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Research Project: Understanding Water-Driven Ecohydrologic and Erosion Processes in the Semiarid Southwest to Improve Watershed Management

Location: Southwest Watershed Research Center

Title: Rainfall simulation experiments in the Southwestern USA using the Walnut Gulch rainfall simulator

item Polyakov, Viktor
item STONE, J.J. - Retired ARS Employee
item Holifield Collins, Chandra
item Nearing, Mark
item PAIGE, G. - University Of Wyoming
item BUONO, J. - Consultant
item GOMEZ-POND, R.L. - University Of Nebraska

Submitted to: Earth System Science Data
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2017
Publication Date: 1/9/2018
Citation: Polyakov, V.O., Stone, J., Holifield Collins, C.D., Nearing, M.A., Paige, G., Buono, J., Gomez-Pond, R. 2018. Rainfall simulation experiments in the Southwestern USA using the Walnut Gulch rainfall simulator. Earth System Science Data. 10:19-26.

Interpretive Summary: This paper presents the results of rainfall simulation experiments on small plots in semi-arid rangelands of southwestern USA. The simulations were conducted under a wide range of rainfall intensities (60 mm h-1 to 180 mm h-1) on plots with a variety of slopes (4% to 40%), ground cover (22% to 99%), and foliar cover (0-85%). Many of the locations have been affected by grazing, wildfire, or brush treatment and were in various stages of recovery or ecological transition during the experiments. Repeat multi-year simulations and detailed vegetation and land management records place the results in a broader ecological context, rare for this type of studies. Runoff and erosion rates on plots were affected by high heterogeneity and complex spatial structure of rangeland sites. Gravelly soils often develop a surface rock layer with increased roughness resulting in complex hydrological interactions. Hence, variability between replicated plots was greater than typically observed on cultivated fields. The scope of this data set combined with state of the art rainfall simulation equipment makes it particularly valuable to advance our understanding of basic erosion and transport processes specific to arid rangelands. Photographs of the plots provide basis for cover structure and connectivity analysis. The data can be used to evaluate and compare management practices, and study ecological states, transitions and thresholds. It can also support erosion model development and validation.

Technical Abstract: The dataset contains hydrological, erosion, vegetation, ground cover, and other supplementary information from 272 rainfall simulation experiments conducted on 23 semi-arid rangeland locations in Arizona and Nevada between 2002 and 2013. On 30% of the plots simulations were conducted up to five times during the decade of study. The rainfall was generated using the Walnut Gulch Rainfall Simulator on 2 m by 6 m plots. Simulation sites included brush and grassland areas with various degree of disturbance by grazing, wildfire, or brush removal. This dataset advances our understanding of basic hydrological and biological processes that drive soil erosion on arid rangelands. It can be used to quantify runoff, infiltration, and erosion rates on a variety of ecological sites in the Southwestern USA. Inclusion of wildfire and brush treatment locations combined with long term observations makes it important for studying vegetation recovery, ecological transitions, and effect of management. It is also a valuable resource for erosion model parameterization and validation.