Velocities of shallow overland flow on semiarid hillslopes |
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| Authors: | Viktor Polyakov Mark A Nearing Jeffry Stone |
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| Institution: | Southwest Watershed Research Center, USDA‐ARS, Tucson, AZ, USA |
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| Abstract: | A series of 188 rainfall plot simulations was conducted on grass, shrub, oak savanna, and juniper sites in Arizona and Nevada. A total of 897 flow velocity measurements were obtained on 3.6% to 39.6% slopes with values ranging from 0.007 m s‐1 to 0.115 m s‐1. The experimental data showed that shallow flow velocity on rangelands was related to discharge and ground litter cover and was largely independent of slope gradient or soil characteristics. A power model was proposed to express this relationship. These findings support the slope–velocity equilibrium hypothesis. Namely, eroding soil surfaces evolve such that steeper areas develop greater hydraulic roughness. As a result overland flow velocity becomes independent of the slope gradient over time. Our findings have implications for soil erosion modeling suggesting that hydraulic friction is a dynamic, slope and discharge dependent property. Copyright © 2018 John Wiley & Sons, Ltd. |
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| Keywords: | flow velocity soil erosion rainfall simulator rangeland |
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