Upstream Channel Changes Following Dam Construction and Removal Using a GIS/Remote Sensing Approach

• Published in: Journal of the American Water Resources Association Vol. 43; no. 3; pp. 683 - 697
• Main Authors: Evans, J.E, Huxley, J.M, Vincent, R.K
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2007; American Water Resources Association
• Subjects: aerial photography; Applied geophysics; dam removals; dams (hydrology); Earth sciences; Earth, ocean, space; effects of dams; Exact sciences and technology; fluvial geomorphology; Freshwater; geographic information systems; geomorphology; GIS/remote sensing; Hydrology. Hydrogeology; image analysis; Internal geophysics; remote sensing; rivers; sediment waves; stream channels; temporal variation; time series analysis; Water resources; Ohio; Atlantic Coastal Plain; Outer Banks; United States; USA, Ohio; stream gradient; geomorphology; effects of dams; reservoirs; geographic information systems; North America; dams; construction; dam removals; sediment waves; GIS/remote sensing; rivers; aerial photography; fluvial geomorphology; remote sensing; bars; bedforms; gravel; sand; sinuosity; channels; spillways; water resource management; growth; dispersion
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/j.1752-1688.2007.00055.x

This study used an innovative GIS/remote sensing approach to study historical river channel changes in the Huron River, a wandering gravel-bedded river in northern Ohio. Eight sets of historical aerial photographs (1958-2003) span the construction of a low-head dam (1969), removal of the spillway (1994), and removal of the dam itself (2002). Construction of the dam modified stream gradients >4 km upstream of the small impounded reservoir. This study tracked changes in the polygon size, shape, and centroid position of 12 sand-gravel bars through a study reach 0.2-4.1 km upstream of the dam. These bars were highly responsive, tending to migrate obliquely downstream and toward the outer bank at rates up to 9 m/year. Historical changes in the size and position of the bars can be interpreted as the downstream translation of one or more sediment waves. Prior to dam construction, a sediment wave moved downstream through the study reach. Following construction of the dam, this sediment wave became stationary and degraded in situ by dispersion. The growth of bars throughout the study reach during this time interval resulted in a progressive increase in channel sinuosity. Removal of the spillway rejuvenated downstream translation of a sediment wave through the study reach and was followed by a reduction in channel sinuosity. These results illustrate that important geomorphologic changes can occur upstream of low-head dams. This may be a neglected area of research about the effects of dams and dam removals.