پژوهشی
Ziba Kounani; Alireza Ildoromi; hossien zenivand; Hamid Nouri
Abstract
1-Introduction Due to the importance of climate change and the effects it can have on runoff, developing a suitable model for simulating the present and future conditions of the catchment areas is of great importance (Rajabi et al, 2012). Nowadays, the LARS-WG and SDSM models are used to downscale environmental ...
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1-Introduction Due to the importance of climate change and the effects it can have on runoff, developing a suitable model for simulating the present and future conditions of the catchment areas is of great importance (Rajabi et al, 2012). Nowadays, the LARS-WG and SDSM models are used to downscale environmental parameters in climate change studies nowadays. Studies show that the SDSM model has less uncertainty and a more complex simulation process, and the LARS-WG model with simpler process and faster performance is more efficient (Aghashahi et al., 2012). Considering that many of Iran's watersheds lack hydrometric stations, it is of great importance to use those methods that can estimate the amount of runoff obtained from the rainfall. Therefore, the present study aimed to investigate the role of climate change in estimating runoff from the Silakhor-Rahimabad basin of Lorestan using a rainfall-runoff model (SIMHYD). 2-Methodology Silakhor-Rahimabad basin is in the catchment area of Dez Dam in Borujerd, Lorestan Province, which is located between N 33º 45¢ and 34º 7¢ and E 48º 29¢ and 48º 57¢. First, the baseline data including observation data of minimum temperature, maximum temperature, precipitation and sunshine during the period 1990-2014, and rainfall-runoff data including evaporation, rainfall and flow data, which were available, were received from the General Department of Aerology and Regional Water Authority of Lorestan Province, respectively. In this study, the daily data from Borujerd metrological synoptic station were used as the basis because they were complete and the elevation of the station was equal to the average of other stations’ elevations. For the evapotranspiration variable, the mean daily data from Rahimabad, Borujerd, and Silakhor stations were used, the mean daily data from the six rain-sensing stations for the rainfall variable. Moreover, Rahimabad hydrometric station at the outlet was used as the base station to observe the runoff variation in the basin. 3-Results and Discussion The results of the evaluation of criteria show that the LARS-WG model has a good ability to simulate rainfall parameters, minimum temperature, and maximum station. The simulated precipitation is in good agreement with the observed values (Table 1 and 2). After assuring the ability of the LARS-WG model to produce the rainfall data, minimum and maximum temperatures of Silakhor-Rahimabad Basin, the output of the HADCM3 model was downscaled under the scenarios A2 and B1, the parameters were predicted and compared with their values in the period 1990-2014 (Figures 2, 3 and 4). The results of the LARS-WG model indicate a decreasing trend of precipitation and temperature rise under both scenarios A2 and B1 for the period 2046-2065. The average amounts of annual rainfall predicted under the scenarios A2 and B1 are 451.445 and 4.420 mm, respectively. If the annual rainfall is 453.8 mm in the base period, the study area will observe a decrease in precipitation from 51.0 to 20.7 percent. The results obtained in the SDSM model under the two climate scenarios A2 and B2 for the future period indicate that the average air temperature is increasing and in the period 2050, the monthly average temperature, compared to the 1990-2014 period, increases in most months of the year. Also, rainfall has a decreasing trend in this period (Figure 5). Investigations show that the model efficiency has a direct correlation with the recharge coefficient, infiltration coefficient and soil moisture storage capacity. The effects of climate change on runoff are presented in Figures 9-16. In the period 2046-2065, the amount of runoff in the studied basin will decrease compared to the 1990-2014 period. This decrease in runoff rate can be attributed to the increase in temperature, followed by an increase in evaporation and a decrease in rainfall. Regarding the study of temperature and rainfall for the future period and monthly runoff, it is observed that the amount of runoff will decrease in the future period. 4-Conclusion In recent decades, the increase in greenhouse gases and thereby, the rise in temperature, have made Earth’s climate system imbalanced and caused massive climate change in most parts of the planet. Therefore, it seems necessary to apply climate predictions in national macro plans, especially in relation to natural disasters. The results indicate the decrease in precipitation and temperature rise in both SDSM and LARS-WG models. Also, in the present study, the SDSM model showed more variations than the LARS-WG model. Finally, the results obtained in both statistical downscaling models indicate the decreased amount of runoff in the studied basin is in the future period. In the study of the effect of climate change on runoff in the studied area, according to the values of Nash-Sutcliff coefficient and the coefficient of determination obtained at the calibration step (0.63 and 0.779, respectively) and the verification step (0.61 and 0.61, respectively), it is observed that the SIMHYD model has acceptable performance in the studied basin. These results are consistent with the findings of Aghashahi et al. (2012), Rajabi et al. (2013), Zolgharnein et al. (2013), Zhang et al. (2014).
پژوهشی
Mehdi Teimouri; Omid Asadi Nalivan
Abstract
1- Introduction Underground water is one of the most important water resources that plays an important role in providing water for agricultural and drinking activities in arid and semi-arid regions (Usamah and Ahmad, 2018, Wu et al., 2019, Kumar et al., 2019). Awareness of the quality of water resources ...
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1- Introduction Underground water is one of the most important water resources that plays an important role in providing water for agricultural and drinking activities in arid and semi-arid regions (Usamah and Ahmad, 2018, Wu et al., 2019, Kumar et al., 2019). Awareness of the quality of water resources is one of the most important requirements in managing, planning, and developing, protecting, and controlling water resources. Using multivariate statistical techniques helps researchers identify the most important factors affecting the quality of water systems and is a valuable tool for water resources management (Pasandidehfard et al., 2019). On the other hand, geostatistical methods are also capable of zoning water quality at the watershed level and can play an important role in completing the assessment of water quality (Ahmadi et al., 2019). The aim of this study is to evaluate the quality of groundwater used for drinking and farming in Hable-Rood Basin, analyze and interpret the quality of these resources using ArcGIS, and perform statistical tests to determine the role of land use and geology formations in water quality. 2-Methodology To do this research, 132 water sources including wells, springs, and Qanats were used during the statistical period of 2008-2018. The watershed can be divided into fifteen main categories in terms of geology. Hable-Rood watershed has 11 main land uses, which has the largest area of the watershed for pasture and the smallest area of the dams. The main components were analyzed (factor analysis) to understand the most important parameters affecting the water quality. This method weighs the components and expresses a special value for each of them (Finkler et al., 2016). Factor analysis has three stages of producing a correlation matrix from all variables (Pearson correlation method), extracting the main factors, and interpreting the results. Duncan's test was also used to check the significance level of parameters among land uses and the type of formations. Geostatistical methods were used for zoning water quality for drinking and farming purposes in the GIS. The spatial relationship of a random variable in the geostatistics was determined by the semivariogram (software GS +). The root mean square error (RMSE) method was used to assess the geostatistical methods and select the best method. It should be noted that the Schoeller diagram and Wilcox diagram were used for the drinking water zoning and agricultural water quality zoning, respectively. 3-Results and Discussion The results showed that the Cl, EC, TDS, Na, Ca, TH, and SO4 vary significantly in different land uses. The highest average was related to industrial areas within the watershed due to the release of industrial materials and the spread and diffusion of groundwater pollution. Also, the parameters of Cl, EC, TDS, TH, and SO4 differed significantly in varied formations. The trend of water quality changes shows the water quality impact of land use, and water quality has decreased sharply in the industrial area, low-yielding land, saline lands, agriculture, and residential areas. The EC parameter showed the highest correlation with TDS at 5% significance level, which is due to a high correlation with the effect of increasing EC on TDS. The pH parameter did not correlate with the other parameters. The factor analysis on the basis of water quality characteristics showed that 88.16% of the water quality variations among land uses were controlled by a single factor (TDS with a weight of 0.99). The factor analysis on the basis of water quality characteristics showed that 91.59% of water quality changes in the formations were determined by two factors (the first and the second factors with weight loads of 0.95 and 0.95 belonged to the TDS and EC parameters, respectively), and the variance percentages of each of factors 1 and 2 were 77.29 and 14.3%, respectively. 4- Conclusion In this research, the effects of geology and land use on groundwater quality were evaluated using multivariate statistical methods and geostatistical methods in ArcGIS. It was determined that some of the groundwater quality parameters were affected by land use and some of the other parameters were under the influence of the geology in the watershed. In general, however, it can be stated that in the first priority, the land use factor and human activities, and in the second priority, the geological factor affecting groundwater quality have the most significant effects. In the formation part of the geology, the dissolution of calcareous and dolomite formations, the chemical processes of salt dissolution, and evaporative formations are the main factors controlling groundwater chemistry in the region. Based on the results, multivariate statistical techniques and geostatistical methods have the ability to recognize factors affecting groundwater quality and the zoning of water quality for different uses and are, therefore, suggested for similar research.
پژوهشی
Fariba Esfandiyari Darabad; Rasoul Bakhshandeh; Masoud Rahimi; Khadijeh Haji; Raoof Mostafazadeh
Abstract
1-Introduction The changes in river processes due to river discharge and sedimentation as a primary principle driving force can affect the geometry of rivers. Determining the amount of sediment and floodplain and water quality study are prerequisites for river management operations. Any change in the ...
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1-Introduction The changes in river processes due to river discharge and sedimentation as a primary principle driving force can affect the geometry of rivers. Determining the amount of sediment and floodplain and water quality study are prerequisites for river management operations. Any change in the steady-state of the rivers will result in physical changes in the rivers and a new reaction to the rivers' behavior. Morphological studies to determine the quantity and quality of river response will predict future river behavior. The downstream river reaches of the Hamzekhanloo River basin is one of the most important agricultural areas of Germi city due to its fertile flood plains and sufficient water availability, which has undergone many changes in recent years. In this study, the Hamzekhanloo River was investigated based on the Rosgen stream classification scheme. 2-Methodology The Hec-Ras hydrodynamic model was used to simulate the Hamzekhanloo River cross-sections and floodwater capacity. The processing of the required data for modeling purposes was performed at the ArcGIS software; the classification of stream reaches was done using the Rosgen stream classification system. Rosgen classification system predicts river behavior based on morphology and hydraulic relationship and flow sediment with specific morphology. Based on Rosgen's method, morphological characteristics of rivers are investigated at four different levels but focuses more on two levels of general geomorphic properties and morphological description. Level 1 (General Classification): Describes the morphological characteristics of the river obtained by combining information on catchment, landform, and valley morphology. Level two (descriptive classification) of the river. 3-Results and Discussion The results of the Rosgen classification scheme showed that the studied river had been classified at the C class in some river reaches, which had high flood sensitivity, high vegetation control, high sediment recovery, and sediment supply potential. Also, these reaches had narrow to wide valleys, constructed from alluvial deposition with a well-developed floodplain. Meanwhile, some sections of the study river fall in the B class according to the Rosgen classification. These reaches exist primarily on moderately steep to gently sloped terrain, resulting in narrow valleys that limit the development of a wide floodplain. These streams display a low channel sinuosity, and streambank erosion rates are normally low. The sensitivity to flooding and sediment supply is high; the influence of moderate vegetation control and recovering potential is excellent. Moreover, the cross-section patterns in the river and the parameters affecting the classification and segmentation of reaches are consistent with the overall pattern on the Rosgen classification model. 4-Conclusions The river bed of the Hamzekhanloo River is a combination of rubble, gravel, and sand. Farmers and gardeners dig the riverbed and store water to irrigate the orchard fields and gardens during the summer, and crop cultivation is observed in the river bed and floodplain. Sand mining is a common activity in the river bed to carry out the development and construction purposes of the area. Sand removal from the riverbed has led to the formation of ponds within the basin, and such alterations have altered the bed and morphology of the Hamzekhanloo River. Thus, Rosgen's model can predict the geomorphic quantification of the Hamzekhanloo River and rivers with similar conditions. This type of river channel morphological classification can be used to develop engineering designs and management implications and river restoration.
پژوهشی
fatemeh parhizkar; Masume Rajabi; Mojtaba Yamani; Davoud Mokhtari
Abstract
1-Introduction For thousands of years, mangrove forests have played a significant role in the economy and sustainable livelihoods of human societies. Therefore, identifying and measuring changes in the boundaries of mangroves over time can play an important role in planning and conducting effective protection ...
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1-Introduction For thousands of years, mangrove forests have played a significant role in the economy and sustainable livelihoods of human societies. Therefore, identifying and measuring changes in the boundaries of mangroves over time can play an important role in planning and conducting effective protection measures and reducing the vulnerability of mangroves to natural and human hazards. This study aimed to investigate changes in mangrove forests and the relationship between these changes and marine hydrodynamics and coastal morphology in parts of the north and east of the Strait of Hormuz for 47 years. 2-Methodology In this study, Landsat satellite images, MSS, TM, ETM +, OLI sensors from 1972 to 2019 were used to monitoring mangrove forest changes in the west of the Hormuz Strait. In the next step, the necessary preprocesses (radiometric and atmospheric corrections) were applied to the images in ENVI 5.3 software. And the classification of images was done by SVM, MLC, and ANN methods, and considering that to finalize the land use map, all classification accuracy indicators should be adjusted with one or more valid statistical indicators. The kappa index and general accuracy are among the statistical methods used. Post-processing operations also included the integration of classes that were applied to make the land use map more eloquent and eliminate single pixels on different classes. In the next step, the Change Detection method was used to detect changes and tell the results of the classifications. The next step is to convert the classified image to polygon and transfer it to the Arc GIS environment to manage the classes. Of course, the class that is most important to us here is the Mangrove Forest class, which was examined in the period 1972-2019. After the changes in the mangrove forests were identified, with the help of 1: 25000 topographic maps, contours of 2 meters of the range were prepared and the slope map was prepared using DEM images of the area. Also, using the half-hour tide data, the minimum, maximum, and average tide rates of Jask, Shahid Rajaee, Hormoz, and Sirik stations were calculated and finally, these data and maps were prepared to examine the development potential of mangrove forests. 3-Results and Discussion Land use maps were developed using Landsat images using three pixel-based classification algorithms (MLC, SVM, ANN) and the accuracy of the results was assessed using random points. The results showed that the highest overall accuracy and kappa coefficient were 99.44 and 0.99 for region A, and 98.41, 0.97, for region B, for SVM, respectively. Our study showed that SVM could be the most appropriate classification method for this study area. Therefore, SVM land use maps were prepared for the study area for 1972, 1987, 2002, and 2019. After preparing the land-use change map, it was stated that mangrove forests in region A accounted for 55.84% and in region B for 36.18%, tidal areas in region A accounted for 27.63%, and in Area B is 36.58 percent, Water Areas A is 3.04 percent, Area B is 1.78 percent, dry land is 15.37 percent and region B is 99.99. 7% have changed over the past 47 years. To explore the potential for the expansion of mangrove forests, we examined the slope of the region and its relationship with the average tide in the region. Comparing the results of the increasing and decreasing trend of mangrove forests with curves corresponding to the average tidal level and morphological features of the region, we conclude that the study area is about the hydrodynamic characteristics of the sea such as the average tidal area and extent. The catchment area, the height of the waves, and the coastal morphology such as slope and sediments and the water entering the areas from the Hasanlangi River and the Gaz and Hivi rivers have a very high potential for further development of mangrove forests. 4-Conclusion The results show that in the northern part of the Strait of Hormuz, the area of mangrove forests has increased in all the years, but in the eastern part of the study, we have always faced a decreasing and increasing trend and we don't see this part significant development during these 47 years in mangroves. However, according to the study of the geomorphic features of the region such as slope, topography, and the presence of Sabkha and Firth and sediments from the rivers of Hassan Langi, Gaz, and Hivi, as well as the average tide of the region and the vast area it covers, The study has the potential to develop mangrove forests. The results of this study can provide significant information about the progress or regression of mangroves in different coastal areas, can significantly help to implement protection measures and rehabilitate Iranian mangroves.
پژوهشی
yaser hoseini
Abstract
1-Introduction Flood is a natural phenomenon, which threatens the life and properties of a large number of people all over the world, yearly. Flood discharge, regarding water resource exploitation, flood control, construction of dams, basin management, and hydrologic studies, is of high importance in ...
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1-Introduction Flood is a natural phenomenon, which threatens the life and properties of a large number of people all over the world, yearly. Flood discharge, regarding water resource exploitation, flood control, construction of dams, basin management, and hydrologic studies, is of high importance in studies. Therefore, the accuracy of these studies and the safety of waterworks and water structures depend on the methods of studies to a large extent. It is impossible to manage water resources in basins without the accurate determination of the peak flood discharge. The advances in flood estimation techniques have made it possible to use rainfall-runoff models to assess the hydrographic properties of the flood in watersheds and decrease the risks of the flood. In studies on water resources, it is of high importance to determine the flood discharge of different basins. Studies of Dile and Srinivasan (2014) and Hoseini et al. (2017) showed that basin level and rainfall can be the most important factor in runoff flow. Consequently, proper simulation and modeling of flood runoff are the important parameters in flood management in the region. However, it is necessary to use new models to determine flood hydrograph parameters. So, this study aimed to determine the peak flood discharge of the Darrehrood basin using regression mode for return periods of 10, 25, 50, and 100 years. 2-Methodology Darrehrood basin is located in Northwest Iran. The basin is surrounded by mountains and is considered the main basin of Ardabil Province. It lies within 47°30' to 48°55' longitude and 37°45' to 39°42' latitude. Its area is approximately 12900 km2. Discharge data were collected from 16 hydrometric stations with a statistical period of 15 years during 2001-2015. Incomplete data related to stations were completed using statistical methods and considering the best statistical distribution of floods in the studied sub-basins, floods with different return periods were calculated then the physiographic characteristics of sub-basins that affect flood rate include: area, slope, shape factor, height average, concentration-time, and curve number achieved using ArcGIS and WMS (watershed modeling system). To evaluate the model, maximum error (ME), root mean square error (RMSE), relative percentage error (ε), mean absolute error (MAE), coefficient of determination (R2), Coefficient of residual mass (CRM), and model efficiency (EF) were used. 3-Results and Discussion The model calibration results showed that the simulated peak discharge and flow volume are in good correspondence with the observed values, so that, the lowest goodness of fit (R2) value in the return periods of 10, 25, 50, and 100 years were estimated to be 97, 96.6, 95.8 and 94.7 %, respectively. The results showed that the linear regression model with very good accuracy can predict the peak discharge in the sub-basins in Darrehrood using the physiographic parameters of the basin and with increasing the return period, the accuracy of the model is slightly reduced. Model evaluation indicators for the return period of 100 years include root mean square error (RMSE), relative percentage error (ε), mean absolute error (MAE), Coefficient of residual mass (CRM), and model efficiency (EF) were calculated 40.75, 52.12, 0.52, 0.92 and 0.62 respectively. Cross-validation diagrams showed that all models were partially underestimated and the scatter of points around the one by one axis was very suitable for the whole return periods. According to the paired t-test of the difference between predicted and actual values in different return periods in the level confidence of 1% are not significant. 4-Conclusions The results of this study show that the model has good accuracy for estimating floods in sub-basins of Ardabil province.
پژوهشی
Alireza Habibi; Hamidreza Masoumi
Abstract
1-Introduction Many studies have been conducted on the water balance of watersheds based on the SWAT model, among which, one can mention the research of by Van Liew and Garbrecht (2003: 413-426), Neitch et al. (2005: 494), Abbaspour et al. (2007: 413-430), Rostamian et al. (2008: 977-988), Faramarzi ...
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1-Introduction Many studies have been conducted on the water balance of watersheds based on the SWAT model, among which, one can mention the research of by Van Liew and Garbrecht (2003: 413-426), Neitch et al. (2005: 494), Abbaspour et al. (2007: 413-430), Rostamian et al. (2008: 977-988), Faramarzi et al. (2009: 486-510), Hoseini (2014: 63-73), Habibi et al. (2016: 275), Nadi et al. (2018: 61-79) and Ghazavi et al. (2018: 54-79). This research is based on the initial field observation and a question that, how much rainfall (rain and snow) transfer to groundwater with the performance of faults and rock units with high permeability? Therefore, according to the geological conditions, the Roodak basin upstream of the Latian dam was selected as the study area. So, SWAT model, field, and tectonic studies have been used to answer the research question. The Roodak basin has more than 420.41 square kilometers area. 2-Methodology The statistical indices of R2 and Nash-Sutcliffe (NS) were used as the most important evaluation criteria to quantitatively evaluate the performance of the ARC_SWAT model in the calibration and validation stages. Calibration and analysis of model were used and performed SUFI2 algorithm in SWAT Cup software and flow data of Roodak hydrometric station. Calibration for the years (2000-2007) and validation based on the statistics of the years (2008-2011) was performed after stimulation using calibrated values for sensitive parameters. Then the basin water balance check was obtained. The relationship between rainfall and permeability has been investigated based on geological components such as fractures, faults, and lithology. Mosha-Fasham fault and Latian fault are the main faults of the study area. The main controller of tectonic activities in the area is the Mosha-Fasham fault and its sub-branches. The main branch of this fault as a thrust has passed through the middle part of the basin and has pushed the Paleozoic and Mesozoic formations on the younger formations. Also, its sub-branches have caused disruption in the geological structures with normal and inverse functions. The northwestern part of the Latian fault is another important tectonic fracture of the Roodak basin and acts in the outlet parts of the basin. In this part, the Emameh River flows along the Latian Fault. The rock units of the region are divided based on field data and remote sensing studies of the 2019 Landsat 8 satellite image by Arc GIS software. From the lithological viewpoint, from old to new rocky and sedimentary units have respectively the following conditions. Red micaceous siltstone and sandstone of Zagoon Formation (Cz). Limestone and dolomitic lime, sandstone, and shale of Mila Formation (Com). Dark fossiliferous limestone and shale of Mobarak Formation (Cm). Oolitic limestone, thin-bedded shale and dolomitic limestone, and thick-bedded dolomite of Elika Formation (Tre). Grey shale and sandstone of Shemshak Formation (TRjs). Conglomerate, sandstone, and coaly shale of Shemshak Formation (Jk). Light grey massive limestone of Lar Formation (Jl). Light color massive orbitolina limestone of Tizkouh Formation (Ktzl). Polygenic red conglomerate and sandstone (Elc). Green tuff of Karaj Formation (Etu). Tuff with shale interbeds of Karaj Formation (Eksh). Dark green shale with tuff interbeds of Karaj Formation (Esh). Green tuff and Tuffy shale interbed of Karaj Formation (Ek). Red marl, gypsy marl, sandstone, and conglomerate of Upper red Formation (Mur). Recent sand and aeolian sand (Qsd). 3-Results and Discussion After running the model, the outputs including runoff, subsurface flow, etc., were obtained as a text file. Using the results of model, sensitivity analysis were identified nine sensitive parameters among the total 17 parameters. By SUFI2 algorithm were determined the optimal values of the sensitive parameters of the model. The results showed that the snowmelt and snowfall temperatures are the sensitive parameters of the model. The share of surface runoff, lateral, and groundwater flow in the monthly flow of Roodak River is presented in Table 1. Table (1): Water balance components of Roodak basi. variable Value (mm) Percent relative to rainfall Rain 585.67 100 Evaporation & transpiration 427 72.75 Water in the soil 10.44 1.78 Surface flow 18.49 3.15 Subsurface flow 118.72 20.27 Groundwater flow 11.35 1.93 Deep infiltration 0.68 0.12 The upstream areas of the basin have rock units with a relatively high permeability in terms of physical and dissolution conditions, based on geological data including fault, fracture, and lithology information. These rock units include limestone and sandstone of the Paleozoic and Mesozoic formations. Therefore, the expected power for the downward flow is high in these areas. In the middle and downstream areas, the intrinsic permeability of rock units is relatively low, due to Tuffy and marly lithology. However, the transferring surface water to depth is accelerated due to the extensive tectonic fractures. In contrast, disrupts this transfer to depths and makes subsurface flow the effect of secondary fillings on fractures. 4-Conclusions Generally, in simulating the Roodak basin flow the values of all indicators and the results of geological studies indicate the acceptable accuracy of the model. By running the ARC_SWAT model it was possible to simulate the monthly flow of the study period in this basin. Also, the statistical comparison has shown acceptable results. So the statistical comparison of simulation and observational hydrographs show a correlation of about 60% with the Nash-Sutcliffe criterion. This study provides useful information on the river flow and water balance of Roodak Basin and helps more accurately with water resources projects. The evapotranspiration potential (PET) is 1025.4 mm. The total water of the basin equal to 247.89 mm included surface runoff, groundwater, and lateral flow. Agricultural products temperature and water stresses were 129 and 80 days which calculated at the SWAT_ CHECK. Therefore, according to the simulation results, it can be inferred that the ARC_SWAT model has acceptable performance in the Roodak basin. Geological evidence indicates that the rock units have high permeability in upstream and low permeability in downstream areas. However, the results of the SWAT model showed that rainfall is flowing in the direction of the Emameh River slope in the form of subsurface flow. This is due to the action of Latian fault in the transfer of surface water to subsurface flow. Also, according to station data, water entering to Emameh River has the highest amount in winter and spring and the lowest level in late summer. Therefore, subsurface water as a base flow provides a significant part of the water in all months of the year. Surface runoff has a large share in the river flow from mid-autumn to early spring. Lateral flow accounts for a very small share of river flow in all months of the year. The simulation accuracy is acceptable in this research in comparison to the results with similar studies. The results of this study can be used by examining the impact of land-use change with different scenarios to predict the effects of management planning and climate change due to rainfall.
پژوهشی
khadijeh Javan
Abstract
1-Introduction Climate change has been a very important issue in recent decades. Recently, frequent climatic events such as storms, floods, and droughts have been reported around the world (Habeeb et al., 2015). These extreme events will have devastating effects on ecosystems, society, and the economy ...
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1-Introduction Climate change has been a very important issue in recent decades. Recently, frequent climatic events such as storms, floods, and droughts have been reported around the world (Habeeb et al., 2015). These extreme events will have devastating effects on ecosystems, society, and the economy (Hallegatte et al., 2013). Among these extreme events, drought plays a more prominent role due to its direct impact on socio-economic development and environmental degradation. Therefore, understanding drought phenomena is important for proper planning and management of water resources (Yilmaz, 2019). So far, various indicators have been proposed to monitor the drought. Undoubtedly the most well-known drought monitoring index is SPI proposed by McKee et al. The World Meteorological Organization has recommended this index as the main indicator of meteorological drought. It is also important to analyze the SPI trend, which provides scientific information for better modeling as well as the prediction of the phenomenon (Golian et al., 2015). A review of research conducted worldwide and in Iran shows that drought trend analysis has been mainly done using parametric tests such as linear regression and non-parametric tests like Mann-Kendall, Spearman, Sen’s estimator, and modified Mann-Kendall. These methods require a set of assumption validity such as serial correlation structure, probability distribution functions, and seasonal trends. For this reason, Şen (2012) proposed the Innovative Trend Analysis (ITA) method, which does not require any assumptions and analyzes the trend of time series based on a comparison of two ascendingly ordered halves. This method has found wide applications in hydro-climatic research and has been considered and used by many researchers. This study aimed to identify drought-prone areas in the Lake Urmia basin using SPI time series and the innovative trend analysis (ITA). For this purpose, SPI values in 12 and 24-month time scales were calculated based on 32-year-long precipitation data (1986-2017) in 8 synoptic stations in the Lake Urmia basin. Then the trend of the SPI series was investigated using the ITA method. Finally, the results of this method were compared with the results of the Mann-Kendall test. 2-Methodology 2.1. Standardized precipitation index (SPI) Among the quantitative indicators in drought analysis, SPI is acceptable as a suitable index for drought analysis due to the simplicity of calculations, the use of available rainfall data, and the ability to calculate for different time scales as well as different spatial scales. SPI can show the impact of drought on water resources. In a general classification, it is possible to use the 1 to 3-month SPI for meteorological drought, 3 to 6-month SPI for agricultural drought, and 12 to 24-month SPI for hydrological drought analyses and applications (Bonaccorso et al., 2003). 2.2. Innovative Trend Analysis (ITA) This method has been proposed by Şen (2012). In this index, time series are divided into two equal parts, which are separately sorted in ascending order. Then, the first and the second half of the time series are located on the x-axis and y-axis, respectively, of a Cartesian coordinate system. If the data are collected on the 1:1 straight line (45°), there is no trend in the time series (Fig. 1). If data are located on the upper triangular area of the ideal line, an increasing trend in the time series exists. If the data pile up in the lower (upper) triangular area of the 1:1 line, there is a decreasing (increasing) trend in the time series (Şen, 2014). Fig (1): ITA method The statistical significance test of the ITA method has been also proposed by Şen (2017). This test is performed based on the construction of confidence intervals and considering the difference between the two population means. If the slope value (s) is between the upper and lower confidence limits, the null hypothesis (H0) is confirmed; otherwise, the alternative hypothesis (H1) is accepted. The type of trend depends on the slope sign. The slope value can be positive or negative; this means that there is an increasing (+) or decreasing (-) trend in the time series (Şen, 2017). 2.3. Mann-Kendall test (MK) The non-parametric Mann-Kendall test is one of the most widely used methods for trend detection in time series. One of the main advantages of nonparametric methods is that the presence of outgoing data affects the result of the data process less than parametric methods. Besides, it is more suitable for data series having a short length and not normal statistical distribution or having missed data (Partal and Kahya, 2006). The positive and negative Z values indicate the increasing and decreasing trend in the series, respectively. 3-Results and Discussion To detect the drought trend in the stations of the Lake Urmia basin, the ITA method was used for the 12 and 24-month SPI series. All SPI series were divided into two 16-year sub-series: from 1986 to 2001, and from 2002 to 2017. To identify the possible trend of the drought as well as normal and wet conditions easily and better, two vertical lines have been added to the diagrams. The red line indicated the drought limit and the green line indicated the limitations of the wet conditions and the area between the two lines representing the normal conditions. According to the figures, the 1:1 line shows the neutral line (no trend) and in the case of no trend, the center point falls on the 1:1 line. The results of the trend analysis of 12-month SPI values showed that the drought and normal periods in Urmia, Saghez, and Mahabad had an increasing trend, but the wet conditions followed a decreasing trend. In Tabriz, an increasing trend was seen in normal and moderately drought periods, and a mild decreasing trend was seen in wet periods. In Takab, wet periods showed a sharp decreasing trend, and a slightly increasing trend could be seen in Sarab. In Sahand and Maragheh, there has been a declining trend in all SPI values, leading to more severe drought and weaker wet periods. The significance analysis of ITA and the Mann-Kendall test showed that in the 12-month SPI time series and based on the ITA method, all stations showed a significant trend, which was increasing in Tabriz and Sarab, and in other stations, it was decreasing. While the Man-Kendall method did not have a significant trend in Urmia, Tabriz, and Sarab, it showed a significant decreasing trend in other stations. In the trend analysis of 24-month SPI values by the ITA method, almost the same results were obtained. However, it should be noted that there was an increase in the slope of the trend for all stations. Another important point is that there were no significant increases in wet conditions. Similar to the results of 12-month SPI and based on two methods, the significance analysis of the ITA and Mann-Kendall test showed that Takab, Saqez, Sahand, Maragheh, and Mahabad had a significant decreasing trend and the difference was only observed in the higher ITA slope as well as the higher Z values in these stations. While in Urmia, Tabriz, and Sarab, there was no correspondence between the two methods. 4-Conclusions In this study, the ITA and Mann-Kendall trend tests were used for the 12 and 24-month SPI time series, determined for the 1970-2017 period, in order to demonstrate the hydrological drought trends in the Urmia Lake`s basin. The results of ITA and Mann-Kendall tests showed that Maragheh, Sahand, Saqez, Takab, and Mahabad had a significant decreasing trend in the 12 and 24-month SPI series. In Urmia, Tabriz, and Sarab, the Mann-Kendall test did not show any significant trends; while the ITA method showed significant decreasing and increasing trends in these stations. The results of this study can be used to manage water resources and understand the characteristics of climate change in the studied area.
پژوهشی
Hadi Abdolazimi; Sayed Hussein Roshun; Sayed Amir Shamsnia; Hamidreza Shahinifar
Abstract
1- Introduction Population growth, industrial expansion, urbanization, and urban construction have led to drastic changes in the morphology of catchments. Land grading and encroachment on rivers and canals have changed the pattern of natural drainage and flow in cities. One of the consequences of this ...
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1- Introduction Population growth, industrial expansion, urbanization, and urban construction have led to drastic changes in the morphology of catchments. Land grading and encroachment on rivers and canals have changed the pattern of natural drainage and flow in cities. One of the consequences of this phenomenon is the increase in the risk of flooding and flooded passages and the increase in maintenance costs of cities and has caused a lot of possible human and financial losses in some cities. In our country (Iran), the occurrence of floods is related to the disturbance of the natural balance and the morphological and physiographic conditions of the watersheds than to the heavy rains. One of the reasons for the flood event is the difference in topographic altitude between different regions of the country, according to which runoff is drained from the highlands to the lowlands in the shortest time. Therefore, the importance of research in the field of flood mapping has doubled. Unfortunately, the recent flood that occurred in April 2017 at the Quran Gate in Shiraz was one of the cases in which human intervention and lack of accurate knowledge about the watershed conditions led to irreparable human and financial losses. The floods killed 19 people and injured 200 others. Due to the occurrence of conditions and prevention of similar events, in the present study, to manage the crisis, especially in the prevention phase, floods zones of Shiraz metropolis using TOPSIS method and Geographic Information System (GIS), be identified and evaluated. 2- Methodology As the capital of Fars province, Shiraz is located on a long plain 120 km long and 15 km wide. The city is geographically located between the coordinates '53 '29 29⁰ to ''47 '41 29⁰ north latitude and ''36 '26 52⁰ to ''02 '37 52⁰ east longitude. The sea level is 1488 meters at the eastern end of the city and about 1700 meters to the west. In this study, a flood mapping was prepared using the TOPSIS method in ArcMap10.3 to identify flood risk areas. In this regard, thirteen criteria, including slope, aspect, elevation classes, precipitation, distance from the canal, drainage density, distance from worn-out urban structures, building density, geological formation, land use, groundwater depth, history of floods, and runoff, were used as information layers. In this study, the TOPSIS decision-making method (similarity to the ideal solution) was used. In this method, two concepts of the ideal solution and anti-ideal solution have been used. The concept of the ideal solution is the best in every way, which is generally not the case in practice, and it tries to get closer to it. In order to select an option to resemble an ideal and counter-ideal solution, the distance between that option and the ideal and counter-ideal solution is measured. The options are then evaluated and ranked based on the ratio of the distance from the counter-ideal solution to the total distance from the ideal and counter-ideal solution. 3- Results and Discussion The most important factor in the study of flood risk areas in the city is identifying and prioritizing effective criteria in creating floods and the study of watersheds in the city, each of which is of varying degrees of importance. The results of the influential factors in flood occurrence can be expressed in the following order; the height criterion is one of the cases with an inverse relationship with the emergence and formation of the flood. The height of Shiraz varies from 1449 meters to 2284 meters. A very steep slope is observed in the northeastern part of Shiraz (Abivardi region towards Chogiah to the Quran Gate), and most of the city is developed in the plains and lower elevations. Most slope directions in Shiraz city are related to the eastern heights of the city (Saadi region 3, Daneshgahian dormitory, Haft Tanan for north and northwest slopes, Shiraz Marvdasht highway, beautiful Quran city gate for west and northwest slopes) (Region 1, Jomhory, Kuhsar Mehdi Abivardi West and Northwest and Chogiah North) (District 6 Mahmoudieh Mansourabad North and West of Drak Heights to the north and northwest slope) (Region 11 Qanat Pisheh North) The western helpers of the North Talaieh Highway (District 10 of Arian Town, Anjireh Town, is the northern and northwestern slopes of Drak). The highest drainage density is related to areas 1 and 6 of Shiraz city. The main geological formations of Shiraz plain with high and low-level sediments are dolomite, limestone with layers of sandstone or marl, limestone, and marl. The lower the permeability of these formations, the higher the score on the map. The final map of the flood-prone areas of Shiraz was classified into five very low, low, medium, high, and very high-risk classes. The results show that areas 2, 3, 11, 7, and 9 are most vulnerable to floods. Also, 2754 hectares of Shiraz city are in the very high-risk category, 6076 hectares are in the high-risk zone, 17390 hectares are in the medium-risk zone, 13418 hectares are in the low-risk zone, and 6658 hectares are in the very low-risk zone. 4- Conclusions Thirteen effective parameters in flood occurrence were used to identify the flood hotspots in Shiraz. Then, using the TOPSIS-GIS approach combination, ten regions were examined. The TOPSIS integrated model is based on the ideal extraction of positive and negative points and determining the distance of each criterion in order to determine the best spatial option in terms of flood hazards. Using geographic information system (GIS) and ArcMap 10.3 software, the layers were prepared, and the best spatial options in terms of flood hazards were determined from the TOPSIS model. Several phenomena are commonly involved in urban flooding, including the limited transmission capacity of urban canals and rivers, drainage and sewage, and decades of urban development without updating the drainage infrastructure of flood-prone areas of Shiraz. Quran, Shiraz Marvdasht Road, Ayatollah Rabbani Boulevard, Haftannan, Chehelmogham Boulevard, Haftannan Boulevard, Saadi Town, Students' Alley, Saadi Gharb, Fazilat Tunnel, Delgsha Boulevard (underpasses), Fig neighborhood, along dry and coastal river crossings Slope, direction of slope, increase of constructions in the river area, increase of impermeable surfaces and building density), District 11 of Shiraz city: Fazilat tunnel, Parvaz town, Rasoul Azam boulevard, Persepolis boulevard, Sibouyeh town, police force town, Shahid Beheshti town, Talab town, buildings located in the foothills (main factors of slope flood, low groundwater depth, constructions in the river area, and inadequacy of urban sewage disposal systems), District 7: Sharifabad, Sahlabad, 20 meters from the sewer, town Imam Hossein, Mehregan town, Kushkak neighborhood, Nasrabad neighborhood and Abu Nasr (main causes of flood: low groundwater depth and inadequacy of urban sewage disposal systems), District 8 of Shiraz city: Isfahan Gate, Takhti St., Keshavarz St., Teymouri St., Imam Ali Bridge, Ali Bin Hamzeh Bridge (main factors Flood due to slope and inadequacy of urban sewage disposal systems), Region 9: Hojjatabad, Bargh, Darati, Modares, Mehdi, Sultanabad, Rezvan and Fajrnegar towns (main causes of increased floods in the area of Chenar Rahdar road), Region 1: Abivardi neighborhood, Mehdi mountain, next to the passages of the martyrs Emdadgar, Fajr, Bahman, reporter (main causes of slope flood and river flood), region 5: Golha town and Nawab Safavid martyr (main factors of flood low groundwater depth, and Inadequacy of municipal sewage disposal systems) Region 2: Glasswork, pottery (Abuzar), tannery, Zahra alley, Fazlabad, Bahar town (Pai Kata), Vali Asr and Sibouyeh boulevard (main causes of floods: low groundwater depth, and lack of Suitability of municipal wastewater disposal systems).
پژوهشی
daniyal sayyad; Ebrahim Omidvar
Abstract
1-Introduction Runoff is one of the most important components of the hydrologic cycle. Since there are no observational data in basins lacking statistics, the process of calibration and validation of hydrologic models seems impossible in these basins. On the other hand, predicting runoffs in basins lacking ...
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1-Introduction Runoff is one of the most important components of the hydrologic cycle. Since there are no observational data in basins lacking statistics, the process of calibration and validation of hydrologic models seems impossible in these basins. On the other hand, predicting runoffs in basins lacking statistics is essential for planning and management of the basin (runoff estimation, ecosystem services, flood control) (Beck et al., 2016). However, predicting the runoff in basins lacking statistics has been comprehensively discussed using the calibrated hydrologic model in basins having observational statistics through the zoning approach (Yang et al., 2019:67). The zoning approach has been identified as the cheapest and most prevalent solution for solving the prediction problem of flows in basins lacking statistics (Cislaghi et al., 2020:348). According to the definition of the zoning approach, predicting runoff in basins lacking statistics is done using data transfer from basins having statistics to the basins lacking statistics (Rojas et al., 2016). 2- Methodology To conduct this study, firstly SWAT model was calibrated and validated in the watershed basin having statistics; then, the calibrated parameters were transferred to Sukcham basin which lacked statistics, to simulate and analyze the flow using hydro office-FDC software. To analyze the sensitivity of parameters in the zoning approach and for simplifying the complex structure of hydrologic models like SWAT, minimizing the number of parameters in the modeling phases was a necessity. To this end, firstly, a sensitivity analysis was done for the basin having statistics using 14 sensitivity parameters affecting the flow. According to the global sensitivity analysis, the parameters were ranked in SWAT CUP-SUFI-2 based on the sensitivity level and considering two P-value and T-stat factors. Later, 14 parameters having high sensitivity in the basin having statistics were calibrated and transferred to the basin lacking statistics (Sukcham) using zoning and physical approaches. 3-Results and Discussion According to the obtained results from sensitivity analysis of 14 sensitive parameters in the flow simulation, SLSOIL, HRU-SLP, CH-S1, CANMX, SOL-AWC parameters were recognized as the most sensitive parameters of the region. The performance evaluation criteria of NSE, R2, and PBIAS models, respectively, for the calibration periods, were 0.6, 0.65, and 10.7 and for the validation, periods were 0.47, 0.63, and 11.88, showing the acceptable accuracy of daily discharge simulation in the daily scale. After calibration and validation of SWAT model in the basin having statistics and the basin lacking statistics (Sukcham), the daily time step was applied for the 2008-2015 period, and the calibrated parameters of the basin having statistics were transferred to the basin lacking statistics through zoning approach and using physical characteristics. Considering Table (9), the average daily outlet runoff, as well as the average volume of annual outlet runoff for the basin lacking statistics (Sukcham), were estimated. The estimation of such information from basins lacking statistics can present managerial views toward controlling the flood and preventing the occurrence of devastative floods as well as providing the required water sources for filling the aquifers and agriculture in dry regions. Considering Figure (9), the moisture indexes (Q10-Q20) were respectively 0.12 and 0.16 m2/s (10 and 20 percent of the days in a year (33 and 73 days)), discharges were 0.12 and 0.16 m2/s or more. Considering the average extracted index from the curve, flow duration was obtained, respectively, 0.115 (30% of days in a year (110 days)), 0.111 (40% of days in a year (146 days)), 0.094 (50% of days in a year (183 days)), 0.081(60% of days in a year (219 days)) m2/s. Moreover, the scope of low flow index (Q70 toQ95) for 256 and 347 days of a year was obtained 0.058 and 0.024, respectively. In addition, the flood index (Q5) was 0.28 m2/s (5% of days in a year (18 days)), for which the flood discharge equaled 0.28 or more. 4-Conclusions Considering the performance evaluation criteria, the performance of SWAT in dry basins having statistics was good and satisfactory in the daily scale of calibration and validation phase. According to the results of administering the SWAT model in the basin lacking Sukcham statistics, the average daily runoff flow (0.107 m2/s) and the average volume of total annual outlet runoff (million m2) of this basin have been estimated. Then, the flow duration curve was drawn for the Sukcham River in the hydro office-FDC software. Considering the results of the flow duration curve of the Sukcham River, it could be concluded that the scope of moisture, moderate and low flow indexes were respectively, (0.12-0.16), (0.081-0.115), and (0.024-0.058) m2/s. Moreover, the flood index (Q5) was obtained 0.28 m2/s for Sukcham River; which meant that regarding 5 % of the days in a year (18 days), the flood discharge equaled 0.28 m2/s or more. The extraction of these results may help in better recognition of hydrologic behavior of basins lacking statistics for planning and management purposes of water sources such as controlling sudden floods and providing drinkable water and agriculture.
پژوهشی
Alireza Donyaii; Amirpouya Sarraf
Abstract
1- Introduction Climate evolutionary theory reveals that climate change has already been evident in the planet's history, but when opposed to historical climate changes, the climatic changes of the last century have two unique characteristics. First, through the nature of the ongoing climate change, ...
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1- Introduction Climate evolutionary theory reveals that climate change has already been evident in the planet's history, but when opposed to historical climate changes, the climatic changes of the last century have two unique characteristics. First, through the nature of the ongoing climate change, human actions play a significant role Second; the speed of recent climatic changes is greater, so that, many changes will be occurring in the Earth's atmosphere during a short term [Telmer et al. 2004]. Nowadays, global warming has significant effects on precipitation and runoff yield and water resources due to the increased concentration of greenhouse gases [Donyaii et al. 2020]. The average meteorological parameters, in particular the annual or seasonal components of temperature, precipitation and runoff, play a significant role in the hydrological cycle and are typically used as an indicator for climate change evaluation on the water supplies available to Iran now and particularly in the future [Donyaii et al. 2020]. Based on the IPCC Fourth Assessment Report Models [AR4], a number of studies have been undertaken to examine the effect of climate change on the hydrological components of watersheds in Iran. In contrast with the Fifth Assessment Study [AR5] models, these models, along with older pollution scenarios, have limited resolution. Therefore, in the watersheds of Iran, climate change experiments with higher resolution climate models under the latest pollution scenarios [RCPs] of the AR5 seem appropriate. According to historical evidence of Gorganroud's high flood capacity in the province of Golestan, Iran, the recognition of the impact of climate change on the watershed's hydrological regime is important for water resource planners. 2- Methodology 2-1- Study area and data set The Gorganroud Watershed is located in Golestan Province, Iran. In this study, the Soil and Water Assessment Tool [SWAT] was employed for hydrological simulation of the watershed based on the downscaled outputs [using the Bias Correction and Spatial Disaggregation [BCSD] method] of fifth assessment report climate change model [MIROC-ESM] for historical and future periods. The trend analysis of hydro-climatic records was done according to the non-parametric Mann-Kendall test. The future projection was conducted for the near [2025-2050], mid [2051-2075], and far [2075-2100] future periods related to historical records in the period of 1985-2005. 2-2- SWAT set-up and calibration, validation and uncertainty analysis In this study, runoff was estimated using the Soil Conservation Service [SCS] method. The Manning equation and Muskingum method were utilized to calculate flow velocity and routing phase, respectively. On the other hand, the SUFI-2 algorithm was employed to calibrate and analyze the sensitivity, and uncertainty of the SWAT model. The sensitivity analysis is based on linear approximation and the degree of uncertainty is calculated by two factors called r-factor and P-factor. The calibration and validation were performed using runoff data in the periods of 1995-2015 and 2016-2019, respectively. The coefficients of determination [R2] and Nash-Sutcliffe [NS] were used as the objective function to determine the goodness of fitness. 2-3- Climate Change scenarios and AR models In the AR5 new emission scenarios based on emission forcing level until 2100 were employed. In order to investigate the future climate change, the Model for Interdisciplinary Research on Climate-Earth System Models [MIROC-ESM] was selected among the newest extracted models presented in the AR5, because the result of this model in Gorganroud watershed showed the highest agreement with observational data. This model consists of four emission forcing scenarios [RCP2.6, RCP.4.5, RCP6.0 and RCP8.5. 3- Results and Discussion 3-1- SWAT sensitivity analysis, calibration and validation analysis Seventeen parameters were chosen for SWAT sensitivity analysis using the 500 simulations of SUFI-2. Results showed that the parameters CN, SOL_BD and SOL_K have the highest relative sensitivity. Based on the results, the coefficients R2 and NS for runoff simulation were estimated to be 0.79-0.77 and 0.74-0.71 in the calibration and validation stage, respectively. Therefore, the results of the model are acceptable and its uncertainty metrics is satisfactory in general. The study results showed that the model has estimated the amount of peak discharge less than the actual amounts, which is confirmed by the average monthly simulated discharge during calibration and validation periods. The results also showed that more than 50% of the observational data in both calibration and validation phases are bracketed by the 95PPU uncertainty estimation band, which indicate a rather acceptable degree of certainty in simulation. 3-2- Climate change simulation results and trend analysis In the near and mid-future, there are increasing changes under the RCP2.6 scenario, but the trends of rainfall are not statistically significant at the 5% level. In the far- future a significant increasing trend is observed under the RCP2.6 scenario, meanwhile in far-future under the RCP4.5 scenario there are increasing changes, but the trends are not statistically significant. In the mid and far future under the RCP6.0 scenario, a significant increasing trend has been observed. Finally, in the mid- future under the RCP8.5 scenario, there is a significant increasing trend. However, the increasing changes in the near and far-future periods are not statistically significant at the confidence level of 95%. The trend analysis of variables indicates that the amount of rainfall will decrease in this watershed during the future periods by the end of the 21st century. The most decreasing alterations in the rainfall and the highest increase in the temperature are achieved under the highest concentration of greenhouse gases [RCP8.5]. Moreover, in the near, mid, and far future, the runoff changes are decreasing under the RCP2.6 scenario, but the trend is not statistically significant. In the mid and far-future periods under the RCP4.5 scenario, there is a statistical significant decreasing trend in runoff; however, the decreasing variation in the near future is not significant. In the near, mid, and far future under the RCP6.0, runoff variations are declining, but the trend is not statistically significant. In the far-future period, under the RCP8.5, there is a significant decreasing trend; however, in the near and mid-future, runoff declining changes are not statistically significant. Reduced rainfall and increased temperature in the watershed will reduce the rate of runoff in the future periods in such a way that the security of the inhabitants of the region will be severely affected. 4- Conclusions Results of evaluation criteria [R2 and NS] showed that the SWAT performance for the simulation of runoff in the Gorganroud watershed was not satisfactory, but it was in an acceptable range. Climate change simulation indicated a decreasing trend for rainfall in all future periods, but this trend was not statistically significant. The temperature variable in all RCPs had an increasing trend. However, temperature trend analysis under the RCP4.5 scenario during the near and mid- future and under the RCP6.0 scenario during the near, mid, and far-future showed a significant upward trend. Runoff under the RCP4.5 scenario during the mid to far-future and under the RCP8.5 scenario during the far-future period followed a significant downward trend. Runoff during the near-future period under the RCP4.5 scenario and throughout the near to mid-future under the RCP8.5 scenario, had declining variations, but its trend was not statistically significant. In general, these results indicated that the amount of temperature will follow an increasing tendency; while rainfall and runoff will follow a decreasing movement in this watershed by the end of the 21st century.
