Document Type

Article

Publication Date

2025

Abstract

Louisiana’s fifty-billion-dollar coastal restoration plan relies on selected interpretations of a small dataset of coastwide land measurements. In the 1990’s, the plan’s founders used a mathematically impossible interpretation of an improbable manipulation of the initial (1932-1990) dataset to justify their misconceptions regarding natural conditions; delta-switching; and a failing, 60-year restoration goal. In 2017, the dataset was updated to 2016 and used to suggest that land loss had slowed to -28 km2/yr (-1 football field/100 min) since 2010. We find that the dataset does not support this suggestion. Rather, we find the dataset supports our hypothesis that increasing precipitation in the Mississippi River watershed since the 1970s coupled with a 2009-2019 hiatus in the Louisiana landfall of strong hurricanes resulted in an abrupt 2009 shift from catastrophic land loss ( -70 km2/yr) to transient gain (42 km2/yr). Our results suggest that the coast’s current vegetation can promote substantial land gain when provided with adequate freshwater flows, the current sediment supply, and relief from strong hurricanes. This ability reflects first-hand descriptions from the 1500s to 1807 of Louisiana’s seaward advancing coast and vast offshore oyster reef. Since the current coast is no longer shoreward of an extensive, living reef and the intensity of hurricanes is expected to increase under a warming planet, we do not expect future gains unless the coast-reef synergy is restored and the rate of global warming declines. Our results lead to the conclusion that the existing plan has not and will not work, a conclusion supported by our examination of the plan’s unrealistic prediction of vegetation patterns in 2050. We propose the development of a new plan – one consistent with

Publication Source (Journal or Book title)

Proceedings of the Louisiana Academy of Sciences

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