PROJECT INFORMATION: 1. NERTO or Professional Development Report Title: Low Flow Reservoir Release Predictions for the National Water Model 2. EPP Intern: Elizabeth Del Rosario 3. CSC Affiliation: Center for Coastal and Marine Ecosystems 4. Home Institution and Major: Texas A&M University-Corpus Christi, Coastal Marine System Science 5. CSC Academic Advisor’s Name, Department: Dr. Richard McLaughlin, Harte Research Institute for Gulf of Mexico Studies 6. NOAA Internship Mentor(s) Line Office, Office/Lab/Branch, Location: Dr. Trey Flowers, National Weather Service, Office of Water Prediction, 205 Hackberry Lane, Tuscaloosa, AL 35401 7. Report Category: Weather Ready Nation Abstract:
The National Oceanic and Atmospheric Administration (NOAA) Experiential Research & Training Opportunities (NERTO) provides EPP/MSI Cooperative Science Center-supported students with a valuable NOAA mission-aligned internship. The National Water Center (NWC) in Tuscaloosa Alabama enables NOAA to deliver water information and services to the nation. The National Water Model (NWM) is a hydrologic model that simulates observed and forecast streamflow over the entire continental United States (CONUS) using the network of USGS stream gages. The NWM simulates the water cycle with mathematical representations of the different processes and how they fit together. The NWM complements current hydrologic modeling which is done in a simplified manner for approximately 4000 locations across the CONUS by providing information at a very fine spatial and temporal scale at those locations, as well as for locations that don’t have a traditional river forecast. The purpose of this NERTO project is to develop data-driven correlations to predict reservoir releases under low flow conditions. This will be done by investigating datasets; the identification of watersheds that have a long record of reservoir releases and other data sets (irrigation demand, soil moisture, etc.); and the development of correlations between thresholds in the data sets and reservoir releases. The correlations will then be used as a predictive measure for the triggering of a release. A minimum of two watersheds that exhibit low flow conditions will be identified and analyzed; additional watersheds will be investigated as appropriate. Reservoirs will be selected and primary purposes for withdrawals determined. This project will look at release requirements, the releases that were made, and then correlate the releases to other datasets to determine what prompted the release decision. The correlations determined will then be used to construct a predictive model that can be used to inform the National Water Model. Summary of Research: For my NERTO, I worked with the National Weather Service-Office of Water Prediction (NWS-OWP) at the National Water Center (NWC) in Tuscaloosa, Alabama. At the NWC I worked with scientists from the Analysis Prediction Division to implement improvements in the NWS National Water Model, with emphasis on improving simulation of management impacts during low-flow conditions. I attended bi-weekly meetings for Reservoir Modeling. I met weekly with my NOAA advisor, Trey Flowers, to discuss my research. I gave a presentation of my findings at the end of my NERTO to the reservoir modeling team. The goal of my project was to develop data-driven correlations to predict reservoir releases under low flow conditions. This was to be done by investigating datasets useful for predicting reservoir releases under low flow conditions; the identification of watersheds that have a long record of reservoir releases and other data sets (irrigation demand, soil moisture, etc.); and the development of correlations between thresholds in the data sets and reservoir releases. The correlations were then to be used as a predictive measure for the triggering of a release. Specific objectives included: 1) Data set preparation. It was necessary to find and assemble datasets for: watershed usage, precipitation, drought, reservoir release requirements, reservoir supply, stream flow, evaporation, elevation, temperature, and gage height. 2) Establishment of correlations. Datasets were analyzed for: release requirements within the watersheds, the amount of water that was released, and what datasets correlated to the amount released. 3) Predictive model development (future work). Datasets hypothesized to correlate releases will be used to predict reservoir releases not used to develop the correlations. My research at the NWC consisted of three parts. The first part involved learning about hydrology and finding available datasets (Table 1) that could potentially be incorporated into the National Water Model. The National Water Model (NWM) is a hydrologic model that simulates observed and forecast streamflow over the entire continental United States (CONUS) using the network of USGS stream gages. The purpose of this was to locate potential datasets to enhance the prediction capabilities of the NWM under low flow conditions. This was done by the investigation of datasets for Lake Livingston Reservoir on the Trinity River in Texas, the Keswick Reservoir and the Shasta Dam on the Sacramento River in California, and the Big Thompson Project on the Colorado River in the Great Plains region. These watersheds were determined by the Reservoir Modeling team at the NWC and were based on available data from the U.S. Bureau of Reclamation and the Army Corps of Engineers. The second part involved looking for data-driven correlations for reservoir releases with instream and environmental flow requirements. Two watersheds were selected for comparison: The Trinity River in Texas, USA (Fig. 1) and the Sacramento River in California, USA (Fig. 2). The Trinity River drains into the Trinity-San Jacinto Estuary. Lake Livingston Reservoir is located on the Trinity River and is under environmental flow regulations to release a required amount of water to maintain seasonal inflow at a downstream USGS stream gage to ensure water researches the estuary (Table 2). Data was collected for the counties downstream and surrounding Lake Livingston. Correlations were established between environmental flows requirements, precipitation, outflow, inflow, and gauged flow. The Sacramento River drains into the San Francisco Bay. The Keswick Reservoir on the Sacramento River has minimum instream flow requirements to maintain the water temperature for downstream fisheries (Table 3). Correlations were established between fisheries data, inflow, outflow, precipitation, water temperature requirement, and gauged flow (Table 4). The results of this research will contribute to anthropogenic research at the National Water Center. It will identify datasets that can be incorporated into the NWM to enhance the prediction capabilities. It will lead to a better understanding of the human component of why releases are being made from reservoirs, whether it is to meet a human use demand, a senior water right, or an instream or environmental flow requirement. This research will be presented as a poster presentation at the AGU Fall Meeting, December 2019, San Francisco, CA, https://www.agu.org/fall-meeting, and at the ASCE EWRI Congress, May 2020, Henderson, NV, https://www.ewricongress.org/. The third part of my research will be used as a chapter in my dissertation. The 80th Texas Legislature (2007) established the Senate Bill 3 process for environmental flows in order to determine environmental flow standards for all of the major river basins and bay systems in Texas. The term "environmental flows" is used to describe the inflow needed to maintain ecologically healthy bays and estuaries. The quantity and timing of freshwater inflow from rivers is important to maintaining the natural salinity, nutrient, and sediment loading regimes which ensure healthy ecosystem function. Increasing demands for water coupled with drought conditions may limit the volume of freshwater reaching the estuaries as well as alter the timing in which the water arrives due to upstream reservoir releases. Two estuary/bay systems were selected for comparison for reservoir releases for environmental flow standards: The Nueces Estuary and the Trinity-San Jacinto Estuary in Texas, USA. The Choke Canyon Reservoir and the Wesley E Seale Dam (Lake Corpus Christi) are located on the Frio and Nueces Rivers (Fig. 1) and are under environmental flow regulations to release a target amount of water (acre-feet) downstream for the Nueces Estuary (Table 2). Lake Livingston Reservoir is located on the Trinity River and is under environmental flow regulations to release a required amount of water to maintain seasonal inflows (cubic feet per second) at a downstream USGS stream gage to ensure water researches the Trinity-San Jacinto Estuary (Table 2). Correlations were established between inflow, releases, precipitation, gauged flow, reservoir storage level, and environmental flow regulations. These correlations will be used to create a predictive model in which a forecasted amount of precipitation can be used to determine if the environmental flow standard will be met by an estimated reservoir release. The results of this research will contribute to a better understanding of the ability of meeting an environmental flow standard based on correlations in precipitation and water rights use allocations. This research will also be presented at the ASCE EWRI Congress, May 2020, Henderson, NV.
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August 2019
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