基于SWAT模型的小清河流域总氮输出模拟研究

小清河流域工业和农业发达,点源和非点源污染均比较严重,致使河流总氮含量严重超标,对下游河口及莱州湾的水生态与环境产生了深刻影响。本文基于实测径流和总氮资料,对小清河流域SWAT模型进行了校准和验证,在此基础上,模拟和分析了流域2008-2013年总氮负荷的时空特征,并对其污染来源进行了甄别。研究结果表明:小清河流域总氮的年输出量与年径流量趋势总体一致,表现出明显的年际特征,总氮负荷多年均值为38.0×103t。空间上,各子流域的总氮输出量均较高,其中,位于农业发达的寿光市和章丘市、工企业较多的邹平县、人口密度大的济南市区等区域的子流域总氮输出量最高。流域总氮负荷主要来自非点源污染源,其中,农业施肥引起的氮素流失和畜禽养殖的污水排放对流域总氮输出的贡献分别为32.5%和29.5%,另外,工业和城镇污水的氮排放量也较高,分别占流域总氮输出量的19.4%和16.5%。为此,须结合点源和非点源污染源对小清河流域氮污染物进行总量控制和削减。

Simulation of total nitrogen transport based on SWAT model in Xiaoqinghe River Basin of Shandong Province

Serious point source and non-point source pollution in Xiaoqinghe River Basin, primarily caused by advanced industries and agriculture, have resulted in the excess of river water total nitrogen, which further have deteriorated the aquatic ecology and environment of Xiaoqinghe Estuary and Laizhou Bay. Based on observed streamflow and total nitrogen data, the SWAT model, established for Xiaoqinghe River Basin, has been calibrated and verified. Then, the spatial and temporal characteristics of total nitrogen load for the period of 2008-2013 have been simulated and analyzed, and the pollution source of total nitrogen has been identified. The results show that accordant with the annual streamflow, the annual total nitrogen load indicates an obvious inter-annual variability with the annual average value of 38.0×10³ t. Spatially, total nitrogen load is relatively high for various sub-basins, among which the highest output in the sub-basins located in Shouguang City and Zhangqiu City with advanced agriculture, Zouping County with many engineering enterprises, Jinan urban district with high population density. The primary source of total nitrogen load is dominated by non-point pollution source. Nitrogen losses from agriculture fertilizer and livestock manure account for 32.5% and 29.5%, respectively of the total nitrogen load. In addition, nitrogen emissions from industries and urban wastewater contribute greatly to the total nitrogen load with the proportion of 19.4% and 16.5%, respectively. Therefore, point and non-point pollution source should be overall considered for the total amount control and reduction of total nitrogen in Xiaoqinghe River Basin.