نشریه منابع آب و توسعه
پیاپی 1 (پاییز 1392)

In this study the effective factors on the salinity increase of surface water in Shamil-Nyan basin dam have been researched using sampling and water chemical analysis. According to the chemical analysis of water samples, the conceptual model of the salinity distribution in this basin was defined. Hydrological computations were performed to estimate flood volume due to each subsidiary basin of the main Shamil-Nyan basin. Studies showed that the salinity of surface water here is due to two main factors: two Hormoz salt plugs in the north of the basin, and marl formations (containing halide and gypsum) widespread over the basin. Since marl formations are diffused over the basin, there is no reasonable way to control their salinity, but the salinity due to two salt plugs can be controlled using evaporative dams. Dams prevent the saline water to be added to the main river of the basin which leads to the dam reservoir. The present Study showed that using evaporative dams, 21.1 percent of water in Shamil-Nyan dam can be reduced. It means that the salt concentration in water can be reduced from 1.80 gr/lit to 1.42 gr/lit.

Ghaemshahr plain faces salt water intrusion due to geological, hydro geological, hydrological and regional conditions, human factors and nearness to Caspian Sea. This plain is located at the northwest of Iran in Mazandaran state and near Caspian Sea with longitude 52°- 35' to 53°-23' east and latitude 35°-44' to 36°-47' north geography situation. These studies using of geophysical, geological and chemical analysis information are drown graphs and maps based on salt water intrusion. These studies show that excessive discharge, continual drought and unsuitable watering methods have led to decrease of access level and therefore, intrusion of salt water into aquifer during the last 40 years. Besides, during different geologic periods, Caspian Sea had undergone much regression and transgression, so some water of this sea remained in Absheron formation sediments and is covered by new Caspian formation above sediments. That’s why connate water aquifer in the different parts of plain was created. The water of these aquifer, because of decreasing fresh water’s vertical pressure or spray method and ions change at the middle parts of plain, entered to fresh water aquifer and changed fresh water to salt water. On the basis of these results it is necessary to control discharge water and regulate watering methods based on agricultural manners. Selecting a suitable method for artificial recharge nearness heights based on access level situation in recharge region is very important, because Ghaemshahr’s aquifer plain is faced with crisis position, so if these practices go on, these aquifers are wiped out in the near future and due to population growth, the expansion of lands under cultivation and continual drought.

Gorgan region is located on the northern limb of the eastern Alborz. This region is bounded by Alborz heights and Gorgan plain to the south and north. Most of the existing faults in the region have NE- SW (N70- 90) trend with left lateral strike slip movement and reverse component (up to thrust). Furthermore, a number of faults also have NW- SE trend with right lateral strike slip movement and reverse component. Khazar and North Alborz faults are the most important faults in the region and make the structural boundary around the region. In this study, initially, major and main faults of the region were extracted by remote sensing techniques and then, controlled by field investigations. After that, the vector data layer of the springs of the study area was provided then both layers (the extracted faults and spring location) were entered into GIS environment to compare of the springs location and faults conditions. The results indicate that, most of the springs are situated on the breakage zones of the major faults. Further investigation of these results; confirm existing relationship between different type of faults and spring distribution pattern. The major faults of the region with southward slope (such as Khazar fault and North Alborz fault) prevent groundwater transition toward the Gorgan plain and thus, cause the appearing of various springs in the surrounding area of these fractures. Second- order fractures with N40- 50 and or N140- 160 strikes, truncated the major faults in 15- 55 and caused to making the transverse current towards the Gorgan plain.

Accurate estimation of flow in streams can have a significant role in water resources management. In this study, estimation of yield of Kakarza River in Lorestan Province was assessed by using aoutocoorelated model then the results compared with intelligent methods such as neural networks. River discharge parameters on a monthly time scale during the period (1361- 1386) are used as input data in the selected model. Correlation coefficient Criteria, root mean square error and coefficient of Nash Sutcliff was used to evaluate and compare the performance of the models. The results show that both two mentioned models were able considerable accuracy to estimate river discharge, but in terms of accuracy, the ANN model with the highest correlation (0.856), minimum root mean square error (0.049 m3/s) and Nash-Sutcliffe efficiency 0.677) were put in the verification phase. The results show that the artificial neural network model has high ability to estimate of minimum and maximum values of river discharge.

Insufficient water for various uses is one of the most important economic issues in wilderness areas. On the other hand with the population growth and economic development, water demand has increased. Thus, water demand management exerted through determination of the economic value of water is essential as an approach to the management and utilization of water resources. This study examined the willingness to pay for safe drinking water by using contingent valuation (CV). The required information was obtained during the spring of 2013, based on 480 completed questionnaires by the people using Mitchel and Carson Method. For measuring individual's WTP Logit model was used and according to MLE method, model parameters were estimated. The results show that the proposed rate and income variables of visitors are the most important factors which are statistically significant at p<1%. Annual average willingness to pay for safe drinking water was estimated 94764.59472 Rials and Value per cubic meter of water 268.06007 Rials. Based on the recent results, it is recommended to calculate the economic benefits of water projects, water allocation, and the economic value per cubic meter of water used based on the actual preferences of consumers. This can help guide policymakers, especially in the private sector to invest in water supply projects.

Groundwater being a hidden resource is often developed without proper understanding of its occurrence in time and space leading to overexploitation and contamination. Dependence on groundwater is increasing continuously in order to supplement the domestic, agricultural and industrial requirements. Therefore, for sustainable and efficient use of groundwater, adequate knowledge of the aquifer parameters needs to be stressed. An attempt has been made to determine the Transmissivity (T), Hydraulic Conductivity (K) and Storativity (S) of the shallow aquifers vis-a-vis optimum yield that can be harnessed safely in Barak Valley by conducting a number of Aquifer Performance Tests in the area under study.

The case study is located in southeast of Tabas, central Iran as a part of Shotori Range. In this area, which is affected by high tectonic processes, many structural elements such as faults, especially thrust faults, folds, joints and fractures have developed. This research has investigated the role of structural elements generally lineaments in groundwater development. For this purpose, first the essential thematic layers such as lineament density, lithology, drainage density, DEM (Digital Elevation Model) and slope were generated by using remote sensing techniques, geological data, topographic maps and Landsat ETM Images. Then the geological structures such as lineaments, faults, folds and joints were evaluated, and the digital layers were prepared. Afterwards, the rank of each layers was weighted then the digital layers were integrated in geographic information system (GIS) based on overlap index method to generate groundwater zonation map. The final map of groundwater potential zoning showed close relationship between potential zones and location of lineament elements concentration. It was also found that the most concentration of groundwater zones having high potential are situated near thrust faults in northwest study area.