Comparison of runoff and sediment yield for two neighbouring catchments in the Philippines

Abstract

During the 1980's two river catchments in the mountains of northern Luzon, Republic of the Philippines, were studied in varying detail (White, 1987; Amphlett and Dickinson, 1989; Dickinson et al, 1990; White, 1992). In one, the Magat catchment, a detailed field programme lasting several years was carried out. This included measurement of runoff and sediment yield rates fron small, single use, catchments, together with a series of nested river monitoring sites where discharge and sediment transport rates were recorded, and a survey of sedimentation in the reservoir at the downstream end of the catchment. In contrast, for the neighbouring Casecnan catchment few sedimet yield data were available, but discharge and rainfall were monitored for a period of six years. In addition, maps of land use, geology/geomorphology, soils and elevation/slope were available for both catchments. This paper provides a comparison of the physical characteristics, the discharge and the sediment yield in the two catchments, with possible explanations for the differences observed. Potential for increasing discharge and sediment yield in the, as yet undeveloped, Casecnan catchment is discussed.