NASA Jet Propulsion Laboratory
Louisiana Ecological Forecasting II 
Bringing Back the Bayou

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>> ERIKA: Over the past 200 years, 50 percent of the original wetlands across the United States have been lost. These wetlands have been altered by human activities primarily through draining and dredging so they can be used for agricultural, urban, or residential development. 

Around 40 percent of the nation’s remaining wetlands are in Louisiana, but the state currently accounts for 80 percent of the annual national wetland loss. This loss is occurring at a rate of about 75 square kilometers per year with the coastal wetlands being projected to be completely gone within another 200 years.

Some direct benefits coastal wetlands offer to the inhabitants of Louisiana is their ability to provide protection from severely damaging storm surges caused by hurricanes, as well as providing a natural barrier from hazardous materials like oil, pesticides and the large amounts of carbon caused by air pollution. 

These wetlands can act as a buffer zone by absorbing water and dissipating wave energy from severe storms. Wetlands also hold a unique variety of flora and fauna and are inherently tied to major issues such as climate change and water quality. 

While much of the Louisiana coast is eroding, there are areas that are actually gaining land, such as the Wax Lake Delta. The Wax Lake Delta is one of two deltas that has continued to grow at a rate of approximately 1.2 square kilometers per year.

This spring the NASA DEVELOP Louisiana ecological forecasting team at NASA Jet Propulsion Laboratory was tasked with building and calibrating a hydrological model of the Wax Lake Delta using Delft3D modeling software and NASA earth observations. This model will enable researchers to examine water flow, sediment transport and delta formation under different conditions.

This project partnered with Alex Kolker of the Louisiana Universities Marine Consortium, who is working on the 2017 Louisiana Coastal Master Plan, as well as Richard Crout at the United States Naval Research Laboratory.

>> ALEX: The Wax Lake Delta is one of the few good examples of an unregulated free flowing deltaic system that is actively growing land. So it is a great system in which you can test hypothesis about building land and calibrating models that one might use to understand how to build land in coastal Louisiana. 

>> MARC: It brings us a different component. Not only can you have a spatially explicit understanding of what’s happening in terms of hydrology and transport of sediments in the delta, but it gives you the ability to forecast.

>> ERIKA: To accomplish our task we used data from three of NASA’s airborne platforms--UAVSAR, AVIRIS-NG, and AirSWOT. The data was processed using the GDAL package within Python and ArcMap to make an initial layer which was combined with tools in Delft3D to make a complex hydrological model.

UAVSAR scenes were initially classified into three land cover types with corresponding elevation values then merged with multiple bathymetry and elevation datasets to create a vegetation elevation layer.

This layer was the basis for our model within Delft 3D. A mesh grid was created to encompass the desired model area and parameters were set based on in situ data.

The Delft 3D model was calibrated using in situ data and water surface height data from the AirSWOT sensor.

The calibrated model is a useful tool that will enable researchers to vary conditions and parameters such as flow rate and sediment volume to virtually examine the effects on water flow, sediment transport and the rate of land building.

Results from the model can contribute to more accurate predictions for future land growth and possible further insight into driving mechanisms of said growth, and potentially inform future efforts to restore areas of land loss along the coast.

>> ALEX: If land loss continues unchecked, South Louisiana’s future is bleak. There’s no doubt about it. So the kind of work this NASA team is doing into looking at the elevation in deltas, how these elevations might change in the future and how they might interact in deltas is critical to helping us to understand how the landscape might change in the future and how it might change as sea level rise accelerates and how we can avoid a bleak future for Louisiana’s coast. 

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