HYDROLOGIC STUDIES OF NORTHERN PRAIRIE WETLANDS: PAST, PRESENT AND FUTURE

The Northern Prairie Region (or Prairie Pothole Region) is a large geographic region encompassing five states in the United States and three provinces in Canada. The region is characterized by a cold, semi-arid climate and a thick blanket of clay-rich glacial till. Due to the unique combination of climate and geology, the region is dotted with numerous wetlands that occur in topographic depressions, referred to as northern prairie wetlands (or “potholes”). Since these wetlands are contained in depressions that are isolated from each other, except during very wet periods, the hydrologic regime of the wetlands has strong seasonality characterized by a sharp rise in water level during snowmelt period, followed by a gradual decline during summer months. Exchange of water between wetlands and the surrounding uplands and between adjacent wetlands via surface and subsurface flow has a major influence on the hydrologic regime. Systematic studies of surface-groundwater interaction in northern prairie wetlands started in the 1960's, conducted by researchers from the U.S. Geological Survey and the Geological Survey of Canada. Findings of these studies culminated in the comprehensive overview by Tom Winter in the highly influential book, Northern Prairie Wetlands, published in 1989. Winter summarized the current state of knowledge and proposed several important questions for future research. In the ensuing two decades researchers from the U.S. and Canada, including Winter and his colleagues, have worked on the questions and added significant bodies of knowledge. We will re-examine Winter's questions, summarize what has been achieved so far, and propose a new set of questions for future hydrologic studies. Some of the key questions for the future will involve impacts of landcover manipulation, wetland drainage, and the long-term meteorological change overriding the decadal-scale wet-dry oscillation.