FY 1999 Progress Report on: Potential Groundwater Recharge from the Infiltration of Surface Runoff in Cold and Dry Creeks

The volume of water available for groundwater recharge through the infiltration of surface runoff in Cold and Dry Creeks was estimated for a 100-year storm and the Probable Maximum Precipitation (PMP) of Skaggs and Walters (1981). A 100-year, 7-day design storm was developed from 40 years of precipitation data measured at the Hanford Meteorological Station (HMS). Runoff measured in Upper Cold Creek was used with HMS precipitation data to calculate curve numbers for the Soil Conservation Service rainfall-runoff model. The estimated water available for recharge from surface runoff produced by the 100-year storm is 3-6 times the annual recharge rate from direct infiltration of precipitation over the Hanford Site. Potential recharge from the PMP is 7-11 times the annual volume of direct recharge.