Nonpoint source (NPS) pollution is a common problem faced in many places around the world. On-site evaluation of NPS pollution is helpful in deciding how serious the pollution is and where a controlling practice can potentially be implemented with the best effectiveness. In this study, a web GIS interface for the Agricultural Policy Environmental eXtender (APEX) model named GeoAPEXOL was developed. The interface serves as a tool to automatically setup the APEX model for a watershed or field and conduct a rapid evaluation of the NPS pollution. A background database including DEM, landuse, soil, climate, and agricultural management was prepared for automating the process of model setup. One important feature of the interface is that NPS pollution can be evaluated for a field boundary considering contribution from upstream areas, which may be located outside the field boundary and is generally ignored by traditional NPS evaluation methods at the field scale.

非点源（NPS）污染是世界许多地方面临的普遍问题。对NPS污染进行现场评估有助于确定污染的严重程度以及在哪里可以最有效地实施控制措施。在这项研究中，开发了名为GeoAPEXOL的农业政策环境扩展程序（APEX）模型的Web GIS界面。该界面用作自动为流域或田地设置APEX模型并快速评估NPS污染的工具。准备了包括DEM，土地利用，土壤，气候和农业管理在内的背景数据库，以实现模型设置过程的自动化。该界面的一个重要特征是，考虑到上游地区的贡献，可以针对田间边界评估NPS污染，