Evaluation of Bridge Scour Research: Geomorphic Processes and Predictions (2011) / Chapter Skim
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Pages 35-40
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From page 35... ...
4.1 4. RECOMMENDATIONS AND RESEARCH NEEDS Under this task, the research team developed draft recommendations for possible adoption of specific research results by AASHTO.
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From page 36... ...
4.2 vegetation, land-use and sediment yields. Although uncertainty clouds the issue of climate change, the implications for basin-scale channel instability, with adverse impacts to bridge safety regionally and nationally, are so serious that research is now critical.
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4.3 development onto alluvial fans in recent years, the design of bridge crossings and roadways must consider the inherent long-term instability of such sites. Thus, the purpose of the proposed project is the development of a manual that outlines the general character of an alluvial fan, discusses active alluvial fan processes in detail, and provides guidance on incorporating alluvial fan processes and impacts in the bridge design.
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From page 38... ...
4.4 4.5 Impacts of Vegetation Restoration, Rehabilitation and Stabilization on Channel Stability in Bridge Reaches Research in river mechanics and fluvial geomorphology has recently established that vegetation exerts much stronger influences on channel forms and processes than was previously thought. For example; rates of bank erosion and lateral channel shifting are significantly lower along rivers flowing through mature, riparian corridors than where native vegetation has been removed from the banks, patterns of vegetation on floodplains have been shown to materially alter channel planform patterns and their evolution, and the presence of large woody debris has been found to limit degradation in incised channels.
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From page 39... ...
4.5 clear spanning certain channels, limits on the location and number of piers in channels, constraints on exposed riprap aprons, minimum deck clearance for wildlife passage, and limits on increased velocities and shear stresses for frequent (2- to 10-year recurrence interval) flood conditions.
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From page 40... ...
4.6 Advanced mapping and monitoring technologies have recently been a research area due to an increasing demand of consistent and reliable bridge monitoring and reconnaissance data. In a digital mapping study sponsored by Iowa DOT, morphological features such as river bank positions and floodplain edges were identified on the ortho-rectified riverside images through an image processing algorithm, and a surface velocity analysis was conducted by applying Large Scale Particle Image Velocimetry (LSPIV)
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