IRAN-WATER RESOURCES RESEARCH
Year:2019 | Volume:15 | Issue:2 |Papers Count:29

Rainfall-runoff process is one of the most important and complex phenomena in the hydrological cycle and therefore different views have been presented for modeling the phenomenon. Obviously, the recognition of the behavior of the catchment can play an important role in selecting the appropriate model as well as 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 multilinear Wavelet-M5 model was introduced and the rainfallrunoff process in 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-stationarity. 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 (i. e. ANN, M5 and WANN) 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, has an increasing trend in Salinity based on long-term chemoghraph. 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 on 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, 33 water samples were collected and a hydrochemical analysis was carried out. Identification of the salinity source and the governing hydrochemical mechanisms in groundwater were carried out using the basic exchange index (BEX), ionic ratio, compound diagrams, and 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 the aquifers condition and its vulnerability to saline water intrusion. Matching these results with the spatial distribution of salinity (EC) indicated the presence of two areas with high salinity and the risk of saline water intrusion in the eastern and northern parts of the plain. The salinity of these water resources was resulted from the 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).

Restoration of Lake Urmia, as one of the major recent issues in Iran, has been considered by the government since 2008. How the water allocation to this restoration plan has impact on agricultural sector in the basin is amongst the main reasons that so far hindered the proper results of the restoration efforts. This study aims to show the impact of water allocation to this Lake on the agricultural sector of related provinces (West Azerbaijan, East Azerbaijan, and Kurdistan). So purposely, in order to evaluate water allocation to Lake, a 50-year period of natural surface flows of watershed’ s rivers was considered under the various hydrological conditions and three agricultural water management scenarios. Results showed that having supplied the Lake water right cause a decrease of 20 to 25 percent in agricultural water right in West and East Azerbaijan provinces. Obviously, such a reduced cultivated area would have high socio-economic impacts especially while the basin has experienced an increase in cultivated area and changing of agronomy into orchards. So, It is recommended that based on international experiences, Lake Urmia Restoration Program 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 in investigating the available water, especially in arid regions, which is applied to manage hydrologic drought and to reduce its impacts. The spatiotemporal changes of hydrological drought phenomenon were investigated in Namak Lake Basin in the present study based on Flow Duration Curve Seasonal Indexes (FDCSI) including Q70, Q80, Q90, Q95 and Q99. For this purpose, 18 stations with the maximum long-term data (43 years) were selected and FDCSI values were extracted for summer (June to November) and winter (December to May). Nonparametric 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 had memory but uniform patterns were 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 slightly 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 experienced more serve drought due to lack of base flow during 1970-2012. Severe decline trend during the summer season might occur due to the temporal patterns of rainfall, increasing evapotranspiration, and finally, over-harvesting of surface and groundwater resources for agricultural purposes. Despite the drastic changes in topography, and climate and consequently hydrologic regime at the basin, the spatial distribution of observational trends showed that the declining trend was distributed homogeneously all over Namak Lake, except its northeastern part. Rainfall regime, inter-basin water transfer (IBT) projects, agricultural lands drainage, industrial and household wastewater have played an important role in the observed positive trend in the northeastern region of the basin during four decades. The results indicated the importance of considering seasonality in low flow indexes; which makes a better reflection of the role of the effective driving forces and as a result, optimum management of streamflow is achieved during the persistent dry periods.

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 and PERSIAN reanalysis dataset 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 and 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 are approximately the same and in most parts of the catchment with the value of CC 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 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 were about 0. 80 and 0. 88, respectively, while in the case of ECMWF these coefficients were respectively 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 increased significantly.

The reliance of a great part of the country’ s water supply on groundwater resources on the one hand, and increasing water level drop of the aquifers on the other hand, significantly increased the importance of groundwater resources management. 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-based 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, Iran is modeled using ABM with stakeholder participation through interviews and semi-structured questionnaires. The results of the implementation of five sample scenarios showed that if the institutions are properly coordinated and the participation of farmers is attracted, it could be possible to reduce about 200 million cubic meters of wells extraction over 10 years, while simultaneously increasing the income of farmers and compensating about 40 percent of negative groundwater balance. Using this model, a better understanding of the sophisticated system of groundwater resources 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 allocation of the dischargeable waste load 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 pollutant sources and attain 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 discharged contaminants from the point and non-point sources to the adjacent river under bankruptcy rules. The conclusion indicated the efficient application of the bankruptcy approach on maintaining the optimal level of oxygen at downstream. According to the research results, CEA and TAL rules discharge less waste load to the river. Also, based on the results methods are dofferentiated according to their appropriateness for high pollutant industries and low pollution industries.

Due to the water crisis and the large share of agriculture sector in water withdrawal, many studies have focused on water efficiency improvement in agriculture emphasizing on optimal crop pattern implementation as one solution. However, less attention has been paid to the effect and role of crop pattern criteria in the determination of crop pattern and efficiency of water resources use. There are many crop pattern criteria which can be used in determining 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. 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 showed that the performance of Tent chaotic genetic algorithms was the best compared to other selected algorithms. In addition, the analysis of optimization problem results showed the priority of the criteria sets as the environmental, economic and social category.

Assessment of suspended sediment concentration in running waters is important in different applications such as monitoring the performance of hydraulic structures, environmental problems, and utilization of agricultural lands. The main goal of this research is the use of remote sensing technology to assess the concentration of suspended sediments on water surface of inflow to the dam reservoirs and also estimating of sediment load brought to the reservoir in flood events during the dam’ s lifetime as well as annually. For this purpose, the laboratory experimental results and images of Landsat satellite have been used. The study area in this research was Ardak Dam in North West of Mashhad. In the laboratory work, the condition of the river was simulated. By using an ASD spectroradiometer, the water reflectance values for different amounts of suspended sediment concentrations in the range of 400 to 2500 nm were measured. Then, these reflectance values were resampled for OLI Bands of Landsat 8 using their spectral response functions. The correlation between reflectance from bands 2 and 5 and the amount of suspended sediment concentration, were of the order of 0. 91. In this research, a range of different sediment concentrations of 0. 16 gr/lit to 100. 05 gr/lit in 90 samples was used. In the modeling stage one from each three samples was kept for model evaluation. In the study procedure, the reflectance in band 5 of Landsat centered at 865 nm R 862 and the reflectance in band 2 of Landsat centered at 482/4 R 482. 5 showed the maximum and minimum sensitivity to the amount of sediment, respectively. As a result, an exponential relationship between sediment concentration and 𝑅 865 − 𝑅 482. 5 was found appropriate. In the evaluation process the RMSE was 1. 57 (gr/lit) and R2 was 0. 91. The evaluation of the results of this study showed that the model presented for estimation of suspended sediment concentration in water was appropriate and showed good performance.

Groundwater storages are the main sources of water in Iran. With the developments in technology, utilization of these resources has been severely increased over the past few decades so that the extracted water is more than the capacity of renewable water. This has led to depletion in groundwater levels, deterioration of these resources and its associated negative consequences. Hence, the proper management of these valuable resources and the sustainability conservation means are of significant importance. For proper management of groundwater resources, decision models can be used with a combined framework of simulation and optimization models. Therefore, in this research, using numerical simulation model (MODFLOW) for a 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 achieving best condition for stability, filling, and restoration of the aquifer over the management horizon, the results indicated an increase of 3, 9. 5 and 10. 6 m of groundwater level, respectively, compared to the beginning of the management period. This 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 showed the best aquifer status under the scenario of applying the restoration index.

This research, using the conditional valuation method, studied the willingness to pay of the citizens of Ahvaz city to improve the quality of drinking water. To study the economic and social factors affecting the willingness to pay, the logit econometric model has been used. Required data has been collected through a field study, completing questioner and interview 400 households in Ahvaz city by Multi-stage cluster sampling method. According to the results, 75 percent of households were willing to pay an amount of money, i. e. 2886 Rials per Cubic meter, to improve the quality of drinking water. Also, according to this study, martial and gender variables do not have a significant effect on the willingness to pay of the customers. The effect of other variables of the model, namely age, education level, household dimension, income, and suggested price were significant. According to the value and high importance of drinking water quality improvement, it is suggested that consistent policies be taken to maintain the standards of the quality of water.

Knowledge on the natural potential of basins is one of fundamental needs to optimal utilization of runoff and thus, rainfall-runoff simulation in basins is of utmost importance. Continuous simulation of rainfall-runoff in Maroun basin is performed in this study 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 is 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, low baseflow and long base time form the outflow. Thus, in this research a dual criteria model of rainfall-runoff including model on rainy days and non-rainy days were examined. Also the input variables effective 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 dual criteria model indicated that the latter was more accurate. Therefore, the Nash-Sutcliff coefficient of single criterion model and dual criteria 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 12 climatological stations in Zayandeh Roud watershed. 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 other kernels were more sensitive in recognizing the four drought characteristics compared to rectangular. While the rectangular kernel showed the highest coefficient of variation (CV) in drought duration, the Gaussian kernel had the least CV in duration and magnitude and the circular kernel 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, northern Iran. 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) were used in two near and far future periods under three emission scenarios including optimistic (RCP 2. 6), middle (RCP 4. 5) and pessimistic (RCP 8. 5) and statistical downscaling model (SDSM). 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. This value was obtained respectively under the three RCP scenarios as 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 as 81, 85, and 76 mm for the near future, and 83, 80, and 79 mm for the far future, respectively. The PMP24 resulted from physical method was 143 mm for the baseline period and 98, 105, and 109 for the near future, and 129, 122, and 126 mm for the far future period, respectively. The results showed that the PMP24 values tend to decrease at the rate of 18-21% in the physical method, 49% in the Hershfield standard method and 65% in the Hershfield revised method. Overall, the PMP24 values tend to decrease in the future and the rate of decrease in the near future was more than the rate of the far future. The spatial distribution maps of PMP24 in the baseline and the future periods showed that the PMP24 values decreased from west to east. Comparison of these values indicated that PMP values obtained from physical method were closer to the actual precipitation of basin and this method obtains more accurate PMP estimates in the study area.

Watershed land use/land cover 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 impacts on water quality induced by change in land use/ land cover, 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 varying between 30 to 120 meters with 30 m incremental intervals. Using geographic information system (GIS) and spatial analysis, 39 watersheds were selected within the Caspian Sea basin and then the relationship between water quality variables and land use/ land cover classes in abovementioned river buffer zones, were examined by the 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 buffer, SAR, K, Na, Cl, pH, EC, TDS, Mg, Ca, HCO3 variables had the highest correlation coefficient with their surrounding land use/land cover. SO4 showed the best correlation in 60 meter buffer zone.

Among the various types of inter-basin water transferring projects, the water transfer from common transboundary rivers incorporates more complexity due to an anarchic atmosphere among riparian states. The emergence of such projects, as one of the alternatives in reducing water resources vulnerability in Iran, has led to an increased importance for examining and mapping the transbondary criteria and considerations. In this regard, considering water purchasing and tranfering from the Murghab transboundary river, flowing between Afghanistan and Turkministan, is being studied as a case study. Preliminary, paper adopts a descriptive-analytical method and studies documents as well as available experiences to examine the project from a variety of view points. Legal and operational considerations for water purchasing have been examined including criterias such as the negotiable water and how it can be calculated, the contract interference, the time of water purchasing, third parties criteria, the environmental risk and the compensation of damages caused due to water purchasing, as well as those criteria related to operational considerations such as the construction development in the riparian states, the environmental commitments of the water transferring and the types of water transferring executive contracts in the given project. After reviewing all alternatives as well as mapping the roadmap of the considerations of the project, three perspectives of cooperation among riparian states, including the cooperation of Iran and Afghanistan, the cooperation of Iran and Turkministan and cooperation of Iran with both states according to the advantages and disadvantages of each, have been explored.

Many hydraulic structures are designed by using the design precipitation with return periods and duration based on concentration time. Therefore, and especially in regions without adequate rain gauge stations Intensity-Duration-Frequency (IDF) curves play a significant role in the design of dimensions and components of these structures. However, the precipitation patterns has changed in various regions of the world following climate change as a consequence of the increasing human activities. Therefore, the historical IDF curves are no longer reliable. In this study, IDF curves were developed for Isfahan meteorological synoptic station. Extraction of precipitation intensity with continuous shortterm 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 shortterm 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 were used under the A2 emission scenario related to the Fourth Assessment Report (AR4) IPCC, as the most reliable tool. Results showed that the predicted IDF for future (2017-2035) will increase even over 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, discharge and precipitation data was prepared and verified during the period of 1387 until 1389. The MODIS sensor data was used at daily time step to monitor the time and location of snow cover surface in the SRM model. ArcGIS software was employed to implement the physical properties of the basin into SRM and HBV models and the snow melt was then simulated. Using the results of parameters values in the calibration step, the validation step was performed. The value of R2 criteria obtained by the SRM and HBV model for the Bujin area was respectively about 0. 71 and 0. 61 for calibration and about 0. 72 and 0. 69 for validation steps. 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 step), showed reliable accuracy of models in runoff simulation. Also, for this basin the SRM model, due to the use of satellite images, showed a more reliable performance in snowmelt runoff simulation compared to the HBV model.

As a natural common resource, water is shared among different stakeholders (local, sub-national, national and international) and is vital for the human overlooking the 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 introduced water systems to global political and security issues. The complex "water, politics and security" nexus has shaped as a result. The purpose of this paper is to examine the nexus of water and politics with a focus on the issue of power. Power is one of the most significant elements in policy making and its implementation and its definition differs in different temporal 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 examined the nature and role of power and hegemony in relations among international riparian countries.

This study aimed at 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 behavior of farmers. Statistical population of the study was 670 farmers in 9 villages in Naghadeh Township. Based on Cochran formula and stratified random sampling, 152 farmers were selected as the study sample. A questionnaire was used for data collecting the validity of which was verified by experts. The reliability of the questionnaire 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 the 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). This could 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 among farmers.

Recognation of performance and prediction of how climate change and human activities affect the groundwater resources is necessary in Groundwater resources management. Groundwater resources play an important role in supplying domestic, agricultural and industrial water in semi arid regions. In such regions, increasing population and water demand along with the climate change, causes negative effect on groundwater guality and quantity. In this research important factors influncing groundwater quality and quantity changes has been investigated. In the first step, GMS10. 05 software was used for determining and simulating characteristics of Mahabad aquifer, in western Iran. After calibration and validation of model, we researched about effective factors influncing groundwater change. To this aim, results was obtained without human activity factors in the first run. In this condition average of groundwater level was obtained to be 3 meters higher than the groundwater level observations. Investigating the constraction of dam as an anthropogenic activity factor showed that the dam construction causes groundwater level to be 1. 11 meters lower than the pervious condition. We then predicted the groundwater EC and SAR using GEP as a function of groundwater level. We concluded that anthropogenic activities in comparison to the natural changes are the primary force which demolishes the groundwater level and guality and changing the 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. The objective of this study was to apply Ordered Weighted 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 data, soil maps and reports, Digital Elevation Model and landsat-8 OLI, were used. Different ordered weights 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 indicated as the selected groundwater recharge zones. The riskaverse procedures (first and third procedures) did not introduce any suitable site for groundwater recharge. However, the second and fourth procedures did suggest 11 and 25 zones, 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 and analysis of drought effects, through SPI index assessment, on the water quality and quantity of the Dez River. For determining the drought, ten-year meteorological data (2005-2014) were achieved through the weather stations of Hussainiya, Dezful, and Shush. For evaluation of drought impact on the water quality and quantity of the Dez River, discharge statistics and qualitative parameters related to seven hydrometric stations along the Dez River were achieved through Khuzestan Water and Power Authority. The mean frequency of dissolved anions and dissolved cations in the hydrometric stations of the Dez River was achieved as HCO3>SO4>C and Ca>Na>Mg, respectively. The variance analysis of the water quality parameters showed that the effect of station and year on the amounts of discharge, EC, TDS, SARIW, pH, concentrations of Cl, HCO3, Ca, Mg, Na, and SO4 had a significant difference (P<0. 01). There was no significant trend for EC variations in stations of Sepid Dashte Sezar, Sepid Dashte Zaz and Tange Pange Sezar. While the trend of EC variations in the stations on the lower reaches of the river was significant and positive. The most severe drought was recorded in 2008 in Hussainiya and Dezful stations and in 2011 in Shush station. During the drought years, the mean water EC of Dez River increased by 15. 24%. According to the results, drought phenomenon is effective on water quality in the company of issues raised by the water transfer, land use change and proper management of pollutant.

Rivers are amongst the most dynamic ecosystems of the world and therefore it is essential to examine their temporal and spatial changes including their water quality. 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 Khodaafarin, Khazangah, and Jolfa, gauge stations using statistical multi-variate analysis, factor analysis, and Principal Component Analysis. At Khodaafarin station, the first three components with the highest eigenvalues explained 53. 5, 15. 7, and 13. 9 percent of variance changes. The first component with the highest explanation of variance had the greatest correlation with parameters of Mg2+, Ca2+, HCO-3, EC, and TDS. The component showed the ions and suspending particles at Khodaafarin station. Among the parameters of the first component, EC had the highest factor loading (0. 98) as the main parameter of the component. At the Khazangah station, the first three components explained 53. 6, 17. 5, and 12. 9 percent of variance, respectively. The first component had the highest correlation coefficient with the parameters of Mg2+, Ca2+, SO4 2-, Cl-, HCO-3, EC, and TDS. In Jolfa station, the first four components with the highest eigenvalues explained 50. 7, 15. 8, 13. 2, and 5. 8 percent of the variance. In the first component, Mg2+ with the highest factor loading (0. 96) was the main parameter of the component.

Lake Urmia located in north-west of Iran has faced a serious environmental crisis as a result of some natural and anthropogenic factors. Regulation of rule curve of dams and their optimum redistribution is among essential actions for ecosystem conservation of the lake. In a simple hydrological method, optimum release from dams is estimated by calculating the runoff of downstream catchment. Accordingly, in this study the rule curves of the major reservoir dams in the Lake Urmia basin (ShahidKazemi, ShahrChai, Zola, Derik, Venyar, Ajabshir and Alavian) has been calculated under three different operation policies (30%, 50% and 80% of MAF). Then by using measured data, monthly value of QResidual (the runoff of the downstream catchment) has been calculated. In the next step, the term of QAAD (the volume of annual available water in the last station on the river) 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 was selected as effective scenario 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 was 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.