Cooperator: USGS Office of Ground Water
Project Chief: Randy Hunt
Location: Statewide
Project Number: 9KH38
Period of Project: March 2003–September 2006
Problem
Knowledge of recharge rates is paramount for understanding ground-water systems and determining water-resource vulnerability. Moreover, the travel time of contaminants in the subsurface, and the time lag before contamination may affect important water resources, depends in part on recharge rates. More accurate estimates of ground-water recharge rates by the USGS will greatly enhance our ability to simulate ground-water systems, and provide a higher level of understanding for informed water- resource-management decisions.
Objectives
The objective of the study is to improve the understanding of the spatial and temporal characteristics of ground-water recharge in humid climates. Work elements include both interpretation of existing data sets and new data collection as needed.
Approach
The approaches used include regression modeling of base flow, coupled ground-water/surface-water modeling, and investigation into the temporal and spatial distribution of recharge in Wisconsin. A second area of work will involve analysis of the long-term Ground Water Observation Well database for climate trends and effects of oceanic climate signals.
Progress (July 2003–September 2004)
A preliminary time series analysis of 23 water-table wells in Wisconsin’s ground-water observation well network was completed; the time series show Monsoonal decadal climate influences. Increasing water level trends from the 1970s through 1999 were noted, with an indication of decline in water levels since 1999. Stream baseflow measurements throughout the state were compiled and analyzed to assess ground-water recharge rates. The results show both regional coherence and appreciable basin variability. A climate/recharge journal article was completed and included in the Wisconsin Academy of Sciences, Arts, and Letters “Waters of Wisconsin” Transactions volume.
Plans (October 2004–September 2005)
Future work will investigate recharge zonation in a highland forest, a glaciated rural area, and an unglaciated rural area of the state. Zonation will be evaluated using hydrologic models and measured data. Time series analysis will be performed on all the Observation Well Network data and selected streamflow data for climate effects and representativeness for the statewide conditions. |
