Assessment of Terrain Scenario Impacts on Hydrological Simulation with SWAT Model. Application to Lai Giang Catchment, Vietnam

Nowadays, terrain data plays a critical role in biological, geomorphological, and hydrological processes analysis. Through numerous studies, the importance of topography quality has been qualified and strengthened. Hydrological responses are acted based on climatic features and inputs controlled by topography map and land use/land-cover (LULC). This study aims to clarify and evaluate the impact of different DEM sources associated with various resolutions (MERIT DEM, NASA DEM, TAN DEM and SRTM DEM 30 and 90 m) on hydrological processes change in real-time monitoring using the semi-distributed hydrological model (SWAT) in open-source platform QGIS. Indeed, the methodological framework has been defined by DEM quality assessment (RSME, R2, NSE) by DEM delineation capability of the river basin to determine the best DEM source of the case study. It is found from the case study that NASA30 DEM is the best terrain amongst DEM scenarios of the catchment with the R2 value of 0.89, the RSME value of 32.82 m3/s, and the NSE value of 0.85. Moreover, the authors have illustrated that DEM quality has many aspects: the current characteristics, dynamic components of catchment storage as transportation, surface flow, groundwater flow, evapotranspiration, and lateral flow. Besides, other DEM sources have also represented good results validated with a performance index. Hence, authors expected these outputs could be considered valuable data to reveal the relationship between different topography sources and hydrological processes in the case of the Lai Giang catchment, Binh Dinh province (Vietnam) or similar catchments.