فصلنامه مهندسی منابع آب
پیاپی 47 (زمستان 1399)

One of the most important issues in earth dams is the control of water leakage and the rate of leakage from the dam body and its foundation. Due to the site of the dams, in order to increase the creep length and reduce the leakage, there are several methods for sealing the reservoir of dams. Construction of the cutoff under the clay core of the dams is one of the most effective methods. In this research, the Eyvashan dam leakage analysis was performed with the aim of evaluating the performance of the cutoff wall model in the section and calculating the total discharge flow rate from the foundation and dam body. The maximum amount of leakage flow in the level pool of reservoir conditions is 26.37 liters per second, which was obtained using multivariate regression and the coefficient of determination of the values of R2 = 0.9929 and R2 = 9930 for Geostudio and Plaxis software, respectively. This indicates a good match between observed and predicted data and the proper performance of the dam in terms of seepage discharge. Also, the water pressure level at the downstream side of the cutoff wall has a sudden drop based on numerical modelling which indicates the correct performance of the cutoff wall.

This study analyses the trends in runoff and rainfall data at monthly timescales observed at three rainfall and one runoff stations of Ardabil plain in 1350-1394 period. The purpose of this study is to analyse the trends in runoff and rainfall time series using MK1, MK2 and MK3 tests. Also, in order to determine the dominant periodic components applied hybrid Wavelet Transform and MK1 test. The results of MK1, MK2 and MK3 tests showed that decreasing trend is prevalent in rainfall (P1) and runoff (R1) of Samian station and positive trend in rainfall of Gilandeh (P2) and Kozatopraghi (P3) stations. Also, rainfall time series have not shown non-significant trend. But runoff time series were shown significant trend. The results of MK after removing the effect of all significant serial correlation (MK3) showed the value of trends decreased in comparison to MK1 parameters. Generally, short-term periods were important in the involved trend at original time series. Thus, the rainfall data showed short-term periods of 2 months (A+D1) in monthly scales, respectively. In the runoff time series, wavelet-based detail at level 3 plus the approximation (A+D3) time series was conceded as the dominant periodic component.

In this research, for the first time, a simulation-optimization system dynamic-based model with Anylogic software for reservoir eutrophication management is presented. Thus, the relationships of the elements related to eutrophication were formulated in different layers of Karkheh Dam and in relation to each other in the system dynamics form. comparing the presented results with the results of the CE-QUAL-W2 and Vensim simulation models over a one-year period showed that the value of the correlation coefficient (𝑅2) for the variables phosphate, ammonium, nitrate, Dissolved oxygen and Chlorophyll-A between the two models of Anylogic and CE-QUAL-W2 is equal to 0.89, 0.81, 0.78, 0.75 and 0.86, respectively, and the value of this coefficient for the mentioned variables is equal between the two models of Anylogic and Vensim. With 0.98, 0.94, 0.90, 0.93 and 0.97, which shows the high correlation between the results of Anylogic model with the two mentioned models. Then, by combining the developed model in Anylogic environment with a simulated annealing optimization model, a simulation-optimization model was developed to determine the optimal values of water releases from different layers of reservoir in 15 years’ horizon considering the quantitative and qualitative objectives. Here, the RMSE between the results of the two models for the lower, middle and upper layers of the reservoir is 0.004, 0.007 and 0.010, respectively, and 𝑅2 is 0.91, 0.9 and 0.79. The results indicated that the results of the two models were similiar. This study showed the effectiveness of the proposed model in the management of dam eutrophication.

Considering that Semnan Province is in an arid and semi-arid region like other dry parts of the country, it is more vulnerable to a water scarcity crisis, So, Semnan Plain was selected to study groundwater level. In order to study the reduction of water level, 20 observation wells were surveyed during the 20-year statistical period (1994-2013). At first, statistical data from the regional water company of Semnan Province were collected and arranged. After entering the data into GIS, using point maps and Kriging interpolation method, the zoning of surface degradation of groundwater in the study area were prepared. For better display, the resulting data were plotted on the graph in Excel. The results of the study showed that during the statistical period over time, the average groundwater level was reduced by 8.6 meters. Monthly surveys also showed that the highest level of surface water loss was due to the months of September, October and November, which lower rainfall and autumn crop start, and as a result, exploitation of groundwater resources is higher. In order to investigate and identify the sensitive areas and the role of land use on the quantity of water in wells, the specifications mentioned for each type of land use were separately examined. The results showed that the most reduction in groundwater level is related to the residential area. Finally, it can be concluded that the region is in critical condition for groundwater resources, and managing these resources is very essential in the Semnan plain.

In arid and semi-arid regions, agricultural development and increasing population have reduced water resources, which will lead to social and environmental consequences for human societies. proper water resource planning in optimal conditions is one of the main challenges of water resources management. In this study, water resources management of the Oshnavieh and Naghadeh plains in Ghadarchai basin was evaluated using WEAP software, for the period of 2000 to 2015. First, the model was calibrated and validated under real conditions. Then, the conditions of area were evaluated by two scenarios of agricultural and population change. Based on the statistical indices, results of the model showed good performance of model in historical period. Scenarios also showed that an increase of 10 to 30% in the agricultural section reduce the average annual flow of the Ghadar River by 0.10 to 0.5 m3 s-1 and increase the water use rate of the region by 8.2 to 24.5 million m3. Due to water scarcity, it can be said that any agricultural development will deplete its water resources. As the Oshnavieh and Naghadeh Plains are one of the important plains of the Lake Urmia basin and the global development trend and population growth, the essential decisions must be made by the region's water managers to properly manage water resources in these plains.

Nowadays, the use of proper irrigation methods to increase the productivity of water use in the agricultural sector due to the limited water resources is considered essential. The aim of the present research was designed with the economical assessment of irrigation different methods (drip irrigation, center pivot and fixed classical sprinkler irrigation) in using new(solar) and traditional (network) energies in irrigated wheat production. This research carried out in Alborz province in 2016 and 2017. In this research, at first, water requirement of this product was determined by Karaj condition and then, the cost and benefits of irrigation different methods using electricity network and solar power in the production of wheat was determined. For economic analysis in order to selecting the best irrigation method used Partial Budgeting Method. In this method, used Cost and Benefits and Marginal Net Benefits. According to the results, water saving in drip irrigation, center pivot to fixed classical sprinkler irrigation were estimated 22.8 and 17.6 percent, respectively. That means the net Benefits of wheat production in fixed classical sprinkler irrigation, center pivot and drip irrigation using electricity network were estimated 84.6, 85.6 and 90.7 Iranian million rials per ha and using solar power were estimated 72.4, 79.7 and 85.3 Iranian million rials per ha. In general, drip irrigation system using electricity network was recommended as better treatment and economic in wheat production, because, substitution of others systems instead of this method, Marginal Net Benefits in this substitution would decrease.