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The Soil and Water Assessment Tool (SWAT) is a basin-scale hydrologic model developed by the United States Department of Agriculture Agricultural Research Service. SWAT's broad applicability, user-friendly model interfaces, and automatic calibration software have led to a rapid increase in the number of new users. These advancements also allow less experienced users to conduct SWAT modeling applications. In particular, the use of automated calibration software may produce simulated values that appear appropriate because they adequately mimic measured data used in calibration and validation. Autocalibrated model applications (and often those of unexperienced modelers) may contain input data errors and inappropriate parameter adjustments not readily identified by users or the autocalibration software. The objective of this research was to develop a program to assist users in the identification of potential model application problems. The resulting "SWAT Check" is a stand-alone Microsoft Windows program that (i) reads selected SWAT output and alerts users of values outside the typical range; (ii) creates process-based figures for visualization of the appropriateness of output values, including important outputs that are commonly ignored; and (iii) detects and alerts users of common model application errors. By alerting users to potential model application problems, this software should assist the SWAT community in developing more reliable modeling applications.
Abbreviations: HRU, hydrologic response unit; SWAT, Soil and Water Assessment Tool.
The Soil and Water Assessment Tool (SWAT) is a basin-scale hydrologic model developed by the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS). SWAT is a product of more than 30 years of joint development by USDA-ARS and numerous universities. Broad applicability and user-friendly model interfaces have led to a rapid increase in the number of new SWAT users. This growth is illustrated by the substantial increase in SWATrelated peer-reviewed publications. For example, 20 articles were published in 2002, but by 2010 more than 100 SWAT articles were being published each year.
Model interfaces, national databases, and automated calibration routines have simplified model application such that the effort to apply SWAT (including calibration and evaluation) is a fraction of that required a decade ago. These advancements allow SWAT application by less-experienced users and those without sufficient background in hydrology, sedimentology, soil science, and nutrient dynamics. A SWAT application can be developed using readily available data and...