By Theryn Henkel, Lake Pontchartrain Basin Foundation
Since 2009, the Lake Pontchartrain Basin Foundation (LPBF) has been actively documenting the development of an emergent delta in the receiving basin, Big Mar, of the Caernarvon Diversion outfall canal on the east side of the Mississippi River south of New Orleans. Since October 2010, in partnership with the Coalition to Restore Coastal Louisiana (CRCL), LPBF has conducted tree plantings within Big Mar as part of a Restore the Earth Foundation grant-funded reforestation effort, called 10,000 Trees for Louisiana.
The Lake Pontchartrain Basin Foundation and the Coalition to Restore Coastal Louisiana conducted a 7th tree planting in Big Mar on October 28, 2013. This planting was conducted as a restoration event opportunity for members of the Mississippi River Delta Restoration Campaign. All of the volunteers were people who work on various parts of the campaign and included staff from Environmental Defense Fund, National Audubon Society, National Wildlife Foundation, LPBF and CRCL.
Twenty-five people, including 18 volunteers and 7 staff, planted a total of 250 trees at five different sites. Two of the sites, with 25 trees planted at each, are demonstration sites. If trees grow successfully at these locations, then future plantings will occur there with many more trees. 125 bald cypress trees (Taxodium distichum) and 125 water tupelo trees (Nyssa aquatica) were planted. Photos from the event can be seen on the Restore the Mississippi River Delta Facebook page and the Coalition to Restore Coastal Louisiana Facebook page.
The focus of these volunteer events is to plant trees that will abate and reduce storm surge. Big Mar is located directly in front of the newly built Hurricane and Storm Damage Risk Reduction System Levees, and a thriving cypress forest will provide some protection to this levee system by buffering storm surge. Big Mar is also located in front of the Braithwaite community, which is outside the federal levee system but has local levees that were overtopped and breached during Hurricane Isaac. A swamp forest in front of that community would provide some storm surge attenuation benefit. Additionally, monitoring the growth of these trees under the influence of the Caernarvon Diversion, at different distances from the diversion, will provide valuable information for future restoration projects. The work being done around the Caernarvon Delta Complex provides a unique opportunity to test the effectiveness of many proposed 2012 Louisiana Coastal Master Plan restoration initiatives, which rely heavily on river diversions.
Ultimately, if the data bears out and the hypothesis is true that the sediment delivered by river diversions builds land – and that the fresh water flowing into a receiving basin lowers soil salinity and the nutrients associated with river water increase growth rates – then this information could be used to manage river diversions more effectively in the future in an effort to do what they are supposed to do, which is to build wetlands that will help sustain coastal Louisiana and protect its people and communities from devastating storm surges.