Quantifying Hydrological Responses to Major Land Cover Changes: A Case Study in Smoky Hill River Watershed in Western Kansas

Abstract

Abstract. Hydrologic response to land use change is one of the key topics in the Intergovernmental Panel for Climate Change assessment. Crop rotation has been a primary land use change in recent several decades in agro-ecosystem of central United States. Understanding hydrological responses to crop rotation is critical for developing appropriate crop rotation guide strategies for sustainable water resources management and protection of public safety. However, these responses are not well demonstrated and there exists only a few comparison analyses regarding impacts of different rotation patterns on hydrological process. Herein, we show how crop rotation, specifically shifted rotation patterns in various periods, can affect stream flow simulation using the Soil and Water Assessment Tool (SWAT) in a typical agro-ecosystem watershed (the Smoky Hill River Watershed) in the Great Plains of the United States. Our results show that, although an accurate crop rotation pattern (2008-2010) slightly improved the simulation performance from 1999 to 2013, precision of stream flow simulation in corresponding and adjacent periods increased significantly. A significant improvement of stream flow simulations in 2006-2008 was also found when applied the corresponding rotation patterns in this period. However, model performance in periods adjacent to 2006-2008 for these two scenarios was not better than that in the periods longer distanced from 2006-2008. The trends of significant improvement to model performance for the corresponding rotation periods suggest that SWAT model capturing more information on crop rotation pattern can lead to a more accurate stream flow prediction. We conclude that selecting various periods of crop rotation patterns has obvious advantage in performance of predicting stream flow. .