Ninety-nine-year Sediment Yield Record of the Middle Cuyahoga River Watershed Contained Within the Ohio Edison Dam Pool PDF Download

Author: Kristofer C. Mann
Publisher:
ISBN:
Category : Cuyahoga River (Ohio)
Languages : en
Pages : 275

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Book Description
The 17.4 m tall Ohio Edison Dam was constructed in 1912 on the Cuyahoga River near the city of Akron, Ohio. The dam was installed for hydroelectric power and to provide cooling water storage for a coal-fired power plant. During the past century, over 6 m of sediment accumulated in the low-velocity dam pool. A dam pool sediment volume of 765,000 m3 was calculated from geographical information system (GIS) analysis of bathymetric maps from 1918 and 2010, and the thickness of sediment determined by coring. Twelve sediment cores were collected to study the nature and spatial variability of the dam pool sediment deposit. Sediment density, grain size, organic content and magnetic mineral content trace metal concentrations reveal changes in sedimentation within the dam pool. Fly-ash, derived from the burning of fossil fuels, is present in large quantity downstream from the former Ohio Edison coal-fired power plant, whereas it is present in low quantities upstream. Core 4 was 210Pb-dated in order to interpret the sediment deposit in terms of past anthropogenic activities. In addition, combining the sediment age model with sediment density and GIS sediment volume analysis allowed changes in mass accumulation rate and sediment yield to be determined. The dam pool sediment deposit was subdivided into three time intervals. The first time period (1912-1928) was termed the Early Years and is characterized by brown mud having low amounts of fly-ash, elevated trace metal concentrations and a high sediment yield. The second time period (1928-1977) was termed the Burning River and is characterized by dark gray mud having abundant fly-ash layers, high but variable metals, and high magnetic concentration. The third time period (1977-2011) was termed the Later Years and is characterized by dark brown mud with low amounts of fly-ash, declining trace metals, low magnetic concentration, and an increasing sediment yield. Since 1977, the sediment quality has improved in response to the Clean Air Act (1970) and the Clean Water Act (1972). The sediment yield has generally increased since 1928. Between 2004 and 2008 there is a pronounced increase in sediment yield attributed to increased upstream erosion following the removal of the Munroe Falls Dam in 2005 and increased extreme flow events since 2003. The Ohio Edison Dam is being considered for removal as a means of river restoration in the Middle Cuyahoga River. Based on the range of sediment mass accumulation within the Ohio Edison Dam pool since 2001, it is projected that the downstream sediment load will increase by about 4,100-8,400 tonnes/yr of sediment or an average of 6,300 tonnes/yr once the Ohio Edison Dam is removed. The increased sediment flux from the Middle Cuyahoga River will increase the need for dredging at the Port of Cleveland and change sedimentary conditions in the Lower Cuyahoga River.