Regardless of the source (riverine, urban drainage, ground failure, fluctuating lake levels or coastal), flooding has the potential to affect the hydrologic component of urban green infrastructure. As a result, the design professional must consider the potential for flooding when contemplating a project.

First, a brief word about planning. The importance of advance planning cannot be overstated. Extensive planning on the front end will save you lots of heartache (time, money and possible embarrassment) on the back end.



(Source: Natural Resources Conservation Service)


DEFINITION
The Federal Emergency Management Agency provides the following definitions:
FLOOD -
"A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least one of which is the policyholder's property) from:

• Overflow of inland or tidal waters; or
• Unusual and rapid accumulation or runoff of surface waters from any source; or
• Mudflow (A river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water. Other earth movements, such as landslide, slope failure, or a saturated soil mass moving by liquidity down a slope, are not mudflows.) ;or
• Collapse or subsidence of land along the shore of a lake or similar body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels that result in a flood as defined above."

FLOODPLAIN MANAGEMENT -
"The operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to, emergency preparedness plans, flood control works, and floodplain management regulations."

RELATED FUNCTIONS
Floodplains, including the wetlands associated with them, serve three primary purposes:

1. Moderating stream flow by reducing large fluctuations in water levels and providing natural storage areas for floodwaters, stream bank erosion is minimized, native vegetation is preserved to provide more beneficial wildlife habitat, and flooding is reduced;
2. Providing wildlife habitat by serving as wildlife corridors, nesting and breeding habitat, and food sources; and
3. Improving water quality through the removal of sediments, nutrients, and pollutants before entering surface waters and by serving as recharge areas for the aquifer, the primary source of drinking water.
   

PERFORMANCE CRITERIA
Depending on the source the number varies, but floods are estimated to account for 40% to 60% of natural disasters.
Thus is incumbent upon the design professional to include include resilency in his/her thinking.
Simply put, resilience is “… the ability of local units (e.g.. organizations, communities) to mitigate hazards, contain the effects of hazards, and carry out recovery activities in ways that minimize social disruption, while also mitigating the effects of future disasters."
Basis of disaster resilience:

1. Quantifiably assess a current state of resilience;
2. Set specific objectives to improve upon it; and
3. Establish remedial tasks and measure progress toward meeting pre-determined resilience targets.

(Source: MCEER, University of Buffalo)

ILLUSTRATION

Flooding is a natural event, resulting when water levels rise to a level that either hasn't been anticipated or properly planned for.
Floods are usually caused by either too much precipitation or snow melt that occurs upstream.

PROGRAMS:
The easiest way to avoid the negative impact(s) (i.e. loss of life and/or property, inconvenience, mold, foundation failure of structures, etc...) caused by flooding is to avoid areas of poor drainage & the floodplain.
Areas of poor drainage can usually be identified by a knowledgeable civil engineer or personnel (usually from the Engineering and/or Public Work Departments) associated with the authority having jurisdiction.
Generally speaking, for areas having a drainage basin greater than one square mile, the Federal Emergency Management Agency has developed maps that identify areas (e.g. Special Flood Hazard Area) subject to flooding. Information concerning the areas that have been mapped appears under ADDITIONAL RESOURCES (toward the end of this document).

However, there, has over the years, has been numerous structures built in areas subject to flooding. Some have done so with a callous regard, others have done so unaware of the risk. Usually it is the task of falls to the property owner, with assistance from the State and Federal Government to solve the problem that has been created. Various programs that have been established include:
FEDERAL EMERGENCY MANAGEMENT AGENCY:
1) The Hazard Mitigation Grant Program (HMGP): Hazard Mitigation Grant Program funds are available following a Presidential Disaster Declaration. Eligible applicants include States, local governments, Indian Tribal governments, and some Private Non-Profit organizations. Communities may apply for HMGP assistance on behalf of affected individuals and businesses, and all funds must be used to reduce or eliminate losses from future disasters. Examples of projects include:

• Elevating flood-prone homes or businesses;
• Acquiring (and either demolishing or relocating) flood-prone homes from willing owners and returning the property to open space;
• Retrofitting buildings to minimize damage from high winds, flooding, earthquakes, and other hazards; and
• Implementing minor flood control projects to protect critical facilities.
  

2) The Flood Mitigation Assistance (FMA) Program:The Flood Mitigation Assistance program provides funding to States and communities for measures that reduce or eliminate the long-term risk of flood damage to buildings, manufactured homes, and other structures insured under the National Flood Insurance Program (NFIP). The program provides grants for mitigation planning and projects with a goal of reducing claims under the NFIP.
3) The Pre-Disaster Mitigation (PDM) Program: The Pre-Disaster Mitigation (PDM) Program assists States, Indian Tribal governments, and local governments with cost-effective hazard mitigation activities that complement a comprehensive mitigation program. The program provides Applicants with an opportunity to raise risk awareness and reduce disaster losses before disasters strike through planning grants and project grants. PDM grants are awarded on a nationally competitive basis.
4) The Repetitive Flood Claims (RPC) Program: The Repetitive Flood Claims (RFC) grant program is designed to reduce or eliminate the long-term risk of flood damage to structures that are insured under the National Flood Insurance Program (NFIP) and have had one or more claim payment(s) for flood damages.
4) The Severe Repetitive Loss (SRL) Program: The Severe Repetitive Loss (SRL) Pilot Program provides funds to assist States, Indian Tribal governments, and local governments participating in the NFIP in reducing or eliminating the long-term flood risks to severe repetitive loss properties, thus reducing outlays from the NFIP. Severe repetitive loss was defined by the FIRA 2004. For a property to be designated SRL, it must:

• Be a residential property currently insured under the National Flood Insurance Program;
• Have incurred flood losses that resulted in either (1) four or more flood insurance claims payments that each exceeded $5,000 with at least two of the payments occurring within a 10-year period, or (2) two or more flood insurance claims payments that cumulatively exceeded the value of the property."

(Source: State of New Jersey, 2007 State Hazard Mitigation Plan, Appendix H FEMA Mitigation Grant Program Fact Sheet)

NATURAL RESOURCES CONSERVATION SERVICE:
ADDITIONAL RESOURCES
Federal Emergency Management Agency - www.fema.gov/
FEMA Map Service Center- http://msc.fema.gov/webapp/wcs/stores/servlet/FemaWelcomeView?storeId=10001&catalogId=10001&langId=-1
National Flood Insurance Program - www.floodsmart.gov/
Association of State Floodplain Managers - www.floods.org/
NFIP State Contacts - http://www.floods.org/index.asp?menuID=274&firstlevelmenuID=185&siteID=1
NRCS Conservation Programs - http://www.nrcs.usda.gov/Programs/
Skokomish Watershed Action Team - community engagement and action regarding floodplain management: http://hccc.wa.gov/Groups/SWAT/default.aspx