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۴۷

چکیده

تولید آب یکی از مهم ترین خدمات اکوسیستمی تولیدی است که تحت تأثیر ویژگی های کاربری اراضی تغییر می کند. این پژوهش با هدف ارزیابی تولید آب در منطقه سیستان و ارزیابی همبستگی مکانی آن با ویژگی های کاربری اراضی بر مبنای سنجه های تراکم و تعداد لکه، بزرگ ترین لکه، شکل سیمای سرزمین و تراکم لبه انجام شد. مدل اینوست برای ارزیابی تولید آب و رگرسیون وزنی مکانی (GWR) برای بررسی همبستگی مکانی بین تولید آب و سنجه های سیمای سرزمین استفاده شد. مجموع تولید سالیانه آب در منطقه حدود 71 میلیون مترمکعب (به طور میانگین 43 مترمکعب در هکتار) برآورد گردید که بیشترین میزان آن در مناطق غربی و کمترین میزان آن در بخش های شرقی مشاهده شد. اراضی بایر و ساخته شده ها به ترتیب با 65 و 4 مترمکعب در هکتار دارای بیشترین و کمترین میزان تولید آب بودند. نتایج GWR مشخص کرد بین تولید آب با سنجه های موردنظر همبستگی مکانی معناداری وجود دارد (0.95<R2<0.98, p-value<0.01) که بیانگر اثر ویژگی های کاربری اراضی بر فراهم سازی خدمات اکوسیستمی تولید آب است. این مطالعه اطلاعات مفیدی در رابطه با میزان تولید آب و ارتباط آن با ویژگی های مختلف کاربری های اراضی در منطقه مطالعاتی ارائه داده است که می تواند در راستای اتخاذ راهبردهای مناسب برای حفظ منابع آبی مورداستفاده قرار گیرند.

Evaluating water yield ecosystem services through land use and land cover impacts in the ecosystems of Sistan region

IntroductionWater yield represents a crucial productive ecosystem service susceptible to alteration due to variations in land use and land cover characteristics. In recent decades, ecosystem services have become an important and major issue in ecological studies and land management. They include goods and benefits that humans obtain directly or indirectly from nature. Ecosystem services are categorized into four groups: production, regulation, support, and cultural. Currently, the reduction and destruction of these services are recognized as critical environmental issues globally. In this regard, the Millennium Ecosystem Assessment has reported that about 60% of the identified ecosystem services are being destroyed, and if this process continues without proper management and planning, the impact will increase significantly over the next 50 years.Material and MethodsThis research was conducted to evaluate water yield in the Sistan region, southeastern Iran, and assess its spatial correlation with land use and land cover characteristics, with a particular focus on landscape metrics including patch density (PD), number of patches (NP), largest patch index (LPI), landscape shape index (LSI), and edge density (ED). The InVEST model was employed to evaluate water yield, and geographically weighted regression (GWR) in ArcGIS 10.5 was utilized to investigate the spatial correlation between water yield and landscape metrics. In this study, various data layers were used, including land use, average annual rainfall, reference evaporation and transpiration, depth of soil limiting layer, plant-accessible water content, plant evaporation and transpiration coefficient, and sub-basin map of the region. The area was zoned using the Tessellation Grid command in ArcGIS 10.5 software, and water production in each zone was extracted using the Extract command. The obtained values were then used as inputs for hot spot analysis.Results and Discussion.The results showed that in 75% of the Sistan region’s land, the amount of water production is less than 60 mm per hectare. The total annual water yield in Sistan was estimated to be approximately 71 mm³ (43 m³ ha⁻¹ on average). By comparing it to other regions of Iran, it was found that the amount of water production in this region is very low. The ecological and climatic conditions governing the region have caused the hot spots of water production to be located in the western areas and the cold spots in the eastern parts. The highest amount of water was yielded in the western areas, while the lowest was produced in the eastern parts. The highest and lowest water yield values were observed in barren and constructed lands, respectively, with values of 65 m³ ha⁻¹ and 4 m³ ha⁻¹. In addition, the results of the research found a significant spatial correlation between water production and different landscape features, including the number, density, size, and shape of spots, indicating that land use characteristics significantly affect water production in the study area. This study provides useful information regarding water production and its relationship with different land use characteristics, which can inform the development of strategies to preserve water resources.ConclusionThe results of GWR analysis indicated a significant spatial correlation between water yield and the following landscape metrics: NP, PD, LPI, LSI, and ED (0.95 < R² < 0.98, p-value < 0.01), suggesting that land use characteristics influence the provision of water. This study provides valuable insights into the quantity of water yield and its correlation with various land use characteristics within the study area. These findings can inform the development of effective strategies to safeguard the region's water resources.

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