Effectiveness of a Coral-Derived Surfacing Material for Reducing Sediment Production on Unpaved Roads, Schoffield Barracks, Oahu, Hawaii |
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Authors: | Alan D Ziegler Ross A Sutherland |
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Institution: | (1) Geography Department, University of Hawaii, 2424 Maile Way, 445 Saunders Hall, Honolulu, Hawaii 96822, USA |
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Abstract: | This study evaluated the effectiveness of two application rates of a coral-derived surfacing material for both traffic and
nontraffic road conditions using simulated rainfall (110–120 mm h−1 for 30–90 min) on 0.75-m (wide) × 5.0-m (long) plots of similar slope (roughly 0.1 m m−1). The coral is a locally available material that has been applied to unpaved roads surfaces on Schoffield Barracks, Oahu,
Hawaii (USA), where this experiment was conducted. The simulations show that compared with a bare control plot, the coral-based
surface application rates of 80 and 160 kg m−2 (equivalent to only 10- and 20-mm thicknesses) reduced road sediment production by 75% and 95%, respectively, for nontraffic
conditions. However, after two passes of the research vehicle during wet conditions, sediment production rates for the two
coral treatments were not significantly different from those on the bare road plots. The overall effectiveness of the coral-derived
surfacing material is unsatisfactory, primarily because the on-road surface thickness associated with the application rates
tested was too small. These rates were selected to bracket those applied to training roads in the study area. Furthermore,
the composition of the coral-based material does not facilitate the development of a sealed, erosion-resistant surface. When
applied at the low rates tested, the coral material breaks down under normal traffic conditions, thereby losing its ability
to counter shearing forces exerted by overland flow on long hillslopes where erosion measures are most needed. These simulations,
combined with observations on roads in the study area, indicate that this material is not an appropriate road surfacing material
for the site—at least for the low application rates examined. These results are preliminary; extended testing of higher applications
rates at the hillslope scale under natural climate and traffic conditions is needed to better judge the effectiveness of this
material over time. |
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Keywords: | Runoff Erosion control Ruts Aggregate sizes Rainfall simulation Trafficking Military training lands |
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