Estimating Ground Water Recharge from Topography, Hydrogeology, and Land Cover

Abstract

Proper management of ground water resources requires knowledge of the rates and spatial distribution of recharge to aquifers. This information is needed at scales ranging from that of individual communities to regional. This paper presents a methodology to calculate recharge from readily available ground surface information without long-term monitoring. The method is viewed as providing a reasonable, but conservative, first approximation of recharge, which can then be fine-tuned with other methods as time permits. Stream baseflow was measured as a surrogate for recharge in small watersheds in southeastern Wisconsin. It is equated to recharge (R) and then normalized to observed annual precipitation (P). Regression analysis was constrained by requiring that the independent and dependent variables be dimensionally consistent. It shows that R/P is controlled by three dimensionless ratios: (1) infiltrating to overland water flux, (2) vertical to lateral distance water must travel, and (3) percentage of land cover in the natural state. The individual watershed properties that comprise these ratios are now commonly available in GIS data bases. The empirical relationship for predicting R/P developed for the study watersheds is shown to be statistically viable and is then tested outside the study area and against other methods of calculating recharge. The method produces values that agree with baseflow separation from streamflow hydrographs (to within 15% to 20%), ground water budget analysis (4%), well hydrograph analysis (12%), and a distributed-parameter watershed model calibrated to total streamflow (18%). It has also reproduced the temporal variation over 5 yr observed at a well site with an average error < 12%.

Applicability Assessment of Estimation Methods for Baseflow Recession Constants in Small Forest Catchments

“…These results suggest that these methods are not suitable for explaining baseflow characteristics of small forest catchments. This study demonstrated that it is more reasonable to use the CR, AR (1), and VK methods to analyze baseflow recession characteristics in small forest catchments. However, all of these methods require the reasonable selection of recession periods in streamflow hydrographs.…”

“…It calculates the recession constant from the relationship between the discharge of pure baseflow data (Q) and the value of the recession slope (−dQ/dt). The recession slope and corresponding flow have linear relationships, as shown in Equation (4), and the solution to this differential equation is Equation (1).…”

“…Increasing demand for fresh water, due to the continued population and economy growth, has necessitated the management of forests and mountain streams [1]; this has been exacerbated by the expanding environmental variations caused by climate change, which have complicated the runoff characteristics of forest catchments [2]. As such, the need for rational interpretations of streamflow hydrograph characteristics is increasing for clean water supplies [3].…”

Water Quality, Hydrology, and Response to Changes in Phosphorus Loading of Nagawicka Lake, a Calcareous Lake in Waukesha County, Wisconsin

“…Lake-stage and water-quality data collected during this study were published in the annual data report series "Water Quality and Lake-Stage Data for Wisconsin Lakes, Water Years 2003(Wisconsin District Lake Studies Team, 20042005).…”

“…Discharges and annual constituent loads were estimated from the concentration data collected each year (described in detail later). Streamflow and water-quality data from all sites were published in the USGS annual water-data report series (Waschbusch and others, 2004;2005).…”