Changes in land cover to reduce erosion and peak discharge of sub-watershed of Danau Limau Manis

Abstract

Land cover change is a strategic issue in the Subwatershed of Danau Limau Manis. The community was triggered by the big earthquake of September 30, 2009, so people moved to the upper watershed. The problem is the increasing number of people, the damage to the watershed ecosystem. This damage can be seen from the erosion of river water and the availability of river water during the rainy season and dry season. An appropriate solution is needed to reduce erosion by modeling land cover. This study aims to determine the value of soil erosion and peak discharge. Erosion using a rational formula using the modified universal soil loss equation model based on land units and peak discharge. The land unit is an overlay of land cover maps, slope maps, and soil maps. Land units that produce erosion and exceed the tolerance limit are carried out with a land cover change scenario using the spatial multi-criteria analysis model. Scenario determination is also based on slope maps, land cover maps, soil maps, river flow density maps, forest area maps, erosion values , and the Padang city spatial plan. The study results explain that the erosion and peak discharge resulting from the existing land cover is quite large, namely 47.89 tons/hectares/year and 152.81 m3/sec. After scenario modeling, erosion decreased by 11.91 tons/hectares/year and peak discharge 15.26 m3/sec.