Date of Graduation

Spring 2018

Document Type

Honors Research Project

Degree Name

Bachelor of Science

Major

Geology - Engineering Geology

Research Sponsor

Dr. John Peck

First Reader

Dr. Caleb Holyoke

Second Reader

Dr. John Senko

Abstract

In order to improve water quality of the middle Cuyahoga River, the Munroe Falls and Lefever Dams were removed in 2005, and 2013, respectively. These dam removals have provided an opportunity to quantify how rivers respond to dam removal. This thesis research extends eleven years of river morphology monitoring by measuring channel sedimentologic properties of sediment samples as well as geomorphic transects in 2016 and determined the volume of impoundment sediment prior to the removal of the Munroe Falls Dam.

In the three years following the removal of the Munroe Falls Dam, flow energy increased and the sediment in the former impoundment coarsened. Between 2015 and 2016, minimal grain size change occurred in the former Munroe Falls impoundment. Downstream of the former Munroe Falls Dam grain size decreased and the channel aggraded as former impoundment sediment was eroded from upstream. The newly deposited sediment was remobilized in 2013 when the Lefever Dam was removed. Between 2015 and 2016, the coarsening of the sediment continued as the channel reaches a state of equilibrium with the post-dam removal flow regime. Similar to changes in the former Munroe Falls impoundment, sediment in the former Lefever impoundment degraded and coarsened following its removal. Minimal change in grain size occurred between the 2015 and 2016 surveys.

In the three years following the Munroe Falls Dam removal, the river channel rapidly incised and laterally eroded into the impoundment sediment. The river channel eroded into to sediment until exposing the pre-dam substrate, as well as bedrock in some locations. Between 2015 and 2016, little geomorphic change occurred in the former Munroe Falls impoundment reach of the study area. The impoundment sediment was deposited downstream of the Munroe Falls Dam and continued to migrate towards the Lefever Dam. Sediments continued to aggrade between the head of the Lefever Dam impoundment and the Munroe Falls Dam until 2006, and then erosion of the sediment began. The rate of erosion increased in 2013 following the removal of the Lefever Dam. Between 2015 and 2016, geomorphic change upstream of the former Lefever Dam has slowed.

The Munroe Falls Dam impoundment sediment volume was determined to be 288,695 m3. During the three years following the dam removal the sediment volume decreased by 62,828 m3. Of the 62,828 m3 volume decrease, approximately 45, 769 m3 was the result of sediment compaction and 17,059 m3 was eroded. In the next nine years (between 2007 and 2016) an additional 17,149 m3 of sediment was eroded.

The porosity of sediment samples was compared to mean grain size to determine if there is a relationship between the two properties. It was determined that within the sand and mud size classes porosity increases as grain size gets finer. In the gravel size class (coarser than -1) porosity is constant at 10-25%. Thus, porosity can be used to estimate grain size in sand and mud sediments but not gravel.

Included in

Geology Commons

Share

COinS