Source: SEAMEO BIOTROP's Research Grant | 2016
Ciliwung Watershed has very important roles as a buffer zone area of Jakarta. To overcome flood problem in Jakarta related and caused by Ciliwung River, there is a need alternatives policy to control Ciliwung River discharge effectively, either using mechanical technique, vegetative technique, soil conservation technique or their combination. Conditon of Ciliwung Hulu Watershed in 2014 becomes worst and so very sensitive from high rainfall since has no capacity to absorp, keep and save water from rainfall, especially high rainfall. Scenario of the building of the two big dams Ciawi Dam and Sukamahi Dam is considered the most effective in controlling Ciliwung River Upstream discharge since it will be able to decline drastically ratio of maximum-minimum discharge from 399,15 (under actual condition) to 28,77 as compared to agroforestry scenario that will reduce ratio of maximum-minimum discharge to 80,40 and zero runoff scenario (combinatiof of agroforestry and soil conservation techniques to produce zero runoff) that will reduce ratio of maximum-minimum discharge to 29,33. The two dams, Dam Ciawi dan Dam Sukamahi requires protection from sedimentation threat and shortage of water supply from upstream area of so that the two dams can still work optimally and effectively and thier life period will not be shortened. The common way to safeguard the upstream area from intensive soil erosion and declining soil infiltration can be done by preventing of tree cutting, coversion of vegetative land to non-vegetative land, and implementation of combination of vegetative and soil conservation techniques to minimize overland flow and soil erosion. SWAT Model and HEC-Geo-HMS Model can be used as a tool or instrument to predict or estimate or assess the effect or impact of land management practices to water and sedimentation in a watershed that consist of several types of soil, land uses and its management in a certain period.