مجله علوم و مهندسی آبخیزداری ایران
پیاپی 45 (تابستان 1398)

Studying climate change impact on hydrological variables such as runoff has attracted more attention over recent years mainly due to the imposed imbalance in climate system by greenhouse gas emission. Hence, initially in this research, the trend and abrupt changes of hydro – climatic variables were studied using data mining approaches in 18 stations over 40 years (1972-2011) in Aji-Chai watershed located in northwestern Iran and secondly, the outputs of climatic variables including temperature and rainfall of HadCM3 under A2 and B2 scenarios downscaled by SDSM in order to studying the climate change impact on runoff. Finally, five data mining and intelligent models including ANFIS, SVM, MLP, M5, M5 Rules were used to rainfall – runoff modeling. The results showed that the hydro – climatic variables have been changed over the last four decades which make it necessary to study climate change and consider its impact on the runoff in the study area. The results showed that the maximum temperature will increases 2.04 and 2.40 degrees centigrade until 2010 to 2050 and 3.87 and 5.11 degrees centigrade until 2051 to 2091 under A2 and B2 scenarios, respectively.  Also the minimum temperatures will increases 1.63 and 1.90 degrees centigrade until 2010 to 2050 and 3.76 and 3.00 degrees centigrade until 2051 to 2091 under A2 and B2 scenarios, respectively. The results of future rainfall prediction showed no specific trend while in some seasons showed increasing and in other cases showed decreasing trend. The results of the model performance evaluation determined the M5 and MLP models the lowest errors. In general, the results of rainfall – runoff modeling indicated inherit uncertainty of the models and the runoff will increase or decrease over the seasons.

In recent years with developing geographic information systems tools, modeling and simulating methods has been developed quickly. Availability of accurate base maps is the basis of the cell sizes determination and preparing digital hydrologic models. Removing errors and minimizing of uncertainty factors in the digital models play the main role in improving the accuracy of the maps. The main purpose of this research is to produce GIS layers for Shaharchi river basin located in West Azerbaijan, according to the base maps of Iran and evaluating the accuracy of these maps. Physiographic parameters and hypsometric charts of the Shaharchai basin were estimated and drawn. Results showed that with increasing cell sizes, average, maximum and standard deviation of the slope decreased. The maximum slope is more dependent on cell sizes than the average and standard deviation. To calculate the watershed slope, at a scale of 1: 25000, a cell size of 15 meters and a scale of 1: 50000, a cell size of 40 meters and a scale of 1: 250,000, 90-meter cell size were distinguished as optimized cell sizes. After calculating the actual average slope of river profile and comparing with the slope amounts of each cell sizes and map scales it is concluded that for preparing river profiles the best cell size is 15 meters for 1:25000 map scale. The percent error of pits in the scale of 1:25000, increased slowly in the cell sizes smaller than 15 meters.

Sediment transport is one of the important indicators of rivers in natural conditions, which is affected by the change in geometric and flow characteristics, and is reflected in the alignment or sedimentation of different river routes. Therefore, providing suitable solutions for sediment control and fixing the longitudinal slope of the substrate and preventing sediment transport from upstream areas with a steep slope into the dams reservoirs, which is a major reason for their useful life, The necessity of carrying out the experiment in this field is justified. This research studies the sedimentation status and how it is controlled using the physical model of short successive dams made of Plexiglass at three altitudes and three different distances when the slope of the substrate and the discharge changes. Dimensional analysis was performed by Buckingham method to determine the variables such as depth ratio to height (y/H) and depth to distance (y/L) as effective factors in determining the percentage of cumulative sediment trapping (Teg). Accordingly, the relationship between the aforementioned ratios with the percentage of sediment trapping using dimension-less factor of Froude number as an independent variable in different scenarios has been investigated and evaluated Walls in the model, have been proposed for different slopes.

Due to groundwater overextraction, during the recent years, Malekan plain aquifer has been faced to a risk of increasing salination. The groundwater flow model of the plain was designed, invesitagion of groundwater flow regime and precise hydraulic parameters estimation, utilizing the various method such as  geological surveys, tomography methods, hydrochemical analysis and simulation of aquifer conceptual model in the GMS interface software package (GMS 10.1.4). The mass transport model was designed, then, to simulate the passways of salinity and dissolved solid concentration (Cl-) in the aquifer, using MT3DMS numerical code. The results show that the flow and transport model has explained the real behavior of the system with a good approximation and there is a good adaptation between the observed and simulated data. The over exploration of groundwater resources, which caused the water table decreasing,also resulted the extending of the saltwater intrusion in the northwestern part of  the plain and thereby the deteriorating of groundwater quality and quantity in northwestern part.

Recently, land subsidence due to natural and human factors changed to catastrophic destruction for the residential, agricultural and industrial areas. In this study, the high potential subsidence areas of Ardabil plain were identified to control and manage this phenomenon. Thus, the seven effective parameters on the subsidence were rated and weighted and the subsidence potential index (SPI) was calculated for study area. The SPI value for the Ardabil Plain was obtained between 80 and 154. Then the results of this method were verified by occurred subsidence which is obtained through INSAR image analysis for the study area. Although the results are acceptable but to increase the framework efficiency and accuracy of results, the fuzzy model adopted to optimize this framework. In this way, seven effective parameters on the SPI were used as the input of the FL model and the value of the corrected SPI by obtained observed subsidence from INSAR images was defined as the output of the model. The results of this method showed that the southern and southeastern parts of the plain have the high subsidence potential.

Watershed projects play an increasingly important role in managing soil and water resources throughout the world. In many developing countries, watershed management practices and planning are usually performed which cannot be identified by stakeholders. This study has been introduced an approach to consider some socioeconomic parameters from the stakeholders aspect which are important for watershed management decisions. The method of study was Descriptive and Analytical. Hasan abdal basin in Zanjan Province was selected as the case study area. The field data has completed with questionnaire. The statistic population of this research was all heads of families of stakeholders which living in this area. Among them, using Morgan table, 160 people were randomly asked questions directly. The Kruskal-Wallis test and Average Comparison were used. The main achievements of these projects were the improvement Stakeholder participatory, flood control, reducing the migration, and increase in agricultural and husbandry income of the results of these designs. The implemented projects haven't a positive impact on the area of agricultural land, Gardens, and rangelands.The people's attitude towards the implementation of positive watershed plans has been evaluated. The implementation of the plans has been effective in promoting stakeholder knowledge.

Climate change is an unprecedented change are taking place. Changes of meteorological parameters such as precipitation, maximum and minimum temperatures. Since weather forecasting is important for these parameters, in this study, the performance of Statistical Downscaling Model (SDSM and Lars-WG) were used to predict temperature and precipitation and mean of these changes for the periods 2046-2065 compared to the base period 1983-2013 at Ardebil station and the model HadCM3 with A2 scenario were predicted. Downscaling models were used for data analysis were Lars-WG and SDSM. The results showed that the Lars-WG model with low mean absolute error for the stations is more accurate than SDSM model.

Stochastic weather generators are widely used in different fields such as hydrological applications, environmental management and agricultural risk assessments. In this study, a popular stochastic weather generator, LARS-WG, was used in relation to reproduce observed statistical properties, including, means and variances of monthly precipitation, maximum temperature, minimum temperature and solar radiation for Kermanshah synoptic station. Climatic conditions, such as the lengths of wet and dry spells and Frost/heat spells were also used to assess the performance of the model. The results showed, LARS-WG performed well in simulating statistics of daily distribution, mean monthly and seasonal distribution, however in terms of standard deviation. The model showed an average performance.model should be calibrated for each basin separately.

Environmental flow is explained as the period of time, quantity and the amount of required water for maintaining the water, fresh, the river’s ecosystem, human beings’ welfare and the life depending on the water. The main goal of this paper is to investigate and compare the hydrological methods including Tennant, aquatic flow, Tessman, analysis of the flow duration curve and the flow duration curve shifting (FDC shifting) in determining environmental flow of two rivers from two different prime basin of Iran, Karaj and Talar rivers with data of 59 and 63 years, respectively. According to the results, the flow duration curve shifting approach for its consideration to different ecological classes, attention to natural flow shifting and the efforts of maintaining this shifting in its own suggested environmental flows, has priority over other approaches and it is also more precise in comparing with others. Therefore, the environmental needs of Karaj and Talar rivers in the classification of environmental management C (the preservation of river’s least environmental condition) are assessed equal to 4.77 m3/s which is 38 percent of the average annual flow and 1.81 m3/s, equal to 24 percent of the average annual flow of each river, respectively.

Sub-watershed prioritization is very important in natural resources and watershed management. This study deals with prioritization of sub-watersheds using a mixed multivariate linear model of New TOPSIS-Regression over morphometric parameters of 11 sub-watersheds. Morphometric parameters include constant of compression ratio, roundness factor, form ratio, slenderness ratio,channel maintenance, drainage density, ruggedness number, The frequency channel, slope, drainage texture rate, The roughness rate, branching ratio and channel length were weighted using multivariate linear regression and observed flood events. Prioritization was performed by TOPSIS decision Method. Results obtained from weighting analysis showed that branching ratio, form ratio and ruggedness number have the most effect on flooding with 0.612, 0.221, and 0.212 scores, respectively. According to the results of prioritization, 4, 6 and 9 Sub-watersheds with the least distance to the positive optimum (0.0062, 0.051, and 0.048, respectively) and maximum distance to negative optimum (0.1734, 0.1809, and 0.1746, respectively) have the highest flooding intensity with maximum scores of 0.7365, 0.7777, and 0.7841, respectively, that should be prioritized for action management and watershed management. In order to validate the results, special deposition and sediment delivery ratio  ​​(SDR) was calculated for each Sub-watershed by PSIAC method using nine parameters including geology, climate, soil, water, topography, land cover, land use, surface erosion and river erosion. Validation of results indicate that the morphometric parameters and  used model has a high performance of prioritization of watersheds prone to flooding and high sediment production;  so that 4, 6 and 9 Sub-watersheds have the highest amount of Special deposition 97.1, 80.2, 70.1 Ton/Hec/Year and sediment delivery ratio 57, 55, and 59 percentage, respectively. The results of this study can be used in watershed management.

A large part of Iran is considered a semi-arid regions and water is a limiting factor for human activities in these areas. One of the ways to eliminate seasonal shortages of water is using groundwater. Underground dams can be used for storing and using underground water, which can be used to improve the management of existing water resources and increase the productivity of these resources.1 . In this research, at first,by using the knock-out criteria, by means of Boolean logic, including geology, land use, slope and fault and using Bollini logic, suitable areas were identified for the construction of underground dams.2. - In the second stage,by using ANP analysis network methods and by using experts' questioning method, other important criteria were chosen to select the most appropriate areas for underground dams including distance from the road, distance from the village and .... In underground dams, subsurface flow has many importance. Therefore, in this research, the SWAT model was used to simulate water flow and subsurface flow in the area and For prioritizing the obtained areas, those areas with proper subsurface flow was identified. after evaluating of the weights of each parameter in the super decision software environment, it used to locate and prioritize the susceptible areas. Eventually, nine favorable points were identified as optimum areas for the construction of a landmine.

For suitable programming and management of water resources, access to perfect information from the discharge at the watershed outlet is essential. In most watersheds, the hydrometric station is not available; then, different models are used to simulate the discharge within watersheds without data. The selection of preferred model for rainfall- runoff simulation depends to the purpose of modeling and available data. In this research the conceptual rainfall- runoff models, SimHyd and AWBM and neural network models, MLP and RBF (by regard the less need to measured data) were used to model of rainfall- runoff process in Bar-Aryeh watershed of Nishabur. The length of data was 30 years (1983-2012) and the length of calibration and validation periods was 5 and 7 years, respectively. RRL and SPSS programs software were used for simulation of runoff. Nash - Sutcliff (ENS), coefficient of determination (R2), the root mean square error (RMSE) used to evaluate the models. Results showed that hydrological models simulate rainfall- runoff process in Bar Aryeh watershed of Neyshabur better than neural network models. Between mentioned models, the SimHyd with ENS, R2 and RMSE equal to 0.632, 0.8 and 0.02 respectively in the calibration period and 0.541, 0.74 and 0.08 in the validation period has better performance than other models which used in this research. The results showed that the Rosenbrock's search optimizer for the hydrological models and the function of tangent hyperbolic for the neural network models have more accurate operations than other optimizers. In addition, used models simulate the minimum and average values of the flow with an acceptable accuracy but the simulation of maximum values did not do well. Because these models do not regard the type and intensity of precipitation, lag time from snowmelt and concentration time of watershed.

Impervious surfaces in urban zones, during rainfall, increase the runoff speed and reduce the opportunity for evapotranspiration. This will increase maximum discharge and reduce the time of concentration of flood in urban storm. In this research, the effect of the development of Mashhad on the urban flood has been studied. The EPA SWMM model was used for this study. The studies showed that the surface of ​​Mashhad in 2016 compared to 1941 was 31.5. The results showed that the maximum discharge in 2016 increased to 307, 259 and 177 percent, respectively, compared to 1941, 1976 and 1986. Also, the results showed that despite the increase in the size of the city in 2016 compared to 1941, the time of concentration from 6 hours in 1320 to 4.5 hours in 1395 decreases.

In this research, in order to assess the biological and mechanical measures of flood and erosion control, two sub-watersheds of Heidari Watershed located in Chaharmahal and Bakhtiari Province with similar climatic, hydrological, edaphic, vegetation and land use conditions as representative areas were selected. To assess the conducted measures, social criteria including education, participation, income level and beneficiaries' satisfaction and technical criteria including flood control, water storage, revenue increase and vegetation enhancement were used. The relationships between criteria, sub-criteria and under consideration options were defined in ANP and AHP models. Then, pairwise questionnaires of the factors in both ANP and AHP models were provided to 30 watershed management experts in Chaharmahal and Bakhtiari Province. The results showed that among the social sub-criteria, participation in the AHP model, and increased revenues in the ANP model, allocated more weights. Also, the flood reduction criterion has gained more weight between the technical sub-criteria, by both models AHP and ANP. Social criteria and increasing vegetation cover are important for selecting biological methods. While water storage and flood reduction are important for selecting mechanical approaches. Finally, the results showed that biological measures are preferable to flood and sediment control. The weight of biological and mechanical operations in the ANP model is 0.60 and 0.40, respectively and in the AHP model, the weights were 0.51 and 0.49, respectively.