SPATIAL ASSESSMENT OF LAND DEGRADATION IN THE KRUENG KHEA SUB-WATERSHED, ACEH BESAR, INDONESIA

Abstract

Land degradation in tropical watersheds is influenced by land-use change, slope, rainfall, and soil characteristics. This study assessed the spatial distribution of land degradation in the Krueng Khea Sub-watershed, Aceh Besar, Indonesia, using a GLASOD-based weighted overlay approach. The analysis covered 9,599.66 ha and integrated four parameters: land cover, slope, rainfall, and soil type. Land-cover data were derived from 2023 Landsat 8 imagery and validated through field observations, while other variables were obtained from secondary spatial datasets. All parameters were scored and weighted using ArcGIS ModelBuilder to produce land-degradation classes. The results show that shrubland dominates the area (48.20%), followed by mixed upland agriculture (14.96%), grassland (12.36%), and paddy fields (10.94%). Although most of the area is relatively flat, 29% occurs on slopes exceeding 15%, increasing susceptibility to degradation. Rainfall is uniformly moderate (2,000–3,000 mm yr⁻¹), and soils are dominated by Chromic Luvisols (70.94%). Moderate degradation is the dominant class (80.05%), followed by low (16.59%) and high (3.37%) degradation. Degradation is mainly associated with shrubland and agricultural land on sloping terrain. These findings highlight the importance of prioritizing rehabilitation in moderately degraded areas to prevent further land degradation.