Summary of stream flow conditions at five riverine parks in the Southeast Coast Network, 2012

Jones, Clark; Gregory, M.

The National Park Service (NPS) Southeast Coast Netowork (SECN) evaluated stream flow variability and the magnitude and timing of specific flow events at five parks within the Network during 2012. The streams and rivers of these parks ranged in size from small creeks to small- and medium-sized rivers that make up significant park acreage along the Chattahoochee, Congaree, Ocmulgee, Wateree and Tallapoosa Rivers. Flow patterns were characterized and put in historical context using U.S. Geological Survey stream flow data, The Nature Conservancy’s Indicators of Hydrologic Alteration software, and Flow software (Dowd 2011), which generates graphical representations of annual stream flow data. Across all parks, high flow pulses were more frequent at two gages, while extreme low-flow pulses were more frequent at nine gages. The average length of each event type ranged 1–10 days for extreme low-flow pulse length and 1–5.5 days for high flow pulses length. Extreme low-flow pulses tended to occur June–October at all parks except Chattahoochee National Recreation Area (CHAT) where extreme low-flow pulses occurred primarily during February and March. High flow pulses primarily occurred primarily from January to May except at CHAT where high flow pulses occurred October–November. No small floods (defined as a flood event with an initial high flow with a peak flow greater than a two-year return interval event) occurred at any SECN park in 2012. At CHAT, the most commonly observed flow conditions on all sections during 2012 (32–42% of the time) were 1000–1500 cfs. These flows are considered optimal for wade and tube fishing, novice rafting, and canoeing. River flows along the sections of the Chattahoochee were below 750 cfs 6–31% of the time. Extreme low flows were more common on Sections 2–4 and a comparison of the number of times daily flow was below 750 cfs at Section 2 and Section 3 (23 and 44, respectively) may indicate that Section 3 was impacted by water withdrawals. High flows (greater than 2,000 cfs), which impaired fishing activities and allowed only mid-level paddling activities at CHAT, occurred approximately 11% of the time on section 1, 11% of the time on section 2, 13% of the time on section 3, and 14% of the time on section 4 of the Chattahoochee River within the Park.

Summary of stream flow conditions at five riverine parks in the Southeast Coast Network, 2012

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