Pennsylvania Water Science Center
Ground-water recharge rates were estimated for 197 watersheds throughout Pennsylvania in a study by the U.S. Geological Survey in cooperation with the Pennsylvania Geological Survey. Recharge estimates were based on two automated streamflow-hydrograph methods -- PART and RORA. The PART program uses a hydrograph-separation technique to estimate base flow. Although base flow is not recharge, it commonly has been used as an approximation of recharge when underflow, evapotranspiration from riparian vegetation, and other transfers of ground water to or from the watershed are thought to be minimal. The RORA program uses streamflow data to estimate ground-water recharge, but it is not a "hydrograph-separation" method. RORA uses the recession-curve displacement method to estimate ground-water recharge, based on a theoretical equation of one-dimensional ground-water flow to a fully penetrating stream in an idealized, homogeneous aquifer.
Recharge estimates based on the PART and RORA streamflow-hydrograph methods can be accessed from the menu below.
The methods and results from the study are documented in:
Risser, D.W., Conger, R.W., Ulrich, J.E., and Asmussen, M.P., 2005, Estimates of Ground-Water Recharge Based on Streamflow-Hydrograph Methods: Pennsylvania: U.S. Geological Survey Open-File Report 2005-1333, 30 p.