Analysis and modeling of watershed-scale nitrogen balance in relation to nitrogen pollution of unconfined groundwater in an alluvial fan

与冲积扇无承压地下水氮污染相关的流域尺度氮平衡分析和建模

基本信息

批准号：
13660238
负责人：
GOTO Akira
金额：
$ 2.18万
依托单位：
Utsunomiya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Field measurements on discharge and water quality of spring water were carried out for accumulation of necessary data. Amounts and processes of effluent nitrogen load from the different pollution sources were also investigated. As the results of nitrogen balance analysis, it was clarified that more than half of the total nitrogen load of the basin came from dairy farming and massive nitrogen from live stock excreta was stored on/in the soil and intruded into the groundwater together with rainwater infiltration. The fortunate fact that despite the high pollutant inflow, the nitrate nitrogen concentration does not reach 10mg/L, the environmental benchmark value, was found to be explained by dilution by the high groundwater recharge rate from the river underflow and paddy field infiltration.Based on the above results, modeling of groundwater quality processes was conducted. The model consists of a groundwater hydrologic model as the basic structure and a pollutant process model (behavior … More equations). As the basic hydrologic model, a lumped system groundwater model based on Tank Model and a distributed system groundwater model were prepared. For the first approach, a lumped system groundwater quality model was developed by combining the L-Q type and dissolution type of pollutant behavior equations to the lumped groundwater model. Application of this model showed that the model calculation could represent the seasonal change in nitrate nitrogen concentration fairly well.Meanwhile, since the distributed property of water quality in the basin cannot be represented by the lumped model, the research proceeded to the next step for developing a distributed system groundwater quality model. A grid type groundwater flow model was employed as the base structure and the same two types of pollutant behavior equations were incorporated. Further, distribution of pollution sources in the basin was handled with the input data. The result of this model could represent the tendency of spatial movement of nitrogen load. Less

对泉水的流量和水质进行了现场测量，积累了必要的数据，并调查了不同污染源的出水氮负荷量和过程，氮平衡分析结果表明，一半以上。流域总氮负荷的一半来自奶牛养殖，而来自牲畜排泄物的大量氮被储存在土壤上/土壤中，并与雨水渗入一起侵入地下水。幸运的是，尽管污染物流入量很大，但流域内的氮仍然存在。硝态氮浓度未达到环境基准值10mg/L的原因是河道底流和稻田入渗导致地下水补给率较高，导致地下水稀释。根据上述结果，对地下水水质过程进行了建模该模型由作为基本结构的地下水水文模型和作为基本水文模型的污染物过程模型（行为方程）组成。第一种方法是将L-Q型和溶解型污染物行为方程结合到集中地下水模型中，建立了集中系统地下水质量模型。同时，由于流域内水质的分布特性无法用集总模型来表示，因此研究进入下一步，建立分布式系统地下水水质模型A网格型地下水。以流量模型为基础结构，引入相同的两类污染物行为方程，并利用输入数据处理流域内污染源的分布，该模型的结果可以反映氮的空间运动趋势。负载较少。