EFFECTS OF WATERSHED TOPOGRAPHY AND LAND USE ON BASEFLOW HYDROLOGY IN UPSTREAM KOMERING SOUTH SUMATERA, INDONESIA

Abstract

The characteristic hydrology of a watershed is playing a major role in ensuring water resource availability.  Rainfall and runoff responses in catchment area are part of the hydrology cycles. There are several factors to determine the characteristic of hydrology at the watershed, i.e. geological, region, soil and land cover. The existence of water resources is very substantial for surroundings. The rapid development in various sectors leads to water demands increase. Optimum utilization of water resources is needed in the sustainability of water resources or the need for integrated water resources management. The consequence of development is land use change, resulting in changes inflow characteristics, flood during the wet season and drought or discharge decrease in the dry season. Many studies associate higher watershed land cover with lower baseflows, attributed to high evapotranspiration rates, while other studies indicate increased baseflow with higher watershed land cover due to higher infiltration and recharge of subsurface storage. Adaptation and mitigation efforts are required to anticipate changes in the flow characteristics. The factors are key controls on base flow through their influence on infiltration, catchment and subsurface storage properties. This review underscores the need for more research that multiple aspects of the watershed system in explaining base flow. The result of average base flow and total flow ratio during 40 years (1971-2010) is 0.296 and the class of the hydrologic function as a BF / TF ratio value which indicated very poorly hydrology function of upstream Komering, although in certain hydrologic function was still in the good category.