The spatial and temporal variability of groundwater recharge in a forested basin in northern Wisconsin

Abstract

Abstract:Recharge varies spatially and temporally as it depends on a wide variety of factors (e.g. vegetation, precipitation, climate, topography, geology, and soil type), making it one of the most difficult, complex, and uncertain hydrologic parameters to quantify. Despite its inherent variability, groundwater modellers, planners, and policy makers often ignore recharge variability and assume a single average recharge value for an entire watershed. Relatively few attempts have been made to quantify or incorporate spatial and temporal recharge variability into water resource planning or groundwater modelling efforts. In this study, a simple, daily soil-water balance model was developed and used to estimate the spatial and temporal distribution of groundwater recharge of the Trout Lake basin of northern Wisconsin for 1996-2000 as a means to quantify recharge variability. For the 5 years of study, annual recharge varied spatially by as much as 18 cm across the basin; vegetation was the predominant control on this variability. Recharge also varied temporally with a threefold annual difference over the 5-year period. Intra-annually, recharge was limited to a few isolated events each year and exhibited a distinct seasonal pattern. The results suggest that ignoring recharge variability may not only be inappropriate, but also, depending on the application, may invalidate model results and predictions for regional and local water budget calculations, water resource management, nutrient cycling, and contaminant transport studies. Recharge is spatially and temporally variable, and should be modelled as such.

An Integrated Field Assessment of Groundwater Recharge

“…Glaciers scoured the Precambrian metamorphic and igneous bedrock surface and deposited 30 to 50 meters [18,19] of unconsolidated sand and coarse glacial till. Vibracores, drill logs, slug testing, and Guelph permeameter studies [20] show that the unconsolidated sediments consist of homogeneous, fine to medium grained outwash sands with hydraulic conductivities of 8 -12 m/day.…”

“…Typically in this region, precipitation falls and accumulates as snow from November through March. The spring snowmelt constitutes the major recharge event of the year, often contributing in excess of 2/3 of the annual recharge [20]. Minor recharge is occasionally associated with spring and/or late fall rains when transpiration and interception are negligible and the ground is unfrozen.…”

“…5). If one assumes that the recharge rate at the clear cut site prior to cutting was similar to the conifer site, which has comparable sediments [20], clear cutting has caused a significant increase in recharge. This result supports findings by previous workers [35,[47][48][49][50][51] that clear cutting causes an increase in recharge rate.…”

“…There has been extensive research on recharge estimation at a variety of scales [2][3][4], including studies that assess spatial and temporal recharge variability [5][6][7][8][9][10][11][12][13][14][15][16]. Nevertheless, groundwater modelers, planners, and policy makers frequently use a single recharge value for an entire watershed calculated as an assumed fraction of the annual average precipitation or as determined by model calibration.…”

Estimation of alluvial recharge in the semiarid

“…GÓMEZ et al (2010) state that the knowledge of the groundwater recharge is needed in resolving issues related to water quality, ecology and human and environmental well-being, as well as modeling of groundwater flow and contaminant transport. The spatial and temporal variability of recharge is one of the most important issues in hydrological research because of its importance to management of groundwater resources (RABELO & WENDLAND, 2009;DRIPPS & BRADBURY, 2010).…”