APPLICATION OF A NUTRIENT MODEL FOR SEDIMENT YIELD AND PHOSPHORUS LOAD ESTIMATION IN AN AGRICULTURAL CATCHMENT IN SOUTH CHINA

摘要

Nutrient transportation from agricultural land to surface water has received much attention throughout the world since it plays an increasingly important role in affecting the water environment. Understanding the nutrient cycle in agricultural systems is essential to reduce non-point pollution for improving water quality. This paper describes the preliminary evaluation of the Xinanjiang-Phosphorus (XAJ-P) model for suspended sediment (SS) and phosphorus (P) estimation in the Xitiaoxi catchment in south-eastern China. It estimates the sediment yields and phosphorus loads on a cell-by-cell basis with a daily time step. The results show that an average of 127.4 ton/yr P was exported to the river in the catchment. Spatial distribution of P loads indicates that the non-point source load from arable land had a dominant contribution with an export rate of 1.63 to 4.92 kg/(ha·yr). It is also found that an annual average P load of 63.7 t was exported from point sources to the rivers. P budget analysis indicate that average P input and output were 71.3 kg/(ha·yr) and 46.2 kg/ (ha·yr) respectively, while the total P utilization efficiency was 59.3%, leading to an average P surplus of 25.1 kg/ (ha-yr) in the arable land of the Xitiaoxi catchment. The application of XAJ-P in the catchment shows that the developed model can be used as a major tool to simulate long-term daily P loads at the catchment scale.