Groundwater: The disregarded component in lake water and nutrient budgets, Part 1: Effects of groundwater on hydrology

Lake eutrophication is a large and growing problem in many parts of the world, commonly due to anthropogenic sources of
nutrients. Improved quantification of nutrient inputs is required to address this problem, including better determination of
exchanges between groundwater and lakes. This first of a two-part review provides a brief history of the evolution of the study of
groundwater exchange with lakes, followed by a listing of the most commonly used methods for quantifying this exchange.
Rates of exchange between lakes and groundwater compiled from the literature are statistically summarized for both exfiltration
(flow from groundwater to a lake) and infiltration (flow from a lake to groundwater), including per cent contribution of
groundwater to lake-water budgets. Reported rates of exchange between groundwater and lakes span more than five orders of
magnitude. Median exfiltration is 0.74 cm/day, and median infiltration is 0.60 cm/day. Exfiltration ranges from near 0% to 94%
of input terms in lake-water budgets, and infiltration ranges from near 0% to 91% of loss terms. Median values for exfiltration
and infiltration as percentages of input and loss terms of lake-water budgets are 25% and 35%, respectively. Quantification of the
groundwater term is somewhat method dependent, indicating that calculating the groundwater component with multiple methods
can provide a better understanding of the accuracy of estimates. The importance of exfiltration to a lake budget ranges widely for
lakes less than about 100 ha in area but generally decreases with increasing lake area, particularly for lakes that exceed 100 ha in
area. No such relation is evident for lakes where infiltration occurs, perhaps because of the smaller sample size. Copyright ©
2014 John Wiley & Sons, Ltd.