Slope Development on a Mississippi River Bluff in Historic Time

Abstract

Using a space-time transformation, hillslope development was examined along a segment of the Mississippi River bluff at Port Hudson, Louisiana. The entire bluff segment was being undercut by a meander of the Mississippi River in 1722. Since that time, the meander has migrated downstream progressively, abandoning the river bluff. A space-time calibration of the hillslopes along the bluff was done by determining the position of the river along the bluff base from historic maps and aerial photographs. In plan, the bluff was divided into three segments: high, intermediate, and low intensity according to processes acting along the base of the bluff. The high-intensity zone represents a zone of active undercutting by the river, while the intermediate zone is characterized by basal scour and the low-intensity zone by basal aggradation. The present rate of retreat for each segment was calculated to be 75, 1.0, and 0.63 feet/year, respectively. The slope profiles within the three zones represent a sequential chang...