Channel Stability on the Lower Ohio River∗

Abstract

The meander loop pattern of the lower Ohio River has changed very little over the last thousand years. Point bar complexes are deposited and destroyed quite rapidly in comparison. KEY WORDS ; Channel stability, Meanders, Ohio River, Point bars.ADIOCARBON dates of organic matter R from the Black Bottom alluvium indicate that the meander loops of the lower Ohio River between Evansville, Indiana, and Brookport, Illinois, have an unusual degree of stabi1ity.l These dates suggest that the Bottom had reached its present outline, at least in the eastern half, by 1,000 years ago or earlier.Since lateral stability of sinuous alluvial channels seems to be relatively rare, the recent history of the Black Bottom portion of the Ohio channel was studied by comparing the original land survey maps, resurveys, topographic maps, and air photographs. We were curious whether other meander loop bottoms on the lower Ohio exhibited the same degree of stability, so we extended the comparison between the land survey maps and recent topographic maps upriver to Evansville, Indiana. GENERAL SETTINGThe meander loop floodplains between Brookport and Evansville have several features in common. Their surfaces all have a topography of ridges and swales, remnants of meander point bar deposits that indicate the river channel has migrated extensively. The loop floodplain surfaces, or bottoms as they are locally called, are higher on their upstream than

Late-Holocene floodplain development, land-use, and hydroclimate–flood relationships on the lower Ohio River, US

“…This mechanistic interpretation was largely based on modern Midwest climatology, where warm-season precipitation is dominant over winter precipitation (~75% vs ~25%, respectively), and the association between many of the largest modern floods and the occurrence of warm-season atmospheric river events originating from the Gulf of Mexico (Dirmeyer and Kinter, 2010; Lavers and Villarini, 2013). Other work from the Midwest, including along the Ohio River (Alexander and Nunnally, 1972; Counts et al, 2015; Stafford, 2004) and White River in Indiana (Herrmann and Monaghan, 2018) also shows variability in floodplain construction and the accumulation of floodplain alluvium that further suggests a connection between Holocene fluvial dynamics and climatic variability. Although climate is accepted as a likely driver of floodplain construction, the nature and timing of floodplain construction on large Midwest streams like the Ohio River is not resolved.…”

“…Some studies suggest that large point bar systems on the lower Ohio River rapidly evolved over the last ~2000 years (Counts et al, 2015), whereas others have concluded that they have been in a dynamic equilibrium for much of the Holocene (e.g. the Black Bottom; Alexander and Nunnally, 1972; Stafford, 2004).…”

Comparative Accuracy in Four Civil War Maps of the Shenandoah Valley: A GIS Analysis*

“…This assertion may seem suspect for those familiar with geomorphic studies of meandering streams flowing through unconsolidated alluvium (Russell 1947; Leopold and Wolman 1960; Schumm 1963; Langbein and Leopold 1970; De Vorsey 1982; Garcia and Brook 1996), since a high degree of meander migration and cutoff is generally characteristic of these fluvial regimes. Even with alluvial channels, though, notable exceptions of meander stability have been observed for the Ohio River (Alexander and Nunnally 1972) and for the Missouri (Moody, Meade, and Jones 2003).…”

Modeling soil-geomorphic associations and Archaic stratigraphic sequences in the lower Ohio River valley

“…Alexander and Nunnally's [21] study of bars reconstructed from historic maps in the Ohio River's Black Bottom, Illinois, indicates the complex architecture of bars. Their study applies to both channel-side and point bars.…”