فصلنامه مهندسی منابع آب
پیاپی 50 (پاییز 1400)

In the presented study, a multiobjective optimization-simulation model was developed to al-locate optimal water, cultivation area and crop pattern to different agricultural sectors. The sectors are located at a region encompassed by three cities; Minoo dasht, Azad shahr and Gonbad kavoos, in Golestan province. The model is a Surface-Groundwater conjunctive use model in which Modflow-GMS model is used to simulate groundwater flow. In the optimiza-tion part, the objectives consist of the maximization of the equity, agricultural benefit and green water ratio. Also, the constraints are related to maximum drawdown in water table, minimum and maximum volume of the reservoir, budget equation, release and cultivation ar-ea. After running the model by multiobjective genetic algorithm method, a pareto solution curve including 63 solution points obtained. The most preferable solution is selected by Con-dorcet method. Then different cooperative game theory method are applied to reallocate the benefit due to forming the grand coalition among the sectors. The results show that the amount of allocated water is a function of the summer crops area. Also it is shown that the most benefit is obtained for Gonbad kavoos, while the most benefit per cultivation area is for Minoo dasht. After that, the grand coalition forming causes to increase benefit up to 14864×109 Rial (20 percent growth). To reallocate benefit among the regions, different coop-erative game methods are applied. The results show that the most reallocated benefit for Minoo dasht, Azad shahr and Gonbad kavoos are obtained from normal nucleolus, nucleolus and proportional nucleolus, respectively.

Estimation of subsurface flow (SUF) is important in many catchments with good vegetation cover and high soil permeability and plays a major role in direct runoff. The concept of SUF in soil is still more complicated in comparison with surface flow, so providing predictive models for SUF basins with simple and practical methods are of interest to hydrologists. In this research, for the first time, surface rainfall-runoff models have been used to estimate the subsurface flow of the hillslopes. Two SCS and Nash models were used to estimate the subsurface of the catchments. In this paper, the unit hydrograph equations of the two models were considered as a function of the subsurface travel time and the amount of infiltration. Equations for calculating the actual SUF travel time were presented for use in models. To validate the results, results of rainfall simulator model were used to measure the surface and subsurface flow. The mean error in the surface runoff peak estimation was 7.8% and in the 6.7% subsurface runoff estimation by SCS model. In the meanwhile, the mean error in the peak runoff runoff estimation was 11.21% and in the subsurface runoff estimation was 11.32% in Nash method. The effect of slope and soil hydraulic conductivity on the SUF hydrograph were evaluated by two models.

Density currents are often the main cause of sediment transport in deep water and reservoirs. To prevent sedimentation in critical locations of dams, various methods have been proposed, including placing obstacles in the path of these currents. in this study, the effect of discharge, inlet concentration, slope and height of trapezoidal permeable obstacle on the behavior of density current has been investigated . 72 experiments were performed with variable discharge of 1, 1.5, and 2 liters per second and variable concentrations of 10 and 15 g/l, slope of 0.5%, 1% and 1.5% and obstacle height of 1,1.5 and 2 times the body of density current. The percentage of flux reduction was determined and the effect of other parameters was evaluated. The results showed that slope, concentration and inlet discharge are the factors affecting the momentum and by increasing each of these parameters, the efficiency of obstacle with heights of 1 and 1.5 times body density current decreases. In case of obstacle with a height of 2 times the body, when the current collides with the obstacle, there is a lot of turbulence, which decreases the momentum of the current, and complete control is performed. Thus, the average percentage of flux reduction for the dimensionless ratio of height 1 is about 38%, for the dimensionless ratio of height 1.5 is about 52% and for the dimensionless ratio of height 2 is about 86%. Finally, linear and nonlinear regression of the average percentage of flux reduction data was obtained.

Side weirs are important and practical hydraulic structures in water conveyance systems that are installed on the side wall of the channel to divert excess water from main channels. In this research, the effect of the height of two-side semicircular labyrinth side weir on the discharge coefficient and water surface profile in 3D by using the FLUENT software. side weirs were used in three, four and five cycles with a height of 10,15 and 20 cm and an opening length of 40 cm. The discharge coefficient and water surface profile obtained from this simulation were compared with experimental results for validation. The computed values have a good agreement with the experimental data and the error percentage for the discharge coefficient is between zero and 7% and the relative error was decreased by decreasing of Froude number. Based on the results, as the height of the side weir increases, the rate of water surface fluctuations in the main channel and along the side weir decreases. On average, with every 5 cm reduction in the height of the side weir, the rate of water surface decreases by 3%. Also, the discharge coefficient of the side weir decreases with decreasing congress radius and with increasing the side weir height and upstream Froude number. Therefore, the semicircular labyrinth side weir of three-cycle with height P = 10cm has a higher discharge coefficient than the other side weirs under study.

Successful management of groundwater resources using numerical models requires knowledge of spatial distribution of hydraulic heads and it's fluctuation, aquifer parameters and other input data. One of the most basical issues in groundwater resources management is the estimation of water table from observation well network data. In this study, three methods of artificial intelligence, geostatistics (Kriging) and IDW with evapotranspiration, air temperature, precipitation and geographic inputs were used to simulate the depth of groundwater Salman Farsi Sugarcane Plantation. The results showed that the highest simulation accuracy of groundwater depth in Salman Farsi Sugarcane Plantation was related to the artificial neural network model with the highest R2 (0/92) index and lowest RMSE and MAE (1.25 and 1.74) values. Also, among the Kriging and IDW models used, the accuracy of the Kriging model was more than the IDW model. Due to the acceptable accuracy of the results of the presented models, the water resource planner and decision maker in this field can apply this optimum interpolated groundwater depth to monitoring the spatiotemporal fluctuation of groundwater depth in this area by updating it's data.

Due to limited water resources, increasing water productivity is very important to achieve water security and food security. One of the basic measures in this area is to determine the difference in product performance between the current situation and the potential situation. Crop potential yield is one of the parameters that can be used to calculate the yield gap and to manage water and soil resources based on the factors affecting production. In this study, the potential yield of major crops in the composition of irrigation network of Qazvin plain has been determined by agronomic method. The results showed that the yield gap in the crop composition of major crops in Qazvin plain was 3339 (kg / ha). Also, the average yield gap due to the composition of cultivation, yield gap of each crop and the area under cultivation of crops in the irrigation network of Qazvin plain, was 26.23%. The results of estimating the potential yield at the level of the irrigation network of Qazvin plain show that not all crops have reached the achievable yield level (75 to 85% of the potential yield) and there has been a high yield in crops such as sugar beet, tomato and alfalfa. Given that in the current situation of operation of the irrigation network, it is very difficult to achieve potential performance, in such cases, the gap between actual performance and achievable performance should be reduced.

Water consumption management and optimal operation of reservoirs are important challenges for sustainable development in arid and semi-arid regions of the world. Increasing water consumption productivity is recognized as an adaptive strategy for coping with drought conditions and increasing water demand due to population growth. Nonetheless, the impact of the increase in water consumption productivity on the operation of reservoirs is neglected in assessment as a management tool. Therefore, in this research, the impact of the increased efficiency in agriculture water on Jareh-Dam operation as a case study has been assessed. For this purpose, an objective function has been developed based on the coefficient of water efficiency to optimize the water release and water storage in the Jareh-Dam. The operation reservoir is then compromised in both optimal and current conditions with considering the four scenarios of water efficiency. Results show that increasing in the coefficient of water efficiency up to 0.5 will result in an increase of 10 percent in the reliability and a 28 percent decrease in the vulnerability. Also, assuming the reservoir performance is constant compared to the base period, with a 17 percent increase in downstream consumption efficiency, a growth of 46.7 percent in the region's gross income is not far from expectation.

The urban planning and management approach in the green city, as an essential and comprehensive part of urban strategies based on ecological management, seeks ecological sustainability and consequently urban sustainability by adapting environmental indicators. In recent decades, the metropolis of Tehran, due to its centrality and consequently the increase in population, has caused the community to enter the ecological area of nature, and especially urban rivers, the natural space of rivers has undergone extensive artificial changes. One of the priorities for the development of blue green space is the rehabilitation and reorganization of urban rivers, which is developing rapidly in the world. This issue has been considered in urban rivers of Iran, including Tehran, during the last two decades. In this article, in particular, the spatial development of Kan River, which is one of the natural and recreational spaces of Tehran, with the approach of revitalization and development of urban rivers and blue green space development options, is presented with a multi-criteria decision support system (MCDM). And the use of the Analytic Hierarchy Process (AHP) has been investigated. In accordance with the natural conditions of the river and the existing artificial spaces affected by urban development, considering the six criteria and the options presented in this research, the criterion of "increasing the visual blue green area of urban rivers" is more important and In addition, among the options offered, the option "Dynamic River Landscapes" was selected as the best option for the development of blue green space.

Water resources and its health is one of the main foundamentals of sustainable development. In this study, the effect of the presence of an urban area in a section of Haraz River located in an urban area was investigated by analyzing 17 physicochemical and biological parameters. Sampling was done at two sections of entrance and exit of the urban area. Sampling time were also determined both before and after rainfalls on the basis of the forecast of specialized meteorological sites about rainfall that caused significant runoff at the city area. Also, three qualitative water Indices, including the U.S. National Sanitation Foundation Water Quality Index (NSFWQI), the Oregon Water Quality Index (OWQI) and the Wilcox agricultural index were determined. The U.S. NSFWQI for the Haraz River was in the mid-range class (50-70), indicating that the river is moderately good in terms of quality. According to the OWQI, Haraz River was mostly in the weak and medium range and needs drastic management changes. According to the Wilcox index, the river's water was placed in C2S1 classification. The amount of lead in the samples was 0-1.2 µg/lit, which in all cases was lower than standard. The results of analysis of variance using SAS showed that the effect of cross section and sampling time on lead and water quality indices were not significant at 5% level. Also, according to the results, the presence of the urban area of Amol city did not have a significant effect on the water quality of Haraz River.