Gulf of Mexico coastal environments are characterized by naturally-formed wetlands and barrier islands that historically protected low-lying areas from tidal action and storm surge.
Human-made levees, floodwalls, and coastal armoring were later constructed to theoretically provide additional protection to low-lying areas where settlements expanded. The structures served to incentivize further development with the belief that low-lying settlements would be safe from flooding. Human-made drainage interventions were favored over natural hydrology and are based on the premise that developed land can be drained into bayous, rivers, lakes, and ultimately the Gulf of Mexico. In non-riverine environments, such as land areas along the highly-controlled and constrained Mississippi River, massive pump and canal systems were designed to drain the land and pump runoff over the levees and floodwalls into the lakes and the Gulf. This approach divorced coastal development from coastal eco-hydrologic processes.
Hydrologic and hydraulic modeling of watersheds and drainage-sheds, as well as analysis of settlement densities, impervious surfaces, wetlands, riparian zones, and rainfall data were conducted along portions of the Louisiana coast to reveal conditions that have led to unprecedented flood levels during recent events. More frequent and intense rainfall events and sea-level rise are predicted to exacerbate the problems.
Results/Conclusions
Advancing coastal resilience requires strategies that address the multiple facets of climate adaptation. Protection and enhancement of natural eco-hydrological processes must be not only implemented but also integrated with adaptive design in urban areas. Terrestrial and wetland ecosystems must be preserved and enhanced to remediate disruption of hydrologic processes and reconstitute a living coast. Habitats must be re-linked to again form highly-functional ecological systems. To mitigate total suspended solids from urban runoff and thereby maintain ecosystems’ functionality, erosion control and sediment management must be employed regionally, not just at the site level as is current practice.
Existing urban development requires implementation of distributed and interconnected green infrastructure within available public, private, and interstitial spaces. Urban ecological land must be expanded and enhanced. This approach will not only reduce runoff, but also maximize infiltration and groundwater recharge, reducing soil subsidence and feeding coastal wetlands.
Ecological resilience of coastal communities must also be pursued through adaptive design and adaptive retrofit approaches, including designing settlements that are elevated, floating, floodable, and water-based.
These strategies for advancing coastal ecological resilience were modeled and analyzed to determine their efficacy in different locations, scales, configurations, proximity, and interconnectivity. Results of the analysis will be presented.