Flow Modeling

For the first time in Louisiana and Mississippi, you will be able to get flow estimates statewide and where there are no flow gauges. The Nature Conservancy (TNC) worked with Research Triangle Institute International (RTI) to adapt and deploy their WaterFALL™ model to estimate stream flow throughout Louisiana’s and Mississippi’s watersheds.

HydroFlows - We developed a web application that allows you to view and interact with model results. Flow information is available for both catchment and sub-watersheds, allowing for analysis at multiple scales. The app provides relevant flow metrics and allows you to explore how those metrics change with future climate change and water use scenarios. HydroFlows currently displays the Index of Hydrologic Alteration metrics, but we can also calculate custom water flow metrics to meet your needs.

OysterFlows - This app demonstrates the connectedness of our estuaries to decisions made upstream in freshwater systems. This eco-flows analysis uses hydrologic flow modeling results and coastal salinity data to illustrate the tradeoffs of potential inter-basin water transfers and water withdrawals on oyster resources at the coast. This tool allows you to explore these relationships in the Sabine and Calcasieu river basins in Louisiana. By allowing you to operate the Toledo Bend Dam, you can see the result of your actions on the health of the Sabine Lake Oyster Reef. In the Calcasieu, you can simulate a water withdrawal scenario from the Calcasieu River and see the result of your actions on the health of oyster resources in Calcasieu Lake.

In addition to these two apps we’ve developed, this hydrologic modeling can also be used to generate additional flow metrics, develop custom analyses and run additional scenarios to investigate water development proposals, like potential new reservoirs, water sales and develop water budgets which are essential to securing freshwater for the future. Contact us if you have a need for a custom analysis!

Explore the HydroFlows and OysterFlows tools on our Louisiana Freshwater Assessment site or check out the Mississippi version of HydroFlows on our Mississippi Freshwater Assessment site! You can also use the Launch Mapping Portal button on this page and choose a geography.

Water Quality Resource Inventory

The Nature Conservancy (TNC) partnered with The Natural Resources Conservation Service (NRCS) to develop a water quality hot spot tool to aid in targeting 12 digit sub-watersheds within 8 digit sub-basins in Louisiana for targeted nutrient reduction conservation practices (e.g., winter cover crops, hydrological restoration, reforestation, etc.). The functional requirements of the application were scoped in a series of joint meetings between Louisiana-based TNC and NRCS staff. As a result of these meetings, three 8 digit sub-basins were chosen to pilot the project: Boeuf, Tangipahoa and Mermentau. In the end, the entire state was encompassed in the assessment. The following water quality traits were also selected for analysis: dissolved oxygen, turbidity, total dissolved solids, total suspended solids, total nitrogen, nitrate, total phosphorus, phosphate, ammonia and inorganic nitrogen.

The tool features three workflows that allow you to explore spatial concentrations, temporal trends or impaired watersheds in Louisiana. Supplemental data such as land cover and soils data are also included to aid in visualizing water quality resources and provide landscape context.

The spatial concentration or “hot spot” analysis was accomplished using readily available existing sample data from the EPA and the Louisiana Department of Environmental Quality (LDEQ). These sample data were interpolated within 8 digit sub-basins (HUC 8) to create heat maps. This allows users to evaluate 12 digit sub-watersheds based on relative concentrations of water quality traits within each HUC 8 along with the supplemental data. The temporal trends display all of the sampling stations and allows you to click on a station to view yearly mean values and monthly values within each year of available data for the selected traits.

Third, you can view impaired watersheds, which are visual representations of LDEQ’s 303(d) Impaired watersheds list. This workflow displays a map of all of the LDEQ sub-segments in Louisiana symbolized by TMDL priority. Sub-segments in green have no listed impairment while listed sub-segments are colored yellow for “low priority”, orange for “medium priority” and red for “high priority”. You can also click on the sub-segment to view the grid of impairments, causes and sources.

In addition to the original three pilot watersheds, The Nature Conservancy elected to expand the application to include all 57 HUC 8 watersheds in Louisiana. The spatial analysis has been extended to all watersheds except those where it is not possible to interpolate because there either were not enough sample points or where the shape of the watershed is too narrow and sinuous to create a heat map. The temporal analysis has also been extended to all watersheds along with all available supporting data.

Explore the tool on our Louisiana Freshwater Assessment site or use the Launch Mapping Portal button on this page and click Louisiana.

Channelization

The Nature Conservancy has created an innovative method for identifying channelized streams and estimating the rate of channelization within watersheds.

The straightening, widening, deepening of stream and river channels can drastically alter the flow regime and function of hydrologic systems. For the first time, you will be able to view channelized bayous, rivers, and streams across the states of Louisiana and Mississippi and view an index of the relative amount of these alterations. This information is critical for ranking and prioritizing watersheds based on their degree of alteration. This method leverages the National Hydrography Dataset (NHD) by calculating the sinuosity and angularity of stream features and comparing with aerial imagery to determine if channelization is present.

View our channelization dataset here.