2011 Annual Report
1a.Objectives (from AD-416)
This research will improve our knowledge-base regarding contributions that different vegetation plant communities play in producing surface runoff and soil erosion rates in rangeland watersheds. We hypotheses that alternative stable vegetative states (i.e., cheatgrass dominated sites) will have different hydrologic responses (i.e., infiltration rates, peak discharge rates, and sediment loads) than historical Wyoming sagebrush plant communities. We further hypotheses that sites that have been revegetated will be intermediate in hydrologic response to the historical and disturbed site conditions.
1b.Approach (from AD-416)
The majority of the state of Nevada is rural and limited hydrologic studies have been carried out to investigate surface water hydrology in remote upland regions of the state. For rainfall, there is a limited network of meteorological stations for which data are available through the National Weather Service. Thus the measurement of surface water contributions in small rangeland catchments with intermittent surface runoff is very limited. We propose to investigate the feasibility of instrumenting existing wildlife guzzlers in Nevada to provide data on precipitation and surface runoff in remote catchments. By using a simple water balance approach with appropriate monitoring equipment for precipitation and water levels in the guzzler storage tanks, the amount of surface runoff generated by a particular natural storm can be determined. The second phase will be to estimate the hydrologic response of the different vegetative states within these catchments with a rainfall simulator (2 m wide x 6 m long) at rates 5, 10, 12.5, 15, 17.5 cm per hour. This will provide the baseline data for the watershed analysis of hydrologic response of specific vegetative states at the hillslope scale. Data from these experiments will be used to validate and improve the Rangeland Hydrology Erosion Model and the Soil Water Assessment Tool and will provide benchmark information for the USDA Conservation Effects Assessment Project.
This project was established in support of Objective 2 of the in-house project: Devise management guidelines, technologies, and practices for conserving and restoring Great Basin rangelands. The research indicates that hand felling Pinyon and Juniper trees can be highly successful in reducing the size of concentrated flow paths, velocity and sediment load. Results from this research also indicate that soil detachment is a far more complex process that cannot be described in one function. There are processes such as soil armoring, detachment capacity of water, and litter dams that are created that contribute to the complexity of modeling soil detachment rates. This research is being used by the USDA to develop concentrated flow equations for use in the Rangeland Hydrology and Erosion Model (RHEM), which is being developed in support of the USDA Conservation Effects Assessment Project (CEAP). This research was used by Natural Resources Conservation Service (NRCS) to establish Nevada State guidelines for Environmental Quality Incentive Program funded projects that are focused on reducing the impact of invasive woody trees. This project also developed technology for modifying wildlife water development storage devices (wildlife guzzlers) to cost effectively document time and length that they are operational and how they can be used to measure precipitation in remote western catchments to enhance our ability to estimate water availability in rural western rangelands where no other source of climatic information is available. Results of this research have been presented at the Joint Federal Interagency Conference, June 27-July 1, 2010, Las Vegas, Nevada. A peer review article has been developed and submitted to the Journal of Rangeland Ecology and Management. The project is monitored through bimonthly meetings with University partners to assess status of the project and make corrections to the research approach as required to meet the goals of the project.