基于NEWS模型的北江流域营养盐输出模拟
Exports by Rivers from Watersheds to River Mouth: Case Study of Beijiang River Basin

摘要 以珠江三大支流之一北江流域为研究区域,应用国际上最新提出的流域营养盐输出模型Global NEWS,经调试后,用其估算北江流域溶解态营养盐的输出总量。通过收集文献统计资料并使用ArcGIS软件建立模拟所需数据库。经率定和验证, 发现模型对DIN的模拟效率系数是0.61, 具有一定的可靠性。模拟结果表明: 1) 2010年溶解态氮的输出总量为3.75万t/a, 与2000年相比增加约9.27%, 其中溶解态无机氮(DIN)占83.51%, 溶解态有机氮(DON)占16.49%; 2) 2010年溶解态磷的输出总量为 4.63万t/a, 与2000年相比增加约30.05%, 其中溶解态无机磷(DIP)占86.21%, 溶解态有机磷(DOP)占13.79%; 3) 北江下游的绥江和中游的连江子流域营养盐输出总量最高, 应重视这些地区的营养盐污染; 4) 北江流域DIN输出量的主要贡献源是大气氮沉降, 其次是生物固氮和化肥施用, 而DIP的主要贡献源是养殖废水, 其次是化肥施用。研究结果也表明, 模型对国内中小型流域具有一定的适用性。
Abstract Global NEWS (Global Nutrient Export from WaterSheds) is an international modeling effort with few Chinese application cases, and this essay applied the model with modifications to Beijiang River Basin, one of the three main sub-basins of the Pearl River, in order to estimate the river basin-level export of multiple nutrient elements and elemental forms from land sources within the river basin to river mouths. A reliable environmental database of Beijiang River Basin was established by literature review and statistics collection, and with the help of ArcGIS technology. Model calibration and verification showed that the Nash-Sutcliffe model efficiency was 0.61 on DIN (Dissolved Inorganic Nitrogen) loads (t/a) exported at the basin mouth, indicating that the model performs reasonably well for DIN. Modelling results show that 1) in 2010, dissolved nitrogen exports (load) from Beijiang River Basin was 37.5 thousand t/a, which was 9.27% higher than that in 2000, with DIN accounting for 83.51% and DON (Dissolved Organic Nitrogen) accounting for 16.49%. 2) In 2010, dissolved phosphorus exports (load) from Beijiang River Basin was 46.3 thousand t/a, which was 30.05% higher than that in 2000, and contained 86.21% of DIP (dissolved inorganic phosphorus) and 13.79% of DOP (dissolved organic phosphorus). 3) Spatially, nutrients exports (load) from Sui River Basin, one of the downstream sub-basins, and nutrients exports (load) from Lian River Basin, one of the midstream sub-basins, were relatively higher than those from other sub-basins, indicating the necessity of controlling nutrient pollution in the two sub-basins. 4) Atmospheric nitrogen deposition was the major source of DIN export load, followed by synthetic fertilizer and biological nitrogen fixation, while animal wastewater discharging was the major source of DIP export load, followed by synthetic fertilizer. The results also show that the NEWS model is applicable to China’s small-to-medium river basins.