Rainfall-Runoff and Sediment Yield Modelling in Volcanic catchment using SWAT, a Case Study in Opak Watershed.

Abstract

Understanding hydrological functions and sediment dynamics in a volcanic area will help decisions makers to a better rehabilitation and reconstruction processes including environmental restoration efforts. The volcanic material can provide the multiple functions; they can improve water quality by allowing water aeration along the river and work as a good aquifer that will keep the water in the groundwater storage. On the other hand, runoff in a volcano has the possibility to induce a more significant hazard. Lahar can cause bigger destruction. The general objectives of this paper were to develop a hydrologic model to characterise the water balance in a volcanic watershed to inform the relationship between rainfall and runoff. The Soil and Water Assessment Tool (SWAT) was chosen to test its applicability in an active volcanic watershed. By using this model, the hydrographs were simulated over the area. From the model, we found that Opak watershed consists of 83 sub-catchments. The highest erosion and sediment yield of the area from 2004 – 2013 were found on the sub-catchment number 83 with the total sediment yield is 147.8 ton/year The model achieved a reasonable fit after calibration. This work can provide information on simulated hydrologic processes and function on an active volcanic watershed using SWAT.