Because Louisiana’s coast is a dynamic, ever changing system, the conditions 50 years from now will be different from those today. In addition, many projects included in the master plan will not be implemented for several years, or even decades, as further design is undertaken and funding is obtained. Given these uncertainties, the most accurate way to evaluate the effects of projects in the master plan is to compare them against the future landscape that would occur without the plan. To capture this comparison, we investigated what we called “Future Without Action” conditions for the next 50 years, meaning conditions that would be present throughout coastal Louisiana if we do nothing further to protect and restore the coast. Because there is no way to identify the specific values for environmental drivers (e.g., eustatic sea level rise, subsidence, precipitation, and evapotranspiration) that will occur over the next 50 years, multiple values were considered for each driver. These values were used to develop three environmental scenarios – low, medium, and high – to examine a range of possible future conditions. (For additional information on the environmental scenarios, please see Chapter 2 of Appendix C – Modeling.)
The following are the Future Without Action Predicted Flood Depth maps at Year 50 for each of the three environmental scenarios – low, medium, and high.
The following are the Future Without Action Predicted Land Change maps at Year 50 for each of the three environmental scenarios – low, medium, and high.
To further illustrate the future without action impacts, the following video shows an animation of the future without action land loss maps for the medium environmental scenario in 10 year increments over the next 50 year period.
Even with the best available data, there are limitations to predicting future conditions. CPRA and its partners base analyses on the best available data for sea level rise, and subsidence. It is important to note that no one can predict the future of these environmental drivers with absolute certainty; the low, medium, and high scenarios are only three of many plausible future outcomes. Therefore, the Future Without Action analyses are not meant to be final predictions and are not meant to capture extreme or unforeseen events or tipping points. It is also important to remember that these flood depth and land loss projections do not yet include the positive effects of master plan projects that will be recommended for implementation in the 2017 Coastal Master Plan.