Location: Great Basin Rangelands ResearchTitle: Vegetation canopy cover effects on sediment erosion processes in the upper Colorado River Basin mancos shale formation, Price, Utah
|CADARET, ERIK - DESERT RESEARCH INSTITUTE|
|MCGWIRE, KENNETH - DESERT RESEARCH INSTITUTE|
|NOUWAKPO, SAYJRO - UNIVERSITY OF NEVADA|
|SAITO, LAUREL - UNIVERSITY OF NEVADA|
Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2016
Publication Date: 8/24/2016
Citation: Cadaret, E.M., Mcgwire, K.C., Nouwakpo, S.K., Weltz, M.A., Saito, L. 2016. Vegetation canopy cover effects on sediment erosion processes in the upper Colorado River Basin mancos shale formation, Price, Utah. Catena. 147:334-344.
Interpretive Summary: This study investigated erosion processes on the highly erosive, rangeland saline soils of the Mancos Shale formation in the Price-San Rafael River Basin in east central Utah. Rainfall simulations were performed at two sites using a Walnut Gulch rainfall simulator over a variety of slope angles and rainfall intensities. The Rangeland Hydrology and Erosion Model (RHEM) were calibrated to provide unbiased estimates of discharge and sediment load in runoff at each site. RHEM simulated the inter-plot variability best at the site with higher slope angles, vegetation cover, and sediment loads. The calibrated surface erosion parameters in RHEM (Kss and K') were substantially greater than any published in prior studies from non-saline environments. The spatial distribution of vegetation canopy cover was quantified using photogrammetric modeling and landscape pattern metrics. As the patches of vegetation became more contiguous and the tortuosity of the bare soil area increased, RHEM over-predicted sediment output. This suggests that vegetation- driven spatial heterogeneity influenced erosion in a way that is not captured by RHEM. RHEM uses a fixed rill density that does not change during a runoff event. Further research that can correctly capture the dynamic nature of rill formation and distribution during a rainfall event as a function of spatial distribution of vegetation should improve estimates of sediment yield in these sparsely vegetated areas.
Technical Abstract: This study provides new parameterizations for applying the Rangeland Hydrology and Erosion Model (RHEM) on the highly erosive, rangeland saline soils of the Mancos Shale formation in the Price-San Rafael River Basin in east central Utah. Calibrated hydrologic parameters (Kss and K') values are generally greater than values reported in previous studies from less saline environments. RHEM did a better job of expressing the plot level variability of runoff and sediment yield at the site with steeper slopes and a greater amount of vegetation. Our results show that RHEM simulates discharge (Price R2 = 0.92 and Ferron X R2 = 0.8) and sediment yield (Price R2 = 0.51; Ferron X R2 = 0.64) well on saline and sodic soils of the Mancos Shale formation despite. Landscape pattern descriptions showed that when vegetation patches have an increase in contiguous relationships (i.e., dense clusters of vegetation) and the tortuosity of soil interspaces reaches high levels, observed sediment loading decreases relative to modeled expectations. These results reinforce prior literature indicating that the spatial distribution of vegetation cover has an impact on sediment erosion processes.