Characteristics of physical catchment at Lake Buyan and Lake Tamblingan, Bali - Indonesia

Lake Buyan Tamblingan located at an altitude of 1200 m above sea level, is a potential area for tourism industry, residential and agricultural area. An oval shaped caldera lake with a diameter of-12 x 7 km, named as "endorheic basin" as a confined basin or closed lake basin. The shape of the caldera is natural container basin morphology and therefore, there is no direct inflow or outflow. The objective of this study is to analysis of physical characteristics catchment at Lake Buyan and Lake Tamblingan. The survey was conducted on October 2013. Rainwater that falls will be collected in a container of water and percolate as groundwater in the basin. There is also a flow of groundwater that flows very slowly out as the springs basin in the lower region. The morphometric showed extensive Lake Buyan 3.67 km2 with a maximum depth of 79.5 m. Those lakes have an area of 1.15 km2 where lake Tamblingan with a maximum depth of 40 m. The average depth of Lake Buyan and Tamblingan is 31.7 m and 23.5 m, respectively. The result of land use changes showed the largest land changes occur in forest cover reached 123.5 ha. Most of the forest cover turned into plantations and agricultural areas. The growth of urban residential in this catchmentfrom 76.4 ha to 118.2 ha, mostly from rice fields and agricultural areas. Sedimentation in lakes Buyan and Tamblingan using hydrological models SWAT, sediment load simulation results lakes Buyan and Tamblingan is 134.2-ton/year and 111 ton/year. If allowed to continue these activities then would threaten the sustainability of the lake.