El Niño–Southern Oscillation Effects on River Flows in the Lower Cape Fear River Watershed, North Carolina

Abstract

Well-known responses of regional precipitation in the southeastern United States to variation in the state of the El Niño-Southern Oscillation (ENSO) can yield similar regional responses of river discharge. Effects of ENSO on gaged river flows were examined in the lower Cape Fear River basin in southeastern North Carolina. Linear regression of monthly flows against sea surface temperatures (SST) in Niño Region 1 + 2 in the eastern equatorial Pacific identified significant effects of SST on flows, in several winter and spring months in the Black, Northeast Cape Fear, and main stem Cape Fear rivers. Major warm-phase ENSO events, as in 1997–1998, yielded almost a doubling of river discharges in the watershed, while typical cold phase events drove approximately 50% reductions in flows. River discharges have important effects on water supply for human needs, delivery of water to estuaries, and fluxes of water-borne materials to coastal waters. ENSO effects on the Cape Fear River watershed therefore have implications for adjacent estuarine and coastal ocean ecosystems at certain times.