Location: Watershed Management Research2012 Annual Report
1a. Objectives (from AD-416):
1) Evaluate the impact of landscape change on fluxes of energy, water and CO2 for Great Basin rangeland ecosystems. 2) Quantify soil-water plant growth relationships and complex terrain effects on soil temperature and moisture using the Reynolds Creek Experimental Watershed as a model system. 3) Expand integrated snow hydrology modeling to larger scales, coupling to belowground processes, including wind effects on precipitation input, and helping to incorporate snow-related processes into ARS watershed and management simulation models (e.g., SWAT, AnnAgNPS, KINEROS, AgES, AGWA, RHEM, ISNOBAL, PIHM, etc).
1b. Approach (from AD-416):
This project is motivated by the following two interconnected aspects of water resources in the western U.S.: 1) water resources and covarying biological resources are concentrated in snow dominated mountainous terrain in which critical processes vary dramatically over short distances; and 2) climate change is affecting hydrologic processes, particularly snow accumulation and melt, in ways that may drastically alter water supply and land management. There are three objectives, two of which focus on field measurement and modeling of critical processes using the Reynolds Creek Experimental Watershed facilities and infrastructure. Those two objectives provide fundamental verification and evaluation data for the third, modeling objective. In the first objective, we combine innovative application of eddy covariance in mountainous terrain with intensive measurement and modeling to evaluate the impacts of ongoing landscape (vegetation) change on the net ecosystem flux of water and CO2. In the second objective, we measure soil water and temperature, along with important climatic parameters, and simulate the water balance and plant production across the rain/snow transition elevation. The third objective focuses on integrated hydrologic modeling to assess the impact of climate warming and landscape change on the seasonal snow cover, soil moisture, groundwater recharge, evaporation and streamflow in mountainous terrain. Model development includes upscaling process models from research to management scales and extending the modeled features to improve management models. The second and third objectives include multi-location research projects in which hydrologic trends at Reynolds Creek are analyzed and compared in a broader, nationwide context.
3. Progress Report:
This report documents progress for the parent Project 5362-13610-010-00D Understanding Snow and Hydrologic Processes in Mountainous Terrain with a Changing Climate which started Feb 2012 and continues research from Project 5362-13610-008-00D Snow and Hydrologic Processes in the Intermountain West. A lot of the progress is in terms of getting projects underway. Post-fire meteorological conditions have been simulated using pre-fire vegetation. Preliminary analysis indicates that post-fire streamflow was not significantly different from pre-fire conditions for the observed snow conditions. The snow drift, however, was noticeably larger post-fire, perhaps due to unusually high wind speeds during the years immediately following the fire, but unrelated to the fire. An appropriate site has been selected for installation of eddy covariance instrumentation over a juniper canopy. ARS researchers in Boise, Idaho, have initiated long-term (30 year) plant productivity simulations using soil water data to evaluate model performance. The instrumentation suite for the study of slope and aspect effects on soil water and temperature has been installed and the Northwest Watershed Research Center (NWRC) is currently monitoring conditions at Johnston Draw. In related research, NWRC has repaired the fiber optic cable for distributed temperature measurements. The system is now functional and NWRC is collecting soil temperature data in complex terrain. Finally, the snow research is progressing with additional programming and the development of a new approach for spatially distributing input forcing data for snow hydrology models. NWRC's cross site comparison projects have just started.
1. Water use successfully simulated for mountainous vegetation communities. Understanding the role of ecosystems in modulating energy, water and carbon fluxes is critical to quantifying the variability in energy, carbon, and water balances across landscapes. ARS researchers in Boise, Idaho, measured and evaluated surface energy fluxes at two rangeland sites, and the data were used to improve simulations of a plant canopy energy balance model, the Simultaneous Heat and Water (SHAW) model. Good agreement was obtained between measured and modeled energy fluxes. Scientists can capitalize upon these results to better describe and model the hydrology of these ecosystems and their response to climate change.