Task 7 - Project 1.4 - South Fort Myers
Flood mitigation benefits within the
South Fort Myers study area are achieved when excess storm water is conveyed and/or stored appropriately. The concept projects reduce flooding levels and duration that inundate structures and roadways. Adverse flooding conditions impact the health, safety, and welfare of residents and have significant economic impact to the community. A reduction in flooding duration is also beneficial, but to a lesser extent than a reduction in flood water levels. These two objectives are achieved when increased stormwater is carried through existing conveyances (culverts, rivers, canals, wetlands, etc.), diverted out of the upstream portion of the watershed, and/or stored appropriately within the watershed.
This regional approach to meeting the flood mitigation goals is necessary since many flooding problems are not solvable on a local level. For instance, if a primary drainage canal does not have sufficient capacity to convey the required flows, then the adjacent communities relying on the canal will experience adverse tailwater conditions that inhibit and/or prevent outflow that was anticipated in the original design of the community. A prerequisite of some of the upstream projects is that downstream improvements must occur first so that flooding problems are not simply transferred from one area to another. The regional model was therefore run with all conceptual projects stitched together to demonstrate the regional effects of the proposed projects.
For the communities adjacent to the southern end of Ten Mile Canal, the existing and proposed peak water levels of the canals in the Island Park community were extracted from the model results for the 100-year, 3-day storm event (August 2017 start). The peak water levels were reduced by six inches or more for approximately 6,000 acres in this area or approximately 1,470 parcels. It should be noted that this is a simplistic way to present graphical results for a region and does not include local-level complexities unique to each community.
The following are concept project summaries of the anticipated flood mitigation benefit for each project.
1.4.1 Ten Mile Canal-North - This flow diversion and storage concept project was developed to direct flood flow away from the southern end of Ten Mile Canal. The modeling results show a 100 cfs upstream diversion into Carrell Canal, 200 cfs upstream diversion into Canal L, and 50 cfs upstream diversion into the Six Mile Cypress Parkway roadside swale. These combine to a total flow diversion of approximately 21,000 acre-feet over a 30-day period. An increase in upstream storage was proposed through redesigning the existing weir adjacent to Page Field Airport, but the increased storage volume was not quantified in the regional model.
1.4.2 Ten Mile Canal-South - This flow diversion and conveyance improvement concept project was developed to provide flood mitigation for the Island Park Road area. The modeling results show a 400 cfs diversion into Canal J, 200 cfs diversion into Canal K, 100 cfs diversion into Canal T, and a 1,100‑cfs increase in capacity for Ten Mile Canal. These combine to a total flow diversion and conveyance increase of approximately 47,000 acre-feet.
1.4.3 Daniels Parkway-South Area - This conveyance improvement concept project was developed for flood mitigation of the communities south of Daniels Parkway, between Six Mile Cypress Slough and Interstate 75. The modeling results show 540 acre-feet of increased capacity in the swale north of the Legends community and a capacity increase of 1,100 acre-feet in the swale south of the Eagle Ridge community.
1.4.4 Briarcliff Area - This conveyance improvement concept project was developed for flood mitigation in the Briarcliff area. While this project was not included in the regional modeling, it is anticipated the project could provide up to 150 acre-feet of increased capacity for an existing area that has limited existing outfall options.
1.4.5 Park Road Area - This conveyance improvement concept project was developed for flood mitigation in the Park Road area. While this project was not included in the regional modeling, it is anticipated the project could provide up to 180 acre-feet of increased capacity for an existing area that has limited existing outfall options.
1.4.6 LCPA Diversion to Estero Basin - This flow diversion and storage concept project was developed for flood mitigation of the downstream portions of Ten Mile Canal and Estero River. The regional modeling results show the project could provide up to 800 acre-feet of increase storage in the wetland areas east of the airport. This project has a secondary benefit of increased wetland hydration.
1.4.7 Six Mile Cypress Slough-South - This flow diversion concept project was developed to provide increase stormwater management in the Six Mile Cypress Slough watershed. While the gate operations were not included in the regional modeling, the model results from the interim project screening report showed this project could provide up to 5,300 acre-feet of increased water management flexibility in the watershed. This project has a secondary benefit of increased wetland hydration.