Author
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NOUWAKPO, SAYJRO - University Of Nevada |
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Weltz, Mark |
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Submitted to: International Rangeland Congress
Publication Type: Proceedings Publication Acceptance Date: 12/1/2015 Publication Date: 7/18/2016 Citation: Nouwakpo, S.K., Weltz, M.A. 2016. Insight into sediment transport processes on saline rangeland hillslopes using three-dimensional soil microtoprgraphy changes. In: Proceedings of the X International Rangeland Congress, July 18-22, 2016, Saskatoon, Saskatchewan, Canada. p. 985-986. Interpretive Summary: Hillslope runoff and soil erosion processes play a vital role on rangeland ecosystem sustainability due to their control on resource mobility but they also have significant implications in off-site resource transport. In general, physically-based soil erosion models such as RHEM divide erosion and sediment transport processes into their primary components. Yet, many primary processes (namely sheet and splash, concentrated flow erosion as well as deposition) are still poorly understood due to a historic lack of measurements. As part of an effort to quantify salt transport from rangelands to Upper Colorado River Basin (UCRB), experimental rainfall simulation studies were conducted in saline rangelands communities in central Utah. The aim of this paper is to gain insight into interaction processes between hillslope topography, vegetation and sediment transport processes. To characterize soil surface response to erosive events, various areal and volumetric surface metrics were calculated from pre and post rain DEMs as well as the difference of DEMs. Erosivity which in this study is represented by runoff discharge drives detachment and transport processes. Factors controlling surface roughness such as vegetation oppose transport of the detached particles and enhance deposition. This is well illustrated in the response of the net erosion volume which shows an increasing effect of runoff and a decreasing effect of vegetation on sediment load. The three dimensional surface change metrics developed in this study were successful at capturing the expression of various erosion and sediment transport processes and how these processes were influenced by hydrologic input and biotic and abiotic land surface characteristics. Deposition volumes were a function of vegetation cover. The key to runoff soil and salt load reduction likely lies in promoting deposition by creating zones of increased roughness along concentrated flow pathways by enhancing vegetation within the flow paths. Technical Abstract: Hillslope runoff and soil erosion processes play a vital role on rangeland ecosystem sustainability due to their control on resource mobility but they also have significant implications in off-site resource transport. In general, physically-based soil erosion models such as RHEM divide erosion and sediment transport processes into their primary components. Yet, many primary processes (namely sheet and splash, concentrated flow erosion as well as deposition) are still poorly understood due to a historic lack of measurement techniques capable of parsing total soil loss into these primary processes. As part of an effort to quantify salt transport from rangelands to Upper Colorado River Basin (UCRB), experimental rainfall simulation studies were conducted in saline rangelands communities of this basin. The aim of this paper is to gain insight into interaction processes between hillslope topography, vegetation and sediment transport processes. To characterize soil surface response to erosive events, various areal and volumetric surface metrics were calculated from pre and post rain DEMs as well as the difference of DEMs. Erosivity which in this study is represented by runoff discharge drives detachment and transport processes while factors controlling surface roughness such as vegetation oppose transport of the detached particles. This is well illustrated in the response of the net erosion volume which shows an increasing effect of runoff and a decreasing effect of vegetation. The three dimensional surface change metrics developed in this study were successful at capturing the expression of various erosion and sediment transport processes and how these processes were influenced by hydrologic input and biotic and abiotic land surface characteristics. Deposition volumes were a function of vegetation cover. The key to runoff soil and salt load reduction likely lies in promoting deposition by creating zones of increased roughness along concentrated flow pathways |
