The Accuracy of SWOT Water Surface Elevation in Florida’s Everglades Wetlands

Observing water level variations in wetlands is important for tracking global water and carbon cycles. The Surface Water and Ocean Topography (SWOT) mission was launched to measure Earth’s surface waters, but its performance in vegetated wetlands was unknown. This thesis presents the first assessment of SWOT over herbaceous wetlands, focusing on Florida’s Everglades. Comparison of SWOT water surface elevation measurements against in situ water levels from August 2023 to March 2024 shows a strong positive correlation and a mean absolute error of 6.7 centimeters for elevations averaged over one square kilometer regions. Accuracy is similar across the observation swath and regardless of season or overpass. SWOT’s performance in large herbaceous wetlands exceeds pre-launch expectations for large open water bodies. These results suggest that water level variations can be accurately tracked in many of Earth’s large herbaceous wetlands, though additional evaluation is needed in shrubby and forested wetlands.