Soil and Water Assessment Tool (SWAT) Model: Current Developments and Applications

This article introduces a special collection of 20 research articles that present current developments and applications of the Soil and Water Assessment Tool (SWAT). The first objective is to review and introduce the research addressed within this special collection. The second objective is to summarize and synthesize the model performance statistics and parameters published in these articles to provide a succinct guide to complement a previous SWAT model summary. Recent SWAT developments in landscape representation, stream routing, and soil P dynamics are presented in this collection. Numerous critical applications of the SWAT model were conducted across a variety of landscape scales, climatic and physiographic regions, and pollutant sources. In this article, model performance in terms of coefficient of determination, Nash-Sutcliffe efficiency, and percent bias across all the studies is summarized and found to be satisfactory or better in all cases. These results are then compiled with a previous synthesis of results to generate a comprehensive assessment of SWAT. Model parameters used to calibrate the model for streamflow, sediment, N, and P in numerous studies are also summarized. This collection demonstrates that research in development and application of the SWAT model and associated tools continues to grow internationally in a wide range of settings and applications.