SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Some challenges in hydrologic model calibration for large-scale studies: A case study of SWAT model application to Mississippi-Atchafalaya River Basin 
Authors:Kannan, K., C. Santhi, M.J. White, S. Mehan, J.G. Arnold and P.W. Gassman 
Volume (Issue):6(1) 
Article ID:17 
URL (non-DOI journals): 
Model:APEX & SWAT 
Broad Application Category:hydrologic only 
Primary Application Category:Hyrologic Unit Model of the U.S. (HUMUS) application 
Secondary Application Category:Conservation Effects Assessment Project (CEAP) based study 
Watershed Description:> 3 million km^2 combined Mississippi and Atchafalaya Rivers, which together drain much of the central part of the U.S. 
Calibration Summary: 
Validation Summary: 
General Comments: 
Abstract:This study is a part of the Conservation Effects Assessment Project (CEAP) aimed to quantify the environmental and economic benefits of conservation practices implemented in the cultivated cropland throughout the United States. The Soil and Water Assessment Tool (SWAT) model under the Hydrologic United Modeling of the United States (HUMUS) framework was used in the study. An automated flow calibration procedure was developed and used to calibrate runoff for each 8-digit watershed (within 20% of calibration target) and the partitioning of runoff into surface and sub-surface flow components (within 10% of calibration target). Streamflow was validated at selected gauging stations along major rivers within the river basin with a target R2 of >0.6 and Nash and Sutcliffe Efficiency of >0.5. The study area covered the entire Mississippi and Atchafalaya River Basin (MARB). Based on the results obtained, our analysis pointed out multiple challenges to calibration such as: (1) availability of good quality data, (2) accounting for multiple reservoirs within a sub-watershed, (3) inadequate accounting of elevation and slopes in mountainous regions, (4) poor representation of carrying capacity of channels, (5) inadequate capturing of the irrigation return flows, (6) inadequate representation of vegetative cover, and (7) poor representation of water abstractions (both surface and groundwater). Additional outstanding challenges to large-scale hydrologic model calibration were the coarse spatial scale of soils, land cover, and topography. 
Keywords:MARB; river basin; base flow; CEAP; conservation effects assessment project; validation; water yield; runoff; streamflow