STUDY OF MORPHODYNAMIC CHANGE IN RIVER DUE TO SABO DAM DEVELOPMENT

The problem of flooding and sediment needs to be a special concern in preserving the ecosystem and the existence of construction along the river body. Until now there has been no practical solution in handling sedimentation rates with natural flushing systems. Sediment material carried by debris flow in the form of suspended load, wash load and bed load shows a decline in the function of the water catchment area. The process can trigger land erosion in the upstream river which accelerates the process of river sedimentation to the downstream river area. Matakabo River is located on Seram Island, East Seram Regency, one of the rivers in Indonesia with typical debris which is categorized as an ephemeral river which has the potential for land erosion in the upstream area and sedimentation in river bodies. This is shown when the debris flow rains in the Matakabo River have a large enough destructive power and potential for flash floods. River morphodynamics function for correct management and prediction of important erosion and sedimentation processes involved in river activities, such as river bank erosion, overflow, sediment balance in dam regulation, sediment wave propagation, interaction with anthropic structures (bridges, weirs), reservoir siltation, renaturalization, sediment mining, aggradation, deformation planning, slope and hydraulic geometry balance arrangements, renaturalization issues. Improvement of river morphodynamics illustrates the morphological process in dynamic river widening as a result of variable sediment input and to identify measures to locally control ecologically valuable habitat development. Aspects such as the balance of sediment range scale, vegetation, and grain size distribution will also be considered because they are important factors that influence the ecological and morphological benefits of river widening. The results showed that the placement of Sabo in the Matakabo River did not really affect the downstream area but affected the upstream part.