1a. Objectives (from AD-416)
To quantify interactive effects of variable climate, dynamic land use, and land management, particularly conservation practices, on surface and subsurface water quality at the watershed scale. Specific objectives are: 1) Develop and implement a multi-site data system to organize, document, manipulate, and compile water, soil, management, and socio-economic data for assessment of conservation practices from ARS Benchmark watersheds; 2) Quantify water quality, water quantity, and soil quality effects of conservation practices across field to watershed scales within the Upper Washita River Watershed; and 3) Quantify accuracy and uncertainty in model output across field to watershed scales and incorporate this information into assessment tools. The anticipated result of the research are new methods to quantify environmental effects of conservation practices implemented on the landscape and tools to support future strategic placement of conservation practices on the landscape.
1b. Approach (from AD-416)
Multi-temporal land use data sets (both current and retrospective) will be developed for incorporation into watershed-scale hydrologic models to determine the effects of changing land use and management on model predictions. Geomorphic assessments and sediment source tracking will be conducted to determine potential sources and contributions of sediments from overland processes and stream banks. The historical and existing hydrologic, geomorphic, geologic, soil, climate, and land use and management conditions that govern the movement of water, sediment, and nutrients through selected sub-basins within the Upper Washita River watershed will be quantified. Hydrologic modeling studies will be conducted at multiple scales to monitor water quantity and quality responses to conservation practice implementation. The soil management assessment framework (SMAF), developed for mid-western soils and cropping conditions, will be used to evaluate the effects of management practices on soil parameters, and evaluate the hydrologic sensitivity to the soil parameters.
3. Progress Report
Scientists from the Grazinglands Research Laboratory (GRL), in cooperation with scientists from Oklahoma State University, initiated a satellite-based retrospective land use study in the Ft. Cobb Reservoir Experimental Watershed (FCREW) and Little Washita River Experimental Watershed (LWREW). Two years of Landsat data have been analyzed and the analysis methodology evaluated. Soil cores were collected at 40 sites in the FCREW from fields representing differences in soil types, land use, and land management. The soil cores have been sectioned and analyzed for nitrates and water soluble phosphorus. Data from the soil cores will be used in modeling studies investigating the impact of land management on movement of agrochemicals through the soil column. A fifth year of six low-flow and six high-flow runoff events were sampled and are being analyzed for selected water quality variables. The data will be used to develop equations relating water quality to streamflow. Water samples were collected on a bi-weekly basis from 15 locations in the FCREW, which are used to help identify potential problem areas within the FCREW and to investigate seasonal variations in selected water quality variables. A portion of the data set was analyzed and presented at scientific meetings. A critical vacancy occurred and certain ground water related research activities had to be suspended temporarily. New collaborations are being developed with ARS colleagues at Bushland, Texas, to address some of these research activities. Acoustic profiling equipment was purchased and training of personnel completed. The acoustics profiling equipment will be used to quantify the amount of sediments accumulated in selected reservoirs and flood-retarding structures in our research watersheds, and related back to land management and conservation practices implemented above the structures. Scientists at the GRL have initiated a remote sensing-based study to produce landscape-scale biomass estimates of Eastern redcedar. Redcedar is an invasive woody species that has been identified as a possible biofuel scource.
5. Significant Activities that Support Special Target Populations
A field tour for the Farming with Grass Conference participants and other stakeholders highlighted key technologies developed at the Grazinglands Research Laboratory that enhances efficiency, reduce environmental and economic risks, and promote sustainability of mixed crop-forage-livestock agricultural systems. About 200 persons, including numerous producers, specialists, and conservationists from over 30 states, and representing small to medium-sized operations, participated in the tour.
Anderson, M.C., Norman, J.M., Kustas, W.P., Houborg, R., Starks, P.J., Agam, N. 2008. A thermal-based remote sensing technique for routine mapping of land-surface carbon, water and energy fluxes from field to regional scales. Remote Sensing Environment. 112:4227-4241.