Abstract:

SWAT (Soil and Water Assessment Tools) model was used to calculate the non-point source pollution in the Meijiang River Watershed, which is a red soil region under the background of subtropical monsoon climate in Jiangxi Province. According to the measured data, SWAT model was adjusted to analyze the temporal-spatial distribution patterns of the non-point pollution load in the region. The hydrological processes and Nitrogen and Phosphorus nutrient loads were also calculated. Results showed that there was significant temporal-spatial characteristic in the watershed. In the time series, Nitrogen and Phosphorus pollution loads had obvious correlation with rainfall, the correlation coefficient was 0.909 and 0.921 respectively. The average annual emissions were mainly composed of infiltration, the contribution rate was 63%, that was associated with high vegetation coverage in the basin. On the spatial distribution, pollutants in the basin were mainly distributed in the Huangpi and Huitong valleys in the middle-lower reaches of the Meijiang, the spatial distribution of organic Nitrogen and that of organic phosphorus were basically identical. The loss amount of soil nutrient such as Nitrogen and Phosphorus under different land-use showed a great spatial variability in the region, the farmland had a high contribution to the non-point source pollution load. The results reveal the temporal-spatial distribution characteristics of non-point source pollution, and can be for reference of the conservation of soil and water and control of non-point source pollution in the watershed.

Key words: SWAT, non-point source pollution, the Meijiang River Watershed