Assessment of the Effects of Riparian Buffer Zones on the Water Quality in the Jinghe Catchment Using the AnnAGNPS and REMM Models

Abstract. Direct discharge of sediments and agricultural chemicals into rivers is a major areal source for water pollution in China and other places. This study was conducted to evaluate the impact on water quality by converting riverside crop fields to riparian buffer zones at river basin scale. The Jinghe catchment of the Weihe River basin in China, a heavily cultivated watershed in the middle reach of the Yellow River basin, was selected for this study. The Annualized Agricultural Non-Point Source Pollution Model (AnnAGNPS) was used to simulate water and sediments loadings from upland fields. These generated upland loadings then were used as inputs to run the Riparian Ecosystem Management Model (REMM) for assessing the impact of riparian buffer zones on water quality, specifically on reducing nutrients and sediment concentration in surface runoff. The whole Jinghe catchment was divided into 4290 homogeneous drainage areas by AnnAGNPS and REMM was run for each drainage area for one year. The yearly output data for each drainage area were spatially integrated over the whole Jinghe catchment. Our study has provided an easy way in using the field-scale REMM model in conjunction with the well accepted AnnAGNPS pollution model in studying ecological engineering projects at river basin scale. The results of this study are anticipated useful in guiding the land use changes in the Yellow River basin in China for improving surface water quality by building riverside riparian buffer zones.