Assessment of soil erosion in social forest-dominated watersheds in Lampung, Indonesia

• Published in: Environmental monitoring and assessment 2019-12, Vol.191 (12), p.726-15, Article 726
• Main Authors: Yustika, Rahmah Dewi, Somura, Hiroaki, Yuwono, Slamet Budi, Arifin, Bustanul, Ismono, Hanung, Masunaga, Tsugiyuki
• Format: Article
• Language: English
• Subjects: Agricultural practices; Agroforestry; Atmospheric Protection/Air Quality Control/Air Pollution; Best management practices; Coffee; Conservation of Natural Resources - methods; Cover crops; Crops, Agricultural; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental monitoring; Environmental Monitoring - methods; Environmental science; Erosion mechanisms; Erosion rates; Forest management; Forest protection; Forest watersheds; Forestry; Forests; Geographic Information Systems; Geological Phenomena; Indonesia; Land cover; Local communities; Monitoring/Environmental Analysis; Quality assessment; Rivers; Soil; Soil erosion; Soil loss; Solid suspensions; Suspended particulate matter; Suspended solids; System effectiveness; Trees; Water analysis; Water quality; Water quality assessments; Water sampling; Watersheds
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-019-7890-5

Social forestry policies grant local communities the right to access protected forest areas contingent upon certain governmental criteria. However, the adoption of social forestry is known to alter land-cover patterns and promote soil erosion. This study assessed the water quality of Sekampung Hulu and Sangharus Rivers in Lampung, Indonesia, based on their total suspended solid (TSS) concentrations. Subsequently, the extent of soil erosion in the two watersheds was determined, and best management practices (BMPs) were recommended for the study area. Water sampling was conducted in 2016 to estimate TSS levels in the two watersheds. Additionally, the Universal Soil Loss Equation (USLE) was integrated with an ArcGIS model to evaluate soil erosion in the watersheds. The results indicated that TSS concentrations in the Sekampung Hulu and Sangharus Rivers ranged from 36–813 mg L - 1 and 16–146 mg L −1 , respectively. Further, the average soil erosion rates in the Sekampung Hulu and Sangharus watersheds were 12.5 Mg ha −1 year −1 and 5.6 Mg ha −1 year −1 , respectively. The results indicated that young coffee trees increased soil erosion rates, especially in areas characterized by vulnerable soil. The USLE results concurred with the TSS analysis and indicated higher erosion rates for the Sekampung Hulu watershed than the Sangharus watershed. The application of BMPs, including conversion to agroforestry coffee, cover crops, and contour systems, was effective in reducing soil erosion in both the Sekampung Hulu and Sangharus watersheds.