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ARS Home » Pacific West Area » Reno, Nevada » Great Basin Rangelands Research » Research » Publications at this Location » Publication #342297
Title: Process-Based Modeling of Upland Erosion and Salt Load in the Upper Colorado River Basin

Author
item NOUWAKPO, SAYJRO - University Of Nevada
item Weltz, Mark
item GREEN, COLLEEN - Bureau Of Land Management
item MCGWIRE, KENNETH - Desert Research Institute

Submitted to: World Conference Soil and Water Conservation Under Global Change (CONSOWA)
Publication Type: Proceedings
Publication Acceptance Date: 5/25/2017
Publication Date: 6/12/2017
Citation: Nouwakpo, S.K., Weltz, M.A., Green, C., Mcgwire, K.E. 2017. Process-Based Modeling of Upland Erosion and Salt Load in the Upper Colorado River Basin. World Conference Soil and Water Conservation Under Global Change (CONSOWA). 147.

Interpretive Summary: Hillslope runoff and soil erosion processes are indicators of sustainability in rangeland ecosystem due to their control on resource mobility. Hillslope processes are dominant contributors to sediment delivery on semi-arid rangeland watersheds. The influence of vegetation on hillslope runoff and sediment production forms the basis of current rangeland hydrology and erosion modeling with the Rangeland Hydrology and Erosion Model. Soil erodibility parameters are functions of many intrinsic (e.g. soil texture, clay mineralogy, etc.) and extrinsic (e.g., management, soil amendments, subsurface hydrology, etc.) factors. In particular, soil salinity and sodicity have been shown to significantly affect soil structural stability with implication in susceptibility to erosion and water quality. While the fundamental understanding of relationship between salinity / sodicity and aggregate stability has been well established in laboratory settings, this information has seldom been incorporated into hydrologic and erosion models. The RHEM has for example has been developed from an extensive experimental data collected on four dominant rangeland community types (i.e. shrub-dominated, sod grass, annual grasses and forbs and bunch grasses). The RHEM model has been successfully calibrated to address soil erosion and salt load on saline rangelands of the Upper Colorado River Basin. Performance on runoff, sediment and salt transport was appreciably improved with the use of the parameter estimation equations developed from saline soils. Additional improvements could be achieved by incorporating additional soil chemical property information and augmenting RHEM concentrated flow prediction with microtopographically-observed erosion/deposition patterns.

Technical Abstract: Hillslope runoff and soil erosion processes are indicators of sustainability in rangeland ecosystem due to their control on resource mobility. Hillslope processes are dominant contributors to sediment delivery on semi-arid rangeland watersheds. The influence of vegetation on hillslope runoff and sediment production forms the basis of current rangeland hydrology and erosion modeling with the Rangeland Hydrology and Erosion Model (RHEM). Soil erodibility parameters are functions of many intrinsic (e.g. soil texture, clay mineralogy, etc.) and extrinsic (e.g., management, soil amendments, subsurface hydrology, etc.) factors. In particular, soil salinity and sodicity have been shown to significantly affect soil structural stability with implication in susceptibility to erosion and water quality. While the fundamental understanding of relationship between salinity / sodicity and aggregate stability has been well established in laboratory settings, this information has seldom been incorporated into hydrologic and erosion models. The RHEM has for example has been developed from an extensive experimental data collected on four dominant rangeland community types (i.e. shrub-dominated, sod grass, annual grasses and forbs and bunch grasses). The RHEM model has been successfully calibrated to address soil erosion and salt load on saline rangelands of the Upper Colorado River Basin. Performance on runoff, sediment and salt transport was appreciably improved with the use of the parameter estimation equations developed from saline soils. Additional improvements could be achieved by incorporating additional soil chemical property information and augmenting RHEM concentrated flow prediction with micro-topographically-observed erosion/deposition patterns.