RELATIVE ELEVATION MODEL OF THE OHIO RIVER VALLEY IN NORTHERN KENTUCKY

The Kentucky Geological Survey has been producing surficial geologic maps as part of the U.S. Geological Survey’s STATEMAP program since 2004. This year the mapping area is a large portion of northern Kentucky, where one of the most significant surficial landforms is the Ohio River valley. A relative elevation model (REM) was produced to visualize different levels of deposition in the valley. The Ohio River is an engineered river system between Pittsburgh, PA and Wickliffe, KY. The locks and dams of the Ohio River are designed to maintain each pool at a constant elevation from the top of one dam to the foot of the next. The Markland pool is maintained at 455 ft elevation and stretches from Warsaw, KY to Foster, KY. The REM depicts elevation relative to the surface of the river, which varies along the length of the river. REMs are typically used along free-flowing rivers, which have natural gradients. The REM for the Ohio River described in this presentation is based on an artificial gradient comprising a series of steps along the impounded length of the river. To create the REM, an arc was drawn using Arc Pro, from the base of the Markland Dam (420’) to the base of the Meldahl Dam (455’). There is a 35 ft increase in water level upstream of Markland Dam and Markland pool is 95.3 miles long. The arc was converted to a multipoint feature class with the points evenly spaced at 2000 ft and a resulting increase in elevation of 0.14 ft between each pair of points. A detrended Digital Elevation Model (DEM) was created and subtracted from the raw DEM to produce the REM for the given area using previously published methods. The resulting REM shows elevation changes in fluvial and outwash terraces along the Ohio River, produces a model to study the terraces from a regional perspective, and helps to correlate the terraces from one depositional plain to the next.