, tectonic activities, high seismicity, and different geological and climatic conditions. Therefore, reducing the effects of natural disasters, particularly landslides, is one of the key challenges for land-use planners and policymakers in this field. In this study, the southern side of the Ahar Chai basin from Nasirabad Village to Sattarkhan Dam is evaluated for the probability of the landslide occurrence. This region is highly susceptible to landslide occurrence because of the extensive manipulation and its natural conditions. Indeed, the occurrence of the large shallow landslides in this region is an indication of this susceptibility. In this study, Linear Regression Model has been used to prepare the landslide zonation.
Methodology
The study area was the southern sides of the Ahar Chai River, from Nasirabad village in Varzaghan to the Sattarkhan Dam, with an area of 128 km2. In order to study the potential of the landslide occurrence in this region, nine main factors including slope, slope direction, lithology, land use, precipitation, distance from the fault, distance from the river, distance from the road, and vegetation were identified. The model which was used in this study was Logistic Regression. This model is one of the predictive statistical methods for dependent variables in which zero and one respectively indicate the occurrence and non-occurrence of landslides. In addition, instead of being linear, the regression of the variables is S-shaped or logistic curve and the estimations are in the range of zero-one. Indeed, values close to zero indicate the low probability of the occurrence and values close to one indicate the high probability of the occurrence.
Discussion
In Logistic Regression model, after entering the data into the Logistic Regression model and using the effective parameters in Idrisi software, the coefficients of the model were extracted. A value of 965, which represents a very high correlation between the independent and dependent variables, was obtained for the ROC index. After determining the validity of the Logistic Regression model, using the above indicators, landslide sensitivity zonation map was prepared. In the present model, the land use factor with the highest coefficient was the best predictive variable in determining the probability of the landslide occurrence in this region. In addition, the SPI index and the distance from the fault had respectively the second and third highest coefficients. After zoning the landslide, the slip area was calculated for each class and its results showed that zones with highest risk had the lowest area percentage and these areas were located in the western slopes.
Conclusion
The results showed that while land use, lithology factors, and SPI index with positive coefficients had higher correlation, the other factors with negative coefficients had lower correlation. Based on the map, the western, southern, and the north-eastern parts of the region have the highest potential for landslide occurrence. Furthermore, the high value of the ROC index and its proximity to number one indicates that landslides in the study area have a strong correlation with the probability values derived from the Logistic Regression Model. In addition, the assessment of the SCAI scaling hazard zonation map shows that there is a high correlation between the hazard map with the existing slip points and the field observations of the area. It can be said that, in addition to the natural factors, some human factors including unstructured road construction may play an important role in the occurrence of the landslides. It is also necessary to avoid making changes in the ecosystems and land use. Finally, any policies to construct structures should be commensurate with the geomorphologic and geological conditions.
Mansor Parvin
Abstract
1-Introduction In recent decades, the demand for water has intensively increased in arid and semi-arid regions of Middle East and North Africa (Souissi et al., 2019:1, 2). Nowadays extensive use of underground water resources has been converted to a challenge in arid and semi-arid regions (Gaur 2 et ...
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1-Introduction In recent decades, the demand for water has intensively increased in arid and semi-arid regions of Middle East and North Africa (Souissi et al., 2019:1, 2). Nowadays extensive use of underground water resources has been converted to a challenge in arid and semi-arid regions (Gaur 2 et al., 2011). Excessive use of underground water resources may cause problems such as the reduction of water level, the reduction of quality and pollution of underground water, which can cause water tension (Souissi et al., 2019, 2). To cope with this hydrologic crisis, optimal programming and management of underground water resources seems essential (Singh et al., 2017, 1440:3). Mahi Dasht plain is one the most important plains of agriculture in Kermanshah and the country and had a significant share in the production of various rainfed and irrigated agricultural products. Underground water resources of Mahi Dasht as the main source of providing the required main water of human societies of Mahi Dasht catchment area has faced the reduction of water level due to improper harvesting and the occurrence of droupht. Zoning and identifying regions in need of being recharged by underground water of Mahi Dasht plain has had an important role in the management and recovery of the balance of these resources and the conduction of this study was a necessity. The purpose of this study was zoning and identifying those regions who are in need of being recharged by underground water of Mahi Dasht using potential recharge index method. 2- MethodologyIn this study, eight parameters of lineaments, drainage density, land use, topography slope, soil, annual rain and geomorphology in potential recharge index method for zoning regions in need of being recharged by underground water were utilized. Each of these eight parameters can be divided into low, moderate, high and very high classes based on their nature and the amount of effect in feeding underground water (Table 1). Based on the categorization of Shaban et al., (2006), each of the classes allocated the following scores to themselves: low class (score 1 to 2 ), moderate class (score 2 to 4), high class (score 4 to 6) and very high class (score 6 to 8). Each of these eigth parameters had their specific weights and lithology parameter of 33% as well as soil parameter of 3% had the most and the least weights (Table 1). Finally, the eigth parameters were scored based on Table 1 and according to the WLC method, they were integrated using the following equation and the RP was provided. Pr=(RFw*RFr)+(LGw*LGr)+(GGw*GGr)+(SGw*SGr)+(LDw*LDr)+(DDw*DDr)+(LCw*LCr)+(SCw +SCr) 3- Results and discussion In the catchment basin of Mahi Dasht, almost 80% of the area had very high, high and moderate potential recharge. The reason behind this issue can be attributed to the appropriateness of geographical conditions and geology of the basin. According to lithology, almost 80% of the area of the studied basin was made up of quaternary deposits and carbonate makers; this issue had an utmost role in recharging underground water resources. In Mahi Dasht basin, Mareg River follows the fault path of Mahi Dasht and mountain areas of the basin specially carbonate regions of that, are extremely tectonic, which leads to the more penetration and high recharging of the underground water resources. Geomorphologic conditions of Mahi Dasht plain is appropriate for being recharged with underground water, since 43% of the area of the basin is made up of torrential-alluvial plain landforms and alluvial fans. Agricultural, garden and jungle uses have included 78% of the area of the studied basin; this issue has an important role in recharging underground water resources of the basin. Almost 58% of the area of Mahi Dasht basin has soils with A and B hydrologic groups, which created appropriate potential recharge for the underground water of this basin. Almost 80% of the area of the studied basin of the constructional plain level of Mahi Dasht has a slope of less than 10 degrees which contrives the appropriate condition for being recharged with underground water in the basin. The studied basin had a mean rain of 590 mm, which stated the appropriate raining condition of the basin for being recharged with underground water resources. Wide parts of Mahi Dasht basin especially in the foothills had a high drainage density, which had an utmost effect in the recharging of underground water resources. 4-Conclusion The level of Mahi Dasht plain has been located in an area having very high recharge potential due to the appropriateness of lithological, tectonic, geomorphologic-topographic, land use, soil and climate conditions. The area having very high recharge potential coincided on rough country regions and geomorphologic, slope and lithological conditions had the highest limitations. Moderate potential area coincided on north mountain basin. Bed outcrop of penetrative carbonate makers, the high lineaments` density and high rains caused moderate recharge potential in these regions. Most of the areas of south heights of the basin were located in the area having low recharge potential due to the bed outcrops of impenetrable makers of Kashkan, Amiran, Gorpi and Ladiolarite. Finally, it could be stated that Mahi Dasht basin wouldn’t face limitations in terms of appropriate areas for underground water resource recharging. The bed and margin of Mareg River and the level of Mahi Dasht plain and its surrounding areas were appropriate for underground water recourses` recharging.
Abolghasem Amir Ahmadi
Volume 4, Issue 12 , December 2017, , Pages 131-152
Abstract
Extent Abstract
Introduction
Gully erosion is a major problem for natural resource management, leading to land degradation and economic losses worldwide. Determining the threshold for research on Geomorphology and natural ecosystems is important for many scholars. Land managers and specialists knowledge ...
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Extent Abstract
Introduction
Gully erosion is a major problem for natural resource management, leading to land degradation and economic losses worldwide. Determining the threshold for research on Geomorphology and natural ecosystems is important for many scholars. Land managers and specialists knowledge about factors affecting the growth of gully enables them to control them and predict their growth rate under similar conditions in other ecosystems. In the study area, this type of erosion has caused many lands to be destroyed, and with runoff and flood runoff, there is a significant amount of sediment that leads to unutilized land. It seems that examining these factors and determining their thresholds will help determine control strategies and more successful implementation of water and soil conservation projects. The purpose of this study was to determine the threshold of effective factors in the longitudinal growth of gullies using data mining techniques in Sanganeh Kalat watershed in the northern part of Khorasan Razavi province.
Methodology
Initially, the location of 23 gullies was recorded using the Global Positioning System (Garmin 76CSX) and the distribution map of the gullies in the study area. Then, the Soil gravel, bare soil, cover, litter in heads of the selected gully were measured.
For this purpose, 15 plots were placed in one square meter and their means and the previously mentioned parameters were determined. In order to measure the physical and chemical properties of the soil, a soil sample was taken from a point at the head of each gully. After they were transferred to the erosion and sedimentation laboratory, the electrical conductivity (ECe), PH, OM, SAR, Clay, Silt and the Sand were measured. Also, the permeability at the top site of head of each gully was calculated using double cylinders. In addition, the amount of water penetration of the soil was calculated. Finally, using the data mining technique (K-Means Clustering and CART Decision Tree), the threshold of the factors influencing the longitudinal growth of gully in the study area was determined.
Discussion
Of the total of 23 gullies studied in this study, the accuracy of the estimation based on the parameters influencing the longitudinal extension of the gullies in the final model were measured and were respectively 100% and 85% for the educational and experimental data sets. The interpretation of the rules extracted from the decision tree of the CART, based on the clustering of the length of the gullies, is as follows:
- The results of the analysis of the CART decision tree algorithm show that when the width of the gullies is 275.32, the SAR is 0.147, the gullies headcuts slope is 1.39, and the percentage of silt would increase from 37.12, long-length gullies (cluster 1) are created.
- In the formation of mid-range gullies, when the ratio of girder width is greater than 198.84, the SAR is less than or equal to 0.174, and the gradient of the gully headcuts slope is less than 0.73, the average length gullies (cluster 2) are created.
- When the width of the gullies is from 108.77 m, the SAR is less than or equal to 0.174, and the gullies headcuts slope is smaller or equal to 0.481, gullies of low length (101.35 to 163.23 m) are created.
Conclusion
The results of the decision tree of CART based on the length of gullies clustering showed that the most important factors affecting the longitudinal expansion of gullies in the study area were gully width, SAR, gully headcuts slope and silt percentage.As a result, the main factor in the longitudinal expansion of gullies is the surface runoff. The second factor is the soil erosion sensitivity in the study area. The main reason for this is the poor vegetation and low soil permeability. In addition, the texture of the soil is another factor that overwhelms the longitudinal extension of the gullies. The prevalence of the amount of silt in the soil texture is due to the lack of adhesion, waste, and the transfer of more sediment, resulting in the longitudinal extension of the gullies.
Kazem Nosrati; Milad Rostami; Zahra Etminan
Volume 6, Issue 21 , March 2020, , Pages 133-154
Abstract
1-IntroductionOne of the most elements in river geomorphology, engineering and management is the channel issue. Rivers are natural and complex systems that their classification offers a better knowledge regarding their processes and forms. Based on dynamic and channel forms, rivers are varied and find ...
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1-IntroductionOne of the most elements in river geomorphology, engineering and management is the channel issue. Rivers are natural and complex systems that their classification offers a better knowledge regarding their processes and forms. Based on dynamic and channel forms, rivers are varied and find natural changes over the years. However, nowadays anthropogenic effects comprising building structures such as bridges, and roads accelerate the destructive process. River classification is a suitable way to increase our knowledge about rivers. One important aspect of river is hydrogeomorphological understanding. Therefore the objectives of this study were to assess and analyze the Taleghan river hydrogeomorphological conditions using the geomorphological quality index method (MQI) in upstream of the Taleghan dam and to validate MQI in this river.2-MethodologySix reaches in upstream of the Taleghan River have been selected and MQI for each reach determined using satellite images and field survey. In order to determine SQI for each reach, three aspects have considered including river processes continuity (longitudinal and crosswise), channel morphological condition, cross-section form, sediment bed loads and vegetation. These aspects investigated in the form of three components consists of geomorphological functions, processes and river forms (F), artificial (A) and channel adjustments (CA).3-ResultsAfter measurement and field observation of the Taleghan River, effective variables on morphological quality index were obtained in reach. MAI and MQI values for each reach were calculated and classification was done based on the range of each class. The condition of each reach based on MQI was explained as follows:The first reach: took place in a mountain area and upstream of the river that on both sides connected to the river and is limited.Based on the NBS model erosion of bank steam is in a minor amount and the average bed slope in this reach is 0.028 with gravel bed.Channel width is variable between 10 to 18 m and has a single channel pattern. The obtained MQI values in this reach is 0.714 that grouped in a good class.Reaches comprising four reaches (two, three, five and six) have the same condition that in the point of human interfering, morphological condition and values of bed and bank erosion have a normal array and grouped in moderate class.In reach 4 the river is fairly limited and flood plain is present discontinuously on one side and the other side is attached to the hillside. The river has a sinuouse pattern and bed load sediment formed by fine and coarse sand. Furthermore, forth reach strongly influenced by human changes consists of gravel and sand quarring, the existence of bridge structure on the river, presence of built-up area and destruction of vegetation along the river.4-Discussion and conclusionThe results showed that reach one with score value of 0.714 due to low human interference and locating in upstream of the river categorized in a good class. Otherwise, reaches two, three, five and six have values of 0.58, 0.54, 0.59 and 0.61, respectively and they are categorized in moderate class; in these reaches in comparison to reach one the values of human interference have been increased. The reach four with MQI score value of 0.49, is categorized in a weak class because of human interference including gravel and sand exploitation and structures such as bridges on the river. The results reveal that the MQI model is approperiate for the classification of rivers in the Taleghan River in southern of Alborz Chain Mountain.
Issa jokar sarhangi; Reza Esmaeali; Sedigeh Baba Alipour
Volume 5, Issue 14 , June 2018, , Pages 135-156
Abstract
Introduction
Drainage density is an important hydrogeomorphologic indicator in determining activity quality of processes of overland run-off, flood intensity, soil erosion and sedimentation load in the basin. Drainage density was defined as the ratio of the total length of streams in a watershed over ...
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Introduction
Drainage density is an important hydrogeomorphologic indicator in determining activity quality of processes of overland run-off, flood intensity, soil erosion and sedimentation load in the basin. Drainage density was defined as the ratio of the total length of streams in a watershed over its contributing area. It describes the degree of drainage network development and was recognized by many authors to be significantly effective on the formation of flood flows. Drainage density is higher in arid areas with sparse vegetation cover. The higher the drainage density, the lower the infiltration and the faster the movement of the surface flow. The structure of watershed topography depends to a large extent on the interaction between slope and channel processes. The applicability of these relatively simple summaries, however, needs to be examined carefully. It is still uncertain how the development of drainage systems with time affects the relation of drainage density with lithology, slope, aspect and elevation. The Behrestagh watershed is a sub-basin of Haraz River basin where in varied geological and topographic conditions and the many overland flow cause soil erosion and destruction of pastures and gardens of the area. This study examines the relationship of drainage density with Geology and topography factors for Behrestagh watershed.
Materials & Methods
The Behrestagh watershed lies between the latitudes of 35° 56΄ N to 35° 59΄ N and longitudes of 52° 16΄ E to 52° 22΄ E. The main stream in the area is Haraz River. Topographic elevations in the study area vary between 1172 to 3548 m. Here, in order to examine drainage density in the studied area, map of the watershed’s streams was prepared first using GIS and Digital Elevation Model (DEM) of that area. Then, effective Geology and topographical properties including lithology, elevation, slope and aspect was considered and classified in ArcGIS environment and finally were overlaid with the streams as a dependent variable. Accordingly, sum of streams length per unit of each factor was calculated and drainage density was obtained. Data were analyzed in SPSS 20. Moreover, collected data were described using descriptive statistics (tables, charts, abundance distribution, mean and standard deviation). Data analysis was performed using one-way ANOVA to obtain differences with other studied variables.
Discussion of Results
In this study, data analysis was performed using one-way ANOVA to obtain differences with studied variables. Results of the statistical test indicated that the relationship of lithology and slope with drainage density in the considered area was significant at .95 and .99 level of confidence, respectively. The relationship of drainage density with elevation and aspect was not significant, as well. The results showed that the most drainage density of the area was observed in elevation lower than 1400 meters (average density of 8.24). Also, the cretaceous melaphyre formation (km) with average density of 8.79 and the slope class of 20 -30 percent showed an average density of 10.7 and the western aspect (domain direction) indicated an average of 5.57.
Conclusions
To determine the geology and topography factors influencing drainage density, data layers of lithology, slope, aspect and elevation were analyzed through overlaying the dispersion map of the watershed’s streams. The results showed that cretaceous melaphyre formation, elevation below 1400 meters, slope of 20-30 percent and the west aspect are sensitive to streams. Also, results indicated a significant relationship between lithology and slope with drainage density in the considered area and slope was found to be the most important topography factor affecting drainage density. Therefore can used from these variables to assess erosion intensity and its control.
Siavash Shayan; Mojtaba Yamani; Manizheh Yadegari
Volume 3, Issue 9 , March 2017, , Pages 139-158
Abstract
Geomorphological features are the basis of natural resources evaluation in the watersheds. These features are affected by many factors such as climate and soil, hydrology, ecology, geology etc. Drainage network in this area was different according to the amount and performance of processes and has different ...
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Geomorphological features are the basis of natural resources evaluation in the watersheds. These features are affected by many factors such as climate and soil, hydrology, ecology, geology etc. Drainage network in this area was different according to the amount and performance of processes and has different effects on their surroundings. Sinkholes are located on the way of this drainage network. In association with the occurrence, the researchers have counting on this subject that the change of soil parameters, indiscriminate harvesting from groundwater, drilling of illegal wells and activity of Shahid-Mofateh thermal power plant are the most important factors for the appearance of these profound sinkholes in the plains of this state. The aim of this study is examining the characteristics of the drainage networks in this region, and study their role in the creating of subsidence in this region. For this purpose all information on geology, hydrology, hydrogeological and geographical data in this area were collected and analyzed. Drainage networks, lithology, slope and elevation of this region were drawn by using of digital topographic maps of 1:50000, geological of 1:100000, DEM and also pictures of Google Earth. Then to evaluate annual changes of runoff we used experimental method of Justin and Katain. The results indicate that the dissimilar changes in morphometric data of drainage network in this area due to the climatic and geological conditions, were most important factors in the intensification of decrease of soil humidity, subterranean water and occurrence of subsidence in this region. Human factors and the over use of water sources were effective in the intensification of subsidence.
Zahra Azhdari; Yashar Falamarzi; Narges Palizdan; Ali Fathzadeh
Volume 3, Issue 8 , December 2016, , Pages 141-160
Volume 1, Issue 1 , January 2015, , Pages 131-144
Abstract
Abstract
Ground water is one of important freshwater sources for human. Since surface water sources are limited in most regions, groundwater can be considered as one of the most available resources for supplying water. This research tries to identify regions which have the most groundwater resources ...
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Abstract
Ground water is one of important freshwater sources for human. Since surface water sources are limited in most regions, groundwater can be considered as one of the most available resources for supplying water. This research tries to identify regions which have the most groundwater resources by analyzing effective geology, topology, hydrology and climate parameters in Abadeh – Eghlid basin. Abadeh - Eghlid basin with 2871 Km² area is one of sub- basins in Abargho- Sirjan desert. This area placed on north east of Fars state and its climate semiarid. In order to find potential groundwater resources in Abadeh - Eghlid, climate information and statistics from synoptic stations in Abadeh and Eghlid (1977-2010) gathered and geology, topology and hydrology information acquired from numeral geological maps with 1: 100000 scale and topographical mps with 1: 50000 scale and by using Analytical Hierarchy Processes (AHP) method in software environment Arc GIS the most suitable regions according to their groundwater sources have been recognized, determined, described and classified. The most area of this basin has good and moderate potential, and high and good potential regions placed in south and southeast areas of basin and also there some areas in northwest of basin
Mohammad Omidfar; Hashem Rostamzadeh; Behroz Sari Sarraf
Volume 5, Issue 15 , October 2018, , Pages 135-152
Abstract
Abstract
Introduction
Flood phenomenon is one of the atmospheric hazards whose frecuncy is remarkable in the northwest of Iran and every year, there are a lot of Casualties and financial losses on different parts of the study area. The aim of this study was the feasibility of using the new Doppler ...
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Abstract
Introduction
Flood phenomenon is one of the atmospheric hazards whose frecuncy is remarkable in the northwest of Iran and every year, there are a lot of Casualties and financial losses on different parts of the study area. The aim of this study was the feasibility of using the new Doppler radar technology to predict the short term flood phenomenon and send timely warning to the relevant organizations and residents of the flood prone areas. To this end, Tabriz Radar products, which can be expanded in a three dimentional structure based on the direction and speed of movement and water content of cloudes in the event of flood of the gallezar village, were selected and carefully monitored. The resuls showed that due to the ability of the radar to penetrate into the clouds and its appropriate spatial and temporal resolution, depending on the formation location and the speed of development of super cells, flood phenomena can be detected several hours before the occurrence. In case of coordination with the crisis organization and prompt warning, it can decrease its damages.
In recent years, Doppler weather radar is one of the new remote sensing technologies that can give valuable information about cloud and type of precipitation. The new technology of meteorology radar can be fruitful in the identification, monitoring, and early warning, and, eventually, reducing damage inflicted to the environment. Therefore, this study aimed to evaluate the efficiency of the products of Doppler radar in monitoring the cells of showery severe rain-producing clouds. The aim of this study was also to evaluate the performance and functional advantages of radars in monitoring and analyzing the characteristics of flash flooding covective cells in the northwest of Iran. For this aim, the production or incoming , direction of motion, and attenuation of floodable convective cells in the study area were monitored by 15-minute time steps by three main radar products including maximum display (MAX), surface rainfall intensity (SRI), and precitipation accumulation. The obtained results can be applied in establishing scientific information and missions in establishing rapid meteorological warning system and, hence, making required decisions in reducing casualties brought about by flood.
Methodology
The area under study is part of the northwest of Iran that is located in the effective range of Tabriz radar. According to the power of the radar waves, its effective range can be used up to 250 km radius. For analytical studies, like this study, it is applicable to the whole range of the northwest of the country. A variety of radar products produced by the radar reaches to more than fifty products. Each product has different output specifications and performance with graphics, charts, and meteorological signs. Of these products, about 20 products are generated and stored by Tabriz radar. Some of the applied products in this study will be briefly discussed. The maximum product of the exhibition is displayed on a graphical screen after processing. It contains information which displays the maximum height and interior density of the cloud. Surface rainfall intensity product showed the intensity of precipitation at a specific level. For this purpose, a surface close to the ground was determined and by the equation between Z-R, the value of z reflection was transformed to the intensity of the rainfall. To achieve the objectives of the study, Azarshahr flood event, which occurred in 2017, was selected using the currently reported weather codes in synoptic stations in the studied area. In sampling, there was an atempt to place cases in different geographical distances and directions with respect to the radar. For the close monitoring of the showers, from the early days of the reported barrage above, the radar products were examined with 15-minute intervals. On the basis of these images, time and place, route, time and peak locations of the activities, and the death of rainfall cell were monitored.
Result and Discussion
In this study, floodable convective cloud cells producing heavy rain showers grew within a few hours from small cumulus clouds (type one without rainfall), into cumulonimbus flood-causing clouds, along with heavy rainfall and hail. The 4 April 2017 flood event convective rainfalls, which created heavy rains in small area was selected. Naturally, in the selected case, the rest of the stations had meager amount of rainfall that was not possible to recognize these convective cells with satellite images or by synoptic maps. Doppler radars had tremendous role in detecting, routing, and monitoring of the maps. Indeeed, with proper management and timely warning, a significant amount of the casualties caused by the phenomenon can be decreased. Cooperation with the crisis organization and prompt warning can also decrease its damages.
Conclusion
Doppler radars have great potential to improve the quality of the rainfall data because of the ability of producing data with a spatial resolution of less than 500 m and 15-minute temporal resolution and its wide coverage. The results showed that the flood event which occurred on April 4th, 2017 was a local rainfall. It was formed in a short time and at a relatively small scale and was invisible by meteorological observations and satellite images. Primary cloud cell (cumulonimbus) of an intense shower rain was formed in the early hours of the morning and gradually was grown and reached the strongest form in the afternoon and early evening and created an intense flood in the form of a shower rain. After intense rainfall event, the cloud cells became weak and collapsed. In some cases, the peak of its convective clouds got to 10 km.
Volume 2, Issue 2 , January 2015, , Pages 137-154
Abstract
Abstract
Sediment yield is one of the important results of soil erosion, that causes on-side and off-site effect. Considering that each year thousands tons of soil from different lands of our country become out of access due to erosion and accumulation in sedimentation areas causing considerable ...
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Abstract
Sediment yield is one of the important results of soil erosion, that causes on-side and off-site effect. Considering that each year thousands tons of soil from different lands of our country become out of access due to erosion and accumulation in sedimentation areas causing considerable damage, it is necessary to identify the potential sediment yield areas, determine the critical areas and employ proper classification, to plan for soil conservation or watershed management. In this study, three models, including EPM, BLM and Fargas, were used for estimating and zoning the erosion and sediment to identify and introduce proper action model to evaluate models for zoning erosion in Kahman drainage basin. The validation of the EPM model showed that this model is not proper for this drainage basin because it showed the amount of sediment estimate more than the actual amount. Based on EPM model the total sediment in drainage basin was estimated 181320/6 cubic meters per year. But based on the information from the hydrometric stations in the area under study, the actual sediment is 75416/8 cubic meters per year. Also, according to field observations of erosion in the area under study, available erosion does not match the obtained erosion from the Fargas model but the BLM model matches the erosion of the drainage basin more.
Mojtaba Yamani; Abolghasem Gourabi; Zahra Abedini
Volume 2, Issue 3 , January 2017, , Pages 137-157
Abstract
Rivers are dynamic systems and their space-time characteristics are constantly changing. This change and displacement creates problems in the human and ecological functions and the study of such changes are the main issues in the fluvial geomorphology. In this study, survey morphological changes in one ...
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Rivers are dynamic systems and their space-time characteristics are constantly changing. This change and displacement creates problems in the human and ecological functions and the study of such changes are the main issues in the fluvial geomorphology. In this study, survey morphological changes in one section of the Babolroud (Bobol River) will be examined during the time period of 1334-93 from Babol city to Kardgarkola village within 18/45 km. Using aerial photo from 1334 and 1383 and satellite images Landsat 8, 1393 the path of the river was digitalized in three time periods with Arc GIS software. To determine the type of changes in each of the beaches spatial and temporal interval were studied and the position of the coastline was compared to the previous coastline. Then, for each beach in each period shifts named layer was prepared and its surface was measured. Then for each time interval (period) studied, the spatial interval was specified. The statistical tables were considered for each time interval to provide possible comparisons between the spatial intervals. Finally, changes in the left and right of each interval in each period was compared to the period before. For a detailed analysis, changes in the stream in each of the study periods were considered after determining the thalweg, the fixed line and the taken transects within the interval of 1000 to 1000 meters. Then, in the Arc GIS, after the determining the transects and thalwegs, and creating a polygon, the area of polygon was compared to the previous periods. Finally, through the implementation of existing disputes, thalweg changes in the riverbed, which determined the cause of the change, was found in each transect. The results show that the interval in the regression process has three periods. The second interval depicted the greatest change. The main reason for this fact in the period of change is excessive land use and human intervention.
Mejid Montazeri
Volume 3, Issue 6 , January 2017, , Pages 137-159
Abstract
Majid Montazeri[1] Abstract In mountainous areas with snow regimes, the precipitation is not usually affected by flood event. However, in some cases extreme rainfall causing flood events is fearsome and destructive. Despite the lack of synchronicity of extreme rainfall and discharge of floods, in some ...
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Majid Montazeri[1] Abstract In mountainous areas with snow regimes, the precipitation is not usually affected by flood event. However, in some cases extreme rainfall causing flood events is fearsome and destructive. Despite the lack of synchronicity of extreme rainfall and discharge of floods, in some cases extreme rainfall coincides with huge floods. For this purpose, daily precipitation data from 23 meteorolgical stations of Chaharmahal and Bakhtiari Province 28.02.2001 to 21.10.2012, daily discharge datga of Beheshtabad hydrometric station in the period 21.03.1998 to 20.03.2011 and atmosphere data at 500 hfa level including variables of geopotential height, sea level pressure, zonal wind, meridional wing, omega, temperature and specific humidity, taken from NCEP/NCAR were used. The based on environmental to circulating approach they were analyzed. Synoptic analysis showed that the difference between systems with solid and liquid precipitation is in the manner of supply of their moisture. Liquid precipitation occurrence, with the establishment of anaticyclone system on the Arabian Sea is coupled. This system, due to warm and humed air mass of Arabian Sea sinks into the AMediterranean deep trough. The warm and humid air mass, the crossing of the Red Sea and the Persian Gulf are strengthened and the moisture content is added. The warm and humid air mass, in the crossing of the Red Sea and Persian Gulf strengthens and the amount of moisture is added. The rises of air causes huge instability in fron of the Mediterranean deep trough system a creates flood-causing precipitation event in the high Zagros and especially in Beheshtabad Basin. [1]- Assistant Professor in Climatology, University of Esfahan, Email:M.Montazeri@geog.ui.ac.ir.
Naser Ahmadi Sani; Karim Solaimani; Lida Razaghnia; Raoof Mostafazadeh; Jalal Zandi
Volume 5, Issue 16 , December 2018, , Pages 139-158
Abstract
Abstract Introduction Due to population growth and human activities and increasing water demand, water availability will be critical and water resource assessment and planning for sustainable use become more complex. The dynamic and long-term laws of runoff are important and have practical value for ...
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Abstract Introduction Due to population growth and human activities and increasing water demand, water availability will be critical and water resource assessment and planning for sustainable use become more complex. The dynamic and long-term laws of runoff are important and have practical value for the sustainable development and planning of water resources. On the other hand, the traditional methods of runoff estimation should be improved regarding the accuracy and spatial variations. The application of GIS extensions is needed to provide water resource assessment data. Therefore, the application of such new techniques has greatly increased in recent years to estimate the runoff characteristics. The SCS method is the most commonly used method for estimating surface runoff, whose accuracy has improved through employing advanced GIS-based tools. The applicability of Arc-CN Runoff tool was tested in different internal and external studies which emphasized the quantitative evaluation of the model results. Methodology In this study, the accuracy of runoff estimation by Arc-CN Runoff tool was evaluated based on the land use map in two different time periods (1996-2011). The Landsat satellite images of 1996 and 2011 were processed and analyzed for land use mapping. Map of soil hydrologic groups was prepared in GIS environment using slope and soil texture maps. The annual rainfall calculations were done using rainfall daily data of several years for stations within the basin. The curve number map was used to estimate runoff using SCS method within ArcCN-Runoff tool in GIS environment. The runoff observations of Karehsang Station were calculated using daily flow data and the base flow was separated. Finally, the accuracy of the estimated runoff was assessed by estimating the percent relative error. Results and Discussion According to the accuracy assessment of land use maps using the ground-based map, the best overall accuracy and kappa coefficient were respectively 90% and 88%. The results showed that the maximum likelihood algorithm and the combination of main and synthetic bands, classified the land use classes of the study area with an acceptable accuracy. The highest percentage of the area was classified as range and dry farming (62.74%) in 2011. The percentage of rangeland, dense forest, and water zones decreased in 2011 compared with 1996.The map of the hydrological groups shown in this study, consisted of groups B, C and D, respectively covering 15.5, 44.5 and 40% of the study area. The average CN in the years 1996 and 2011 was estimated to be around 79.6 and 81.6. The average estimated rainfall of the study area using the arithmetic mean, inverse distance weighting, and kriging methods in 1996 were respectively 486.24, 424.4 and 486.1 mm. The estimated annual rainfall values were equal to 521.5 (arithmetic mean), 514.6 (inverse distance weighting) and 521.5 (kriging) mm. Runoff height was the highest in bare lands and residential uses, and the minimum of runoff height values were estimated in good and medium rangelands. Conclusion The mean values of total runoff, base flow, and surface runoff have increased in 2011 compared to 1996. The highest CN values in both periods consisted of bare lands and residential area. The runoff height in different land uses and the total runoff height increased in 2011 (11.38 mm) compared to 1996 (8.8 mm), which can be partly due to the degradation and land use change. The results of this study showed that the ArcCN-Runoff tool improved the accuracy of potential runoff estimations, while the relative error of runoff estimation in both periods was relatively low and acceptable. Thus, the implemented tool can be used to assess and estimate runoff height. The results showed that the relative error of runoff estimation in both periods was in agreement and the error amount was relatively low (10%). In addition, the used methods and tools were evaluated with 90% accuracy in both periods and can be used for runoff estimation in data-scarce watersheds.
Ezzatollah Ghanavati; Ali Ahmadabadi; Mansour Sadeghi
Volume 6, Issue 18 , June 2019, , Pages 139-159
Abstract
IntroductionA flood is an exceptional stream that may be flooded from the natural bed of the river. Usually, the maximum observed discharge during a year is named a flood or an annual flood. It is one of the natural disasters which has the highest damage in the world, after an earthquake. Losing life, ...
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IntroductionA flood is an exceptional stream that may be flooded from the natural bed of the river. Usually, the maximum observed discharge during a year is named a flood or an annual flood. It is one of the natural disasters which has the highest damage in the world, after an earthquake. Losing life, land, and property, especially along the river, are among its most perilous environmental hazards. A comprehensive flood management seeks to use structural and non-structural methods to prevent flood intensity and minimize its human and financial losses. Although we can minimize their damage, there is not any possibility of controlling floods. Qomroud Basin with an area of 3563 km2 (356300 hectares), is located in provinces of Markazi and Qom and in a geographical position of 50° 2 33 to 50° 54 29 East and 33° 57 37 to 34° 39 28 north latitude. Its minimum and maximum heights are respectively 964 m and 3145 m and its average slope is 13.6 %. The perimeter of the basin is 452.7 km and is part of the main catchment area of Iran's central plateau. After several destructive floods with significant damage in recent years, especially after the huge flood of April 2009, the need for desirable flood management in the Qomroud River basin is very urgent.MethodologyThe purpose of this research was to control the floodwaters of the Qomroud Basin by determining the appropriate flood conservation areas using a multi-criteria decision-making technique. Flood diversion and storage is a well-known method for dealing with the risks and damage of a flood. It can also improve the quality and quantity of underground water. In fact, flood control and artificial feeding of aquifers are among its important results. The Weighted Aggregates Sum Product Assessment (WASPAS) model is a new multi-criteria decision-making technique (MCDM) that was introduced in 2012 and can be effective in complex decision-making issues. It is based on the combination of two models of multi-criteria decision making WSM (weight aggregate model) and WPS (weighted production model) and is more accurate and has the ability to rank. Its application has four stages. In this hybrid model, it has been attempted to use a combined benchmark to determine the final importance of each option, which combines the parity contribution from WSM and WPS for the final evaluation of the options. In this study, the variables of gradient, soil, land use, groundwater depth, landform, surface permeability, roughness, accumulation flow index, lithology, elevation, and drainage density as effective factors in location for diversion and flood storage were used. The model (WASPAS) which is one of the most recent multi-criteria decision-making models was used to calculate the indicators' weights and rank the options and prepare the final map.ResultThe results obtained through this model have identified the areas susceptible to flood storage, with high accuracy and in the least possible time. Scoring each criterion is based on their relative importance. After determining the score of each criterion, a multi-criteria evaluation of the GIS was obtained using the overlapping operation, WASPAS model, and the final map (synthesis) of land potential relative to the flood reserve. The relative heights of slope and land use were respectively 0.136, 0.12. The relative weights of the height and the density of drainage were respectively 0.06 and 0.04, with the least importance for zoning susceptible flood reservoirs.Discussion and conclusionBy combining their results with the WASPAS model, it was possible to identify the susceptible areas to storm-storing with high precision and in the least possible time. The results showed that the Qomroud basin was divided into five classes including very high with 24 percent, high with 28.2 percent, moderate with 24.9 percent, low with 15.2 percent, and very low with 7.7 percent. Thus, there were nine very suitable areas found in the central, south, northwest and eastern parts of the basin for flood diversion and storage. The aforementioned areas were also recognized for field purposes for the desired purposes.
Behroz Nasiri; Mohammd Hosain Naserzadeh; Meysam Toulabi Nejad; Zahra Zaree Chaghabalaki
Volume 2, Issue 5 , January 2017, , Pages 141-166
Abstract
Behroz Nasiri[1] Mohammad Hosaien Naserzadeh[2] Meysam Toulabi Nejad[3]* Zahra Zareei Chaghabalaki[4] Abstract The current study investigates the effect of ENSO atmospheric-oceanic pattern as an effective factor in hydrological conditions of Kashkan River. To do so, the related data of Southern ...
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Behroz Nasiri[1] Mohammad Hosaien Naserzadeh[2] Meysam Toulabi Nejad[3]* Zahra Zareei Chaghabalaki[4] Abstract The current study investigates the effect of ENSO atmospheric-oceanic pattern as an effective factor in hydrological conditions of Kashkan River. To do so, the related data of Southern Oscillation patterns using East Angelina university website was gathered, and the statistics period of 1984-2010 was considered. The related data of Kashkan’s annual discharge was also collected using related references. Pearson coefficient analysis was used in order to analyze the monthly and annually data, with at least (p_value=0.01) 0.99% significant level. For assessing the effect of cold and warm phases of this macro-scale weather pattern, discharge’s annual data based on the mentioned monthly phases was considered and Independent two-tail t-test was run. Applying this test, the meaningfulness of differences among discharge’s annual data in cold and warm phases was investigated. Finally, the cause and atmospheric relationship between data was analyzed using Synoptic map analysis. The results show that Kashkan River’s discharge has a meaningful significant coefficient with ENSO index in October, November and December. Also the result of synoptic map analysis shows that in years with warm phase of ENSO (El-nino), autumn raining around Kashkan River increased about 26 percent over the long term. But in the cold phase autumn raining in that area had been about 10.5 percent less than the normal amount. Running the Independent two tail t-test on the annual discharge shows that in the years with warm phase of ENSO, the average amount of Kashkan River’s annual discharge has been 35 percent more than the years with cold phase of ENSO. [1]- Assistant Professor in Climatology, the University of Lorestan [2]- Assistant Professor in Climatology, the University of Lorestan.. [3]- Ph.D Student in Urban Climatology , University of Kharazmi (Corresponding author), Email:meysam.toulabi@gmail.com . [4]- Ph.D Student in Climatology ,the University of Loresta.
Vahid Nourani; Narges Azad; Mahsa Ghasemzade; Elnaz Sharghi
Volume 3, Issue 7 , October 2016, , Pages 141-159
Abstract
Vahid Nourani[1] Narges Azad*[2] Mahsa Ghasemzade[3] Elnaz Sharghi[4] Abstract This paper aims to detect trends and investigate the relationship between long-term time series of the Urmia lake water level and other hydro-climatologic parameters, including precipitation, runoff, temperature and relative ...
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Vahid Nourani[1] Narges Azad*[2] Mahsa Ghasemzade[3] Elnaz Sharghi[4] Abstract This paper aims to detect trends and investigate the relationship between long-term time series of the Urmia lake water level and other hydro-climatologic parameters, including precipitation, runoff, temperature and relative humidity, in monthly, seasonal and annual scales using Mann-Kendall (MK) and discrete wavelet transform (DWT). The MK test and sequential MK analysis were applied to different combinations of DWT to calculate components responsible for trend of time series.The results showed that 8-month period was important in the involved trend at the original monthly time series. Also there is a significant negative trend in different scales of lake water levels and runoff time series. In general, rainfall, relative humidity and temperature time series did not show significant trends.The results of this research indicate that downward trend in the rainfall time series has more effective role in Urmia lake drying. In addition, the sequential MK test was used to find the start points of changes in monthly time series. The results showed a significant decreasing trend from 1377 in the lake water level and runoff time series. Finally, the results of Sen’s trend analysis, also confirmed the results of the proposed wavelet-based MK test. [1]- Professor of Water Resources Engineering. [2]- Master Degree Student of Water Resources Engineering (Corresponding Author), Email:narges.azad1991@gamil.com [3]- Master Degree Student of Water Resources Engineering. [4]- Assistant Professor of Water Resources Engineering Department of Water Resources Engineering Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran.
Foruzan Ahmadi; Kazem Nosrati; Mohamad Mehdi Hoseinzadeh
Volume 6, Issue 20 , December 2019, , Pages 141-164
Abstract
1-IntroductionAccelerated soil erosion is a serious problem in Iran, leading to degradation of soil and water resources, reduction of soil fertility, destruction of range and agricultural lands, desertification, recurring floods, sedimentation of reservoirs, and pollution of fishery habitats. Hence, ...
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1-IntroductionAccelerated soil erosion is a serious problem in Iran, leading to degradation of soil and water resources, reduction of soil fertility, destruction of range and agricultural lands, desertification, recurring floods, sedimentation of reservoirs, and pollution of fishery habitats. Hence, understanding of the potential soil erosion process and opposition to this erosion are necessary environmental. To this end, uptake and refinement of sediment source tracing or fingerprinting techniques has expanded dramatically as an alternative approach to traditional methods of identifying key sediment sources. Sediment source fingerprinting involves discriminating potential sediment sources on the basis of differences in source material properties or tracers and determining the relative contributions of these sources to sampled target sediment. different kinds of sediment sources have been used so far in sediment fingerprinting techniques (e. g., land use, geology, sub-basins, surface and subsurface erosion) but, there is a little attention paid to the selecting the soil erodibility groups as sediment sources. Therefore, the main objective of this study are the Kouhdasht watershed dividing into different erodible units based on soil erodibility index and determination of the contribution of each unit in sediment yield using an un-mixing Bayesian uncertainty model and to find its relationship with soil organic carbon stock. 2- MethodologyKouhdasht basin with 1138 km2 area located in 33° 17´ to 33° 41´ north latitude and 47° 20´ to 47° 50´ eastern longitude in western of Lorestan province. samples were collected in two stages; first, 81 samples in order to estimate erodibility, second, in order to determine the contribution of each source to sediment yield, 70 soil samples were collected form sources and 12 sediment samples collected at the basin outlet. The soil erodibility was calculated based on the soil texture and based on the geometric mean of the soil particle diameter. Based on the amount of soil erodibility, the area was divided into three different erosion units as sediment sources. To determine the contribution of sediment sources to sediment yield used fingerprinting technique is based on estimation of uncertainty.3- ResultsThe erodibility of the study area varied from 0.0386 to 0.0663. Erodible units were identified as sediment sources based on the values obtained from the erosion parameter and according to the results of selecting the optimal combination of tracers. The results showed that the first erosion unit 2%, the second erodible unit 5%, and the third erosion unit 93% contributed in the region's sediment yield. The relative importance of erodible units in sediment yield was obtained by dividing the share of each resource in the production of sediment into the percentage covered by each source. The relative importance of the first, second and third erosion units is 0.08, 0.28, and 1.57, respectively. Regarding the role of organic carbon in erosion, the amount of organic carbon storage in different erosion units of the area was also measured. The amount of organic carbon storage in each erosion unit is first, second and third ones were 70.5, 64.3 and 54.6 mg / ha respectively. 4- Discussion and conclusionThe third unit with 93% has the largest contribution in sediment yield and with 54.6 mg / ha, it has the lowest amount of organic carbon storage in the area. Considering that this unit is most used in agriculture and geologically under quaternary sediments, showed that the parts that are under cultivation and quaternary sediments have both high erodibility and the highest contribution to sediment yield. Measurements of organic carbon storage also showed, there is the least amount of organic carbon storage in this unit and this suggests that in the third unit, the damage caused by the loss of fine sediments such as clay is higher. Given that the third unit is under agricultural use this can be attributed to the type of land use and exploitation. Therefore recommended more attention to the type of use of land and soil management and conservation programs implemented in the region.
Alireza Salehipour Milani; Mojtaba Yamani; Ebrahim Mogimi; Rziye Lak; Maksour Jafarbeiglou
Volume 2, Issue 4 , January 2017, , Pages 143-170
Abstract
Alireza Salehipour Milani[1] Mojtaba Yamani[2]* Mansour Jafarbeiglou[3] Raziye Lak[4] Ebrahim Mogimi[5] Abstract During recent years, with the construction dam on main rivers, the occurrence of hydroecological drought during the last decades, and high evaporation of water reservoirs, the extent of the ...
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Alireza Salehipour Milani[1] Mojtaba Yamani[2]* Mansour Jafarbeiglou[3] Raziye Lak[4] Ebrahim Mogimi[5] Abstract During recent years, with the construction dam on main rivers, the occurrence of hydroecological drought during the last decades, and high evaporation of water reservoirs, the extent of the Urmia Lake has considerably decreased. Besides, salinity rate has increased to 650 milligram per liter. According to this hydrological situation organism cannot live in the Urmia Lakes. There is a lot of information about current chemical characteristics of Urmia Lake but we don’t have sufficient information about paleo hydrology and paleo salinity of the Lake especially in Quaternary. Investigation of The Urmia Paleo Lake terraces, their evolution and changes in elevations and changes in biostratigarphy characteristics are evidences for paleo environments of this lake. Dominant shell fragments of the Urmia Lake terraces are Gostropoda, Ostracoda, Foraminifera and Bivalves. In this study, type and spacious of shell fragments are investigated and the living environment situations of the organisms during formation of each lake terraces are determined. Using biostratigraphic study results and correlation between these environmental changes with elevation changes of lake terraces, Hydrological and ecological situations of The Urmia Lake during Quaternary was reconstructed. The results of biostratigraphy shows, in contrast to the current situation of water in the Urmia Lake (Hyper saline), most of the organisms lived in brackish and fresh water during formation of the lake terraces. [1]- Ph.D in Marine Geology Management; Geological Survey of Iran. [2]- Professor in Geogarphy University of Tehran (Corresponding author, Email:myamani@ut.ac.ir. [3]- Professor in Geogarphy University of Tehran. [4]- Associate Prof. of Research Institure for Earth science Geological Survey of Iran. [5]- Expert of Geological Survey of Iran.
Mohammadmehdi Hosseinzadeh; Somayyeh Khaleghi; Faraz Vahedifar
Volume 4, Issue 10 , June 2017, , Pages 145-164
Abstract
The bank erosion is the dominate phenomena in the Qaranqoo Chai River, upstream of Sahand dam, at this time of the year leading to changes in river, increasing the radius of curvature at the bends, and straight channel widening. Consequently, it damages the land and the river's facilities and causes ...
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The bank erosion is the dominate phenomena in the Qaranqoo Chai River, upstream of Sahand dam, at this time of the year leading to changes in river, increasing the radius of curvature at the bends, and straight channel widening. Consequently, it damages the land and the river's facilities and causes numerous changes in the pattern of the river, sediment production, and sediment transfer to Sahand dam. In this research, a Bank Erosion Hazard Index (BEHI) was used to evaluate annual bank erosion in the Qaranqoo Chai River. To this end, 9 cross-sections were selected and some parameters such as bank full width, average bank full height, root depth, root density, bank angle, surface protection, bank material, and bank stratification were measured. The results of the BEHI method showed that both of the right and the left banks were eroded and that the erosion risk was moderate to very high in all of the right bank's cross sections except its cross-section 4 which had a very low erosion risk. In addition, the erosion risk of the left bank's cross sections were very low to extreme. Indeed, due to the low root density and loose material, the right bank's cross-sections had higher erosion risk than those of the left bank. Moreover, the erosion risk was reduced in the middle of the river because its root depth was higher than the banks' root depth. Indeed, BEHI incorporates bank variables that are factors in entrainment, surface erosion and mass erosion. These variables are bank–height ratio, root–depth ratio, weighted root density, bank angle and surface protection. Variables have empirical values that are, in turn, converted to index values and summed for a total BEHI score. Scores are adjusted by bank material and bank material stratification. BEHI scores are then categorized by erosion potentials. A greater score indicates greater erodibility. Bank height is the distance from bank toe to the top of the bank.
Sanaz Daei; Meysam Salarijazi; Khalil Ghorbani; Mahdi Meftah Halaghi
Volume 5, Issue 17 , March 2019, , Pages 145-163
Abstract
Introduction
There are many models for flood prediction that are based on different conceptual bases. The standard SCS-CN method was developed in 1954 and it is documented in Section 4 of the National Engineering Handbook (NEH-4) published by Soil Conservation Service (now called the Natural Resources ...
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Introduction
There are many models for flood prediction that are based on different conceptual bases. The standard SCS-CN method was developed in 1954 and it is documented in Section 4 of the National Engineering Handbook (NEH-4) published by Soil Conservation Service (now called the Natural Resources Conservation Service), U.S. Department of Agriculture in 1956. The document has been revised several times. It is one of the most popular methods for computing the volume of surface runoff for a given rainfall event from small agricultural, forest, and urban watersheds. The method is simple, easy to understand, and useful for ungauged watersheds. The method accounts for major runoff producing watershed characteristics, viz., soil type, land use/treatment, surface condition, and antecedent moisture condition. Recent researches focus on the improvement of this model and improve its efficiency but it is necessary to evaluate the improved models for Iran's watersheds. The purpose of this study was the comparison of standard SCS-CN and developed three parameter Mishra-Singh models for flood hydrograph and peak estimation using data of five watersheds in Golestan Province.
Methodology
Study Area and Used Data
Five watersheds (including Galikesh, Tamer, Kechik, Vatana, and Nodeh) located in Golestan Province were considered to evaluate different models for flood hydrograph estimation. The characteristics of the selected watersheds are different. For Tamer, Galikesh, Kechik, Nodeh, and Vatana watersheds, the areas are equal to (1527, 401, 36, 790 and 11 km2), the parameters are (289, 139, 26, 208 and 20 km), the mean altitudes are (1131, 1358, 928, 1540 and 899 m), the mean slope of the watersheds are (19, 27, 19, 28 and 33%), the length of the main channels are (94, 58, 10, 66 and 8 km), and the number of rainfall-runoff events are (10, 13, 3, 9, and 4 cases).
Descriptions of Models
The standard curve number (SCS-CN) model was based on the following basic equations:
(1)
(2)
P is total rainfall, Q is excess rainfall, CN is curve number, Ia is initial abstraction, and S is maximum retention.
Using the concept of the degree of saturation (C=Sr), where C is the runoff coefficient (= )), Mishra and Singh (2002) and Mishra et al. (2006) modified the original SCS-CN model after the introduction of antecedent moisture Mas:
(3)
The relationships developed by Mishra et al. (2006) for Mare:
(4)
(5)
P5 is prior 5-day rainfall depth.
Three model accuracy criteria including root mean square error (RMSE), Nash-Sutcliff efficiency (NSE) and percentage error in peak (PEP) were applied to compare the results of models (Adib et al., 2010-2011).
Results
There were 39 rainfall-runoff events, of which 25 and 14 events were respectively selected for the calibration and validation steps. The parameters of investigated models for different events and watersheds and related model accuracy criteria were calculated. The root mean square error (RMSE) and Nash-Sutcliff efficiency (NSE) criteria can be used for the analysis of the flood hydrograph simulation while percentage error in peak (PEP) criteria is suitable for the analysis of the flood peak discharge simulation. In the Gallikesh watershed, for the developed three parameter Mishra-Singh and standard SCS-CN models, the RMSE criteria values were (16, 11.05, 2.8, and 10.63) and (17.94, 14 , 6.56 and 13.56), the values of NSE values were (-0.88, -84.44, -0.9 and -4.77) and (-1.37-, -1.38, -9.7, and -8.4), and the PEP values were (0.4, -1.4, 0.55, -0.3) and (0.24, -2.11, -1.39 and -0.62). For the Nodeh watershed in different events, the RMSE criteria values were (13.22, 23.57, 79.53 and 68.15) and (11.83, 22.74, 88.96 and 69.92), the NSE values were (-6.88, -2.7, -0.17 and -66) and (-5.31, -2.46, -0.46 and -69.5), and the values of PEP were (-1.19, -1.98, 0.83, -2.48) and (-1,-2.4, 0.99 and -2.57) for the developed three parameter Mishra-Singh and standard SCS-CN models were calculated. In the Tamer watershed for two models of developed three parameter Mishra-Singh and standard SCS-CN, the values of different criteria estimated as the RMSE criteria values were (13.04, 26.85, 5.9 and 19.26) and (12.04, 92.62, 5.26 and 48.81), the values of NSE criteria were (-0.92, -20.3, -4.9 and -0.14) and (-0.73, -252.5, -3.75 and -6.37), and the PEP criteria values were (0.52, -0.2, -0.8, and 0.62) and (0.62, -5.14, -0.74 and 1.09). In Vatana and Kechik watersheds for the developed three parameter Mishra-Singh model different criteria were calculated as the RMSE values (2.5) and (1.5), the NSE criteria values (0.51) and (-0.07), the PEP criteria values (0.45) and (-0.3). However, in these two watersheds for the SCS-CN standard model, the RMSE criteria values were (4.8) and (2.91), the NSE criteria values were (-0.82) and (-2.93) and the PEP criteria values were (0.95) and (0.6).
Discussion and Conclusion
The values of root mean square error (RMSE), Nash-Sutcliff efficiency (NSE) showed that the developed three parameter Mishra-Singh model improved the accuracy of the flood hydrograph estimation relative to the standard SCS-CN model for 71% of the studied events and the difference between two models for remaining 29% event was negligible. Also, the values of percentage error in peak (PEP) revealed that the three parameter Mishra-Singh model led to a decline equal to 78% in flood peak estimation in comparison with standard SCS-CN model application. In addition, the standard SCS-CN and the three parameter Mishra-Singh models were respectively 64% of and 57% of the studied cases. In this study, the accuracy of the standard SCS-CN andthedeveloped three parameter Mishra-Singh models compared the flood hydrograph and peak estimation considering data of five watersheds in Golestan Province. The investigation of the model accuracy criteria revealed that the developed model led to a considerable improvement of flood estimation in studied watersheds.
Mehdi Komasi; Hesam Goudarzi
Volume 6, Issue 19 , September 2019, , Pages 145-162
Abstract
Introduction Groundwater monitoring has an important role in water resource management. Groundwater monitoring network can provide groundwater levels, but sometimes this information is too much and not useful. Optimum water management requires sufficient information on the quantitative and qualitative ...
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Introduction Groundwater monitoring has an important role in water resource management. Groundwater monitoring network can provide groundwater levels, but sometimes this information is too much and not useful. Optimum water management requires sufficient information on the quantitative and qualitative features of the aquifer. Assessing and anticipating the level of groundwater through specific models helps to predict groundwater resources. In recent years, with the demonstration of the capabilities of smart models in modeling time series, these models have been enhanced in groundwater modeling. The optimization of the monitoring network is a process for having the best combination of existing stations, adding new stations, or redefining a monitoring network based on the predetermined goals. Methodology The present study aimed to develop an optimal network monitoring model with two goals of maximum entropy value at monitoring stations and minimizing the costs of monitoring the groundwater level network. In this study, data from 29 stations in the current monitoring network were used to optimize the groundwater monitoring network in Silakhor plain located in Lorestan Province. Firstly, using the entropy method, the amount of entropy in each of the 29 stations of the monitoring network was determined. Then, the amount of the entropy matching for each station was compared with the amount of entropy of the time series of rainfall, in order to determine the optimal station water supply through the available network. Finally, the prediction of the location of data using the Empirical Bayesian Kriging (EBK) method in the ArcGIS software was carried out and evaluated by the results of four models of the K-Bessel Detrended, K-Bessel, Exponential Detrended and Whittle Detrended. Results The time series of rainfall is directly related to the feeding of aquifers. In fact, the amount of precipitation entropy and its variations at different times affect the amount and variation of entropy of groundwater level at the same time. If the entropy value obtained from the station is not consistent with the season's entropy variations in rainfall, it is said that the station is able to scare water based on the uncertainties of the rainy season and aquifer feeding. The results of the research showed that the entropy variations for eleven stations of the existing stations were similar to the entropy variations of the rainy season, and also the entropy of this station was higher than the other stations. The results obtained from the first step indicated a network with 11 stations out of 29 available stations. The RMSE value of this network was 0.75 m. At this point, by reducing 62% of the network station, peak network costs and RMSE value were optimized. The comparison of the optimal network and the existing network showed that the optimal network could reduce cost of monitoring stations and had a similar zoning in Silahkor plain rather than existing monitoring network. Data interpolation was modeled in ArcGIS software and in the Geostatical Analysts section by the EBK method. The absoluteness of the estimation in interpolation and location is one of the main features of the EBK model. In this sense, the value of the estimate of the quantity at the sampling points was equal to the measured value and the estimate of variance was zero. The EBK model uses four semi- modifications to interpolate the groundwater level. The least square standardized error between the actual and estimated values in the EBK method was K-Bessel Detrended with a half-value of 0.99. In addition, the EBK method with the K-Bessel Detrended half-change was based on the average mean power of error (20.87) and the highest correlation coefficient (0.82) was the best interpolation method. The EBK methods were respectively ranked in the Whittle Detrended, K-Bessel and Exponential Detrended models. Discussion and conclusion Considering that the implementation of water resources monitoring programs is costly and requires time, a method for optimizing the existing network is necessary. The results of the research were suited to the adequacy of the network with 11 stations of 29 monitoring stations for the Silakhor plain aquifer. The optimized monitoring network, in comparison with the existing observation network, was able to reduce the number of stations in the monitoring network by 62% and improve the spatial distribution of stations. In addition, investigating the predictive results of the groundwater level and comparing it with the actual level in the aquifer area indicated the accuracy of the EBK method. In addition, the comparison of the aquifer zoning using a network with 29 monitoring stations with the network with 11 monitoring stations showed the level of groundwater level with an acceptable estimate, which indicated that the precision of the entropy criterion was in the selection and optimization of the monitoring stations.
Seyedeh Nastaran Hashemi; Mohammad Akbarinasab; Taher Safarrad
Volume 4, Issue 13 , March 2018, , Pages 147-164
Abstract
Introduction
Remote Sensing is an effective tool for detecting and monitoring plume areas. Landsat8 satellite can be used for marine applications and the reason that it was used in this study was the need for a higher resolution to detect a Plume. The satellite has a resolution of 30 m and there is ...
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Introduction
Remote Sensing is an effective tool for detecting and monitoring plume areas. Landsat8 satellite can be used for marine applications and the reason that it was used in this study was the need for a higher resolution to detect a Plume. The satellite has a resolution of 30 m and there is a 16-day spatial resolution. It was the first time that the remote sensing was used to detect the Arvand River's Plume. Because of human population growth and industrialization, there is an increasing pressure on coastal areas and it is important to evaluate the quality of water. Accordingly, remote sensing plays an important role. Considering the vast amount of water covering the surface of the earth, using field measures to study water resources is costly. For this reason, it has taken its place in the processing of satellite imagery. An interesting mesoscale feature of the continental and shelf sea is the plume produced by the continuous discharge of fresh water from a coastal buoyancy source (rivers, estuarine or channel). Coastal plumes resulting from the continuous discharge of brackish or fresh river water are common features ofcontinental and shelf seas. Inside the plumes, a set of physical and chemical processes occur. Plume areas are excellent sources of nutrients. They have a great impact on marine ecosystems. They are identified as water masses with decreased salinity relative to the ambient ocean water. The Arvand River is a permanent river located in the Gulf region and the Oman Sea. The length of its central part is 84 km and its length is about 190 km. The annual average of the discharge is estimated to be 761 to 792 m3 /s. The tides are mixed at the mouth of the Arvand River.
Methodology
In this study, in order to detect the Arvand River plume, Landsat8 satellite images of October 2016 were used. The downloaded images did not have any cloud cover. River plumes with very high sediment loads have been widely studied by remote sensing technology. The suspended sediment increased the radians caused by surface water. It was in the visible and near-infrared region of the electromagnetic spectrum. The amount of impurities based on NDWI index was negative and the water was purer than the positive NDWI. The plume had more suspended sediments than its surrounding waters, so its NDWI index was less than the sea's. The plumes were identified as water masses with decreased salinity relative to the ambient ocean water.
The plume had more radians (energy) than the surrounding waters. Indeed, the NDWI index of the plume had a lower content and the Salinity Ratio Index of the plume was lower. Then, to detect plume verifications, an image of the Sentinel-2 satellite of October 2016 was also produced. The Sentinel-2 satellite in the blue, green, red, and infrared bands had a resolution of 10 m. The Sentinel 2A satellite was launched in 2015. Using the ENVI software, the radiometric correction was first performed on images. After obtaining radiance and reflectance, the NDWI index and Salinity Ratio were calculated. These four conditions were considered for the detection of the plume. Then, using the scatter plot, the thresholds mentioned in the algorithm were determined, Finally, using the decision tree, the subscriptions of these four indicators were extracted and two plume and non-plume were obtained. In addition, in this study, the NSMI index was used to classify suspended material concentration, and the results showed how the plume dispersion was developed based on this index. In addition, to determine the core of the plume and coastal waters, the NSMI index was used. The more the water, the cleaner and purer it is. The NSMI was more negative. When the water had more suspended sediment, the NSMI was more positive. The NSMI had a fluctuation between one to one negative.
Discussion
In this study, the scientific theories in relation to a plume were proved through the indicated indices. Also, through the use of an algorithm and Landsat 8 satellite imagery, successful results were obtained from the Arvand River Plume. In this study, plume and coastal waters were categorized using a decision tree. In addition, four different water zones were determined based on the spectral properties. Providing accurate and up-to-date information on the dynamics of the plume can lead to the better protection of the coast.
Conclusion
The results of this study can be used to monitor water quality. In October, Radian Band 4, Radian Band 2, NDWI, and salinity ratio matched the preconditions. The core of the plume was based on the distance from the river mouth.The Plume Core (the part with the highest concentration of suspended matter) was located adjacent to the mouth of the Arvand River.
Hamidreza Babaali; Reza Dehghani
Volume 4, Issue 11 , September 2017, , Pages 149-168
Abstract
Introduction
Flood is one of the hazardous natural disasters that causes loss of life and financial problems every year. Therefore, scientists have tried to assess the quantitative variability of this phenomenon as much as possible. In this study, the recorded data in Kahman Aleshtar watershed area, ...
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Introduction
Flood is one of the hazardous natural disasters that causes loss of life and financial problems every year. Therefore, scientists have tried to assess the quantitative variability of this phenomenon as much as possible. In this study, the recorded data in Kahman Aleshtar watershed area, which is located in Lorestan province, was used to investigate the precision of the different flood peak discharge prediction models. In addition, the wavelet and artificial neural network models were selected for the modeling of the flood peak discharge and the results were compared to examine the accuracy of the studied models.
Methodlogy
Daily flood peak discharges of the basin in Kahman station, which were applied for the calibration and validation of the models, were selected and observed. For this purpose, maximum daily precipitation rate, at a daily scale and between the years 2001-2012, and flood peak discharge were respectively used as the input and output parameters. The wavelet-based neural network which was based on the combination of the wavelet theory and neural networks were created. Indeed, it has the benefits and features of the neural networks and the charm, flexibility, strong mathematical foundations, and the analysis of the multi-scale wavelets. The combination of the wavelet theory with the neural network concepts for the creation of the wavelet neural network and feed-forward neural shock can be a good alternative for estimating the approximate nonlinear functions. Feed-forward neural network with sigmoid activation function is in the hidden layer. While at the nerve shocked wavelet, the wavelet functions as the activation of the hidden layer feed-forward networks are considered, in both these networks and scale wavelet, the transformation parameters are optimized with their weight. Artificial neural networks inspired by the brain's information processing systems, designed and emerged into. To help the learning process and with the use of the processors called neurons, there was an attempt to understand the inherent relationships among the data mapping, the input space, and the optimal space. The hidden layer or layers, the information received from the input layer, and the output layer are the processing and disposal.
Based on the artificial neural network structure, its major features are high processing speed and the ability to learn the pattern, the ability to extend the model after learning, the flexibility against unwanted errors, and no disruption to the error on the part of the connection due to the weight distribution network.
The first practical application of the synthetic networks with the introduction of the multilayer perceptron networks was consultation. For training this network, back propagation algorithm is used. The basis of this algorithm is based on the error correction of the learning rule. That consists of two main routes. By adjusting the parameters in the MLP model, error signal and input signal occurs. Determining the number of the layers and neurons is the most important issue in simulation with the artificial neural network. The criteria of the correlation coefficient, the root mean square error, and the mean absolute error were used to evaluate and compare the performance of the models.
Results
The results showed that both models in a structure, consisting of 1 to 4 delay, gives better results than any other structure. In addition, based on the results of the evaluation criterion, the model which was used to wavelet neural network model, was the most accurate (R=0.921), and the lowest root mean square error RMSE=0.005m3/s and the lowest average absolute error MAE=0.003m3/s the validation phase is capable.
Conclusions
Wavelet neural network model outperformed the artificial neural network. Consequently, it can be effective in forecasting the daily flood peak discharge. It can also facilitate the development and the implementation of the surface water management strategies. Finally, predicting the piver flow process is a major step in water engineering studies and water resources' management.
Amir Hossein Halabian; shamsolah Asgari
Volume 4, Issue 12 , December 2017, , Pages 153-177
Abstract
Extent Abstract Introduction One way to decrease flood damage is to zone the potential of flood in watersheds. In other words, separating the flooding areas and determining the effective factors in flooding can play a special role in preparing a suitable medium and long term policy making for optimal ...
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Extent Abstract Introduction One way to decrease flood damage is to zone the potential of flood in watersheds. In other words, separating the flooding areas and determining the effective factors in flooding can play a special role in preparing a suitable medium and long term policy making for optimal exploitation of lands. Some of the studies which were based on zoning the potential of flooding worldwide and Iran includes Hawkins (1979), James et al. (1980), Bales et al. (1981), Enayat Rasoul et al. (1994), Suwanwerakamator (1994), Singh (1997), Francisco et al. (1998), Stephen (2002), Sinnakaudan et al. (2003), Sanyal and Lu (2004), Levy (2005), Meyer et al. (2009), Cook et al. (2009), Qin et al. (2011), Bakhtyari Kia et al. (2011), Al-Ghamdi et al. (2012), Ismail et al. (2013), Demir and Kisi (2016); in Iran: Qaemi and Morid (1375), Qanavati and Farajzadeh (1379), Abdi and Rasouli (1380), Omidvar et al. (1389), Malekian et al. (1391), Lajevardi et al. (1392), Nasrinnejad et al. (1393). In this research, Mishkhas watershed was studied in terms of flooding potential using multivariate statistical methods of factor and cluster analysis and geographical information system (GIS). Finally, the watershedflooding map was drawn in three classes of low, moderate and high. Zoning the flooding potential in this watershed can help reduce the damage caused by this natural hazard. Such studies can be a basis for future planning of regional and local developments. Methodology One of the appropriate criteria for understanding the potential of flooding in basins is classifying them according to geometry, physiography, permeability, and climatic criteria. In this study, the topography maps of geographic organization (1:50000), and the geological map of vegetation (1:250000), land use, soil maps of Ilam province (1392), precipitation data, and multivariate statistical methods of factor and cluster analysis have been used. In this research, Mishkhas watershed was divided into 12 sub-watersheds and their flooding intensity was classified into 3 classes. According to the aim of the research, the maximum instant debit, daily precipitation, and the date of watershed floods during the statistical period were selected. In addition, the effective criteria in watershed flooding was calculated using ArcGIS software including geometry, physiography, permeability, and climatic parameters for Mishkhas sub-watersheds. Then, they were analyzed using factor analysis and 28 parameters were summarized in the form of 5 main factors (form, stream, slope, drainage, and runoff). Finally, the intensity of the sub-watersheds' flooding were c 3 high, moderate, and low classes according to the mentioned criteria. Discussion In this research, the total criteria which were used were operating by a type R factor analysis. The results of this research decreased 28 initial criteria to 5 superior factors including (1) form, (2) stream, (3) slope, (4) drainage, and (5) runoff. According to calculations done on the criteria in the first factor, sub-watersheds 1, 2, 3, 5, 9, 11, and 12 with the highest flooding, sub-watersheds 6, 8, 10 with moderate flooding and sub-watersheds 4 and 7 with the lowest flooding intensity were identified. The first factor indicated the reverse relationship between the watershed's form and flooding intensity. That is, the more its length and area, the less its flooding intensity. In the second factor (stream) it was specified that sub-watersheds 1, 10, 3, and 12 have high flooding, sub-watersheds 7, 8, 5, 2, and 9 have moderate flooding, and sub-watersheds 11, 4, and 6 have low flooding. It was also indicated a reverse relationship between stream density and flooding intensity. In the third factor (slope), it was specified that sub-watersheds 6, 5, 1, 9, 10, and 11 have high flooding intensity, sub-watersheds 2, 4, and 8 have moderate flooding intensity, and sub-watersheds 7 and 12 have low flooding intensity. The sub-watersheds with high flooding intensity are located in northeastern and eastern parts of the basin which are mostly mountainous and have high height difference and slope. Sub-watersheds with low flooding intensity have little height difference, low slope, and relatively suitable vegetation. The calculations done on the fourth factor (drainage) indicated that sub-watersheds 12, 7, 4, and 2 have high flooding intensity, sub-watersheds 5, 6, 10, and 11 have moderate flooding predisposition, and sub-watersheds 1, 3, 8, and 9 have low flooding predisposition. Sub-watersheds with high flooding have been operated as the main drain of watershed. The results indicated that 33% of sub-watersheds have high flooding in terms of drainage factor. According to calculations done on the fifth factor (runoff) sub-watersheds 12, 3, 4, and 5 have high flooding intensity, sub-watersheds 1, 2, 6, and 8 have moderate flooding intensity and, sub-watersheds 7, 9, 10, and 11 have low flooding intensity. According to the factor's score, Mishkhas watershed is divided into three high, moderate, and low flooding classes and the zoning map of sub-watersheds' flooding intensity has been prepared. Conclusion In this research, factor analysis and cluster analysis were used for studying the flooding intensity of Mishkhas watershed and the role of sub-watersheds in flooding of this area. According to factor analysis results, 28 initial criteria reduced to 5 factors including form, stream, slope, drainage, and runoff. Analyzing the factors indicated that sub-watersheds 3, 5, 8, and 9 in form factor, sub-watersheds 1, 6, and 11 in slope factor, sub-watersheds 2 and 7 in drainage factor, and sub-watersheds 4, 12, and 10 in runoff factor have extra flood hazard intensity. Sub-watersheds were divided into 3 groups including high, moderate, and low flood producing based on the similarity of flooding intensity, erosion, vegetation, and human activities. For separating the sub-watersheds in homogenous groups, three homogenous groups were identified after data standardization by a standard model and applying Euclidean distance and Ward method. The first group's sub-watersheds 1, 2, 3, 4, 5, and 6 have high power to produce run off because of having high height and slope, low vegetation and permeability, and high flooding capacity. The second group's sub-watersheds 7, 8, 11, and 12 have high power to produce runoff, because of high slope, low vegetation, high height, low permeability, and high flooding power. In the third group's sub-watersheds 9 and 10, the flow was decreased because of decreasing the slope and increasing the permeability, so they indicated lower power to produce runoff. In fact, sub-watersheds play fundamental roles in flooding of this watershed that affect large downstream agricultural lands.
