Date of this Version
The North Dakota Prairie Pothole Region is one of the most unique and important wetland environments for waterfowl in North America. A water balance climatology is developed for this region for the period 1895-1990. A monthly water balance time series for the 96-year period was computed utilizing the Thornthwaite water balance methodology and a regional time series developed from area-weighted National Climate Data Center divisional data. Results illustrate the unique seasonal dynamics of the mean soil moisture regime, the frequency distribution of selected water balance variables over the period of record, and the large intra-annual and interannual variability which characterizes the hydroclimatic environment of the Northern Great Plains. Long-term analysis of the water balance variables revealed statistically-significant linear trends toward warming and increased soil dryness. The increased soil dryness trend, however, has been concentrated in the summer months after the peak waterfowl breeding and migratory period. Trends toward decreased precipitation and increased spring soil dryness, although suggested by the data, are not conclusive at the 0.05 level. Inferences related to waterfowl production, global warming, historic loss of wetlands, and resource management issues are noted.