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Singer, M.J., Dept. of Land Air/Water Resources, University of California, One Shields Avenue, Davis, CA 95616, United States
Shainberg, I., Inst Soil Water/Envi Sci Volcani Ctr, PO Box 6, Bet Dagan, Israel
The first few millimetres of soil largely control the soil's response to the eroding forces of wind and water. The tendency of soils to form surface seals and crusts influences the processes of wind and water erosion differently. For wind, dry particle size distribution and particle organization determine the shear strength and threshold wind velocity necessary to initiate particle movement. In loams and clay loams, seals and crusts decrease roughness but increase surface soil strength, generally decreasing wind erosion. Conversely, in sand and sandy loams, loose erodible sandy material may either deposit on the crust and is subject to erosion or it may disrupt the crust, accelerating the erosion process. For water erosion, particle size distribution and structure determine infiltration rate, time to ponding, and energy required for soil particle detachment. Seals and crusts tend to decrease infiltration rate and time to ponding thus increasing overland flow and soil erosion. This paper briefly reviews how permanent and time-dependent soil properties influence surface seals and crusts and how these affect soil erosion by wind and water. The tendency of a soil to form a seal and crust depends to some degree on the time-dependent property of soil structural stability, which tends to increase with increasing clay content and smectitic mineralogy which are permanent properties. These permanent properties and their effect on structure are variable depending on dynamic properties of exchangeable sodium percentage and soil solution electrical conductivity. Antecedent water content prior to irrigation or rainfall, rate of wetting before an erosive event and aging, the time between wetting and an erosive event, greatly influence the response of soil structure to raindrop impact. The effect of these dynamic processes is further influenced by the static and dynamic properties of the soil. Weak structure will be less influenced by wetting rate than will a soil with strong structure. Process-based models of wind and water erosion need to consider the details of the interactions between soil static and dynamic properties and the dynamic processes that occur prior to erosive events. © 2004 John Wiley and Sons, Ltd.
פותח על ידי קלירמאש פתרונות בע"מ -
הספר "אוצר וולקני"
אודות
תנאי שימוש
Mineral soil surface crusts and wind and water erosion
29
Singer, M.J., Dept. of Land Air/Water Resources, University of California, One Shields Avenue, Davis, CA 95616, United States
Shainberg, I., Inst Soil Water/Envi Sci Volcani Ctr, PO Box 6, Bet Dagan, Israel
Mineral soil surface crusts and wind and water erosion
The first few millimetres of soil largely control the soil's response to the eroding forces of wind and water. The tendency of soils to form surface seals and crusts influences the processes of wind and water erosion differently. For wind, dry particle size distribution and particle organization determine the shear strength and threshold wind velocity necessary to initiate particle movement. In loams and clay loams, seals and crusts decrease roughness but increase surface soil strength, generally decreasing wind erosion. Conversely, in sand and sandy loams, loose erodible sandy material may either deposit on the crust and is subject to erosion or it may disrupt the crust, accelerating the erosion process. For water erosion, particle size distribution and structure determine infiltration rate, time to ponding, and energy required for soil particle detachment. Seals and crusts tend to decrease infiltration rate and time to ponding thus increasing overland flow and soil erosion. This paper briefly reviews how permanent and time-dependent soil properties influence surface seals and crusts and how these affect soil erosion by wind and water. The tendency of a soil to form a seal and crust depends to some degree on the time-dependent property of soil structural stability, which tends to increase with increasing clay content and smectitic mineralogy which are permanent properties. These permanent properties and their effect on structure are variable depending on dynamic properties of exchangeable sodium percentage and soil solution electrical conductivity. Antecedent water content prior to irrigation or rainfall, rate of wetting before an erosive event and aging, the time between wetting and an erosive event, greatly influence the response of soil structure to raindrop impact. The effect of these dynamic processes is further influenced by the static and dynamic properties of the soil. Weak structure will be less influenced by wetting rate than will a soil with strong structure. Process-based models of wind and water erosion need to consider the details of the interactions between soil static and dynamic properties and the dynamic processes that occur prior to erosive events. © 2004 John Wiley and Sons, Ltd.
Scientific Publication
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