Picturing Pre-Drainage Everglades Hydrology: How Fuzzy Is It?
Jayantha Obeysekera, Christopher McVoy, Winifred Park Said, Joel VanArman, Randy VanZee, and Jenifer Barnes. South Florida Water Management District, West Palm Beach, Florida
Previous research efforts have amassed an extensive collection of historical information regarding pre- and early post-drainage conditions in the Everglades. Synthesis of this information has yielded maps of pre-drainage landscape extents and semi-quantitative descriptions of soils, vegetation and hydrology. While the collections of specific pre-drainage observations such as water depths or flow directions are helpful, perhaps even more important is the overall “picture” or conceptual model that emerges from synthesis of the full body of information. This picture provides a sense of the pre-drainage hydrology of the Everglades in its entirety, including inflows and outflows across borders. Some aspects of this picture which can help guide more quantitative modeling of pre-drainage hydrology include uniformity/nonuniformity of the landscape, seasonality of outflows, location of outflows, and seasonality of inflows.
The research presented here used this previous historical work to guide sensitivity analyses of the Natural System Model. These analyses focussed on pre-drainage topography and conveyance capacities of the cuts through the coastal ridge. It is well known that the topography of the Everglades has a major influence on the hydropatterns of the natural system. All available information was used to derive plausible estimates of pre-drainage topography. Similarly, a range of plausible estimates of eastern outflow capacity were considered. Sensitivity analyses were conducted using a combination of these different estimates of model inputs.
As a complement to the sensitivity analyses, a water budget approach was taken to improve understanding of pre-drainage hydrology. In the 1940s, Parker et a.l (1955) conducted comprehensive hydrologic and environmental studies of the Everglades region. This data, although they characterize a drained system, has been used to compute water budgets, rainfall-runoff relationships, and inflows and outflows in subregions of the Everglades. The purpose of this effort was to determine if inferences regarding the predrainage system can be made from the data collected in the 1940s.
Jayantha Obeysekera, Hydrologic Systems Modeling Division, South Florida Water Management District, 3306 Gun Club Rd, West Palm Beach, FL 33406. (561) 682-6503. .