Flood Hazard Mitigation Plan for Miami Gardens, Florida

Introduction

The City of Miami Gardens is vulnerable to natural hazards, particularly flooding, because of its geographic location and exposure to extreme weather events such as heavy rain. One of the major drivers of these extreme weather events — and the increased likelihood of heavy rain and subsequent flooding — is global climate change. Climate change contributes to unprecedented weather incidents through which the earth cools and warms over geologic time. While the city has created canal systems and neighborhood drainage systems to help manage stormwater during periods of heavy rainfall, the problem of flooding continues to persist. When flooding occurs, it leads to considerable business disruptions, power outages, and other significant negative impacts on the community.

A hazard scenario in this area would involve a series of storms characterized by heavy rainfall lasting several weeks. The city's weather department has issued warnings that the heavy rains will continue for several weeks and will have significant negative effects on the community. Local residents have begun evacuating the area in anticipation of the flooding and its associated impacts. Based on target asset inventory and analysis, the flooding will have significant effects on the human population, energy infrastructure, and transportation infrastructure. There is therefore a need for an effective hazard mitigation plan that incorporates public education and awareness, redesign of the canal systems, and routine training and exercises to determine the readiness of emergency response agencies. Additional measures include regular inspections of evacuation routes, shelters, and medical facilities, as well as enforcement of building codes that address natural disasters. These measures require collaboration among various emergency preparedness and response stakeholders and agencies.

Flooding in the City of Miami Gardens can be primarily attributed to global climate change — broadly defined as a change in the state of the climate caused by internal processes and external factors such as volcanic eruptions, solar cycles, and anthropogenic changes in land use or the composition of the Earth's atmosphere. As a natural phenomenon through which the earth has cooled and warmed periodically over geologic time, climate change is a major contributing factor to natural hazards and unprecedented weather patterns. In recent decades, the frequent and rapid warming of the earth has emerged as a critical issue, particularly because of its severe consequences, including natural hazards. Effects observed in the City of Miami Gardens include coastal erosion, submergence, and flooding. In Florida, the most vulnerable area to these effects is Southwest Florida, owing to its low topography, subtropical environment, coastal counties, and porous geology ("Flood Risk Assessment," 2014). The City of Miami Gardens is similarly vulnerable, especially to flooding driven by extreme weather events.

History of Flooding in Miami Gardens

The City of Miami Gardens, located in a flat, low-lying area of Miami-Dade County, is no stranger to natural disasters, particularly flooding. The city experiences flood hazards ranging from rainfall associated with tropical storms to other weather systems such as heavy rain events and hurricanes. Flood hazards are also partly attributable to the presence of lakes, canals, rivers, and other water bodies within the city. Miami Gardens' groundwater table sits just below the ground surface, a condition that further contributes to the risk of flooding.

During rainy seasons, the city's canals and lakes are typically full, and the groundwater table rises to near the surface. When heavy rainfall occurs during these periods, stormwater runoff produces occasional localized flooding because the water has nowhere to drain. Furthermore, extreme weather systems can force man-made canals to overtop their banks or become backed up, resulting in localized flooding in areas near the canals. These flooding problems can be exacerbated by backup in secondary canals and neighborhood drainage systems ("Flood Awareness," n.d.). Many areas in the City of Miami Gardens have experienced extended flooding as a result of past flood events, including Hurricane Irene in 1999 and the No-Name Storm in 2000. These events caused significant business disruptions, loss of electricity, and other substantial negative effects on the community.

Hazard Scenario

A series of storms has brought significant and widespread heavy rainfall to the City of Miami Gardens over the past four weeks. The city is currently experiencing heavy rains due to slow-moving storm systems and unprecedented warm temperatures. Miami Gardens' weather department has issued warnings that the heavy rains will continue over the next several weeks. The department has stated that the ongoing rains will continue to have significant negative effects on the community, as they will clog storm drains, saturate soils, and fill local reservoirs. This situation means that the strong storm system is likely to result in flooding. The canals and neighborhood drainage systems in the city will become so backed up that water will have nowhere to drain. In light of these warnings and prevailing conditions, many local residents have begun evacuating the area out of concern for negative impacts such as business disruptions and power loss.

References

"Flood Awareness." (n.d.). Miami Gardens. Retrieved from City of Miami Gardens, Florida website:

"Flood Emergency Response Plan." (2004). FM Global. Retrieved June 23, 2014, from

"Flood Risk Assessment." (2014, May). Floodplain Mitigation Plan. Retrieved from Town of Cutler Bay, Florida website:

"The Local Mitigation Strategy." (2012, June 30). Hazard Mitigation for Miami-Dade County and its Municipalities, Departments and Private Sector Partners. Retrieved from Miami-Dade County Government website:

"Working Together." (n.d.). Local Mitigation Strategies for Flooding. Retrieved June 23, 2014, from http://mitigation.eeri.org/files/resources-for-success/00056.pdf