基于水流路径与景观单元相互作用的非点源污染模拟研究

从污染物进入受纳水体的载体水流着手,沿水流路径模拟污染物迁移过程中各景观栅格单元与周边景观栅格单元的相互作用关系,并将这种相互作用分为"推动"和"阻碍"两个方面,综合两种作用计算空间不同位置景观栅格单元污染物的入河迁移系数.同时,通过水文累积计算,获得河道水质空间分布特征.最后,以东北海伦地区4个子流域作为案例研究区,模拟得到流域污染源和水体污染程度的空间分布示意图,并利用2007、2008年10场降雨后流域出口的水质监测数据与模拟值进行了比较分析.结果显示,模拟N含量与监测TN值显著相关,模拟P含量与监测颗粒态P含量显著相关,表明该研究方法能定性地描述流域N、P污源染以及受纳水体水质时空分布特征.但模拟计算出的N、P含量均远远高于实测值,说明该模拟方法还需进一步改进以达到准确量化的目标.

Modeling non-point pollution based on interactions between flow path and landscape units

This paper describes a simulation model for non\|point source pollution assessment at a landscape scale based on the interactions between landscape units during pollutant transport along the flow path. By differentiating the interactions into "pull" and "drag" effects, the loss of a pollutant to the receiving water body can be estimated. Thereafter, the spatial distribution of water quality conditions along the river channel is obtained based on flow accumulation values. We applied this model to four watersheds in Hailun of Heilongjiang in Northeast China. The modeling results were compared with observed data for ten storm events within two years, for which the simulated nitrogen and phosphorus concentrations correlated significantly with measured total nitrogen and particulate phosphorus concentrations. These results indicated that the method is able to describe the spatial and temporal distribution of nitrogen and phosphorus source pollution and water quality characteristics in a watershed. However, the simulated nitrogen and phosphorus concentrations were higher than the observed. Further improvement of the method with respect to qualitative water quality assessment is suggested.