North Carolina Water Science Center
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Apparent Flow Losses in the Cape Fear River
Cape Fear River looking upstream from Buckhorn Dam
The U.S. Army Corps of Engineers is required to release water from B. Everett Jordan Lake such that a minimum (target) flow of 600 ft3/s (± 50 ft3/s) is measured at the USGS streamgaging station located on the Cape Fear River at U.S. Highway 401 at Lillington (USGS Sta. 02102500).
The drainage area in this 24-mile reach increases from 1,689 mi2 at Jordan Lake dam to 3,464 mi2 at the Lillington gaging station (resulting in an intervening drainage area of 1,775 mi2). Much of the intervening drainage area in this reach includes the Deep River basin, and the downstream-most gaging station on the Deep River at Moncure (USGS Sta. 02102000) has a drainage area of 1,434 mi2.
During some low-flow conditions, the sum of the estimated releases from Jordan Lake and the measured streamflow on the Deep River at Moncure is greater than the streamflow recorded downstream at the gaging station at Lillington. Consequently, either the target at Lillington is not met, or excessive water is released from Jordan Lake in an attempt to meet the target.
The difference between the inflow to this area (sum of releases from Jordan Lake dam and flow in Deep River at Moncure) and outflow from the reach (flow in the Cape Fear River at Lillington) could be because either (1) flow is measured inaccurately at one or more of the 3 measurement locations or (2) flow is being "lost" from the reach from surface-water diversions, possible alterations due to storage behind dam structures, ground-water withdrawals, evaporation, recharge (loss) to the ground water system, or a combination of these factors.