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2015 USGS 104b Program Grants

Project Number: 2015TN110B
Title: Measuring evapotranspiration and soil moisture to close the hydrologic budget under different land-uses in Tennessee
Team: Thanos N. Papanicolaou and Christopher Wilson, UT Civil and Environmental Engineering

Evapotranspiration (ET) is a major component of the land surface water cycle, as it directly affects the amount of water available for runoff and recharge, and hence human consumption. Despite the relative importance of ET to the hydrologic cycle, especially in the US Southeast, which has some of the highest mean annual ET in the country, it is one of the least systematically measured parameters. In this study, we are working to help address two critical gaps in our current ET monitoring and modeling capabilities: (1) the lack of understanding about the effect of soil moisture on ET in regions exhibiting high landscape heterogeneity; and (2) a limited ability to transfer this information from relatively small scales to larger scales of societal importance. Past research has used meteorological properties (such as solar radiation, air temperature, relative humidity, and wind speed/ direction) and reference crop corrections to determine potential ET, but neglected the role of soil moisture at the soil boundary surface (i.e., top 30 cm) on actual ET. We are focusing this study in Eastern Tennessee, which is experiencing gradual urbanization at the interface of existing agricultural areas leading to highly variable land covers and soil conditions. A mobile array of state-of-the-art sensors is being developed that is capable of measuring not only the rate of ET under multiple land-uses throughout the region, but also the resulting change in soil moisture. The mobile array of state-of-the-art sensors will measure ET, Leaf Area Index (LAI), and soil moisture changes. It will provide essential but missing data for a GIS Data Management System for water resources research in Tennessee, as well as ground-truthing data for satellite-based estimates of ET and soil moisture to develop regional scale water budgets for long-term water resources planning, management, and risk analysis. To date the different monitoring sensors have been ordered. Upon receipt, they will be assembled and calibrated in-house under controlled conditions. We will conduct select field measurements using a systematic protocol and the mobile array at different land uses in the area. Our monitoring protocol has been developed to capture the heterogeneity of moisture patterns and ET emissivity and is complemented with measurements of soil properties and infiltration. For each monitoring location, our ultimate goal is to quantify water budgets. In addition, we will compare the measured ET, LAI, and soil moisture data to satellite-based, remote sensing data (from MODIS) for ground-truthing. We have begun collecting some of the remote sensing data. The results from this comparison will be an initial step for scaling ET across Eastern Tennessee. Currently no students have been funded; we are waiting for the sensors to arrive. This work was essential in developing a larger 104G proposal related to water budgets as well as providing verification data for larger modeling efforts with the USDA.

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Project Number: 2015TN111B
Title: Evaluating Environmental and Biological Impacts of Acid Runoff from Pyrite-Bearing Rock Formations
Team: William Sutton and De’Etra J. Young, Tennessee State University, Agricultural and Environmental Sciences

Acid rock drainage (ARD) from iron-sulfide bearing geologic formations in road cuts and road construction can have negative impacts on receiving streams due to low pH, occurrence and transport of metals from the site, and the potential impact of these hazards on biota. The iron-sulfide minerals that cause acid-mine drainage (pyrite, marcasite, pyrrhotite) are commonly found in southeastern United States shale formations. Consequently, ARD typically releases coinciding metals, as well as acidity to aquatic ecosystems. During the warm, dry season, the ARD escarpments continue to seep acidic waters, rich in minerals that reflect the geochemistry of the rock. The reduction in rain and increase in air temperature leads to evaporation and concentration of acidic seepage waters, resulting in the temporary storage of highly soluble efflorescent sulfate salts. Our study proposes to evaluate the potential environmental and biological consequences of ARD at each of two total sites in the Chattanooga and Fentress shale formations in Middle Tennessee. Overall, the primary objectives of the investigation are to identify chemical and hydrologic conditions that affect the release of acid and minerals from ARD sites into headwater streams and evaluate biological impacts of ARD on stream-dwelling fauna, primarily streamside salamanders. Collectively, our study will couple the geochemistry of first-flush aquatic inputs and the downstream impacts of ARD inputs on stream biological integrity. The results of this study will provide information on the impacts of ARD and potential remediation strategies that can be used by local, state, and federal agencies to diminish negative environmental impacts. In addition, as amphibian populations are in decline globally, our study will fill in distributional gaps in our knowledge of Middle Tennessee amphibian populations and aid in the identification of vulnerable and declining populations of stream-dwelling salamanders.

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Project Number: 2015TN112B
Title: Characterizing Stream Sediment Source Potentials in Small Urbanizing Watershed
PI: John Schwartz, UT Civil and Environmental Engineering

Streams in urbanizing watersheds are impacted by hydromodification due to increased impervious surfaces and development activates. Urbanization causes widespread changes to stream hydrology and channel processes. Historically, attempts to mitigate these impacts have been through stormwater control measures (SCMs) designed to attenuate peak flows and match some pre-existing conditions. However, many MS4 communities still face channel erosion problems leading to excessive instream sediment and biological impairment. Understanding how alteration to watershed hydrology, resulting from increased urban land-uses, impacts channel processes is necessary to either preserve or restore ecologic integrity and reduce sediment yield. However, the linkages between urbanization, stormwater management/policy, and stream channel response are still poorly understood over the range of watershed settings. The goal of this research is to improve our understanding of the relationships between urbanization, fluvial geomorphology, and stormwater management/policy in order to improve the efficacy of invested mitigation funds.

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