پهنه بندی دشت کبودرآهنگ به منظور احداث سد زیرزمینی به روش ترکیب نقشه های فازی

استفاده از آب زیرزمینی یکی از راه‌کارهای مقابله با کم‌آبی در مناطق خشک و نیمه‌خشک است. کمبود منابع مالی، زمانی و تکنولوژیکی به‌علاوه شرایط فیزیکی سبب می‌شود که استفاده از آب در نواحی خشک در اغلب کشورهای در حال توسعه با محدودیت‌هایی مواجه باشد. طی چند سال گذشته استفاده از سدهای زیرزمینی به‌عنوان راه‌حلی برای غلبه بر مشکل کم‌آبی در مناطق خشک و نیمه‌خشک مورد توجه قرار گرفته است. در این مقاله، به روش ترکیب نقشه‌های فازی در سیستم اطلاعات مکانی (gis)، مکان‌های مناسب برای احداث سد زیرزمینی در دشت کبودرآهنگ، واقع در شمال استان همدان شناسایی می‌شوند. برای این منظور، پارامترهای موثر در احداث سد زیرزمینی همچون شیب، موقعیت چاه‌ها، چشمه‌ها و قنات‌ها، مسیر رودخانه‌ها، محل قرارگیری گسل‌ها، موقعیت روستاها و شهرها، وضعیت راه‌های ارتباطی و همچنین ضخامت آبرفت برای منطقه موردمطالعه جمع‌آوری شد. سپس با استفاده از ابزارهای تحلیل مکانی، لایه‌های اطلاعاتی مربوط به هرکدام از پارامترها به‌صورت لایه‌ی رستری و با استفاده از عملگر فاصله اقلیدسی و درون‌یابی بر‌اساس روش مثلث‌بندی دلونی آماده‌سازی شده و به کمک ترکیب نقشه‌های فازی، استانداردسازی بر روی معیارهای مختلف انجام گرفت. با جمع‌بندی تحقیقات و استانداردها، نقشه‌های معیار به کمک عملگرهای فازی با هم ترکیب شد؛ در روش عملگر اشتراک فازی منطقه‌ای به وسعت 3342 هکتار و در روش عملگر ضربی فازی منطقه‌ای به وسعت 2393 هکتار، حدود یک درصد منطقه مطالعاتی و در روش عملگر گامای فازی منطقه‌ای به وسعت 35574 هکتار، 10.32 درصد منطقه مطالعاتی، دارای پتانسیل بسیار مناسب برای احداث سد زیرزمینی مشخص شدند. نتایج نشان داد که در صورت وجود داده‌های مناسب مکانی و نقشه‌های با دقت، روش ترکیب نقشه‌های فازی می‌تواند نتایج مناسبی برای پیشنهاد مکان‌های مناسب احداث سد زیرمینی را ارائه نماید.

Spatial zoning of Kabodarahang plain using Fuzzy Logic in geospatial information system for the construction of an underground dam

Introduction Iran is mostly located in arid and semiarid regions, and groundwater is its only water resource. The present study introduces a method based on spatial zoning evaluation which takes advantage ofFuzzy Logic and Geospatial Information System to design possible sites for an underground dam, and ranks them according to their suitability. The usability of this method for the construction of an underground dam in Kabodarahang Plain in the north of Hamedan Provincewas evaluated in the present study.   Materials & Methods Groundwater use is considered to be a solution of water scarcity in arid and semiarid regions. Lack of sufficient financial resources and adequate technology as well as specific physical conditions make it difficult to provide clean water in arid areas of most developing countries. Over the past few years, underground dams has been considered as a way to overcome water scarcity in arid and semiarid regions. The present study seeks to identify suitable locations for the construction of an underground dam in Kabodarahangplain in north of Hamadan province using fuzzy logic in GIS environment. As one of the case study areas of Qareh Chai River,KabodarahangPlain isthe largest plain of Hamedan province with an area of 3448 square kilometers and an average height of about 1789 meters above the sea level.It is located between 48°14ˊ 51 ̋ to 49° 5ˊ 11 ̋ eastern longitude and 34°  50ˊ 6 ̋ to36°14ˊ 31 ̋ Northern latitude. To reach the goal of the present study, effective parameters in the constructionof underground dam, such as land slope, positionof wells, springs and aqueducts, rivers channels, positionof faults, location of villages and cities, position of paths and the thickness of alluvium were collected from the study area. Based onthe possibility of performing different spatial analyses in geographic information system environment, zoning ofKaboodarahang plain was evaluated from the point of view of an underground dam construction usingfuzzy logic and GIS tools in the present study.   Results & Discussion Similar to membership in classical series,“And” operatorin Fuzzy Logic is used when two or more different criteria can help in solving an issue. This operator extracts the minimum membership level of pixel units in a specified positionand use it in the final map.Fuzzy multiplication operator multiplies membership level of pixel units in specified positionsof different factors and use the result in the final map. This operator is used when mapsof different criteria have a subtractive effect on each other.Fuzzy gamma operator is the general form of algebraic multiplication of fuzzy multiplication and addition operators to the power of gamma. It is used when increasing and decreasing effects are present in the relations between different criteria. Following the preparation of layers in Arc Map software, Euclidean distance operator and interpolation based on triangulation method were used to convert parameters to raster layers. Based on the background research and standards used, the criteria maps were combined using fuzzy operators. Using Fuzzy membership operator, an area of 3342 hectares, using fuzzy multiplier operator an area of2393 hectare (around one percent of the study area) and using the fuzzy gamma operator, an area of 35574 hectares (10.32% of the study area) was selected as having a very good potential for underground dam construction.Slope Map is also one of the most important criteria in determining areas appropriate for underground dam construction. It is suggested to use a largerscale topographic map to improve the accuracy and increase the possibility of errors. Intelligent algorithms can also be used to determine the threshold level for standardization of the criteria. Since different organizationswork in the field of data collection, it is also suggested to providea suitable mechanism to assess the potential of other plains through consultation and coordination with other relevant organizations. It is recommended to use other parameters and factors affecting the selection of suitable areas for the construction of underground dams, such as soil type or physical and chemical properties of soil in future studies.   Conclusion Zoning maps prepared by fuzzy logic in GIS environment can be used to determine the appropriate location forthe constructionof underground dams. Fuzzy operators provide special conditions which make them more reliablecompared to traditional methods.Appropriate areas for construction of underground dam were identified in GIS environment. A decision making model can also be produced based on the input parameters.It is suggested to enter general information of the area to perform the initial investigation of potential areas and then add field study information to complete the model.