ABSTRACT

Changes in meander patterns of the Red River in northeast Texas from 1860 to 1980 were identified from various maps, aerial photographs and fieldwork for a 430 km reach from the Denison Dam on Lake Texoma downstream to Texarkana. Denison Dam closure in 1943 resulted in increased daily base flow and substantially reduced frequency and intensity of flood peaks downstream. The Red River responded to the closing of the dam by increasing in width, depth, meander wavelength, amplitude, radius of curvature and channel length. Changing only discharge and sediment load downstream of the dam reveals a geologically instantaneous fluvial response to the dam closure. Qualitative prediction of these recent changes on the Red River is generally confirmed by empirical studies in the literature.

Three ancient meander patterns preserved on the Holocene Red River flood plain record a different hydrologic regimen in which well-sorted, clay-rich sediment was transported in a paleoriver having low wavelength, amplitude, width and depth with high sinuosity. Bankfull discharge (Q) is estimated to be quite low. Archeological remains dated in the Archaic period suggest these features formed about 5,000 ± 1,000 years BP.

In perspective, the isolated hydrologic changes which occurred as a result of the closure of the Denison Dam are minute by comparison to the climate-related changes the Red River has undergone over the last 5,000 years.