An Analysis of Erosion Hazard Levels Using the USLE Method in the Mandalika Special Economic Zone

Abstract

The Mandalika Special Economic Zone (SEZ) is located in Pujut District, Central Lombok Regency, West Nusa Tenggara Province, which has been designated as a tourism area. Land use changes due to tourism development have caused increased erosion, sedimentation, and flood discharge. This study aims to estimate the extent of erosion and sedimentation in the watersheds located in the Mandalika SEZ, namely the Tebelo, Ngolang, and Balak watersheds. Erosion calculations were performed using the Universal Soil Loss Equation (USLE) method, and sedimentation was calculated using the Sediment Delivery Ratio (SDR) following the Menhut (2005) method. The results show erosion rates of 101,189.01 tons/year (Tebelo watershed), 79,158.05 tons/year (Ngolang I watershed), 16,387.94 ton/year (Ngolang II watershed), 123,557.66 tons/year (Balak I watershed), and 2,701.15 ton/year (Balak II watershed). The level of erosion hazard in all watersheds varies from very light to very severe. The sedimentation values produced reach 8,666.24 m³/year (Tebelo watershed), 7,019.14 m³/year (Ngolang I watershed), 1,986.82 m³/year (Ngolang II watershed), 9,990.7 m³/year (Balak I watershed), and 447.25 m³/year (Balak II watershed).