[Impact of the land-use change on the non-point source nitrogen load in Yunmeng Lake watershed]

Take potable water sources in Linyi City Yunmeng Lake watershed as a case study, it obtains the nutrient export coefficient of land use by the export coefficient model and simulative rainfall experiment. On the basis of GIS and RS, it analyses the effect of the non-point source (NPS) pollution load because of the land-use change during the past 25 years. The result indicates that the TN increased from 3.77 x 10(3) t in 1986, to 4.45 x 10(3) t in 1995, to 5.5 x 10(3) t in 2010; As far as land-use type is concerned, the TN from farm-land increased year by year, the contribution rate is 80.11% in 1986, 82.60% in 1995 and 85.59% in 2010, the forestland and the grass-land load have a little change, but the contribution rate decreased gradually, the residential load increased by a large margin, however, the contribution rate is very little. As for the sub-basin, the higher the proportion of the farm-land is, the more the TN load increased. There is a significant positive correlation between the farm-land and the nitrogen (TN) load, so the farm-land is the sources of the nitrogen. Conversely, there are negative correlations between the forest-land, grass-land and the TN load; therefore, the forest-land and grass-land are the sinks of the nitrogen. Therefore, it can adjust the land-use structure to reduce and control the TN loss to water environmental pollution.