Understanding the Interactions between Stream Flow, Sediment Transport and the Topography of the River Bed

Principal Investigator: Dr. Roger Kuhnle

Problem:

For a given flow discharge, the amount of sediment being transported by a river at any given location at any given moment in time is not a simple determination. The size and concentration of sediment and the presence of river bed topography such as bedforms and bars can affect the flow characteristics of a river in ways which are still poorly understood. Yet for assessing the impact of agricultural practices on stream flow and ecology, for predicting sedimentation rates in lakes and reservoirs, and for evaluating the risk of flooding, accurate determinations of sediment transport and river bed topography are required.

Objective:

The aim of this research is to determine how the presence of sediment of a certain size and concentration can affect flow within a river, and how the presence of bedforms such as ripples, dunes and bars can impact both the rates of sediment movement and river flow processes.

Description of Work:

In cooperation with scientists from Binghamton University and the University of Leeds, UK, experimental work has been initiated to isolate the effects sediment in transport can have on flow velocities, turbulence and flow resistance, and define the characteristics of the flow in the presence of bedforms. Measurements of flow velocity and the concentration of suspended solids have been obtained using laser-based technology, providing unrivaled data-sets to evaluate these complex fluid-sediment-bed interactions.

Benefit:

The goal of this research is to provide better predictive technologies for flow characteristics, total sediment load and bed topography in streams and rivers. These results will be used by the USDA, other federal agencies and academia to assess problems of sedimentation, flood risk, channel evolution processes, stream restoration and ecological habitat.