Mississippi River Bank Failure, Fort Jackson, Louisiana

Abstract

Failures in Deltaic Plain sediments have resulted in bank recession in a slowly growing bend-way of the Mississippi River near Fort Jackson, Louisiana. Hydrographic surveys dating back to the early 1930's show that failures occur at a rate of one per 12–15-year period along this bend. Each failure destroys an area about 150–200 feet wide and 1000 feet long, thus threatening the levee on the south bank of the river. Comparison of borings made in the laded and unfailed parts of the riverbank indicates that deep-seated shear failures take place, resulting in lateral wedge-type failures initiated by progressive over-steepening of the bank slope by river erosion. Evidence of physical disturbances in the cohesive, fine-grained deltaic sediments in the unfailed bank suggests that incipient weaknesses may contribute to failures along this bend.