Document Type

Poster Presentation

Celebration Date

4-20-2011

Abstract

The Little Kankakee River (LKR) in LaPorte County, Indiana is an uncommon example of a good, cold-water fishery in northwest Indiana. However, the river has variable sedimentation levels; deep silt often covers gravel and sand, smothering invertebrates, a key food source for higher trophic organisms. The LKR contains a naturally-decomposing, abandoned beaver dam. The purpose of this study is to monitor its impact upon upstream and downstream silt levels. This research intends to identify possible sources of variability in silt levels, benefiting restoration teams in determining effects of dam removals. Furthermore, understanding the impact and pattern of silt levels could aid the monitoring of river health. Water depth, silt depth, flow rate, and a description of the river bed are measured and recorded. Flow rate fluctuations will be charted against monthly precipitation, noting changes in flow. It is predicted that the beaver dam causes fluctuating siltation by collecting silt upstream and then releasing variable amounts during dam decomposition. Preliminary results indicate the narrow sections of the river have faster water flow and less silt. The beaver dam impedes flow, widens the river, and reduces velocity, allowing fine sediment to accumulate. It is predicted that if the beaver dam decomposes rapidly, then trapped silt above the dam will percolate rapidly through the system stopping at wide sections of the river. If the beaver dam deteriorates slowly, then silt accumulations may not be measureable and leave silt in the system much longer.

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