Groundwater Recharge Rates in Minnesota as Related to Precipitation

Abstract

Quantitative estimates of recharge rates and storage coefficients in sufficient detail are essential to any meaningful state water-resources management, policies, plans and legislation. A methodology was developed to derive quantitative estimates of groundwater recharge rates and storage coefficients for unconfined aquifers in the various hydrologic regions of Minnesota. Recharge estimates are based on information from groundwater hydrographs. Statistical analysis of groundwater level fluctuations and their correlation with precipitation, evaporation, stream discharge were evaluated. Harmonic analysis and autoregression analysis of water levels were done. Storage coefficients were estimated from pumping test data, soil moisture method and empirical equations. Groundwater recharge rates were determined by combining data on groundwater level fluctuations and storage coefficient evaluation for unconfined aquifers in Minnesota. This work is fundamental to the ultimate goal of an interactive water resources model of the state.