Long-term changes in pond permanence, size, and salinity in Prairie Pothole Region wetlands: The role of groundwater-pond interaction

• Published in: Journal of hydrology. Regional studies 2018-06, Vol.17 (C), p.1-23
• Main Authors: LaBaugh, James W., Rosenberry, Donald O., Mushet, David M., Neff, Brian P., Nelson, Richard D., Euliss, Ned H.
• Format: Article
• Language: English
• Subjects: Climate variability; Groundwater solutes; Prairie-pothole wetlands; Wetland hydrology
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2018.03.003

•Groundwater input was largest source of major solutes to a prairie wetland pond.•Movement of wetland pond water into groundwater exported solutes during drought.•Budget imbalance exceeding budget uncertainty indicated unmeasured loss in some years.•Relation of budget components varied between wet and dry periods in 20 year span. Cottonwood Lake area wetlands, North Dakota, U.S.A. Fluctuations in pond permanence, size, and salinity are key features of prairie-pothole wetlands that provide a variety of wetland habitats for waterfowl in the northern prairie of North America. Observation of water-level and salinity fluctuations in a semi-permanent wetland pond over a 20-year period, included periods when the wetland occasionally was dry, as well as wetter years when the pond depth and surface extent doubled while volume increased 10 times. Compared to all other measured budget components, groundwater flow into the pond often contributed the least water (8–28 percent) but the largest amount (>90 percent) of specific solutes to the water and solute budgets of the pond. In drier years flow from the pond into groundwater represented > 10 percent of water loss, and in 1992 was approximately equal to evapotranspiration loss. Also during the drier years, export of calcium, magnesium, sodium, potassium, chloride, and sulfate by flow from the pond to groundwater was substantial compared with previous or subsequent years, a process that would have been undetected if groundwater flux had been calculated as a net value. Independent quantification of water and solute gains and losses were essential to understand controls on water-level and salinity fluctuations in the pond in response to variable climate conditions.