Assessing soil erosion and flood risk areas in Santa Rosa-Silang [Philippines] Watershed using LiDAR [Light Detection and Ranging] data and SWAT [Soil and Water Assessment Tool] modeling
2019
Gunay, C.J.C. | Magcale-Macandog, D.B. | Bragais, M.A.
The physical impacts of extreme weather disturbances such as storms and typhoons had been increasing in Santa Rosa-Silang Watershed, where rapid land use conversion and high population pressure are major environmental issues. In this study, the Soil and Water Assessment Tool (SWAT) model was used to analyze the hydrology and sediment yield in the 102-km sq watershed. Spatial information such as digital terrain model and land cover map, both processed and validated using remote sensing and Light Detection and Ranging (LiDAR) data, and soil map together with 36-year rainfall and temperature data, were imported in the model's platform to generate surface inflow, outflow, and sediment yield in the 49 hydrologic response units (HRUs) in the watershed. With these, specific HRUs vulnerable to flooding and erosion were identified and most of these areas were reflective of the high risk barangays previously identified by the local government. Flash flood and erosion occurrences in these areas were primarily due to the low permeability and weak stability of their land cover during extreme rainfall. The results of this study can be an initial scientific basis in developing area-specific mitigation and adaptation strategies to climate-related natural disasters.
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