平原地区复合土地利用系统中氮磷流失敏感区界定

为正确识别平原地区复合土地利用系统中氮磷流失敏感区，利用美国农业部水土保持局设计的水文模型中的〖WTBX〗CN〖WTBZ〗值描述地表状况，反映不同土地利用条件下下垫面对土壤氮、磷流失的影响；运用等标污染负荷计算方法评估不同类型污染源强度；建立了复合土地利用系统中土壤氮、磷流失敏感区的综合指数评价体系。构建的氮、磷流失评价方法在浙江大学华家池校区的应用评价结果表明，氮磷流失敏感性高的区块主要为研究区内的居民区、畜牧场和一些施肥量大的种植区，而敏感性最低的区块集中在具有良好植被覆盖的绿化区。高的污染源和高的迁移因子叠加区构成了高的流失敏感区.

DENTIFICATION AND EVALUATION OF CRITICAL AREAS OF NITROGEN AND PHOSPHORUS RUNOFF IN COMPLEX LAND USE SYSTEMS IN PLAIN AREA——A CASE STUDY IN HUAJIACHI CAMPUS, ZHEJIANG UNIVERSITY

Economic development and population explosion are two major driving forces that alter local land use and increase non point source pollution.To overcome the threat of severe pollution and protect limited water resource,it is necessary to develop an integrated evaluation approach to understand the risk of the nitrogen and phosphorous leached from soils in complex land use systems.Based on analysis of factors influencing P and N runoff from fields,a comprehensive index assessment model was designed.To simplify the complex land use,runoff curve number (〖WTBX〗CN〖WTBZ〗) of Soil Conservation Service (SCS) of America was employed to express the differences in surface runoff resulted from different land use,and the equivalent standard pollution index method was taken to calculate the intensity of various type of pollution sources.A case study of Huajiachi Campus,Zhejiang University was taken to evaluate its reliability.The model was modified according to the real situation,to ensure its good performance.The results indicated that the high pollution sources plus high pollutant transportation potential can result in high risk of nitrogen and phosphorous leaching.The residential area,stock farm and heavy fertilized farm were high risk areas,while areas with well vegetation covered had low risk.The assessment model established in the paper can be applied to evaluate runoff potentials of N and P leached from complex land systems.