Modeling soil subsidence in a subtropical drained peatland. The case of the everglades agricultural Area

Abstract

The Everglades, located in South Florida, USA, have been accumulating organic soils (peats) for 5000 years. The northern portion of the natural Everglades, called the Everglades Agricultural Area (EAA), has been drained for more than 100 years and has experienced soil subsidence since then. Rates of soil subsidence in the EAA have changed over time, due mostly to changes in land use and water management. The purpose of this study was to adapt a model of peat dynamics to the EAA based on historic and current data to explore parameter estimation and to identify information/parameters that might be useful to model and predict soil subsidence in organic soils. Model optimization predicted a predrainage peat thickness of 2.57 m and a current subsidence rate of 0.65 cm yr−1. Model evaluation indicated that increasing biomass input to the soils from the current dominant crop (sugarcane) had the greatest potential to reduce future subsidence, while increasing water table depth or reducing the aerobic decomposition rate could also help reduce subsidence. To decrease subsidence in the EAA and improve soil conservation, farm practices that increase biomass input and water table depth would need to be implemented. Adding a seasonal water table component to this model and improve estimates of biomass input to the soil are the next steps to improve predictions of soil subsidence in the EAA under alternative management scenarios.