مجله تحقیقات منابع آب ایران
سال پانزدهم شماره 2 (پیاپی 49، تابستان 1398)

Rainfall-runoff process is one of the most important and complex phenomena in the hydrological cycle, therefore different views have been presented for the development of the modeling. Obviously, the recognition of the behavior of the catchment can play an important role in selecting of the appropriate model for saving time on the simulation. Previous studies have shown that the multi-linear models have an acceptable performance in the case of watersheds which usually have a regular rainfall pattern. In this study, the multi-linear Wavelet-M5 model was introduced and the rainfall-runoff process of the Aji Chay catchment was investigated. At first, the main rainfall and runoff time series were decomposed to several sub-time series by the wavelet transform to overcome its non-stationary, then the obtained sub-time series were imposed as input data to M5 model tree to forecast the runoff values and also the results were compared to the other models by the root mean squared error and determination coefficient criteria. The results showed that the performance of the proposed hybrid Wavelet-M5 model increased up to 69% compared to the sole M5 model tree for the Aji Chay catchment.

The coastal aquifer of the Naqadeh plain, located in the southwestern part of the Urmia Lake. Based on long-term chemoghraph, salinity has an increasing trend. Considering the undesirable results of saline water intrusion such as hygiene effects, human health and environmental problems, more studies are needed in this regard. Based on the classification of TDS values, about 48% of the groundwater resources of this plain are inappropriate for drinking and agricultural purposes. In order to monitor the groundwater resources of the plain, water samples were collected from 33 sampling points and a hydrochemical analysis was carried out. Identification of the salinity source and the governing hydrochemical mechanisms governing groundwater were carried out using the basic exchange index (BEX), ionic ratio, compound diagrams, geological and hydrogeological interpretations. Cl and Br halogens were also used for salinity studies due to their conservative behavior. Hydrochemical facies evolution diagram (HFE) was used as a useful method for identifying of the aquifers condition and its vulnerability to saline water intrusion. The matching of these results with the spatial distribution of salinity (EC) indicates the presence of two areas in the eastern and northern parts of the plain with high salinity and the risk of saline water intrusion. The salinity of these water resources is related to water-rock interactions, dissolution of saline formations, rainfall reduction, evaporation increase with formation of ponds in the dry seasons, infiltration of saline water and drainage of surface water, development of agricultural activities and probability of rising saline water (Upconing).

One of the important issues in our country is the restoration of Lake Urmia and it has been considered by the government since 2008. These efforts and high costs have had none impacts such as allocation of water to the lake on agricultural sector. This study aims to show these effects on the agricultural sector of border provinces. So purposely, in order to evaluate three agricultural water management scenarios a 49-year period of natural surface flows of watershed’s rivers is considered under the various hydrological conditions. The results showed that to provide the lake water demand caused 20 to 25 reduction of agricultural water demand in the West and East Azarbaijan provinces. It is obvious to achieve this, we certainly would have high socio-economic impacts, and recently we experienced changing of crop lands into orchards in the watershed. So, It is recommended that based on international experiences, the committee of restoration of the Lake Urmia provide an accessible framework and novel services for the ecology, otherwise, optimal utilization of credit and time shall not be presented.

Low flow is an important component for investigating the available water, especially in arid regions, which is applied to manage drought and to reduce it. The spatio-temporal changes of hydrological drought phenomenon based on Flow Duration Curve Seasonal Indexes (FDCSI) including Q70, Q80, Q90, Q95 and Q99 in Namak Lake basin were investigated in the present study. For this purpose, 18 stations with the maximum long-term data (43 years) were selected and FDCSI values were extracted based on summer (June to November) and winter (December to May) seasons. Non-parametric tests including Mann-Kendal, Modified Mann-Kendal and Sen Slope Estimator were performed to determine the time trend. Furthermore, Hurst exponent was applied to investigate the long-term memory. Based on Hurst results, most of the time series have memory but uniform patterns are not recognized for them. The significant decreasing trend was identified based on summer and winter seasonal indexes at 55-66% and 38-50% of the total stations, respectively. In addition, a slight increasing trend was observed at 5-11% of study stations at a significant level of 95 and 99%. The evaluation of the results of seasonal indexes showed that summer flow had more serve drought due to lack of base flow during 1970-2012. Severe decline trend during the summer season might occur due to the time patterns of rainfall, increasing evapotranspiration, changing land use and finally, over-harvesting of surface and groundwater resources for agricultural purposes.

Currently, in most of the catchments, the lack of ground-based gauges is one of the most important problems for accurate hydrological modeling. According to the quick developments of satellite-based technologies and the computer’s computational power, several rainfall datasets have been developed with different spatial and temporal resolutions. These datasets usually are based on remote-sensing techniques or the combination of land surface models (LSMs) and general circulation models (GCMs). This research addressed the efficiency of ECMWF reanalysis dataset and PERSIAN for hydrological modeling using VIC-3L large-scale model over the SefidRood catchment. The results of statistical analyses at daily time scale indicated that the correlation coefficient (CC) between ECMWF, PERSIAN, and ground-observed dataset is about 0.83 and 0.48, respectively. In addition, at monthly time scale, the performances of both rainfall datasets approximately are the same and in most parts of the catchment, the value of CC is higher than 0.80. Hydrological analyses by VIC-3L model showed that despite having low efficiency in estimating rainfall, the PERSIAN dataset led to better simulation of runoff when it compared to ECMWF. For example, the Nash-Sutcliffe (NS) coefficient between daily and monthly simulated runoff using PERSIAN and observed runoff at the outlet of SefidRood catchment are about 0.80 and 0.88, respectively, while in the case of ECMWF these coefficients are about 0.67 and 0.72. Moreover, by using the PERSIAN dataset, the performance of the VIC model in simulating daily and monthly peak flows significantly increases.

Regarding the supply of large amount of water demand from groundwater resources on the one hand, and increasing water level drop of the aquifers on the other hand, the importance of groundwater resources management is significantly increasing. Due to the complexities in the socio-ecological systems related to the groundwater resources, there is a need for tools to model these complexities in the form of effective agents’ relations. Agent-based modeling (ABM) is a computer simulation with a comprehensive approach of stakeholders, or agents that interact with each other and with their environment based on certain behavioral principles. In this paper, farmers, effective institutional agents and aquifer behaviors and their interactions in the Shabestar-Sofian plain is modeled using ABM with stakeholder participation through interviews and semi-structured questionnaires. The results of the implementation of five sample scenarios show that if the institutions are properly coordinated and the participation of farmers is attracted, it could be possible to reduce 202 million cubic meters of wells extraction over 10 years, in addition to increasing the income of farmers simultaneously and to compensate about 40 percent of negative groundwater balance. Using this model, a better understanding of the sophisticated system of groundwater resources management can be obtained, stakeholder participation can be attracted, and by defining scenarios in a participatory process, better solutions can be achieved in the decision-making process.

The optimal dischargeable waste load allocation to the pollutants is important for improving the quality of rivers. The purpose of this paper is applying some bankruptcy rules, one of the Game theory methods, to allocate the waste load to pollutants and reach the standard dissolved oxygen in Zarjub River, Gilan. Based on the proposed framework, a combination of QUAL2Kw model, particle swarm optimization algorithm and bankruptcy rules are used in this research. In this paper, particle swarm optimization algorithm has been used to optimize point and non-point sources discharged contaminants of river adjacent in QUAL2Kw under bankruptcy rules. The conclusion indicates the efficient application of the bankruptcy approach on reaching the optimal level of oxygen at downstream. According to the research results, CEA and TAL methods discharge less waste load to the river. Also, based on the results some methods are appropriate for high pollutant industries and some methods are acceptable for low pollution industries.

Due to the water crisis and the large proportion of agriculture sector in water withdrawal, many studies have been done on water efficiency improvement in agriculture. One of the proposed solutions is optimal crop pattern implementation. However, less attention has been paid to the effect and role of crop pattern criteria in the determination of crop pattern and water resources use efficiency. There are many crop pattern criteria to determine crop pattern and crop efficiency in a selected area, selecting different criterion results in different outcomes. Therefore, proper selection of criteria is pivotal to the optimal use of water resources. In this paper crop pattern criteria has been evaluated relying on sustainable development, therefore eleven criteria have been selected as the main criteria and prioritized for Pistachio and Damask rose in Kavirdaranjir Basin. To prioritize the criteria an optimization problem, which its objective function is based on sustainable development, has been developed. The problem has been solved, using random and chaotic (Tent, Henon, and Logistic) genetic algorithms. The results show Tent chaotic genetic algorithms performance is the best comparing other selected algorithms. In addition, the analysis of optimization problem results shows the priority of the criteria is the environmental, economic and social category.

Estimation of suspended sediments in flowing waters is a matter of importance due to the different aspects such as the performance of hydraulic structures, environmental problems, and ... The main goal of this research is using remote sensing technology to estimate the concentration of suspended sediments at the water level entering the reservoirs of dam by flood since the dam was constructed and its annual estimation. For this purpose, the experimental results and 〖ETM〗^+ data of Landsat satellite related to the reflection spectrum of suspended sediments at various concentrations. In a lab work by using an ASD spectro radiometer, the water reflection values containing different amounts of suspended sediments were measured in the range of 400 to 2500 nm. Then, these reflection values for OLI Bands of Landsat 8 were reexamined using their spectral response functions. In the study of the correlation between bands with the amount of suspended sediments, band2 (blue) and band5 (infrared) were detected most appropriate. In this research, a range of different sediment concentrations in 90 samples of 0.16 gr⁄lit to 100.05 gr⁄lit was used.
In the reviews, Landsat 5 band reflection centered at 865 nm and Landsat 2 band reflection centered at 482/4 showed the most and least sensitivity to the amount of sediment respectively. Therefore, a relationship with appropriate correlation was diagnosed between reflection differences of these two bands 〖R_865-R〗_482.5 and concentration of suspended sediments. In this relation, its RMSE was 1.57 and R2 parameter determination factor was

Groundwater storages are the main-source of water in Iran. With the developments in technology, utilization of these resources has been increased severely over the last few decades as the extracted water is more than the capacity of renewable water and has led to a depletion in groundwater-levels, a deterioration of these resources and associated negative consequences. Hence, the proper management of these valuable resources and the sustainability conservation are significant. Today, for proper management of groundwater resources, decision models can be used with a combined framework of simulation-optimization models. Therefore, in this research, using numerical simulation model (MODFLOW) over the management horizon of ten-years and ant-colony-optimization-algorithm, simulation-optimization model for the Namdan aquifer located in Fars province, Iran was developed. Three indices of sustainability, filling and restoration of the aquifer are considered to restoration management of groundwater resources in the study area, in line with Iran aquifer restoration plan. Based on the objective of reaching to the best condition of stability, filling, and restoration of the aquifer over the management horizon, the results has been indicated an increase of 3, 9.5 and 10.6 m of groundwater-level, respectively, compared to the beginning of the management horizon, which highlighted the necessity of proper-selection of objective-function considering the main objectives of the management plan and provided the feasibility of assessment on the requirements to implement the plan. Also, the use of three-indicators of reliability, utility and vulnerability to examine the results of scenarios shows the best aquifer status under scenario of applying the restoration-index.

In this research using the conditional valuation method, tendency to payment of the citizens of Ahvaz city to improve of the equality of drinking water has been studied. To study the economic and social effecting factors on measure of tendency to payment, the logia's econometric model has been used. Required data has collected through a field study, completing questioner and interview with 400 households in Ahvaz city by Multi-stage cluster sampling method. According to the results 75 percent of households, were willingness to pay an amount of money to improve the equality of drinking water. As they tend to pay 2886 Rials per Cubic meter to improve healthy drinking water per month. Also, according to this study, martial and gender variables don't have significant impact on the tendency to payment of households. Other variables of model, namely age, education level, household dimension, income, and suggested price have been significant. According to the value and high Importance of improve quality of drinking water, it is suggested that some policies be taken to maintain the standards of the quality of water.

Knowledge on the natural ability of basins is one of fundamental needs to optimal utilization of runoff. Thus, rainfall-runoff simulation in basins is of utmost importance. Continuous simulation of rainfall-runoff in Maroun basin performed using Artificial Neural Networks (ANNs) in order to evaluate the ability and accuracy of ANN for runoff estimation. Considering the fact that the number of rainy days per year less than sunny days, so runoff is caused by two different mechanisms. In continuous rainfall time and a few days later, runoff mainly is from high discharge and low base time. But on most days when there is no rainfall, baseflow has low discharge and long base time .Thus, in this research a double criterion model of rainfall-runoff includes model on rainy days and non rainy days were examined. Also efficient input variables on runoff in the Maroun basin are determined using the partial mutual information (PMI) algorithm. Comparison of statistical criteria between the single criterion model and double criterion model indicated that the double criterion model were more accurate. Therefore, the Nash-Sutcliff coefficient of single criterion model and double criterion model for test stage of network were 0.86 and 0.94 respectively.

Drought management and planning are based on recognizing drought characteristics and its spatial and ‎temporal extent. In the present research, SPEI12 was calculated using 4 kernels including rectangular, ‎triangular, circular and Gaussian at the 12 Zayandeh Roud watershed’s climatological stations. Four ‎important characteristics of drought including the time of occurrence, duration, magnitude and severity ‎were evaluated by applying the highest weight to the 5th month. It was revealed that kernels other than ‎rectangular were more sensitive in recognizing the four drought characteristics. While the rectangular ‎kernel showed the highest coefficient of variation (CV) in drought duration, the Gaussian kernel has the ‎least CV in duration and magnitude and the circular kernel has the least CV in severity. Moreover, it was ‎found that the Gaussian kernel was more successful in detecting the occurrence of drought in comparison ‎with others. Finally, the results of this research indicated that rectangular kernel i.e. using equal weights ‎for all months in deriving SPEI, may lead to overestimate or underestimate drought characteristics.‎

In this study, the impact of climate change on 24-h probable maximum precipitation (PMP24) was investigated in a part of Qareh-Su basin located in Golestan province. For this purpose, the daily and hourly climatic data during years 1987–2017 were applied. In order to generate future data, the outputs of CanESM2 model as a general circulation model (GCM) under three emission scenarios including optimistic (RCP 2.6), middle (RCP 4.5) and pessimistic (RCP 8.5) and statistical downscaling model (SDSM) were used in two near and far future periods. The PMP24 values were estimated using physical, Hershfield standard and revised methods in the baseline and future periods under the three scenarios. The PMP24 value was estimated 421 mm for the baseline period, using Hershfield standard method. These values under the three RCP scenarios were obtained 202, 228, and 213, for the near future and 216, 201, and 230 mm for the far future. The result of Hershfield revised method was 230 mm for the baseline period. The PMP24 values under the three scenarios were calculated 81, 85, and 76 mm for the near future, and 83, 80, and 79 mm for the far future. The PMP24 resulted from physical method was 143 mm for the baseline period. These values were 98, 105, and 109 for the near future, and 129, 122, and 126 mm for the far future period.

Land use/ land cover of watersheds has great impacts on water quality of rivers. The water quality of rivers can be degraded due to changes in the land use/land cover patterns within watersheds as human activities increase. In this study, to determine the relationship between te impacts, which are induced by change in land use/ land cover on water quality, the relationship between land use and water quality variables has been examined. The effects of land use/land cover changes were investigated in different buffer zones. Using geographic information system (GIS) and spatial analysis, 39 watersheds were selected within the southern Caspian Sea Sub-basin, and then the relationship between water quality variables and land use/ land cover classes, in different river buffer zones varying between 30 to 120 meters with 30 m incremental intervals, were examined by Spearman correlation test and multiple linear regression. Due to the fact that two or more independent variables may affect the dependent variable, multiple regression modeling approach was used. The results showed that integrated land use data in intermediate areas could provide the most reliable model for predicting chlorine (R2 = 0.813) and sodium (R2 = 0.77). In addition, in riparian areas with 30 meter, SAR, K, Na, Cl, pH, EC, TDS, Mg, Ca, HCO3 variables had the highest correlation coefficient with their surrounding land use/land cover.

Among the various types of inter-basin water transferring projects, the water transferring from transboundary rivers due to enter to an anarchist atmosphere among riparian states has more complexity. Considering the emerge of such projects, as one of the options on the table in reducing water resources vulnerability in Iran, has led to increase the importance of examining and mapping the considerations of the studies. In this regard, considering the Murghab transboundary river between Afghanistan and Turkministan as a case study to Iran, preliminary paper adopts a descriptive-analytical method and studies documents as well as available experiences to examine the project from a variety point of views. Therefore, legal and operational considerations for water purchasing including factors such as the negotiable water and how it can be calculated, the contract interference, the time of water purchasing, the third party, the environmental risk and the compensation of damages caused due to water purchasing, as well as those of operational considerations factors such as the construction in the riparian states, the environmental commitments of the water transferring and the types of water transferring executive contracts in the given project have been examined. To the end, after reviewing all directions as well as mapping the roadmap of the considerations of the project, three perspectives of cooperation among riparian states, including the cooperation of Iran with Afghanistan, the cooperation of Iran with Turkministan and cooperation of Iran with both according to the advantages and disadvantages of each have been explored.

Many hydraulic structures are designed by using the design precipitation with return periods duration time based on concentration time. Therefore, in any region, Intensity-Duration-Frequency (IDF) curves play a significant role in the design of dimensions and components of these systems especially in regions without adequate rain gauge stations. However, following climate change due to the increasing human activities precipitation patterns has changed in various regions of the world. Therefore, the historical IDF curves are not applicable. In this study, according to the Isfahan meteorological synoptic station IDF curves were developed. Eextraction of precipitation intensity with continued short of 24-hour precipitation has been done by using fractal theory. In the present study, extractions of the IDF curves were divided into three periods: the historical period (1967-1993), the present period (1994-2016), and the future period (2017-2035). It was perceived that precipitation intensity with short-term duration increased because of changes in the climatology, and IDF curves are shifted upwards. In this study, to predict the daily precipitation weighted output 15 AOGCM models under the A2 emission scenario related to the Fourth Assessment Report (AR4) IPCC, as the most reliable tool were used. The results show that the predicted IDF for future (2017-2035) will increase about 52 percent related to past IDF (1967-1993) in this region.

The snow melt forecast in mountainous basins plays an important role in the management of water resources. For this reason, snow hydrology in mountainous areas is of great importance. In this study, due to the lack of snow data in the Bujin area, SRM and HBV models were used to simulate snow melting. At first, rainfall data, precipitation data was prepared and verified during the period of Water Year 1387 until 1389. The MODIS sensor data was used in one-day time intervals to monitor the time and location of snow cover surface in the SRM model. ArcGIS software was used to implement the physical properties of the domain. Implementation of SRM and HBV models was performed using snow melt simulation. Then, using the results of the values of the parameters in the calibration step, the validation step was performed. The estimation rate of the R2 parameter obtained by the SRM and HBV model for the Bujin area is about 0.71 and 0.61 for calibration and about 0.72 and 0.69 for validation steps, so that these results, together with the values of the other evaluation criteria such as Nash-Sutcliff (coefficient of 0.71 for SRM model and 0.61 for HBV model at validation stage), showed good accuracy of models in runoff simulation. Also, the SRM model, due to the use of satellite images, showed a more reliable performance in snowmelt runoff simulation than the HBV model in this basin.

Water as a natural common resource is shared among different stakeholders (local, sub-national, national and international) and is vital for the human, which ignores political, economic and cultural boundaries. The direct link between water security, human security and the national security of the states on the one hand, and the existence of numerous international transboundary river basins and aquifers throughout the world on the other, has led water systems to a political and security issue in the world. It has shaped the complex "water, politics and security" nexus. The purpose of this paper is to examine the nexus of water and politics with a focus on the issue of power. Since power is one of the most significant elements in policy making and its implementation; hence, the definition of power differs in different time and spatial conditions. Accordingly, understanding of the nature and dimensions of power and hegemony (as one of its derivatives) is so significant. Power plays a crucial role in water interactions as coupled complex human-natural systems. Generally, argued by Warner (2004), up-streamers use water to get more power and down-streamers use power to get more water. Considering the role and serious impact of power in hydropolitics in general and water diplomacy in particular, this paper critically examines the nature and role of power and hegemony in relations among international riparian countries.

Purpose of this study was investigating factors affecting the acceptance of water management plan for restoration of Lake Urmia by farmers in Naghadeh. Sociological model of environmental behavior by Fietkau and Kassel (1981) was used for analyzing farmers’ behavior. Statistical population of the study was 670 farmers in 9 villages in Naghadeh. Based on Cochran formula and stratified random sampling, 152 farmers were selected as the study sample. A questionnaire was used for data collecting which its validity was verified by experts and its reliability was confirmed by calculating Cronbach's alpha. Correlation results showed positive and significant relationships between acceptance of water management plan for restoration of Lake Urmia with farmers' attitude towards lake restoration and water management plan, farmers' facilities, farmers' knowledge about lake restoration and water management plan, subjective norm, sense of responsibility, land ownership and level of education. Results of logistic regression indicated that farmers' knowledge about lake restoration, farmers' facilities, farmers' attitude towards lake restoration and attitude towards water management plan as the most important determinant factors of two groups of farmers (adopters and non-adopters of water management plan) have been able to correctly classify 92.1% of the total respondents. 64 to 88 percent of variance of the variable acceptance of water management plan was determined by independent variables entered in the model. Based on the findings, suggestions were made regarding the design and implementation of educational and extension programs to increase the acceptance of water management plan for restoring Lake Urmia by farmers.

For groundwater resource management, recognation of performance and prediction climate change and human activity effects on groundwater is necessary. In this research GMS10.05 software was used for determining and simulating characteristics of Mahabad aquifer. After calibration and validation of model, we researched about effective factors influncing groundwater change. For this aim in first step, results was considered without human activity factors .In this condition average of groundwater level was 3m more than groundwater level observation . investigating about dam constraction as a anthropogenic activity factor showed, dam construction causes groundwater level would be 1.11 lower than pervious condition. In this research we then predict groundwater EC and SAR using GEP as a function of groundwater level. We conclude anthropogenic activity in compared with natural change is primary force driving the groundwater level and guality down and changing irrigation of groundwater class to C3S1. The result of this study is applicable in developing criteria for adaptation groundwater resouce management in future.

Due to the depletion of groundwater resources in dry climates, establishing an effective procedure to delineate artificial groundwater recharge zones is of great importance. Then, the objective of this study was utilizing Ordered Weight Average (OWA) multi-criteria evaluation method and fuzzification of layers to produce suitability maps of Salafchegan study area located in Qom province. To do this, different data layers including observation wells, soil maps and reports, Digital Elevation Model and landsat-8 OLI, etc. were used. Different ordered weight with different tradeoff (four procedures) were used to create suitability maps. Finally, by using a land-use filter as well as applying condition of proximity to tributaries and lineaments, few zones were chosen as the selected locations to groundwater recharge zones. The risk-averse procedures (first and third procedures) did not introduce any suitable location for groundwater recharge site. However, the second and fourth procedures did suggest 11 and 25 location, respectively. To assess correlations of the information layers and results, principal components analysis was used. Results suggested that the slope and infiltration layers have strong positive correlation (more than 75%) and the electrical conductivity (EC) has a negative correlation with other layers (more than 50%).

The aim of this study was the evaluation of drought effects through SPI index assessment on the water quality of the Dez River. For the determining the drought, ten-year meteorological data (2005-2014) were achieved through the weather stations of Hussainiya, Dezful, and Shush and for impact evaluation of drought on the water quality of the Dez River, discharge statistics and qualitative parameters related to seven hydrometric stations along the Dez River achieved through Khuzestan Water And Power Authority. The mean frequency of dissolved anions and cations in the hydrometric stations of the Dez River achieved like HCO3>SO4>Cl and Ca>Na>Mg. The variance analysis of the water qualitative parameters showed that the effect of station and year on the amounts of discharge, EC, TDS, SARIW, pH, Cl, HCO3, Ca, Mg, Na, and SO4 had a significant difference (P

It seems essential to understand temporal and spatial changes in water quality of rivers as one of the most dynamic ecosystems of the world. In this research, we have analyzed temporal and spatial changes in the parameters of water quality of Aras River in the period 1999-2011 at the gauge stations of Khodaafarin, Khazangah, and Jolfa, using statistical multi-variate, factor analysis, and Principal Component Analysis. The first component with the highest explanation of variance has greatest correlation with parameters of Mg2+, Ca2+, HCO-3, EC, and TDS. The component shows the ions and suspending particles at Khodaafarin station. Among the parameters of the first component, EC has the highest factor loading (0.98) as the main parameter of the component. At the Khazangah station, the first three components explain 53.6, 17.5, and 12.9 percent of variance, respectively. The first component has the highest correlation coefficient with the parameters of Mg2+, Ca2+, SO42-, Cl-, HCO-3, EC, and TDS. In Jolfa station, the first four components with the highest eigenvalues explain 50.7, 15.8, 13.2, and 5.8 percent of the variance.

Lake Urmia located in the north-west of Iran has been facing a serious environmental crisis because of some natural and anthropogenic factors. Regulation of rule curve of dams and optimum redistribution of those is essential for conservation the ecosystem of the lake. In a simple hydrological method, optimum flow regime that should be released from dams is estimated by calculation of run off of down stream catchment. In this regards, rule curve of the major reservoir dams (Shahid Kazemi, Shahr Chai, Zola, Derik, Venyar, Ajabshir and Alavian) in the Lake Urmia basin under three different operation policies (30%, 50% and 80% of MAF) has been calculated. Then by using measured data, monthly value of QResidual (the run off of the down stream catchment) has been calculated. In the next step, the term of QAAD (the volume of annual available water in the last station) for each scenario has been determined. The results revealed that by using 80% of MAF (as scenario 3), the value of QAAD would be positive for all the assessed stations; so scenario 3 is selected as effective action for restoration of the lake. Finally for scenario 3, monthly value of QCAH (the nearest hydrograph to natural hydrograph of rivers) in the last station for each rivers and the term of QRW (the monthly volume of water for releasing from dam) have been calculated.

Calculation of stronger indices requires extensive meteorological data that may not be recorded in some areas, but in most areas rain gauges record rainfall data. In this research, the RDI and SPEI indices simulated with acceptable accuracy using the SPI index (only rainfall data is required for its calculation). Simulation was performed using generalized estimating equations (GEE) and then validation of these simulation models was performed using different goodness of fit measures (NSE, RMSE, MAE, R2 and comparison with 1:1 line (using t-test)). The calculated values of different goodness of fit measures indicated the acceptable validity of fitted GEE models. Comparison between goodness of fit parameters and validation coefficients indicated that, in general, the SPEI model has better than RDI model. Models validation showed that the difference between simulated and observed data was not significant at 5% significance level. Results indicated the better performance of simulation models in arid region of the Fars province.