SWAT Literature Database for Peer-Reviewed Journal Articles

Title:A GIS-Based regional planning tool for irrigation demand assessment and savings using SWAT 
Authors:Santhi, C., R.S. Muttiah, J.G. Arnold, and R. Srinivasan 
Journal:Transactions of the ASAE 
Article ID: 
URL (non-DOI journals):http://ddr.nal.usda.gov/handle/10113/5474 
Broad Application Category:hydrologic only 
Primary Application Category:irrigation impacts or irrigation BMP scenarios 
Secondary Application Category:hydrologic assessment 
Watershed Description:Lower Rio Grande Valley region (27 irrigation districts) 
Calibration Summary: 
Validation Summary:R^2 = 0.91; simulated versus reported conveyance efficiency 
General Comments:The study describes a new canal irrigation routine that was used in SWAT. Cumulative irrigation withdrawal was estimated for each district for each of three different conservation scenarios(relative to a reference scenario). The percentage of water that was saved was also calculated. 
Abstract:Regional planning for irrigated agriculture requires a thorough understanding of the hydrological processes and spatial and temporal variations associated with hydrological factors such as rainfall, soils, and crops grown in different units of the region. The objective of this study was to improve the capabilities of a basin-scale hydrologic simulation model for regional planning of irrigated agriculture. In this study, a Geographical Information System (GIS) based hydrological model, Soil and Water Assessment Tool (SWAT), was configured as a regional planning tool with a canal irrigation capability for estimating irrigation demand. The tool was capable of simulating hydrological processes associated with soil-plant-water interactions and capable of capturing the spatial and temporal variability of the major factors, which are important in regional planning. The tool was applied to the irrigation districts in the Lower Rio Grande Valley in Texas. It was validated for crop evapotranspiration and canal conveyance efficiency and applied to analyzing the demand and potential water savings of alternative water conservation measures. Estimated potential water savings were 234.2, 65.9, and 194.0 Mm3 for conservation measures related to on-farm management improvements, replacing sugarcane with corn, and improving canal conveyance efficiency, respectively. Results indicated that on-farm management measures might be as beneficial as improving canal conveyance systems. The planning tool (with hydrological modeling and GIS capabilities) and estimations made would be useful for regional planners and irrigation district managers. The tool could be used for other irrigation systems as well.