مكانيابي سد زيرزميني با استفاده از روش تحليل سلسله مراتبي مطالعه موردي: حوضه آبخيز دشت كوير

Suitable site selection for groundwater dams construction using analytical hierarchy process Case study: Dasht- e -Kavir Watershed

با توجه به فصلي بودن آبراهه ها در مناطق خشك و نيمه خشك و انتقال آب سطحي به زير سطح زمين استفاده از سازه هايي كه كنترل و ذخيره كننده جريان براي فصول كم باران سال باشد ضروري است. به دليل پرهزينه و زمانبر بودن مكانيابي سد زيرزميني، استفاده از تكنيك هاي سيستم هاي اطلاعات جغرافيايي همراه با فرايندهاي تصميم گيري به عنوان يكي از ابزارهاي كاربردي در اين مطالعات محسوب مي گردد. سدهاي زيرزميني سازه هايي هستند كه در مسير جريان آب زيرزميني ساخته شده و باعث بالا آمدن و ذخيره آب در مخزن خود مي شوند. منطقه مورد مطالعه بخشي از حوضه آبخيز دشت كوير است كه در شمال غرب استان سمنان واقع شده است. هدف از اين مطالعه تعيين محل مناسب احداث سد زيرزميني با استفاده از تلفيق و امتيازدهي به لايه ها در محيط نرم افزارسيستم اطلاعات جغرافيايي به منظور تغذيه و كنترل آب هاي زيرزميني در بخشي از حوضه آبخيز دشت كوير براي حفظ منابع آب در فصول كم باران مي باشد. دراين تحقيق به منظور اولويت بندي مكان هاي مناسب جهت احداث سدهاي زيرزميني،ازروش تحليل سلسله مراتبي استفاده گرديد كه با در نظر گرفتن معيارهاي ارزيابي، شش مكان مناسب جهت احداث سد زيرزميني در مرحله دوم مكانيابي مشخص شد. در مرحله پاياني به علت نظرات و عقايد مختلف كارشناسان و براي تامين نظرات و خواسته هاي تمامي گروه هاي دخيل در اين امر 5 سناريو براي وزندهي و ارزش گذاري معيارهاي اصلي تعريف شد كه طي اين پنج سناريو وزن نهايي براي هر يك از 6 محور محاسبه شد. نتايج بدست آمده، نشان داد كه مناطق جنوبي دشت داراي پتانسيل خوبي براي احداث سدهاي زيرزميني مي باشد.

Introduction: Problem related to water scarcity has always been one of the most important issues to be considered in arid and semi-arid regions. Due to the seasonality of surface water drainages and subsurface structures in these regions، it is necessary to use structures which control and store the water flow in order to use during arid seasons. One of these types of structures is underground dam to control the flow of water in the subsurface. In semiarid and arid areas in which desert are progressing، exploitation of water has been focused on underground surface water resources having the trouble of stability. In semiarid and arid areas in which desert are progressing، exploitation of water has been focused on underground surface water resources having the trouble of stability (Ouerdachi، L.، et al.، 2012). These conditions require the use of surface and underground short dams for exploiting water in developing countries with arid weather situations. At present، these kinds of structures have been desirably featured in terms of both implication and efficacy in performance (Nilsson 1986، Cavalcanti، N.B.، 2001). Materials and methods: The area studied being part of Semnan province and its surroundings are 216467 hectare in width which geographically have the coordinates of 53D 81M to 53D 15M eastern length and 35D 13M to 35D 85M northern width. Evaluation of station climes studied by both Domarten and Amberje indicates that the studied span has a semi dry-cold climate at heights reaching cold-arid climate where lower-height areas exist. The situation of considered area is shown by Figure 1. With respect to climatic conditions، there are many syllabic flows throughout side hills of the area where underground dam’s establishment is a proper way to control aridity problem in arid seasons of this area. The most significant data of this study are related to topography، geology، underground water، and aqueduct resources. Software's used in this research are both expert choice to prioritize and Geography information systems to combine data. In this research، basic criteria of evaluation including water، pedestals، fountain، economic-social criteria have been targeted at the highest range placing indicators and incidentals criteria at other categories of AHP. Then، proper locations for underground dam establishment have been prioritized. Results and discussion: Based on Gorry and Morton method، decision-making supportive systems are either the systems capable of transporting data or computerized systems which can be used to solve our problems clearly or partly clearly known or unknown respectively (Gorry، G. A.، and Morton، M.S.، 1971). Decision-making supportive systems are models which receive vast majority of data and deliver many solutions specifically designed to overcome the existing problem (Klosterman، R.E.، 1997). Decision support system (DSs) used in identifying proper location to underground dam establishment possess AHP mode and are used in three stages. Conclusion: Considering climatic conditions over the area studied and existing stream، Underground dam establishment highly affects both performance revising and balancing act in underground water removal. Using new methods instead of traditional and time-consuming ones can highly help with saving time and cost to underground dam location-finding. In the first step of this research، presented DSs considering eliminating criteria in the area 216467 hectare in width assign suitable pedestal in each limit which is capable of potential underground dam establishment. Then، in second step، the most suitable strait in each limit is assigned to the underground dam establishment. In the latest step after weighting each main criterion at its related map and as well adding total values of map pixels together in a software called GIS، 8 locations to underground dam establishment at the second step of location-finding in fifth scenario were prioritized as follows: First scenario (weights equality of four main criteria) locations: 5، 3، 2، 4، 6، 1 Second scenario (priority with water criterion) locations: 5، 3، 2، 6، 1، 4 Third scenario (priority with pedestals criterion) locations: 5، 6، 4، 3، 1، 2 Forth scenario (priority with fountain criterion) locations: 3، 6، 4، 5، 1، 2 Fifth scenario (priority with economic-social issues) locations: 3، 1، 5، 4، 2، 6 As shown in most scenarios، pedestals A and D mostly take first to third place. Furthermore، theses pedestals as the best ones catering for all groups’ opinion to underground dam establishment can be offered.