Anomalous trend in soil evaporation in a semi-arid,snow-dominated watershed |
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| Institution: | 1. Nicholas School of Environment, Duke University, Durham, NC 27708, USA;2. USDA Agricultural Research Service, Northwest Watershed Research Center, Boise, ID 83712, USA;1. School of Geosciences, China University of Petroleum, Qingdao, Shandong Province, 266580, China;2. School of Earth & Environment, University of Leeds, Leeds, West Yorkshire, LS2 9JT, England, UK;1. State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, China;2. USDA-Agricultural Research Service, 215 Johnson Hall, Washington State University, Pullman, WA 99164, United States;1. Division of Earth and Ocean Sciences, Nicholas School of the Environment; Center for Nonlinear and Complex Systems, Duke University, Box 90230, Durham, NC 27708, USA;2. Department of Earth and Environmental Sciences, Tulane University, 101 Blessey Hall, New Orleans, LA 70118, USA;3. Department of Geological Sciences, University of North Carolina at Chapel Hill, 104 South Rd, Mitchell Hall, Chapel Hill, NC 27515, USA;4. UNESCO-IHE, PO Box 3015, 2601 DA Delft, Netherlands;5. Deltares, PO Box 177, 2600 MH, Delft, Netherlands;1. Department of Mathematics, The University of Iowa, Iowa City, IA 52242, USA;2. IIHR – Hydroscience & Engineering, The University of Iowa, Iowa City, IA 52242, USA |
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| Abstract: | Soil evaporation in arid and semi-arid regions is generally moisture-limited. Evaporation in these regions is expected to increase monotonically with increase in precipitation. In contrast, model simulations in a snow-dominated, semi-arid Reynolds Mountain East (RME) watershed point to the existence of an anomalous trend in soil evaporation. Results indicate that soil evaporation in snow-dominated watersheds first increases and then subsequently decreases with increasing precipitation. The anomalous variation is because of two competing evaporation controls: (a) higher soil moisture in wetter years which leads to larger evaporation, and (b) prolonged snow cover period in wetter years which shields the soil from the atmosphere, thus reducing soil evaporation. To further evaluate how the competition is mediated by meteorological and hydrogeological characteristics of the watershed, changes in the trend due to different watershed hydraulic conductivity, vegetation cover, and snowfall area fraction are systematically studied. Results show considerable persistence in the anomalous trend over a wide range of controls. The controlling factors, however, have significant influence both on the magnitude of the WY evaporation and the location of the inflection point in the trend curve. |
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