SWAT（Soil and Water Assessment Tool）是由美国农业部（USDA）的农业研究中心（ARS，Agricultural Research Service）Jeff Amonld博士1994年开发的。模型开发的最初目的是为了预测在大流域复杂多变的土壤类型、土地利用方式和管理措施条件下，土地管理对水分、泥沙和化学物质的长期影响。它是一种基于GIS基础之上的分布式流域水文模型，近年来得到了快速的发展和应用，主要是利用遥感和地理信息系统提供的空间信息模拟多种不同的水文物理化学过程，如水量、水质以及杀虫剂的输移与转化过程。现在使用的SWAT2005版本可以在Arcview、ArcGIS等常见的软件平台上运行，具有良好的用户界面

-SWAT (Soil and Water Assessment Tool) by the United States Department of Agriculture (USDA) Agricultural Research Center (ARS, Agricultural Research Service) Jeff Amonld Dr. 1994 developed. The original purpose of the model developed to predict the complex soil type in large watersheds, land use and management measures under the conditions of the land management of water, sediment and chemicals in the long-term impact. It is a distributed hydrological model based on GIS basis, and in recent years has been the rapid development and application of spatial information is provided by the use of remote sensing and geographic information system to simulate a variety of different hydrological physical and chemical processes, such as water, water quality and pesticide transport and transformation process. The now use SWAT2005 version can run on a common software platform Arcview, ArcGIS, has a good user interface