THE POTENTIAL OF DEBRIS FLOW DUE TO NATURAL DAM IN WAY-ELA RIVER MOLUCCAS

The cause of the decline in the quality of the watershed (DAS) is the result of the interaction between climatic factors (especially rainfall), geomorphological conditions (geology, soil and topography), the impact that occurs in the Way Ela river basin at the time of the collapse of the natural dam or natural dam. the occurrence of sediment in the upstream of the river due to landslides, resulting in the river flow turning into groundwater, the sediment supply continues to grow with large volumes, especially at high flood discharge, sediment transport occurs in the Way Ela watershed due to cliff landslides that occur in high rainfall, In the area around the river, landslides are indicated in the form of soil fractures, the land use of the Way Ela watershed is relatively good, this can be seen from the use of land that is still green even though debris flows often occur during the rainy season. The purpose of this research is to find the characteristics of rivers that are vulnerable to debris flow. Based on the variables obtained, a landslide potential mapping is carried out using the equation x. Based on the results of the mapping of landslide-prone areas using Hec-Ras simulation, the characteristics of landslides and landslide-prone areas are obtained. Based on the simulation data, it can be concluded that the Way Ela River still has the potential for flooding of debris flow in the future