SWAT模型非点源污染模拟对空间单元划分的响应  

Effect of Spatial Unit Delineation on Simulating Non-point Source Pollution by SWAT Model

作　　者：王琳[1,2] 朱良君[1,2] 朱阿兴[1,3,4] 刘军志[3] 沈琳[3] 

机构地区：[1]中国科学院地理科学与资源研究所/资源与环境信息系统国家重点实验室,北京100101 [2]中国科学院大学,北京100049 [3]虚拟地理环境教育部重点实验室(南京师范大学)/江苏省地理环境演化国家重点实验室培育建设点/江苏省地理信息资源开发与利用协同创新中心,江苏南京210023 [4]威斯康星大学(麦迪逊)地理系

出　　处：《沈阳农业大学学报》2016年第4期460-466,共7页Journal of Shenyang Agricultural University

基　　金：国家水体污染控制与治理科技重大专项项目(2013ZX07103-06-005)

摘　　要：流域空间离散化是SWAT等分布式非点源污染模型的基础,不同的空间单元划分方案会对模型模拟结果产生影响。为合理配置SWAT模型非点源污染模拟中的空间单元划分方案,以太湖地区中田舍流域(42km2)为研究区开展研究:根据汇流累积量阈值和土地利用-土壤-坡度分级面积阈值设计25种子流域(SUB)-空间响应单元(HRU)划分方案,其中以真实河网提取阈值、HRU面积阈值为0%-0%-0%作为基准方案进行日尺度模型率定,并利用该套模型率定参数探讨SWAT非点源污染模拟对空间单元划分的响应。结果表明:模型率定期径流、泥沙、总氮和总磷Nash-Sutcliffe效率系数分别为0.575,0.671,0.483和0.758,模型可以较好表达流域过程;不同的空间单元划分通过对土地利用类型的筛选以及流域过程相关参数的改变影响污染物模拟结果,且模拟结果对HRU划分的敏感性高于子流域划分。因此,利用SWAT进行非点源污染模拟时,应在保证径流、泥沙模拟精度的基础上,进行尽可能详尽的HRU划分(如土地利用-土壤-坡度分级面积阈值分别为0%-0%-0%或0-5%-5%),以更好体现流域空间异质性,避免过粗的HRU集总带来模拟结果的失真,而子流域划分则选取能体现真实河网的适中阈值以体现子流域空间异质性即可。The representation of spatial heterogeneity by distributed models, such as SWAT （Soil and Water Assessment Tool）, acomprehensive, semi-distributed, and process-based continuous model, is based on spatial discretization. Therefore, the predictedpollutants of distributed NPS models are directly affected by different spatial unit delineation schemes. To better understand therelationship and achieve a suitable spatial unit delineation scheme of SWAT model, this paper analysed the sensitivity of nonpointsource pollution simulation to spatial unit delineation. Zhongtianshe watershed （42 km2） located in Jiangsu Province wasselected as the study area because of its severe non-point pollution. A total of 25 spatial unit delineation schemes were designedaccording to different subbasin and HRU delineation methods based on accumulation area threshold and area percentage thresholdof landuse, soil and slope gradation, respectively. Each of the 25 schemes were simulated under a same calibrated parameters setderived from the reference scheme, i.e., a scheme with an accumulation area threshold of 1.52 km2 based on real digitalizedstream links and HRU area threshold of 0%-0%-0%. The model calibration showed a good result with Nash-Sutcliffe efficiencycoefficients of runoff, sediment, total nitrogen and total phosphorus equal to 0.575, 0.671, 0.483 and 0.758 in calibration period,respectively. The predicted pollutants output are more sensitive to HRU delineation method than subbasin, the reason of whichmay attribute to lumped landuse areas and the parameters changes of relevant watershed processes. Therefore, some recommend issues may be drawn in SWAT modeling of non-point pollution： the proper HRU delineation level would be as detailed aspossible under the assurance of the simulation accuracy of runoff and sediment, which may avoid the unreal simulation causedby lumped parameters of rough HRU delineations; as for the proper subbasin delineation level, a moderate accumulation areathreshold which could represent the real s

关 键 词：SWAT 非点源污染 空间单元划分 子流域 水文响应单元 敏感性 

分 类 号：X52[环境科学与工程—环境工程] P33[天文地球—水文科学]