Evaluating Peatland Vulnerability to Sea Level Rise and Saltwater Intrusion using Coupled Simulations of Coastal Transport and Soil-Plant Mechanistic Models in the Florida Coastal Everglades
Abstract
Driven by accelerated sea level rise (SLR) and saltwater intrusion, sawgrass-dominated peatlands in the Florida Coastal Everglades are undergoing rapid change, and in some areas, limiting their ability to build elevation to keep pace with SLR. Declines in sawgrass net primary productivity (NPP) due to increased salinity and seasonal dry-down contributes to a negative carbon (C) balance and a corresponding loss of peat soil. Here, we coupled a mechanistic peat elevation model (EvPEM) to the Biscayne and Southern Everglades Coastal Transport (BISECT) model, developed by the U.S. Geological Survey and calibrated for coastal sawgrass peatlands, in order to simulate the effects of declines in peat soil elevation on water stage and groundwater salinity over 13 years. The EvPEM simulates net ecosystem C balance and marsh surface elevation change by combining the interplay among sawgrass NPP, litter decomposition, turnover rate, and peat oxidation as a function of salinity and inundation. The BISECT is a landscape-scale two-dimensional model that assesses the effects of freshwater pulses and SLR on flow rates, groundwater levels, hydroperiods, and salinity in the greater Everglades. We applied peat loss rates, obtained as outputs from the EvPEM, to the BISECT baseline digital elevation model and then simulated BISECT for various SLR scenarios. The integrated simulations illustrate how peat elevation loss alters the water flow and salinity dynamics, that culminates in the conversion of vegetated coastal peatlands into un-vegetated open-water areas while subsidizing atmospheric C gain. The ongoing model integration work provides valuable insights into the management of freshwater pulses to the Florida Coastal Everglades that aim to minimize the rate and extent of saltwater intrusion and decrease losses of vulnerable coastal peat soil and their associated carbon stocks.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB048.0009I
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 0469 Nitrogen cycling;
- BIOGEOSCIENCES