A Multifunctional Conceptual Framework for Ecological Disturbance Assessment

Through a multi-dimensional approach, this research explores the response of semi-arid watersheds to ecological disturbances caused by human activities. To accomplish this objective, we selected a pilot area situated in the Ardabil Province (Iran), and a total of 29 different driving forces (D1-D29) were identified. Subsequently, two statistical tests, the chi-square test and Spearman correlation, were applied to screen the optimal driving forces. The optimal driving forces weighting was conducted using both equal and CRITIC methods. Four multifunctional disturbance indices—MDI_L (land use), MDI_D (demography), MDI_P (pollution), and MDI_H (hydrology)—were calculated. The overall disturbance index (ODI_A, _G), derived from arithmetic and geometric means across 27 sub-watersheds, indicated that both screening methods similarly identified the optimal driving forces. Characterization for MDI_L involved irrigated, dry farming, agricultural and residential areas, rangeland territories, residential and agricultural areas, using a 600 m buffer. For MDI_D, density of population and density of workers in agriculture were considered, while specific sediment yield and density of mining operations were crucial for MDI_P. Finally, slope played a significant role in MDI_H characterization. The mean multifunctional disturbance indices (0.24–0.52) were obtained almost similarly by all integration methods. The higher values of ODI_A and ODI_G were also estimated according to Spearman correlation-based rather than Chi-Square-based. The spatial mapping also revealed that central and western sub-watersheds were more under disturbances stress.