Assessment of Soil Vulnerability Index for surface runoff in Kawal watershed, Bintan island

Abstract

The quantity of transformed land cleared after deforestation in the basin demonstrates the severity of soil erosion on Bintan Island. Deposition of eroded material causes eutrophication, blockage, and silting of channels and water bodies, as well as flooding in lowlands and coasts. Heavy rainfall and sparse cover of vegetation ravaged the structure of soil, further preventing it from storing and absorbing water, which increased surface runoff and had an impact on rising erosion rates. The goal of this study was to evaluate the vulnerability class of surface runoff using SVI. The SVI class is based on slope extracted from the digital elevation model, hydrologic soil group, and soil erodibility. The results of the SVI classification for mapping surface runoff susceptibility resulted in areas with low criteria of 7% (664 ha), medium 14% (1,229 ha) and high 79% (7,069 ha). The major influences on the high vulnerability of surface runoff in the Kawal watershed on Bintan island appeared to be rainfall, soil type, land use, and slope gradient.