Relative Contribution of Climate Change and Anthropogenic Activities to Streamflow Alterations in Illinois

Abstract

Rainfed agricultural systems have become more vulnerable to climate change due to their significant dependence on natural precipitation. Drastic changes in precipitation, superimposed with anthropogenic activities, including land use land cover change, can modify the hydrologic response, especially in agricultural watersheds. In this study, Fisher Information and cumulative sum charts (CUMSUM) methods were applied to detect the hydrologic regime shifts in six watersheds in Illinois, USA. The regime shift analysis identified shifts in streamflow regime in three agricultural watersheds, mainly around the 1970s; whereas, no significant change in streamflow was observed for forest-dominated watersheds. Furthermore, the Budyko framework was used to determine the relative contribution in streamflow alterations (i.e., regime shifts in streamflow) for the agricultural watersheds, which evidenced significant shifts in streamflow. The Budyko analysis inferred that alterations in streamflow could be primarily attributed to anthropogenic activities with a comparatively lower contribution from climate in agricultural watersheds. The relative contribution from anthropogenic activities were 71.66%, 81.46%, and 74.04%; whereas, the relative contribution from climate were 28.34%, 18.54%, and 25.96% for the Sangamon, Vermillion, and Skillet agricultural watersheds, respectively. The techniques used and the results obtained from the study would be helpful for future research in assessing the vulnerability and impact of management practices in a highly managed agricultural watershed.