پژوهشی
Ali Ahmadabadi; Mohamad Fathollahzadeh; Tayebeh Kiani; Fateme Emadodin
Volume 6, Issue 19 , September 2019, Pages 1-18
Abstract
Introduction ...
Read More
Introduction The history of reviewing Iran's glaciers may be less than 80 years old and there are not enough records and opinions before it. For example, Esther, a Finnish geologist, didn’t know about the Quaternary glacier in Iran (Peru, 1984). Cirques are depressions with variables and often semi-circular volumes which have several examples according to the size and shape of the rippling. The simplest form has a slender floor (Mahmoudi, 1988). Deepening of the cirques is the result of an exploration and gentle rubbing on the floor of the glacier. In fact, the formation of the glacier cirques is that at first the glaciers form in the slopes and grooves in the range. Then under the influence of the slope of the hillside, the glaciers move from their original location to the bottom of the grooves which are curved and their depth is increased. This phenomenon is due to the movement of snow ice in the lower part. As a result, the stones appear on the bottom of the cirques (Moghimi, 2008). In this study, the glacier cirques of Oshtorankuh area were divided into two sections of the northeastern and southwestern cirques with respect to the northwest trend of the eastern south. It is related to the normalized snow cover index (NDSI) using Landsat 8, scheduled for April 2016. Materials and methods Normalized Difference Snow Index (NDSI) is a standard for determining snow levels and it is one of the remote sensing techniques for surveying the status of the mountainous and snowy areas. The basis of this index is the determination of the satellite images and the amount of light and heat reflected from a snow-covered surface. Considering the difficulties of accessibility to mountainous areas for the identification of snow-covered surfaces, using remote sensing will be very useful. NDSI is used as an automatic snow extractor algorithm with a set of thresholds and pixel-to-pixel values. This index is based on the fact that snow has a high reflectivity in the visible area and low reflectivity in the infrared range. It is used to detect snow from the cloud and areas without snow (Nolin et al., 2000). The NDSI is non-sensitive to exposure conditions and is adjustable to atmospheric effects. In other words, this index depends on both its reflection values in a band and the amount of digital reflection in pixels. Discussion In order to calculate the Normalized Snow Cover Index (NDSI), Landsat 8 was introduced in April of 2016, and Erdas Imagine combination of 6 bands was used. Then, using the formula (1), NDSI was calculated: Equ (1) NDSI= NDSI: Normalized-Difference Snow Index OLI3: Band 3 Landsat 8 OLI6: Band 6 Landsat 8 image After calculating the NDSI and taking into account the altitudes above 3500 m with the help of the altitude digital model, the correction of the errors caused by the reflection of snow-like surfaces was carried out. Finally, the area covered with snow and ice of the Oshtorankuh area was determined. Given that the snow and ice in the cirques center in the warmer seasons melt away from the snow and ice of the inner walls of the cirques, the walls and boundaries of each cirques was determined by these snow and ice coverings. Therefore, normal snow cover levels (NDSI) can be used to identify and determine glacier cirques, but it is necessary to mention that the satellite images used in this method were related to the history of the boundaries of all cirques and the minimum amount of snow and ice which were detected by the NDSI. Finally, 33 glacier cirques were determined and positioned. Then, with respect to the Oshtorankuh along the northwest-southeastern direction, the cirques were divided into two strata of the northeastern slopes including 18 cirques and southwest slopes including 15 cirques. Conclusion Glacier cirques aresemi-circular cavities with variable volumes due to their size and shape that feature rugged and different samples. The cirques are also important for the glacier's natural heritage. They were active in the past and due to the glacial processes that occur in the present time they are the most important landforms of glacial erosion. In this study, the glacier cirques of Oshtorankuh area were divided into two sections of the northeastern and southwestern range cirques with respect to the northwest trend of the eastern south. It was related to the normalized snow cover index (NDSI) and Landsat 8 which was scheduled for April 2016 was used. The point which should be taken into account is that the determination of cirques by the Normalized Snow Covering Index (NDSI) of satellite imagery should certainly be related to the time period in which the limits of all cirques have a minimum snow level. It is self-identifying by the Normalized Snow Cover Indicator (NDSI). After determining the glacier cirques of the area, the characteristics of the cirques were determined in each domain and compared with each other. It was found that the cirques of the northeastern stretch have more developed and more typical cirques due to the less radiation received and the activation of glacial shaping processes in relation to water erosion along with glacial processes.
پژوهشی
Taher Goli; Hesam Kavian; Rahim Kadkhodayi Ilkhchi; Ahad Nouri Mokhoori
Volume 6, Issue 19 , September 2019, Pages 19-36
Abstract
Abstract Introduction Qum Tapeh dunes are wind sand dunes that are located between longitude of 46° 1' to 46° 2' east and latitude of 38° 14' to 38° 15' north. These dunes, covering an area of about 6 km2, are located in the northwest of Tabriz and southeast ...
Read More
Abstract Introduction Qum Tapeh dunes are wind sand dunes that are located between longitude of 46° 1' to 46° 2' east and latitude of 38° 14' to 38° 15' north. These dunes, covering an area of about 6 km2, are located in the northwest of Tabriz and southeast of Sufian. Sedimentary rocks including sandstone, dolomite, and limestone are the most common rocks in the area. Generally, from the Neogene to the present day, the physical and chemical weathering of sedimentary rocks – mainly clastic ones – has provided detrital particles such as gravel, sand, and shale and chemical deposits such as limestone, gypsum, and salt in this region. Rapid winds in east-west direction and vice versa play an important role in sorting and distribution of the sediment particles. The sustainability of winds with constant energy has been associated with the transportation of fine particles; moreover, the accumulation of coarser particles would result in the development of sand dunes. Methodology In this research, the systematic sampling was first carried out for the granulometric analysis of sediment, investigating its constituents, and the recognition of the transportation agent. Discussion and conclusion Granulometry was performed by using a dry sieving method, with a sieve distance of 0.5 phi to silt (4 phi) by Carver (1971) method, Accordingly, the particles size in sediments of Qum Tapeh sand dunes was determined in the range of coarse sand to silt and clay. The results showed that the particles’ diameter in the sand dunes varied from 0.25 to 0.0039 mm (i.e., size of sand to silt and clay). The average sorting index was 0.321phi, which indicated that the sediments were well-sorted. The mean skewness was +0.357, which meant that the particles were fine skewed, and that the most important mechanism for transportation of these sediments was saltation. Also, the average kurtosis index was 1.726, which meant that they were very leptokurtic. The unimodality of the sediments also enhanced their sorting. Fine particle size, good sorting, and positive skewness indicated the effective role of wind in the transportation and distribution of sediment particles in the area. Comparing the kurtosis index and the sorting may lead to the conclusion that the more their kurtosis, the better their sorting. The petrography study showed that siltstone was the most important rock fragment in wind sediments of Qum Tapeh. The main constituents were clastics with very small amounts of carbonates, of which quartz was the most abundant (65%) mineral found in these sediments. The size of quartz in the sediments varied from silt to very coarse sand, and it often showed undulose extinction. In some monocrystalline quartz grains, there were some types of inclusions that were mostly zircon and muscovite. Monocrystalline quartz grains were mainly composed of plutonic and sedimentary quartz. The higher percent of monocrystalline quartz in comparison with polycrystalline quartz, as well as the presence of quartz grains with overgrowth cement indicated long-term transport and recycling of sediments in the area. The amount of feldspar in the sediments was 23%, which suggested that the potassium feldspars were more abundant than plagioclase. In terms of geomorphology, the sediments of this area were divided into categories of floating sand, shelter sand, and sand dunes. Also, the most important sand dunes were formed as longitudinal dunes. The direction of wind in the formation of these dunes was not clear, but it may have been in two directions.
پژوهشی
Sayyad Asghari Saraskanroud; Rasoul Hassanzadeh; Zahra Miri Atashgah
Volume 6, Issue 19 , September 2019, Pages 37-56
Abstract
Introduction Land-use studies, using remote sensing techniques, are vital tools for generating rational information for proper decision-making in natural resource management. (Habtamu Teka et al., 2017). Land-use change has the potential to affect land cover and vice versa. ...
Read More
Introduction Land-use studies, using remote sensing techniques, are vital tools for generating rational information for proper decision-making in natural resource management. (Habtamu Teka et al., 2017). Land-use change has the potential to affect land cover and vice versa. Land use change affects the biodiversity and aquatic ecosystems, and change in the watershed affects water quality, resulting in an increased runoff consumption, reduced land use, and evacuated groundwater. Therefore, land-use change information for water selection, planning, monitoring, and management is important in order to meet the change in land use due to the demand for human and welfare requirements without compromising the quality and quantity of water (Ang Kane Hawa, 2017). Methodology Case Study The Aliabad watershed of Horand with the southwest-northeast trend is located at the geographical coordinates of the southeastern part of the eastern part of the eastern province of East Azarbaijan and the southeastern part of Horand. Including the Horand, Majidabad and Yali Yurt mountains, the Eight Shrines, the Cay Thai Castle and Mount Everest, it covers an area of 165278 km2. The Ali Abad River is the main river of this basin, which performs the drainage system of the area and the Dojak and Horand Rivers are the most important branches that join this river. Data and research method The data which was used in this study included Landsat images, which included TM and OLI sensors with track 168 and row 33, with a resolution of 30m between 1992 and 2017. To obtain the amount of water created by new gardens, a pure water irrigation project for Iranian crops, which has become a software called NETWAT was used. Landsat images in the pre-processing stage were used for the atmospheric and radiometric FLAASH corrections. The strongest method of atmospheric correction, and rescale operations were performed on corrected images to ensure accurate numerical calculations. Meanwhile, in the 2017 image, to increase the accuracy of the classification, the method of fusion of multinuclear images with a pancreatic image was made and the spatial resolution up to 15m improved. The processing of images to detect and determine the type of land use in two time intervals was done through supervised classification methods. Of four types of classification, the Maximom likelhood method was chosen due to a better processing and the absence of unknown pixels. Finally, the layer Land use in twelve classes was selected by selecting the number of educational specimens including the first class forests (4181 pixels), second class forests (3958 pixels), garden lands (2665 pixels), first class rangeland (32704 pixels), rangeland grade (30837 pixels), agriculture (7544 pixels), residential land (1911 pixels), shore lands (3257 pixels), blueberries (167 pixels), Bayer lands (2332 pixels), blue areas (131 pixels) and river beds (800 pixels). In addition to the necessity of using large-scale images, field observations and the use of lateral information were necessary to identify some activities at different levels of the earth (Zebiri, 92). Therefore, field observations were also needed to enhance the accuracy of the user classification. To analyze the data, ArcGIS, ENVI were used. After the processing and evaluating the accuracy of the images and examining the results of the classification, there were several ways for assessing the accuracy of the classification. The most common way was the selection of a number of pixels of the specified sample and comparing them with the classification that made these data. The ground truths were called reference data (Alawi Panah, 91: 159-152). The net irrigation project of Iran's products was from the National Project Plan (TOTEK). An optimization of the national consumption of Iranian agricultural water was carried out by the Meteorological Organization of the country and the Ministry of Jihad-e-Agriculture in collaboration with Dr. Amin Alizadeh and his research team. In order to estimate the water consumption of the basin in gardening affairs, based on the method of work, this functionality was constructed using the FAO-Penman-Monteith function and based on this function, the annual consumption of trees was calculated. Finally, the consumption of each tree was estimated as the average annual consumption. Results The verification of the accuracy and results of the classification of images by the Kappa coefficient were performed and the obtained coefficient with the acceptable status showed that the classification of the images was done satisfactorily and the images could be cited for the continuation of the research. In land use maps of the AliAbad River watershed, in each of the periods of 1992 and 2017, the lands were divided into 12 classes. Based on the comparison made between the two maps, land use changes in each of the 12 classes were presented. Based on the results of two time intervals in the Aliabad Chay catchment area, it was determined that the area of the cultivated lands increased by about 5.51 km2 (Table 1). In the field studies, it was concluded that the irrigation Garden lands were built on the basis of ribs by the city's people on the upstream gardens until 1992. The Pearson parametric test showed that there was a significantly positive and strong correlation between the increase in the area of the gardens and the increase in the depth of the wells (0.935). It should be noted that by increasing the area of gardens in the land use, the depth of the wells was increased for the extraction of water from the basin. However, the correlation between rainfall changes and depth of wells (Basin flood) was negative (-0.580). The basis of the net irrigation plan for irrigated crops in Iran, and using the produced function, the annual water demand of these products was calculated in terms of planting area (Table 1 and Table 2). (Table 1) Calculation of the water requirement of cultivated trees in the first six months with the NETWAT software Tree type April May June spring season July August September summer season Apple 8 44 91 143 151 138 103 392 Walnut 10 55 109 184 172 160 119 451 Apricot 13 52 86 151 122 117 53 292 Cherry 8 44 91 143 151 134 89 374 Average 39 115 377 621 596 549 364 1509 (Table 2) Calculation of the annual water requirement of cultivated trees with a built-in function Tree type Annual water requirement (cubic meter per sq. Km) Apple 760000 Walnut 886900 Apricot 490000 Cherry 698000 Average consumption of trees 708725 Total consumption in newly built gardens is 5.15 square kilometers 3,649,934 Discussion and conclusion The study area of this research is one of the important agricultural areas of East Azarbaijan Province, and the Ali Abad Chai River is considered as the only source of water supply in the region. The classification of land use in the region, especially the increase of basin gardens, which is the most important water user in the river, was done by Maximim Likelhood method. The Pearson's parametric test was used in the SPSS software to prove that the basin's decline was caused by variation in the gardens, and the 25 year rainfall variations in the basin and the changes in the gardens were investigated with regard to the depth of the wells. There is was significant relationship between rainfall variations in the basin and the decline of the basin, but there was a significant difference between the changes in the use of gardens and the decline of the basin, and there was a very strong and positive correlation between these two variables. Therefore, it should be acknowledged that in the Aliabad watershed, if the irrigation process of the gardens is not scientific and practical and the management of water storage is not done, the flow of the river in general is disturbed in these seasons. In the warm seasons, permanent changes in geomorphologic and ecological activities will be lost and the negative effects will be felt by the inhabitants of the region.
پژوهشی
Mahsa Ariapour; Mehdi Bashiri; Ali Golkarian
Volume 6, Issue 19 , September 2019, Pages 57-77
Abstract
Introduction Mass movement, according to their nature, variety, hazards for human lives, and properties, have always been a matter of interest to various scholars. Considering that the occurrence of this phenomenon has a complex mechanism and complex factors and variables can affect it, extensive studies ...
Read More
Introduction Mass movement, according to their nature, variety, hazards for human lives, and properties, have always been a matter of interest to various scholars. Considering that the occurrence of this phenomenon has a complex mechanism and complex factors and variables can affect it, extensive studies to identify the effective factors, classification, zoning, and modeling of this process have been conducted. In this study, landslides of three watersheds in the southeast of Neishabour city were investigated and the hazard zonation map was prepared, using bivariate statistical methods of the information value and area density. There are few studies regarding the application of different data mining methods to determine the effective variables in the occurrence of landslides and most studies are based on other statistical methods. Data mining is called as knowledge discovery in databases and is a way to discover new and beneficial information through a lot of data. Some of the most important data mining algorithms include the decision tree, random forest, boosting aggregate demand, support vector machine, logistic regression, and neural network algorithm. The data mining extracts useful information from large volumes of data and has shown a good performance. Therefore, the aim of the present study was to prioritize Methodology The present study aimed to investigate the factors affecting the occurrence of a landslide and its zoning in three watersheds including Kharv, Harimabad and Grineh watersheds in the Razavi Khorasn province. First, 99 landslides were identified in the area and the landslide distribution map was prepared. Then, all effective factors on watershed landslides, in 15 information layers including the altitude, slope, aspect, climate, land use, pedology, vegetation cover, geology, evaporation, temperature, rainfall, land type, distance from road, distance from fault, and distance from river were digitized in the ArcGIS environment. Then, using data-mining algorithms in R software, the preferable algorithm and effective factors on landslide occurrence, were introduced. Finally, the landslide hazard zonation in the GIS software was done using bivariate statistical models. Results The results showed that the random forest algorithm with an accuracy of 92% is the best one and the variables of geology, climate, aspect, distance from road, altitude, pedology and land type are the most important variables in algorithms modeling. The most probability of occurrence of watershed landslides placed in areas with west and northwest directions, slopes higher than 30 degrees, dominant type of the environmental factors affecting the occurrence of a landslide including the altitude, slope, aspect, climate, land use, pedology, vegetation cover, geology, evaporation, temperature, rainfall, land type, distance from road, distance from fault, and distance from river using data mining algorithms, zoning its sensitivity, and bivariate statistical models of information value and area density in three watersheds including Kharv, Harimabad, Grineh watersheds in Razavi Khorasan province. mountains, the semi-humid climate, 1500 to 2000 mm evaporation class, entisols, dense vegetation, the gardens, bushes and shrubs land uses, being close to the roads and faults and being far from the rivers, and the altitudes of 2000 to 2500 m with the phyllite, boulders and sandstone formations. The results of the zoning map evaluation using the information value and density area methods showed that 45.45% and 55.55 % of landslides were respectively located at the high and very high risk zones and the rest were in very low, low, and moderate risk zones. As a result, in both methods, most of landslides were in the high and very high risk zones that indicated the suitable accuracy of the model. Discussion and Conclusions According to the results of this research, variables including the geology, climate, aspect, distance from road, altitude, soil science, and land type were considered as the most important factors in the occurrence of a landslide. In addition, factors such as slope, land use, vegetation cover, distance from fault and distance from river were identified as the most important factors influencing the development of landslide and classified as natural factors, which could be influenced by human factors. The comparison of two mentioned methods showed that the area density method was more appropriate than the information value method for the study area.
پژوهشی
Jamshid Yarahmadi; G. Rostamizad
Volume 6, Issue 19 , September 2019, Pages 79-100
Abstract
Introduction Hydrological droughts occur after meteorological and agricultural droughts. In other words, this kind of drought is the final stage of the drought cycle and is affected by global climate change. Nowadays, many studies on hydrological droughts are based on the Threshold Level method, which ...
Read More
Introduction Hydrological droughts occur after meteorological and agricultural droughts. In other words, this kind of drought is the final stage of the drought cycle and is affected by global climate change. Nowadays, many studies on hydrological droughts are based on the Threshold Level method, which is based on the Run Theory. According to this view, a drought is described as the length of a period in which hydrological variables, or discharges, are below the specified threshold level. To the researchers' knowledge, there have never been a major research on hydrological droughts in Iran and studies in this field are very limited in comparison with other types of droughts. Most of the researches in hydrological droughts have been done in the monthly and annual time intervals. However, the present study was conducted to investigate the hydrological droughts on a daily basis with the objectives of identifying and monitoring them and determining their occurrence and severity in the studied area. Methodology In this research, the Threshold Level Method was used to identify the hydrological droughts in the DaryanChai sub-basin in the northern part of Lake Urmia. Using the computer program NIZOWKA2003 based on the partial time series (PDS), the droughts in the hydrometric station of the Daryan during a thirty one year period (1982-2014) were calculated. Hydrological drought characteristics including time of occurrence, duration, severity, and minimum observed flow during dry period were calculated based on the NIZOWKA2003 software. In addition, frequency analysis, probability of the number of drought occurrences, duration, and volume deficiency in different return periods were calculated using the mentioned computer program. Here, the threshold level was chosen based on the flow duration curve (FDC), which was based on the daily flow rates of the selected hydrometric station and prepared using the NIZOWKA2003 program. The IC method was used to integrate the minor and mutual dependency periods of hydrological drought. Based on the characteristics of dry periods, the probabilistic distribution and frequency analysis of dry periods, the probability of the occurrence of drought and characteristics of dry periods (duration and volume deficit), fitting different types of statistical distributions and selecting the most suitable ones based on the fitting values (chi Score) were calculated using the NIZOWKA2003 computer program. Results The results of the calculations showed that a total of 38 periods of a hydrological drought occurred in this river. Approximately about 20 events from all detected drought occurrences lasted more than 200 days. The longest period of drought with 577 days lasted between the end of June 1988 and March 1990. Less than two months later, the second largest hydrological period with 365 days lasted between the beginning of May 1990 and the end of June 1991. Regardless of these two months, the largest hydrological drought period with 950 days was between 1988 and 1991. The severest hydrological periods were respectively 8987 and 6133 cubic meters, coincided with the largest hydrological drought periods. Moreover, the calculations showed that this river's water volume has fallen by 117 million cubic meters over the period of 31 years. Based on the results of Chi-square test and Akaya's criterion, Poisson distribution was the most appropriate distribution of the probability of the occurrence of drought occurrence. Among the various probabilistic distributions, Weibull's distribution was the most appropriate distribution of the duration of the hydrological drought events. Accordingly, the probability of the occurrence of a dry period of at least 13 day duration is likely to occur in this river. Additionally, the maximum observation dryness event of 578 days was estimated with a probability of non-exceeding 0.99 % at the Daryan hydro-station. The probable distribution of Weibull was selected as the most suitable distribution of the hydrological drought severity. Based on the Weibull method, the maximum water deficit volume was estimated at 13730 cubic meters with a low probability (0.01%). In contrast, the highest probability of the severity of drought (about 70%) in the Daryan Chai was estimated at 253,000 cubic meters. The results of the calculation of the return periods showed that in half of the cases, the probability of the occurrence of a dry period was with a duration of 170 days and an intensity of 2276 cubic meters with a 2-year return period. Discussion and conclusion Until the last decade, little research has been conducted on the hydrological droughts in Iran.In very few studies, the analysis of the low flows from the point of view of frequency analysis has been addressed.The lack or shortage of hydrometric data in many parts of the world has been the main limitation in hydrological drought studies. In this research, the Threshold Level Method was used to extract thehydrological dry periods and their characteristics. Despite the fact that this method has been extensively used in drought studies, its selection is still one of the controversial issues in such studies. Using the daily time series can provide complete and accurate information from the start and end dates of drought events. However, the use of this time basis in drought studies, especially hydrological droughts, is not common in the world and in Iran.The only studies in Iran, based on the daily time series, were conducted by Bayzidi and Saghafian (2011), Mesbahzadeh et al. (2017), and Mostafa Zadeh et al. (2018). Almost all other studies have been based on monthly or annual basis. However, the use of a daily time series is often associated with the problem of having minor andmutual dependency periods. There are several ways to overcome this problem. The Interevent Critria. (IC) is one of these methods which was used in this research.The efficiency of this method has been previously reported by Zelenhasićand Salvai(1987), Hisdal et al. (2003), Tallaksen et al. (2004), and Baiziidi and Bayzidi and Saghafian (2011).
پژوهشی
Abdolkarim Veysi; ebrahim moghimi; Mehran Maghsoudi; Mojtaba Yamani; Sayed Musa Hosseini
Volume 6, Issue 19 , September 2019, Pages 101-123
Abstract
Yamani[1], Sayed Musa Hosseini[2] Introduction Shahu karstic aquifers are the main sources of drinking and agricultural water in Paveh, Javanrood and Ravansar cities. Therefore, according to the important role of karst aquifers in supplying water to local communities in Kermanshah Province, recognizing ...
Read More
Yamani[1], Sayed Musa Hosseini[2] Introduction Shahu karstic aquifers are the main sources of drinking and agricultural water in Paveh, Javanrood and Ravansar cities. Therefore, according to the important role of karst aquifers in supplying water to local communities in Kermanshah Province, recognizing their hydrodynamic characteristics for qualitative and quantitative management plays an important role in water policy planning in the province. The aim of this study was to identify and analyze the characteristics of karstic Dolines in the Shahu area and its relationship to the hydrodynamic characteristics of the water resources of the region. The identification of the sinkholes and their dispersion along with the morphometric analysis of these forms in the study area can be used in discussions on morphological characteristics and environmental hazards assessment and provide usable data for environmental planning. Methodology The purpose of this study was to evaluate the hydrogeological characteristics of Kavat and Holi springs in connection with the development of Karst geomorphology, which is based on library, field, and applied research. To this end, CCL, elongation index, sinusoidal index, D/H ratio, the analysis of the nearest neighbor in order to analyze the Dolin characteristics of the region and time series analysis methods were used. In addition, automatic correlation and spectral density were used in order to study the hydrodynamic characteristics of aquifers in the study area. The data on discharge and precipitation of hydrometric stations and rain stations of the Ministry of Energy were also used during the period of 2003-2014. The sinkholes identified in the Karst Shahu area were derived from 10-meter digital elevation model. Extensive field activities were carried out to check identified forms. A descriptive table including location, geology and morphometric characteristics for each doline were calculated. The doline morphometric characteristics were recorded. Then the data were analyzed by statistical methods in SPSS software. In this study, parameters including density, area, diameter, depth, slope and distance from faults were analyzed. The analysis of the hydrograph subsidence curve was used to evaluate the type of flow system in the karstic aquifers of the study. Finally, to evaluate the results obtained from the time series analysis, the results of the hydrograph curve analysis and karst geomorphological features in Shahu area were considered and the hydrodynamic features in the study aquifer was determined. Result According to CCL method, 104 dolins were identified in the shahu area. These dolines covered 11km2. The majority of the dolines were located in the central and northwestern parts of the study area. The mean depth of dolines in Shahu was 15m. The morphometry of the hollows generally tended to be elliptical or stretched. In the Shahu area, elliptical dolines were predominant forms. This indicated the significant role of rock mass in the evolution of the dolines. Semi-circular hollows were the lowest type of hollows in the study area. These types of dolines represented the initial forms of the dolines and were in a young stage. The number of dolines associated with distance from fault showed that the farthest doline was located in 3400 km, while more than 60 percent of Dolines were located within 0 to 500 m of faults in the region. Dolin density was related to the area of Karsts and the number of dolin in the study area. Dolin density in the study area reached over 1.5 per km2. The results of the analysis of the nearest neighbor showed that the mean of the nearest neighbor for Dolines in the study area was 0.86, which indicated the cluster distribution of Dolin. The cluster distribution of the Dolines indicated the evolution of the karstic system of the Shahu area. Correlogram of Kavat Spring had three distinct sections. In the first section, there was a quick drop in flow and within 10 days. This represented a quick flow in the karstic conduit. In the second part, the fluctuation was in the upper range of 2%. It is indicative of a semi-fast current in large fractures. In the third section, the fluctuation was mainly in the range between -2 and 2 and had a roughly uniform shape indicating a basic flow and a low inertia and low dynamic reserve in the aquifer. The Holy Spring Correlogram also showed almost the same situation and consisted of three distinct sections. Consequently, the aquifers showed the behavior of a developed karst. The spectral density function of both studied fountains provided a broad spectral band at frequencies below 17% and less than 15%. Ravansar spring at frequencies above 17% had a good filtering effect. And this value for a holly spring was higher than 15%. Indeed, distinct peaks at different frequencies over a period of time led to the identification of periodic events and, thus, to the recognition of the characteristics of the karstic system. The spectral density function indicated low inertia of studied aquifers, poor filtering, rapid flow and expansion of karstic channel networks in this aquifer. Discussion and conclusion The comparative evaluation of the karst geomorphology in relation to the hydrodynamic properties of aquifers in the study area suggested the development of the karst system in Shahu area. The results showed that relatively large parts of the shahu karst area were covered with dolines. The Dolin morphmetery features helped to recognize Dolines origin. More than 90 % of the Dolin area was elliptical doline which had a dissolution origin. The high dolin density in this region indicated the development of karst system. Differences in the Dolin morphometric characteristics indicated that the Dolin type was different from the origin of formation, the conditions and the time of formation. The analysis of the hydrodynamic characteristics of the Kavat and Holi springs also indicated the development of Shah's karstic system. The analysis of the hydrograph of the studied springs suggested a high degree of karstfication and the presence of a quick flow and the presence of karst coundit in Shahu area. The automatic correlation function of the springs confirmed the multiplicity of the behavior of the karstic system, the rapid response to precipitation, and the small volume of dynamic reservoir of aquifers. Accordingly, the existence of the developed karst forms, the multiplicity of elliptical dolin, their high density, the presence of joints, the abundant fracture in karstic masses, the presence of large karst conduit in the Shahu area indicated the development of the karst system and was confirmed by hydrodynamic surveys. [1]- Professor, Factualy of Geography, University of Tehran, Tehran, Iran. [2]- Associate Professor, Factualy of Geography, University of Tehran, Tehran, Iran.
پژوهشی
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, ...
Read More
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.
پژوهشی
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 ...
Read More
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.
پژوهشی
Behrooz Sari sarraf; Tahereh Jalali Ansaroodi
Volume 6, Issue 19 , September 2019, Pages 163-185
Abstract
Introduction In the recent decades, the growth of the industrial activities and the increase in greenhouse gases have imbalanced the Earth's climate which is called the phenomenon of the climate change. This phenomenon directly affects the hydrological parameters. While climate change directly affects ...
Read More
Introduction In the recent decades, the growth of the industrial activities and the increase in greenhouse gases have imbalanced the Earth's climate which is called the phenomenon of the climate change. This phenomenon directly affects the hydrological parameters. While climate change directly affects surface water resources through changes in the major long-term climate variables such as air temperature, precipitation, and evapotranspiration, the relationship between the changing climate variables and groundwater is more complicated and difficult to quantify. The large amount of water is needed in different parts of arid and semi-arid regions provided through groundwater resources. In recent decades, the quantity and quality of water resources have been reduced by unprotected exploitation. In addition, climate change and global warming increase the severity of the problem. Therefore, the predicted effects of climate change on groundwater recharge play an important role in the management of these resources in the future. In this study, Global circulation models, HadCM3 under A2 and B2 scenarios, were used for investigating the impact of climate change on groundwater recharge rates between 2017 and 2030, in the Tasouj aquifer. Methodology In this study, to investigate the climate change in Tasouj basin, the required data were obtained from two sources including Global model output AOGCM which was based on the HadCM3 model and the observed data of the precipitation and temperature of Tabriz synoptic station with the statistical length of 1961 to 2016. To downscale the general circulation modal, the statistical method of SDSM was used. The Hydrologic Evaluation of Landfill Performance model (HELP) simulates all of the important processes in the hydrological cycle including surface runoff, evapotranspiration, vegetative growth, soil moisture storage, and vertical unsaturated drainage for each discrete layered soil column. In general, the modeled hydrologic processes by the program can be divided into two categories of surface and subsurface processes. The modeled surface processes are snowmelt, interception of rainfall by vegetation, surface runoff, and evaporation of water. The modeled subsurface processes are evaporation of water from the soil, plant transpiration, vertical unsaturated drainage. Vegetative growth and frozen soil models were also included in the program to aid modeling of the water routing processes. The required general data included growing season, average annual wind speed, average quarterly relative humidity, monthly normal mean temperatures, maximum leaf area index, evaporative zone depth and latitude. Result According to the simulation of Hadcm3 model, during the period of 2017-2030, the average monthly temperature in all months of the year will increase in the studied area. The highest amount of heating in the average temperature will happen in July about 2 degree Celsius. The highest decrease in precipitation will occur in April and May about 9 mm than the base period. The highest percentage of precipitation in Tasouj basin is used for evaporation. During 14 years of the prediction, the year 2020 has the highest and the year 2029 has the lowest amount of evaporation. In terms of runoff caused by precipitation, the year 2023 with 9.69 percent of precipitation will have the highest runoff. The lowest and highest amount of recharge will respectively happen in 2021 and 2027. The depth of water precipitation is significantly affected by soil moisture and with increasing soil moisture; the depth of water percolation to soil will decrease. The soil moisture content is negative in 2027. Consequently, the highest amount of recharge due to precipitation will happen in Tasouj basin. In the base period, the year 1990 had lowest precipitation and the year 1963 had the highest precipitation. Due to having a negative soil moisture storage in 1990, of 148 mm of annual precipitation, about 76.28 mm was spent for recharge. The amount of runoff is almost zero in this year and the rest of precipitation is evaporated. Despite the high annual precipitation in 1963, due to the high moisture content of the soil, the amount of recharge is only 4 percent of precipitation and most of the precipitation changes to runoff and evaporation. The status of evaporation, runoff and recharge in 2022, as the forecasted most precipitation year, is similar to 1963. Discussion and conclusion In recent years, the climate change has led to significant changes in the weather and the condition of surface and underground water resources in different locations. The response of the groundwater resources to drought and climate change is not as rapid as that of the surface water, but considering that the renewability of these resources takes much longer than that of the surface water, the impact of long-term drought on groundwater resources is much more serious than that of the surface water resources. Therefore, the monitoring of the condition and maintenance of the sustainability of these resources is important. In this way, by using a step by step approach, the impact of climate change on recharge, evaporate, and runoff for the 2017-2030 period was investigated and the simulation result showed that with increasing temperature and decreasing precipitation, of three parameters of evaporation, recharge, and runoff, the evaporation dominated the other parameters. But the high consumption of basin and the increase of temperature and precipitation decrease prevented Tasouj aquifer from returning to its balance. Therefore, a principle planning to control the harvest and treatment of aquifer by underground dam and artificial nourishment is necessary
پژوهشی
Saeed Negahban; Diyana Dortaj
Volume 6, Issue 19 , September 2019, Pages 187-209
Abstract
Introduction Rivers are sensitive to tectonic movements and there is a close relationship between river formations and tectonic movements. The term morphotectonic states the relationship between geomorphology and tectonics, and in many cases morphotectonic, is considered to be geometric tectonics. In ...
Read More
Introduction Rivers are sensitive to tectonic movements and there is a close relationship between river formations and tectonic movements. The term morphotectonic states the relationship between geomorphology and tectonics, and in many cases morphotectonic, is considered to be geometric tectonics. In recent years, geomorphic tectonics has been a significant tool for identifying active tectonic forms and providing seismic hazard maps and understanding the history of current land surveys. There are several methods to study the tectonic condition of a region or basin. In the meantime, geomorphic indicators in the evaluation of the tectonic activities are useful and reliable tools because they can be used for areas that have experienced a tectonic activity. They are easily identified. These indicators allow geomorphologists to quantitatively measure and reasonably compare different landforms and compute morphological indices. The studied area is considered to be an active area in terms of its location (folded Zagros) and the tectonic is considered as an active region. Accordingly, the evaluation and the study of tectonic activity and its effects in regional planning and land use planning and environmental management are of great importance. In this study, the morphotectonic status of the Sirvan basin was evaluated. Materials and Methods In this research, in order to investigate the effect of tectonics on the studied sub-basins, the sources and findings of the research in the field of research were collected through library studies. In addition, to evaluate the studied sub-basins, geomorphologic indices and evidence were used. The research data included 30m DEM, STRM, the topographic map of 1: 50000 and the geological map of 1: 100000of the studied basin. The ARCGIS software was used to evaluate the indicators and final output mapping. According to the objectives, in order to investigate the effect of tectonics on the studied sub-basins, eight indicators including mountain front (SF) index, drainage basin asymmetry index (AF), longitudinal gradient of the river (SL), reverse topographic symmetry index (T), surface congestion index (P), hypersonic integral index (Hi), sinusoidal river index (S), and basin shape index (BS) were used. After assessing the basin based on the existing indicators, the studied sub-basins for each of the indicators and the final results were obtained. Results and Discussion In this study, to evaluate the tectonic condition of the studied sub-basins, each of the indicators was considered. The results of the SL (Sudden Slope) evaluation indicated that the Sirvan sub-basin with SL of 3133 was the most active sub-basin for this indicator. The evaluation of the T index (inverse topographic symmetry index) indicated that the Shevishe River basin with a coefficient of 4 had the highest degree of asymmetry. The P (Surface Water Condensation) evaluation indicated that the highest density was achieved by 397. It was related to the Gheshagh sub-basin, and according to this indicator, the sub-basin was considered to be the most active sub-basin. Based on the HI index (hipsometric integral) Shoeisheh sub basin with a coefficient of / 420 was considered to be the most active sub-basin. In terms of S (sinusoidal river), the sub-basin of Gheshlagh with a coefficient of 1.31 had the lowest coefficient and, therefore, the most active sub-basin for this index. It was also considered as the longest and most active sub- basin for BS (basin shape) of Gheshlagh basin with a coefficient of 2.14. Conclusion In this research, the geomorphic indices were used to study the tectonic conditions of the studied sub-basins. The results of the assessments were different in different sub-basins. Consequently, according to the Smf index (indicating the extent of tectonic congestion and erosion in the region), of the studied sub-basins, Shevishe basin with a Smf level of 11.1 was the most active sub basin. In terms of the AF index (detection of tilt in the drainage basins due to tectonic activity), of the studied sub-basins, the Gheshlagh basin with a factor of 4.70 had the highest stroke. After assessing the basins based on the existing indicators, in order to classify the basins in terms of tectonic activity, the tectonic activity (Lat) partial evaluation index was used. The results of this indicator indicated that, of studied Sub-basins, Shevisheh sub basin with Class 2 average, had a more active status than the other sub-basins. Accordingly, it is necessary to pay attention to the status of tectonic activity of the sub-area in carrying out any planning, land use planning and management, avoid any risky actions, optimize the use of natural resources, and reduce the harmful effects of any planning.
