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Ground-water, surface-water, and precipitation departures from monthly means for sites located near Middle Dam, Maine were normalized and then plotted in order to examine the relations between them during periods of drought. The ground-water well, 443647070552302, is located near Middle Dam, at Lower Richardson Lake, Maine and is run by the USGS in cooperation with Florida Power and Light observers. The data are a combination of continuous-recorder data and individual water level readings. The ground-water record is composed of the records from two companion wells located near Middle Dam to provide a period of record from 1944 to 2002. The surface-water site, 01052500, Diamond River at Wentworth Location, NH is also run by the USGS. Streamflow record at this station runs from 1941-2002. The data for the precipitation site located near Middle Dam were supplied by the Northeast Regional Climate Center of Cornell University and run from 1948 through 2002.
For all three datasets (groundwater, surface water, and precipitation) the departure from the mean for each month was calculated as the difference between the monthly mean, and the long- term monthly mean, divided by the long-term standard deviation for that month. A positive value indicates above-normal conditions and a negative value indicates below-normal conditions.
This preliminary look at the relationships between ground-water, surface-water, and precipitation at this site, shows that while streamflow responds fairly quickly to precipitation as expected, changes in ground-water level often lag in response time. Even in months when precipitation is above normal, the ground-water level does not always rise back up to normal. This indicates that ground-water responds more slowly than surface-water to precipitation, and that the relationship between precipitation, ground-water and surface-water is complex.
