A recent study of natural groundwater storage reservoirs in New England by hydrologist David Boutt at the University of Massachusetts, Amherst found that upland aquifer systems dominated by thin deposits of surface till – a jumbled, unsorted material deposited by glaciers – make up about 70 percent of the active and dynamic storage for the region. As Boutt explains, “This is the first time that the relative role of upland vs. valley groundwater storage has been quantified. These results point to the importance of these thin glacial sediments in landscape-scale hydrologic budgets. This is really important for understanding how water gets into streams, supplying base flow during summer months and droughts, and for recharging valley fill aquifers.”
He adds that the “till reservoir” is traditionally neglected as an important groundwater storage reservoir because of its limited thickness and perceived low conductivity. But his new study highlights “the importance of a process-based understanding of how different landscape hydrogeologic units contribute to the overall hydrologic response of a region.”Shallow tills of Massachusetts and New England are really important storage reservoirs of water for recharge to alluvial aquifers and for base flow to streams,” he adds. This subsurface material fills and drains on a multi-annual basis and serves as the main mechanism to deliver water to valley fill aquifers and underlying bedrock aquifers. The results of the study are published in the journal Hydrological Processes.