RAPID:Geomorphic Changes to the Amite River Channel and Floodbasin Induced by the August 2016 Flood in Louisiana

The Water Institute Of The Gulf, Baton Rouge LA

Investigators

Abstract

The long-duration Louisiana rainfall event of August 2016 was not anticipated and the extent of flooding came as an unwelcome surprise. This RAPID project will document how human interventions on the landscape surrounding the Amite River may have influenced the extent and patterns of flooding. Specifically, mining of gravel from the river and floodplains has led to large areas of mobile sand and channel shortening as well as the subsequent remobilization of sediment into cypress swamps and delta regions. Data gathered from this project will map the extent of high water and sediment deposition in order to develop models that will help predict the response to future heavy-rainfall episodes. This RAPID project will support a field effort (1) to document the geomorphic response of the Amite River to the August 2016 rainfall, (2) to analyze channel planform changes and cross-check with remote-sensing images and (3) to develop numerical models for predicting morphological response to future events. In addition, the research will examine flood layer deposition in the lower Amite River basin to quantify and map the sediment distribution from the flood. Choking of the lower basin channel by bed-load material may have exacerbated backwater flooding in some areas. However, the sediment may also nourish the cypress-tupelo swamps in the lower basin that have been sediment-starved due to isolation from the Mississippi River and are drowning under rising sea levels.