Erosion Potential Based on Erodibility and Plasticity Index data on Cilengkrang, Bandung, West Java, Indonesia

Abstract

Cilengkrang is a sub-village in the north of Ujung Berung and Cijambe sub-District Bandung Regency, Indonesia. It is located on the west of Cikeruh sub-watershed. This subwatershed is part of greater upstream Citarum watershed. This area has been developed rapidly by new settlement and villa. However, the available data of erosion potential in this area is less convenient. The erosion is a severe problem that has a strong relation to flood potential. This study starts with collected engineering geological data from 14 samples. These samples were taken from different soil types from its engineering characteristics. Based on the field and laboratory observation, this area is form by fine-grained soils as a result of residual soils from young volcanic rocks - the silt and very fine sand content range from 49 to 70 % of the total soil. The erodibility value (K) in this area is from 0.03 to 0.06. These values are indicating moderate soil erodibility class. The plasticity index (PI) also shows value from 9 to 48 %. This value is pointing low to high plasticity behavior of this soil. The regression linear shows strong correlation between PI and K with r = 0.7. This correlation is interpreted that the cohesion controls the soil characteristic in Cilengkrang area and affect the moderate erodibility value. This study hopefully giving new insight that soil mechanic data is can also support data on erosion potential.