River Bed Sediment Classification Using Acoustic Doppler Profiler
Abstract
Restoration or rehabilitation of degraded stream and river habitats requires definition of a target condition and preferably post-implementation monitoring to gage progress toward the target. Stream habitat has been characterized by computing statistics based on measurements of water depth and velocity at each point of a horizontal grid. In many cases stream bed type and cover, both qualitatively assessed, were included as additional grid variables. Resultant statistics describing the central tendency, variability and spatial distribution of these three or four variables and their combinations have been used to explain key differences between more- and less-degraded streams and to infer biotic responses. Usually the required data are collected by wading observers, but application to larger rivers is problematic. Collection of water depth and velocity information may be automated across a wide range of stream sizes using an acoustic Doppler profiler (aDp). Herein we suggest that aDp data may also be used to infer bed hardness and thus type by extracting the return signal strength from the bottom track signal and using this information to compute the echo intensity at the bed. A method for computing echo intensity, along with key assumptions is presented. Echo intensity is computed for a range of river environments and related to the size and related characteristics of bed material. Habitat maps for river reaches depicting water depth, velocity and bed type developed from aDp data sets are presented.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.H43B0987S
- Keywords:
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- 1813 Eco-hydrology;
- 1834 Human impacts;
- 1856 River channels (0483;
- 0744);
- 1895 Instruments and techniques: monitoring