APPLICATION OF DIGITAL ELEVATION METHOD ( DEM ) FOR FLOOD ESTIMATION ON UPSTREAM CILIWUNG RIVER, WEST JAVA, INDONESIA

Flood generally caused by the high speed of urban growth that is not balanced by efforts to avoid it. The decrease of vegetation closing and the disappearing of the natural reservoir can cause the lack of field ability to restrain rainfall and disturb surface stream flow that influences the balance of hydrology along the river basin. Hydrology models tended to be spatially distributed. By computer support with higher memory capability and faster speed, the increase of development and usage of spatially distributed models substitute lump parametric models or aggregate to spatially simple. Furthermore, there are many efforts of integration forms, either database or hydrology models with Geographic Information System (GIS). The approach of the integration of spatially distributed hydrology model and GIS is used to simulate the hydrology process interactively with the basis of spatiotemporal, with a variety of land use, rainfall, and detention reservoir volume changes (embuing/ small dam). The DEM which emerges land surface morphology information is used to represent hydrology process of surface runoff. Topography structure extraction algorithm will be the slope and the current direction is an important factor in describing drainage network. The elevation numbers and its descendants are depicted in grid cells in 50 m x 50 m measurement. The result shows such as in flood hydrograph which is varied base on land use, design rainfall and detention reservoir (embung/ small dam).