基于SWAT模型的青山湖流域氮污染时空分布特征研究

基于SWAT模型构建了青山湖流域的氮负荷模型,利用2005~2011年的径流观测资料和2011年7月15日~8月4日的水质监测资料对模型进行率定和验证.青山湖流域氮污染的主要来源包括农田化肥、农村生活、畜禽养殖、城镇点源及湿沉降,其中对流域出口TN浓度贡献最大的来源是化肥施用,占34.3%.对流域现状氮负荷的时空分布特征进行分析,结果表明:NO3--N流失量的时空分布特征明显,6~9月的流失量最大,占62.5%,空间上中部流失量比西北部自然林区域大,坡面流是NO3--N主要流失途径;有机氮流失量较大的区域主要分布在中部农田比例较高的子流域.研究结果可为流域的氮污染控制和研究提供科学依据.

Analysis of temporal and spatial characteristics of nitrogen pollution in Qingshan Lake basin based on SWAT model

A nitrogen load model has been constructed for Qingshan Lake Basin based on SWAT model. The model was calibrated and verified using the runoff measurements during 2005to 2011and water quality measurements during July 15to August 4, 2011. Main nitrogen sources include fertilizer use, domestic sewage, livestock, urban point source and wet deposition, among which fertilizer use is the biggest contributor to TN concentration at the outlet of the basin, amounting to 34.3% of the total. Temporal and spatial characteristics of the nitrogen load distribution have been analyzed using the model. The results show that seasonal characteristics of NO3--N loss are distinct, with 62.5% of the yearly total loss concentrated on the period of June to September; highest in the middle region and lowest in the northern west region (covered mostly by natural forest); overland flow is the main loss route for NO3--N; the highest loss of organic nitrogen is found in the middle region of the basin where farmland is the dominant land-use type. The results of the present study can contribute to the management and study of nitrogen pollution in basins.