Cold Region Hydrologic Variability Due to Recent Wetting in the Northern Great Plains

Abstract:

The watersheds of the Northern Great Plains (NGP) have experienced a cycle of extreme wet and dry periods over the last four decades due to the highly variable cold and semiarid continental climate. The influences of such extreme climate shifts on the cold region hydrologic cycle result in devastating effects such as drought and flooding. Since the mid-1980s, watersheds in the NGP have faced a large and abrupt surge in precipitation with a few occasional short dry periods resulting in elevated streamflow and subsequent flooding. Nevertheless, the impacts of the recent wetting on snow processes such as snow accumulation, blowing snow transport, in-transit sublimation, fill and spill hydrology, frozen soil infiltration and streamflow generation mechanisms in headwater catchments are poorly understood. In this study, we utilize a field-tested, physically-based and distributed cold region hydrologic model (CRHM) to detect underlying mechanisms of hydrologic changes to these climatic extremes in the Upper Sheyenne River Basin (USRB) above Harvey, ND during 2004-present. Snow surveys within the study area are conducted to create a better understanding of snow processes. We have discretized the USRB into ~1000 hydrologic response units (HRU) based on land surface properties such as elevation, vegetation, slope, aspect, pothole density and its storage capacity. The model will be evaluated against distributed snow observation and streamflow. Our current model setup will decipher the underlying mechanism of hydrologic changes to recent wetting and explain the high variability of streamflow in the USRB.