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Title: Remote determination of bridging/fording sites
Authors: Coutermarsh, Barry A.
Dwinal, Benjamin.
Keywords: Military bridges
Fords (Stream crossings)
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: ERDC/CRREL ; TR-03-8.
Abstract: Ice that forms in soil voids during the freezing process pushes soil grains apart, reducing particle cohesion and soil strength, and making soil more erodible. This report summarizes 18 experiments to measure erosion rates in a soil that was frozen and thawed once and in the same unfrozen soil. We hypothesized that soil freeze–thaw (FT) processes significantly increase upland hill slope erosion during subsequent runoff events. We selected a frost-susceptible silt to provide an upper bound on this effect. For each experiment, we prepared two identical bins, one as an unfrozen control, the other to be frozen and thawed. We tested three soil-moisture ranges, three flow rates, and two slopes, and measured the cross-sectional geometry of the rills that developed and sediment losses through time for each bin. The cross-section measurements detailed erosion at specific locations along the bins; sediment loss measurements indicated erosion integrated along the entire bin. The results are the first to quantitatively define the differences in sediment loss and rill formation caused by FT cycling. We will analyze data from these experiments and do additional experiments to further define FT effects in the soil-erosion process. (However, these results already demonstrate the importance of FT weakening to soil erosion.) Good regional sediment management in cold climates requires that erosion prediction models accurately account for important processes such as soil-FT cycling to avoid significant underprediction of soil losses on hill slopes and in watersheds in cold climates.
Appears in Collections:Technical Report

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