Hydrological Modeling in an Ungauged Basin of Central Vietnam Using SWAT Model
Ammar Rafiei Emam1, Martin Kappas1, Linh Hoang Khanh Nguyen2, and Tsolmon Renchin31Department of Cartography, GIS and Remote Sensing, Georg-August University Goettingen, Germany 2Faculty of Land Resources and Agricultural Environment (FLRAE) Hue University of Agriculture and Forestry (HUAF), Vietnam 3Remote Sensing and Space Science Laboratory, National University of Mongolia (NUM), Mongolia
Received: 25 Jan 2016 – Accepted for review: 09 Feb 2016 – Discussion started: 18 Feb 2016
Abstract. Hydrological modeling of ungauged basins which have a high risk of natural hazards (e.g., flooding, droughts) is always imperative for policymakers and stakeholders. The Aluoi district in Hue province is a representative case study in Central Vietnam, as it is under extreme pressure of natural and anthropogenic factors. Flooding, soil erosion and sedimentation are the main hazards in this area, which threaten socio-economic activities not only in this district but also those of the area downstream. To evaluate the water resources and risk of natural hazards, we used Soil and Water Assessment Tools (SWAT) to set up a hydrological model in the ungauged basin of Aluoi district. A regionalization approach was used to predict the river discharge at the outlet of the basin. The model was calibrated in three time scales: daily, monthly and yearly by river discharge, actual evapotranspiration (ETa) and crop yield, respectively. The model was calibrated with Nash-Sutcliff and an R2 coefficients greater than 0.7, in daily and monthly scales, respectively. In the yearly scale, the crop yield inside the model was calibrated and validated with RMSE less than 2.4 ton/ha, which showed the high performance of the model. The water resource components were mapped temporally and spatially. The outcomes showed that the highest mean monthly surface runoff, 700 to 765 mm, between September and November, resulted in extreme soil erosion and sedimentation. The monthly average of actual evapotranspiration was the highest in May and lowest in December. Furthermore, installing "Best Management Practice" (BMPs) reduced surface runoff and soil erosion in agricultural lands. However, using event-based hydrological and hydraulically models in the prediction and simulation of flooding events is recommended in further studies.
Rafiei Emam, A., Kappas, M., Hoang Khanh Nguyen, L., and Renchin, T.: Hydrological Modeling in an Ungauged Basin of Central Vietnam Using SWAT Model, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-44, 2016.