ارزيابي آسيب‌پذيري مخاطره‌ي بيابان‌زايي در حوضه‌ي آبريز مند با تاكيد بر رهيافت ويكور توسعه‌يافته (E-VIKOR)

Vulnerability Assessment of desertification hazard using Extended Vikor E-VIKOR in the Mond watershed

بيابان‌زايي و تخريب زمين‌هاي مستعد كشاورزي در برخي مناطق خشك و نيمه‌خشك به صورت مخاطره‌ي طبيعي اكوسيستم‌هاي طبيعي و زندگي انساني را به مخاطره انداخته است. بنابراين، ارزيابي و شناخت مناطق مستعد بيابان‌زايي ضروري به‌نظر مي‌رسد. در ايران، به‌خصوص مناطق جنوبي به علت شرايط آب‌و‌هوايي خشك و نيمه‌خشك جزو مناطق مستعد بيابان‌زايي محسوب مي‌گردد. اين پژوهش با هدف ارزيابي و تحليل ميزان آسيب‌پذيري بيابان‌زايي در حوضه‌ي آبريز مند در سواحل شمالي خليج فارس انجام شده است. حوضه‌ي آب‌ريز رودخانه‌ي مند در محدوده‌ي استان بوشهر و جنوب استان فارس قرار دارد. به علت حساسيت و شكنندگي محيط طبيعي در اين بخش به شناسايي مناطق مستعد تخريب خاك و بيابان‌زايي با استفاده از معيارهاي جنس زمين، ميزان فرسايش (پتانسيل فرسايش آبي)، ميزان بارش، شيب، سطوح ارتفاعي، كاربري زمين اقدام شده است. همچنين، سنجش از دور را براي حجم پوشش گياهي با كمك شاخص NDVI استفاده كرديم. تلفيق معيارها و سرانجام ارزيابي به كمك رهيافت ويكور توسعه‌يافته (E-VIKOR) انجام شده است. نتايج پژوهش نشان مي‌دهد بيش از نيمي از سطح حوضه‌ي مند در طبقه‌ي با خطر بيابان‌زايي متوسط قرار دارد و در صورت تداوم روند فعلي تخريب خاك همه‌ي اين پهنه‌ها مستعد تبديل‌شدن به بيابان را دارند. زوال اكوسيستم‌‌هاي طبيعي و كاهش كيفيت حيات انساني از پيامدهاي چنين روندي خواهد بود.

Land degradation in arid, semi-arid and sub-humid areas, leads to desertification and land degradation is a concept that refers to any reduction of soil potentials. In Iran, that 85 percent of its area is classified in arid and semi-arid climates, and one percent per annum growth rate of desertification and its increasing trends, finding ways to evaluate this phenomenon and its causes in the form of models seems essential. In Iran, especially southern areas due to their arid climatic conditions, are considered to be areas prone to desertification. This study aims to evaluate and analyze the vulnerability of desertification in the Mond watershed located in the northern coast of the Persian Gulf. In order to evaluate the potentials of desertification in the Mond watershed, geological, the erosion (water erosion potential), rainfall, slope, elevation levels and land use maps are used. To identify vegetation cover conditions Landsat ETM + sensor data and normalized vegetation index (NDVI) are used. Where in reflected in the near-infrared band (Band 4, Landsat ETM+) and the reflection in the visible band (band 3 sensor ETM+) respectively. Overlaps and combines the above criteria is done using E-VIKOR (VIKOR developed) a method of multi-criteria decision-making models (MCDM). This method is based on a compromise plan proposed in the compromise solution is justified determines solutions that are as close to the ideal solution and has been created through special credit decision-makers. VIKOR use linear approach normal. The normal value in VIKOR is not related method unit of measure. Also standardization effective indicators of desertification has been done using a linear scale. In this study, the ANP method (Analytical Network Process) was used for weighting criteria. Analysis method Network, is one of the popular methods of multi-criteria decision problems. This method complex relationship between and among the elements of the decision by replacing hierarchical network structure considers. Table 1 shows the weights of the effective criteria in desertification. In this study 7 criteria are used that results show criteria’s of climate and vegetation, have the most effective measures in the area of desertification and erosion (water and wind) have the least amount of importance in the region.