Evaluating the impacts of climate change and switchgrass production on a semiarid basin

Abstract

Climate and land use changes greatly modify hydrologic regimes. In this paper, we modelled the impacts of biofuel cultivation in the US Great Plains on a 1061‐km2 watershed using the Soil and Water Assessment Tool (SWAT) hydrologic model. The model was calibrated to monthly discharges spanning 2002–2010 and for the winter, spring, and summer seasons. SWAT was then run for a climate‐change‐only scenario using downscaled precipitation and a projected temperature for 16 general circulation model (GCM) runs associated with the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios A2 scenario spanning 2040–2050. SWAT was also run on a climate change plus land use change scenario in which Alamo switchgrass (Panicum virgatum L.) replaced native range grasses, winter wheat, and rye (89% of the basin). For the climate‐change‐only scenario, the GCMs agreed on a monthly temperature increase of 1–2 °C by the 2042–2050 period, but they disagreed on the direction of change in precipitation. For this scenario, decreases in surface runoff during all three seasons and increases in spring and summer evapotranspiration (eT) were driven predominantly by precipitation. Increased summer temperatures also significantly contributed to changes in eT. With the addition of switchgrass, changes in surface runoff are amplified during the winter and summer, and changes in eT are amplified during all three seasons. Depending on the GCM utilized, either climate change or land use change (switchgrass cultivation) was the dominant driver of change in surface runoff while switchgrass cultivation was the major driver of changes in eT. Copyright © 2014 John Wiley & Sons, Ltd.

Hydrologic cost-effectiveness ratio favors switchgrass production on marginal croplands over existing grasslands

“…Goldstein and Tarhule [ 13 ] also predicted reduced streamflow by 8.2% during winter, 26% during spring, and 44% during summer and increased ET by 44% during spring and 22% during summer in the Skeleton Creek watershed due to switchgrass production, but their conversion scenario involved 89% of the watershed area (both grassland and all cropland) being converted to switchgrass. It is not clear what driving factors would be necessary to result in such a dramatic land use change.…”

“…About 80% of the grasslands are in land capability class III or higher and are not well suited for crop production. The land cover in the watershed is representative of other watersheds in the SGP where winter wheat and grasslands are predominant [ 13 ].…”

“…These increases in ET were predicted to result in a reduction in streamflow by 5.6 to 20.6% during spring and 6.4 to 31.2% during the summer. Similarly, in the Skeleton Creek watershed, Goldstein and Tarhule [ 13 ] predicted an increase in ET and a decrease in runoff during the spring and summer following conversion of 89% of the watershed (currently under grassland, winter wheat, and rye) to switchgrass production.…”

Comparative Analysis of Bioenergy Crop Impacts on Water Quality Using Static and Dynamic Land Use Change Modeling Approach

“…They represent 'what-if' scenarios to address questions of long-term impacts relating to land management changes, and their use may be helpful to understand non-point source levels before any field monitoring [29,30]. SWAT model is one such tool that has been extensively used to predict the effects of different land management scenarios on water quality, pollutant loadings and sediment yields [31][32][33][34]. There are more than 3800 peer-reviewed journal articles published with the application of SWAT model since 1984 (SWAT literature database, available at https://www.card.iastate.edu/swat_articles/).…”

Spatial and Temporal Evaluation of Hydrological Response to Climate and Land Use Change in Three South Dakota Watersheds

“…With the advancement of computational resources, computer models can discretize geospatial heterogeneity of watershed characteristics at fine resolution and generate sound simulations of the hydrologic cycle. The Soil and Water Assessment Tool (SWAT) is a computer simulation tool (Gassman et al ., ; Neitsch et al ., ; Arnold et al ., ), which has extensively been used for land use and climate change impact assessment studies in various parts of the world ( e.g ., Guo et al ., ; Wang et al ., ; Mango et al ., ; Goldstein and Tarhule, ; Li et al ., ). However, most of these studies involve scenario testing by varying climate input data or adjusting proportions of land use classes in the model to determine watershed sensitivity and response to these changes ( e.g ., Hernandez et al ., ; Gassman et al ., ; Schilling et al ., ; Pervez and Henebry, ).…”