基于L-THIA模型与3S技术的大亚湾陆域非点源总氮污染研究

Non-point source pollution load of total nitrogen in Daya Bay catchment based on L-THIA model and 3S techniques

以大亚湾为研究对象,采用3S(GIS、RS和GPS)技术划分了汇水区范围并处理获得土地利用、土壤水文单元及降水等下垫面信息,运用L-THIA模型(Long-term Hydrologic Impact and Non Point Source Pollutant Model)构建了总氮(TN)这一指标的大亚湾汇水区非点源污染模型,并通过径流量与负荷量模拟结果与不同方法计算结果的比对验证了模型的合理性。结果表明,大亚湾陆域非点源TN年均负荷量为2 559 t;土地利用类型中耕地、建设用地和园地的负荷量和单位面积流失强度均较高,是TN流失的主要土地利用类型;汇水区涉及的11个镇(街)中惠州市稔山镇、平海镇对TN负荷量的贡献合计超过50. 0%,占据了77. 7%的TN流失关键源区,是非点源污染防治需重点关注的区域。来源贡献的定量识别和关键源区的空间识别为大亚湾陆域非点源TN污染的有效控制提供了重要的科学依据。

Based on catchment delineation,land use,soil hydrologic group classification and precipitation data processed by 3 S( GIS,RS and GPS) techniques,a non-point source pollution model for the index of total nitrogen( TN) of Daya Bay was built used the Long-Term Hydrologic Impact and Non Point Source Pollutant model( L-THIA). The model rationality was verified by comparing the modeling results of runoff and load and the results of different methods. It showes that the annual non-point source TN load of Daya Bay was 2 559 tons. The farmland,built-up area and orchard were the main types of land use for TN loss due to the high load and loss intensity. Among 11 towns,Renshan town and Pinghai town contributed more than 50. 0% of TN load and occupied 77. 7% of critical source areas. Thus more attention should be paid to these towns in the work of non-point source pollution control. The quantification of load contribution and the identification of critical source area will help local decision makers to administrate the non-point source nitrogen pollution effectively and efficiently.