Estimating non-point source pollution loads of a small watershed in Northeast China with AnnAGNPS Jian Ma 1,3 , Xin Chen* 1,2 , Yi Shi 1,2 , Caiyan Lu 1,2 , Guangyu Chi 1,2 , He Li 4 , 1. State Key Laboratory of Forest and Soil Ecology Institute of Applied Ecology, Chinese Academy of Sciences 2. Key Laboratory of Terrestrial Ecological Process Institute of Applied Ecology, Chinese Academy of Sciences Shenyang, China 3.Graduate University of Chinese Academy of Sciences, China; 4.Liaoning Provincial Meteorological Bureau, China First author: mroger@163.com; *Corresponding author: chenxin@iae.ac.cn Abstract— Non-point source pollution has became a major water pollution source in Northeast China. A small typical agricultural watershed was selected to test the validity of the annualized agricultural non-point source (AnnAGNPS) model in Northeast China. The best available data were assembled in the analysis. The model validity was tested by nitrogen and phosphorus concentration data. A good correlation was observed in predict nitrogen concentration while a not satisfactorily result was got in predict phosphorus concentration. The model’s performance released the model could be used in predicting nitrogen NSP load in Northeast China but not suitable for predicting phosphorus NSP load .Keywords: AnnAGNPS, Watershed modeling, non-point source pollution, Northeast China I. INTRODUCTION Non-point source pollution (NSP), especially resulting from agricultural activities, has been identified as a significant source of water quality pollution.[1]Overused fertilizer can leave excessive Nitrogen (N) and phosphorus (P) in soil which can be easily discharged into receiving water when irrigation practices and rainfall events occur. Those excessive N and P can induce the eutrophication phenomenon in receiving water and losses of biodiversity in the aquatic ecosystem. [2]Therefore knowledge of N and P emissions from different pathways and sources is a key issue concerning the protection of water quality and sustainable watershed management practices. [3]Environmental models have be proved to be a effective way in evaluating pollutant loads from NSP[4] In those models the NSP loads model Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) is specially designed to predict the loads from agriculture. The AnnAGNPS is an expansion of AGNPS[5] It is a continuous simulation, batch process, pollutant-loading model. AnnAGNPS is written in ANSI FORTRAN95 and worked with ARCView 3.x with spatial analyst module. It contains hydrology, sediment, nutrient, and pesticide transport components which can predict the watershed loads of water, sediment by particle size class & source of erosion, chemicals-nitrogen, phosphorus, organic carbon and pesticides. Though AnnAGNPS model had been proved availability in many south areas in China, there was little report for it was applied in north especially in northeast[2,6-10]. In this paper the main objectives were (1) to calibrate and validate the AnnAGNPS model of a small watershed in northeast China, and (2) to predict the most susceptible to NPS pollution areas. II. MATERIALS AND METHODS A .Study area The study area locates at Qing Yuan county in Liaoning Province China. The watershed area determined from this study is 3956.68 ha(39.5km2) with a north-easten direction of flow unnamed stream.(Fig.1) The study area is mainly covered by forest and cropland along the stream. The predominated crop is corn. 2012 International Conference on Computer Distributed Control and Intelligent Enviromental Monitoring 978-0-7695-4639-1/12 $26.00 © 2012 IEEE DOI 10.1109/CDCIEM.2012.77 297