Map focused on areas near the cities of Franklin and Carlisle, Ohio
To understand the flood impacted areas at different river stages along the Great Miami River a new Flood Inundation Map was initiated by the Miami Conservancy District and the Ohio Silver Jackets to help people understand the risk of flooding in the Franklin and Carlisle communities. Predictions of river levels and flood warnings can be more meaningful to the public when understood in terms of areas that will be inundated. The Ohio Silver Jackets is an interagency team dedicated to working collaboratively with Federal, State, and local stakeholders. They develop and implement hazard mitigation actions that leverage available agency resources including funding, programs, and technical expertise.
A web-based mapping tool is used to increase awareness and knowledge of the risks associated with natural hazards. This knowledge can also be used to support communities in developing plans and projects to manage living with these risks.
An area at risk of flooding is associated with Miami Conservancy District's Franklin-Carlisle Overflow. The overflow is a part of the integrated flood protection system built and maintained by the Miami Conservancy District. The system provides flood risk reduction to communities along the Great Miami River and includes dams, levees, floodwalls, and the Franklin-Carlisle Overflow.
Miami Conservancy District owns and maintains three levees along the Great Miami River at Franklin as part of the system. The levees are designed to pass Miami Conservancy District flood protection system design event known as the Official Plan Flood (OPF) plus freeboard on the earthen levees. For the OPF to flow safely past Franklin, some flow must pass through the Franklin-Carlisle Overflow. The Overflow does not convey floodwater from the Great Miami River on a regular basis. However, a significant high water event would result in flow through the Overflow.
As recently as January 2005, the Great Miami River overflowed its banks and flooded properties at the mouth of the Franklin-Carlisle Overflow. In March 1913 and January 1959, the Franklin-Carlisle Overflow also carried flow from the river across the normally dry land. A small increase in the discharge in 2005 would have resulted in flow through the overflow.
The following table lists the stage of the Great Miami River at the Second Street Bridge in Franklin.
| Date | Stage (ft) |
| Flood of 1913 with MCD flood protection system | 21**estimated |
| January 22, 1959 | 17.6 |
| January 22, 1937 | 16.7 |
| March 6, 1963 | 16.6 |
| January 7, 2005 | 16.5 |
| February 27, 1929 | 16.3 |
The OPF discharge on the Great Miami River at Franklin is 135,000 cfs, whereas the 1913 flood discharge was 267,000 cfs. The OPF discharge is not associated with a specific frequency event but is larger than the FEMA 1-percent annual chance (100-year) of 62,800 cfs and the FEMA 0.2-percent annual chance (500-year) discharge of 75,300 cfs. A Flood Risk Management study for the Great Miami River at Franklin and Carlisle, OH was conducted in 2015 as part of an USACE Planning Assistance to States (PAS) program. The purpose of the study was to perform detailed hydraulic analyses at various discharges to identify, quantify, and evaluate the impacts of existing structures from the Franklin-Carlisle overflow channel. This study led to the development of the new Flood Inundation Map web-based mapping tool.
How to use the Flood Inundation Map:
The following partners collaborated to create the flood inundation map tool:
