GIS and Remote Sensing in Hydrology, Water Resources and Environment
(Proceedings of ICGRHWE held at the Three Gorges Dam, China, September 2003). IAHS Publ. 289, 2004, 336-342Nutrient export patterns from an agricultural catchment in southeast China
Wenzhi Cao, Huasheng Hong, Yuzhen Zhang, Shiping Yue & Yuanhong Ding
Key Laboratory for Marine Environmental Science, Ministry of Education, Environmental Science Research Centre, Xiamen University, Xiamen, Fujian 361005, China
wzcao@jingxian.xmu.edu.cn
Abstract The sources and magnitude of agricultural nutrient export from a catchment are not identical. Nitrogen and phosphorus export patterns and their Critical Source Areas (CSAs) were identified in a 1.74-km2 mountainous agricultural catchment. During baseflow the concentration of nitrate nitrogen (NO3-N) increased downstream, but dissolved reactive phosphate (DRP) concentration decreased downstream from the uppermost site to the outlet. The upstream area—segment 1 is a CSA for DRP export, but the outlet areas—segments 6, 7 are CSAs for NO3-N loss during baseflow. Two precipitation events with a similar precipitation magnitude but different duration were used to test the AGricultural Non-Point Source (AGNPS) model. During stormflow, CSAs for both NO3-N and DRP, defined through the AGNPS model tested, are side-slope areas where citrus has been planted.
Key words
agricultural non-point source model; critical source area; flow regimes; nutrient export; Wuchuan Catchment