Use of the Effective Monthly Recharge model to assess long-term water-level fluctuations in and around groundwater-dominated wetlands

Autor: John C. Smith, Tracy L. Thornton, Kerby M. Dobbs, G. Richard Whittecar, Stephen A. Stone, John M. McLeod
Rok vydání: 2017
Předmět:
Zdroj: Ecological Engineering. 99:462-472
ISSN: 0925-8574
DOI: 10.1016/j.ecoleng.2016.11.038
Popis: Effective Monthly Recharge (W em ) calculations use historical weather data to estimate monthly-scale water level changes in precipitation-and-groundwater-driven wetlands. This time-weighted water-budget procedure relates first-of-the-month hydraulic heads measured in a monitoring well or small pond with precipitation and evapotranspiration data for preceding months and generates a regression equation used to estimate historic water levels. This study developed an enhanced procedure more robust than used with previous W em studies. Two data sets of water-table fluctuations in humid-temperate southeastern Virginia (U.S.A.) allowed verification of the model procedure—a 30-year record from a shallow well maintained by the U.S.G.S., and a 6.5-year record from a mitigation wetland measured before and after construction. Analyses of Predicted Heads and Observed Heads at both sites indicate that the W em model can replicate reasonably the seasonal patterns of water-table fluctuations and the range of values of hydraulic heads at a monthly scale. Within the limitations set by the assumptions of the procedure and the range of water fluctuations during the calibration period, W em calculations may be used to generate synthetic hydrographs for periods with appropriate weather data. Analyses of two sites in Missouri and Nebraska (U.S.A.) suggest that the W em procedure may prove useful also in climatic regions with relatively strong seasonal forcing, but additional testing is needed to verify the range of model applicability. These reconstructions could support long-term decisions in the management of wildlife habitats or design of mitigation wetlands.
Databáze: OpenAIRE