برآورد و بررسی تداخل حریمی چاه های بهره برداری جهت شناسایی مناطق آسیب پذیر آبخوان (مطالعه موردی: آبخوان سنجابی کرمانشاه)

در شرایط اقلیمی کشور، با توجه به حجم عظیم برداشت از منابع آب زیرزمینی توسط چاه‌ها و نیز با در نظر گرفتن تعداد چاه‌هایی خصوصاً در سنوات اخیر حفر گردیده، محاسبه حریم به منظور اعمال مدیریت صحیح بر حفظ و بهره‌برداری بهینه از منابع آب زیرزمینی از اهمیت ویژه‌ای برخوردار است. در این راستا یکی از مسائل که دست اندرکاران حفاظت از آب‌های زیرزمینی را به خود مشغول کرده، تراکم و نزدیکی چاه‌های بهره برداری از یک سو و اضافه برداشت توسط بهره‌برداران از سوی دیگر می‌باشد. از این رو؛ در این تحقیق، در ابتدا تابع چاه حل ریاضی گردیده و شعاع تاثیر هر یک از چاه‌ها در دو حالت اعمال دبی اصلاحی (بر اساس سطح زیر کشت) و دبی پروندهای (دبی پروانه بهره‌برداری) بدست آمد. سپس نقشه شعاع تاثیر کل چاه‌های محدوده ترسیم و سپس نواحی دارای تداخل حریمی مشخص و ترسیم گردید. بر اساس نتایج بدست آمده متوسط دبی آبکشی کل چاه‌های بهره‌برداری در حالت دبی اصلاحی و پرونده‌ای به ترتیب 18.37 و 11.14 l/s محاسبه گردید که نتیجه این تفاوت دبی آبکشی در اختلاف کل مساحت تداخل حریمی به میران 30 درصد (116.6 کیلومتر مربع) بدست آمد. همچنین نتایج نشان داد در خوشبینانه‌ترین حالت، قریب 20% از کل مساحت آبخوان دارای تداخل حریمی می‌باشد. این مسئله باعث می شود هنگام بهره برداری همزمان از چاه های همجوار، مخروط های شدید افت ایجاد شده و آبخوان تحت استرس های غیرمعمول قرارگیرد که در طولانی مدت موجب ایجاد افت دائمی و ماندگار در آبخوان و در بلند مدت منتج به فرونشت زمین گردد.

estimation and study of privacy interference of exploitation wells to identify vulnerable areas of the aquifer (case study: ravansar-sanjabi aquifer in kermanshah)

introduction in iran climatic conditions due to the large groundwater abstraction volume by wells and also increase the number of drilled wells especially in recent years it makes the calculation of water resources privacy very important in order to apply proper management on the conservation and optimal use of groundwater resources. in this regard, one of the issues that concerns those involved in groundwater protection is the density and proximity of exploitation wells and overdraft by exploiters. observing the privacy of water resources is not only to prevent the water level of adjacent sources from decreasing but also means the allowable withdrawal to the extent of the aquifer potential. calculating the wells privacy and aqueducts and observing it is essential in the optimal management of groundwater resources. in most cases, incorrect estimation of the well privacy and aqueducts or non-compliance with the relevant rules will cause many problems and can lead to disputes between farmers and farmers as well as damage to groundwater resources. material and methods in this study, first, the hydrodynamic coefficients of the studied aquifer were determined. in the next step, the quantitative privacy of all wells in the aquifer area was determined. then, the impact radius of each well was calculated using a mathematical model in two modes of corrective discharge (based on the area under cultivation) and file discharge (discharge recorded in the exploitation license). finally, a map of the impact radius of the wells in the gis environment was drawn and based on it, the areas with privacy interference were identified. due to the interference of wells with each other, various solutions were proposed to improve the current situation to be used by decision makers.results and discussion based on the obtained results, the average discharge of all exploitation wells in the corrective and case discharge mode was calculated to be 18.37 lit.s-1 and 11.14 lit.s-1 (116.6 km2), respectively. the results also showed that in the most optimistic case about 20% of the total aquifer area has privacy interference. this causes the local wells to undergo simultaneous operation, severe localized cones and the aquifer to be subjected to unusual stresses, which in the long perform causes a permanent and lasting decline in the aquifer and in the long perform results to subsidence of the earth's surface.conclusions the results of the present study indicate that the fact unfortunately in most plains of the country that have agricultural uses there is a privacy interference between exploitation wells and as a result of high density of wells and proximity to each other radius of impact of two or even several wells together overlap. in addition, more harvesting of aquifer potential and capacity from wells increases the aquifer vulnerability and the likelihood of future problems. it should also be noted that the ravansar-sanjabi aquifer is one of the aquifers that has more unfavorable conditions than other aquifers in the province and in recent years due to stresses caused by droughts and unauthorized withdrawals has a sharp drop in water level. therefore, the need for more comprehensive studies in other plains and aquifers of more sensitive and more water stress areas can provide more complete results. because it should be noted that due to the current climate and drought, groundwater resources can not be properly renewed and recharged, and according to experiences in other parts of the country, the current trend continues to cause a sharp drop in aquifer levels and consequently subsidence and will sink.