Flooding is a natural phenomenon in Florida, commonly occurring along streams, rivers, lakes and coastal areas.  Floodplains, the low-lying lands that are subject to inundation from floodwaters, provide a variety of benefits, including, water storage, filtration, erosion control, habitat and recreation.  However, rapid population growth has changed the face of the state’s landscape.  Urbanization has brought with it increased impervious surface areas, causing more severe storm water runoff.  Unchecked development has fostered construction of drainage systems in a piecemeal fashion without a comprehensive design that fully considers the potential flood hazard.

     South Florida experienced excessive and unexpected rainfall on October 3-4, 2000 caused by a low-pressure system moving into the area between Cuba and Key West.  As the system moved over Florida, it produced over 15 inches of rainfall in less than 15 hours as recorded at the Miami International Airport.  Flood warnings were issued for all counties from Miami-Dade through Volusia on the east coast.  Localized flooding was the worst in Miami-Dade County.  One report indicated that the average height of floodwaters was approximately 18 inches. Communities in West Miami had homes flooded by as much as four feet of water, with many of these homes being inaccessible. Governor Jeb Bush declared a State of Emergency due to the flooding on October 4, and a Presidential Major Disaster Declaration immediately followed the Governor’s declaration.

     In southeast Florida, storm water drainage is accomplished through a complex network of primary, secondary and tertiary drainage channels.  Thousands of neighborhood drainage elements carry excess water into hundreds of secondary canals operated by independent drainage districts, county and local governments. These secondary canals, in turn, drain into primary canals operated by the South Florida Water Management District.  The higher flood levels and duration of the flooding in South Florida appears to have been caused by conveyance problems in the primary, secondary and tertiary systems.  Impediments to conveyance include the excessive rainfall, outdated designs and equipment, poor canal maintenance, and inadequate coordination between the primary and secondary system operators.

     Fortunately, Miami-Dade County and its 30 cooperating municipalities had already developed a Local Mitigation Strategy.  A Local Mitigation Strategy is a plan that a community can develop on a voluntary basis to promote hazard mitigation and manage post-disaster recovery and redevelopment.  The process helps communities identify areas that are most vulnerable to natural disasters and then to design policies, programs and projects to reduce future losses.  Miami-Dade County and its cities were in general agreement that they must join together to address the regional storm water drainage problems that cross municipal jurisdictional boundaries.  Consequently, they had a ready list of viable projects prepared.  When it came time to make recommendations to the state and the Federal Emergency Management Agency on how to apply funds available from the Hazard Mitigation Grant Program for this disaster, Miami-Dade County was far ahead of the game.

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