Constraints on water resources and increasing the number and variety of water users has led to appeal of the importance of optimal water allocation. The Khanmirza watershed in Chaharmahal Va Bakhtiari Province, has experienced unsustainable development by relying on groundwater resources. As a result of this imbalance, a dramatic drop occurred in the aquifer of the Khanmiza plain. The Khanmirza watershed allocation model in WEAP environment were developed to investigate the allocation and spatial changes, considering the base year( 2015), the horizon year of the plan( 2025), and the one-month timeline. The four scenarios examined in the WEAP model included the reference scenario, pessimistic scenario, optimistic scenario and realistic scenario over the next ten years. The results showed that 51 million cubic meters of demand, in a pessimistic scenario, 79 million cubic meters, in an optimistic scenario, 30 million cubic meters, and in a realistic scenario 41 million cubic meters cannot be provided. Therefore, given the high volume of water requirements in the agricultural sector, the need for special management and planning in this area to prevent groundwater loss is quite tangible. It is also clear that the use of water for agricultural in the studied area acts as a competitor to the environment and without land use management, water management will face tension.

Utilizing hydrological models allows for the correct and sustainable planning of water resources management. In this research, with the aim of simulating the flow of the Aland watershed (located in the Aras river basin) as a watershed under the influence of human activities, the WEAP model was developed, calibrated and validated. For this purpose, an 11-year statistical period (2001 to 2011) was used to calibrate and a five-year period (2011 to 2016) was used to validate the model. The model simulation results at the basin outlet showed statistical indices of the coefficient of determination and Nash-Sutcliffe Efficiency (NSE) were 0. 96 and 0. 85, in the calibration period, respectively, and during the validation period there were 0. 79 and 0. 78, respectively. These results indicate the good performance of the WEAP model in simulating hydrologic behavior, including rainfall-runoff, base flow, groundwater and other components of the water balance of the Aland watershed. In this research, the simulation results of drinking water supply scenario from the Agh Chay Dam indicate a reduction in groundwater level drop and an increase in the volume of aquifer at an annual rate of 5. 4 million cubic meters.

In this study, the WEAP model was used to analyze the continuation of the existing situation (reference scenario) and the impact of implementing the defined scenarios s1 (increasing drip irrigation with 85% efficiency and sprinkler irrigation with 65% efficiency), s2 (increasing the cultivated area) , s3 (change in cropping pattern), s4 (water demand management by 20%), s5 (40% reduction of inflow to the reservoir in the planning horizon) and the combined scenarios from these scenarios for the optimal allocation of the Jiroft reservoir water. The results of the different scenarios show that in the reference scenario, the total amount of agricultural demand is 1559.8 million cubic meters, of which 19.7 million cubic meters are not supplied. According to scenario s1, the total amount of agricultural demand is 801.8 million cubic meters, which is fully met, and the amount of dam water storage in this scenario will be 66730 million cubic meters. The results also show that the amount of water demand and unmet water demand does not change in the combined scenario S145 compared to the combined scenario S14. Still, the water storage in the dam reservoir decreases by 66037 million cubic meters. The results of this study have shown that the WEAP model offers the most effective solutions to meet the varying water needs of the Jiroft Plain and reduce the negative effects of drought. Changing the current cropping pattern increases the amount of storage and the unmet water demand also decreases.

Today, conservation and protection of water resources and optimum utilization and equitable economy and it is a global issue And therefore the century of water as a universal human challenge is to learn. Water is the primary factor limiting agricultural production, thus increasing the need for optimum utilization of water resources, especially in Agricultural use, which comprises the bulk of the country's water resources is felt. This paper presents an algorithm for performance evaluation Zayandehrood Dam with emphasis on the centrality of water. To achieve the objectives of this study used modeling method reservoir operation. WEAP model to be acceptable The simulation of water resources systems. Thus collected after the completion of the required information, file input Formed WEAP model is calibrated for a period. Then the optimal exploitation policies Reservoir model in various scenarios of water use in the basin, and in each case the WEAP model was implemented and results. Results are evaluated. In this study, 5 scenarios were evaluated four scenarios that reduce crop acreage Macro and three scenarios and two scenarios of growth required to reduce Nyazaby drinking water industry, and the combination of these two scenarios. scenarios SC2 inter strongest consider Insurance and Insurance Water needs and the maximum volume of water stored in the reservoir during the year better than the other scenarios for reservoir. We carry in our drought.

One of the most important problems of water resources operation systems, specifically surface reservoirs in confronting hydrologic variability, is considering drought phenomenon effects on operation methods. As well as flow variations relative to average flow, duration of the drought is another important factor. One way to resist the drought is suitable operation of water resources during drought conditions. There are several models developed for water resources management such as WEAP software. But such models do not have water resources modeling capability during drought conditions. Therefore, developing such capability on WEAP model is highly important for water resources engineers. Developing the hedging rules for operation based on WEAP software was investigated by this research by which an extension program was developed in WEAP software. Developing such model would enable us to jointly optimize and simulate on basins. In order to test the capability of the complementary program, modeling was performed on operation of Gorganrood river reservoirs. Then the results of the developed model were compared to the ordinary WEAP software results. The results indicated 1 to 38 percent increased capability of WEAP software on modeling for hydrologic drought conditions. It is worth mentioning that the complementary model was developed as a general model by which the model can be used on different basins.

Nowadays, due to increased water consumption and demands, optimum water allocation should be taken as a serious need. In this research, WEAP and Vensim softwares are used to plan and manage the water resources and demands in Nazloo River basin, located in West-Azarbaijan province. By use of these softwares, two models were prepared: One for supplying water demands of the region using river flows (without Nazloo dam) and the other one with the same condition but by considering the Nazloo dam operation effect. Water demands of the region were assessed up to 2016, river flow of the past 40 years was analyzed, and river discharge of 2013-2016 was estimated by ARIMA method. Results showed that average differences between the results of WEAP and Vensim softwares were 3. 74% and 8. 91% for the with-dam and no-dam options, respectively. The highest water deficiency was in water supply to agricultural demand in September, which with construction of the dam, the average supply in this month increases from 15. 8% to 94% of the demand amount. To verify the obtained results of the unmet water demand in various years, the SPI index was used, which in 72. 5% of the cases it was consistent with the results of the softwares. In general, without constructing the dam, water needs of industry and environment will be mainly supplied, but there would be some deficiencies in water supply for agriculture. For water supply, instead of constructing a dam with a storage capacity of 154 MCM, a dam with a capacity of 100 MCM will be enough.

The uneven distribution of water in the world has caused many countries to face water shortages. The lack of water has made the production of agricultural products a challenge. Water-scarce countries invest in the farms of water-rich countries as a strategy to provide needed agricultural products. This strategy is known as extraterritorial cultivation. The Hirmand watershed is facing limited water resources due to its dependence on the Hirmand transboundary stream from Afghanistan. In this research, the aim is to simulate the strategy of extraterritorial cultivation of agricultural products in order to manage water shortage in the Hirmand catchment area. In this regard, the Hirmand watershed was modeled using the WEAP model, and the current and future status of water resources and uses were simulated. Then the extraterritorial cultivation strategy was simulated as a scenario. Wheat, barley, and corn products were selected as the target of extraterritorial cultivation. The results showed that in the current situation, the Hirmand catchment area faces a water shortage of 582.812 million cubic meters per year, and 41.16% of the water demand in the Hirmand catchment area is not met. 72.42 percent of the total water shortage in the Hirmand catchment area is related to the agricultural sector, and 27.58 percent is related to the environmental sector. After applying the extraterritorial cultivation strategy, the water shortage in the agricultural sector is reduced by 93.89% and reaches from 364.524 million cubic meters per year to 22.242 million cubic meters. In the environmental sector, the water shortage will decrease by 95.19% from 219.911 million cubic meters per year to 10.570 million cubic meters per year. Applying the extraterritorial farming strategy has redistributed water resources in the Hirmand catchment area.

Water is one of the most basic environmental resources and plays an important role in human life. The Sistan river is the only source of water supply in this area and is completely dependent on the border river of Hirmand. The water of this river fluctuates greatly due to the interference of the country of Afghanistan, climate changes and the existence of Hamon international wetland, which has made the issue of decision-making regarding the management of water resources in Sistan region more than in other regions. This study, using the WEAP model, deals with modeling the effects of changes made in the water resources system in the Sistan region, which has special weather conditions. The results of this study showed that policies implemented in recent years have a positive effect on increasing water resources and decreasing water shortages in agriculture, drinking water, and the environment sectors, and supply-side policies combined with demand-side policies like increasing irrigation efficiency and reducing the per capita consumption of water can have a greater effect on economic, social and environmental development. It was also found that domestic water needs were met in all months, but in the agricultural sector, only 20% of agricultural water was provided to farmers in the summer months. Therefore, based on field observations, the agricultural sector is facing more problems in supplying water to the regions. Finally, for environmental needs, 184,000 cubic meters of water needed by Hamon Hirmand has not been supplied.