Calibrating Complexity: A Comprehensive Approach to Developing Stage–Storage–Discharge Relationships for Geographically Isolated Wetlands (GIWs) in W-C Florida

Abstract

Geographically isolated wetlands (GIWs) play a critical role in regional hydrology, streamflow, groundwater recharge, evapotranspiration, and water quality. Despite their importance, research on quantifying discharges from these wetlands remains scarce. This study focuses on the hydrological characterization of GIWs in W-C Florida, a region where they cover a significant proportion of the land surface. The paper introduces a new procedure for developing Stage–Storage–Discharge (rating) characteristics essential for deterministic hydrological modeling in larger geographic areas. The approach synthesizes and extends previous research methodologies and offers simplified key modeling coefficients (m and n), which act as intelligent calibration knobs. These coefficients, when coupled with easily derivable physical attributes such as areas, slopes, and elevations, allow for the accurate simulation of downstream discharge timings and magnitudes, including flood behavior. The proposed method was tested using observational data from well-calibrated models. The results indicated a relative error of −7.2% for stage–storage and 15% for stage–discharge. GIS-based techniques were evaluated against surveyed data, and the results showed an accuracy of 0.16 m (0.52 ft) in estimating both the invert elevation and the maximum depth of GIWs. This effort will ultimately contribute to a better understanding and management of these critical ecosystems.

Application and Evaluation of Stage–Storage–Discharge Methodology in Hydrological Study of the Southern Phosphate Mining Model Domain in Southwest Florida

“…The classification framework draws on the extensive research conducted by [27,28] and previous modeling experience by [7,12] as well as accepted knowledge of the area. The RCHRES module within HSPF was employed to simulate each categorized hydrofeature (wetlands, streams, lakes, and rivers).…”

“…Geographically isolated wetlands (GIWs) were delineated as wetland RCHRESs, characterized by their limited surface water connectivity, elevated invert levels, and unique groundwater ET extinction depths-the depth beyond which plants can no longer access water within the soil (the sum of the root zone depth and capillary zone depth). These wetlands typically exhibit visible water storage for only part of the year, estimated to last approximately 2/3 of the year (238 days [28]), and visibly dry beds during the dry season and rarely discharge but for a brief period each year.…”

“…In a separate study conducted by Alshehri and Ross [28], Mueses's [30] model underwent refinement to more accurately replicate the stage-discharge relationship of geographically isolated wetlands (GIWs), wetlands that conditionally connect or rarely discharge to downstream alluvial wetlands. In this application, wetlands identified through a GIS corridor analysis as GIWs were modeled as wetland RCHRESs.…”

“…The development of stage-storage-discharge relationships within hydrological models has been more straightforward for smaller, less complex watersheds where good DEM data exist. However, for larger domains such as IHM-INTB and the Peace River Watershed model, this task becomes more challenging [27,28], requiring systematic parameterization and innovative methodology employing general and geographic information system (GIS) data to establish reliable sand vast stage-storage-discharge relationships for these complex systems. This approach utilizes a GIS and DEMs to extract critical hydro-geospatial parameters and spreadsheet operations to prepare the many stage-storage-discharge relationships required for these expansive networks.…”

“…The principal objective of this study was to create a robust computational tool based on the Alshehri and Ross [27,28] framework for isolated and alluvial wetlands. Their prior research primarily focused on developing a methodology to accurately characterize the relationships between stage, storage, and discharge.…”