Application of Swat model to assessing the impact of agricultural practices to nutrient transport in the Cong watershed, Thai Nguyen province

Abstract

In recent years, water quality in the Cong River has degraded seriously. Non-point source pollution from agricultural land has been one of the main reasons of the problem. In this study, SWAT model, after successfully calibrated and validated on hydrologic and sediment simulations was used and calibrated on nutrient transport simulation. The overall objectives of this study were to simulate and assess spatial and temporal variations of nutrient yield influenced by agricultural practices in the Cong Watershed. Model performance was evaluated based on surface water quality data observed in the watershed. The calibration process was conducted with respect to the monthly simulation of Nitrogen and Phosphorus at period of 2010 – 2015 and 2013 – 2015, respectively. The model performance was evaluated with two statistical criteria, namely Nash-Sutcliffe efficiency (NSE) and coefficient of determination (R2
). The present study revealed that, the calibrated SWAT could achieve acceptable accuracy in the nutrient transport simulation. The study also indicates that land uses and agricultural practice, i.e., tillage and fertilizer and manure applications, had a great impact to the spatial and temporal variations of nutrient generated and transport within the watershed.