Nitrogen and Phosphorus Loading of Agricultural Non-point Sources in Jiulong River Watershed Based on GIS
- 海洋环境－已发表论文 
以实测资料和相关研究资料为基础,分别选取适当的算法对USLE方程和SCS模型中的各个参数进行了率定,并借助ARC/INFO的GRID模块使各参数分别以栅格图层存储。利用GIS的空间运算分析能力,估算了九龙江流域土壤侵蚀量和年径流量,并进一步计算了流域的溶解态氮磷负荷和固态氮磷负荷。以100m×100m的网格为基本计算单元,以污染源输出经验模型进行了氮磷负荷的估算,实现了模型在空间上的分布式模拟,对九龙江流域农业非点源进行了定位、定量研究。Empirical models-USLE, SCS-CN and empirical equations are used to quantity the nitrogen (N) and phosphorus (P) loadings in a Geographic Informa tion Systems (GIS) environment. Various GIS layers, including land-use, soil t ypes and DEMs layer are created for the entire watershed by ARC/INFO, which are used to extract the parameters for USLE and SCS-CN models. The GIS layers are mostly organized in ARC/INFO GRID (the grid cell size is 100 m×100 m). The cur ve numbers (CNs) method is used to estimate surface runoff and the CNs is adjust ed depending on the antecedent moisture condition (AMC) before each storm. USLE is employed to predict the soil loss in Jiulong river watershed. Then, combined with the results obtained from the CNs methods and USLE model, the empirical equ ations for calculating the nitrogen and phosphorus loadings are provided to calc ulate N and P loadings in forms of dissolved N and P, particulate N and P based on ARC/INFO GRID. As a result, the spatial distribution of N and P loadings in t erms of sub-watersheds, land-use type and counties in Jiulong river watershe d are obtained and analyzed, which makes it easy to identify the critical source areas so as to efficiently control the agricultural non-point source pollutio n in Jiulong river watershed. The results show that excess fertilizer use and li vestock farm contribute significant N and P loadings from many counties. The con tribution of livestock farm to N and P loadings from some counties such as Xinlu o district and Zhangzhou could occupy up to 40%～47%and 51%～62%, res pectively.