Category: Hydraulics & Waterways

395308 - Spatial variability of overbank sedimentation in restored ephemeral urban streams

Monday, Jun 4
8:30 AM – 5:30 PM

Many streams in Western Tennessee have suffered deep channel incision, because of the historic channelization and subsequent downcutting of the larger, higher-order rivers to which they tribute. In the case of urban and suburban creeks, incision can be exacerbated by the increase in peak flows and the potential long-term decline in bed-load sediment delivery caused by land development activities.

The Tennessee Department of Environment & Conservation - West Tennessee River Basin Authority, in collaboration with the Tennessee Chapter of the Nature Conservancy, will conduct a series of stream restoration projects in highly-degraded, ephemeral urban creeks in the area of Jackson, Tennessee. These are not typical restoration exercises, with a focus on increasing habitat for aquatic species, as these channels only flow for a short time, during and immediately after rainfall events. Their primary goals are enhancing hydrologic detention, controlling knickpoint migration (‘grade control’), and reconnecting the newly-configured channels to regraded, lowered floodplains.

The main objective of this research is to quantify the sediment retention within the restored sections, induced by the construction of grade-control/hydrologic detention structures, together with reconfigured channels and floodplains. For monitoring sediment accumulation in project reaches, initial and post-construction surveys will be conducted at different scales along each reach with traditional techniques (DGPS, auto-level), as well as a drone-mounted Lidar. Then, after sizeable flood events, the reaches will be resurveyed. Differencing of the surface elevations will allow estimation of the sediment volume retained in each event. In addition, for understanding sediment budget at the event scale, suspended and bedload sediment samples will be collected during selected events. Several upstream and downstream cross-sections will be monitored through time to identify geomorphological changes caused by the restored sections. This poster presentation explains the detailed methods that will be used for the multi-scale analysis of floodplain sediment accretion.

Co-Authors: Claudio Meier, Memphis – University of Memphis

Patricio Muñoz-Proboste

Graduate student
The University of Memphis
Memphis, Tennessee