Floods are the deadliest, costliest and most common form of natural disaster in the United States and in the world. They are caused by hurricanes, heavy rainfall, overflowing rivers, broken dams, overfilled urban drainage basins, tsunamis, water channels with steep sides, and ice- or snow-melt. Floods are difficult to predict, which means states must be prepared to respond at all times.
Forms of Flood Mitigation
Flood mitigation approaches fall into two categories—structural and nonstructural. Structural forms of mitigation mitigate harm by reconstructing landscapes. They include floodwalls/seawalls, floodgates, levees, and evacuation routes. Nonstructural measures reduce damage by removing people and property out of risk areas. They include elevated structures, property buyouts, permanent relocation, zoning, subdivision, and building codes. Structural solutions have lost popularity over time as old dams and floodgates have failed.
FEMA released a report in 2017 called "Innovative Drought and Flood Mitigation Projects" that evaluates four disaster mitigation approaches highlighted by an EPA-commissioned report: "Aquifer Storage and Recovery, Floodwater Diversion and Storage, Floodplain and Stream Restoration, and Low Impact Development (LID)/Green Infrastructure (GI)." The report assesses each approach based on cost, efficacy, feasibility and fulfillment of Hazard Mitigation Assistance (HMA) requirements.
The report finds that all four options are consistent with HMA’s requirements and guidelines and will effectively mitigate the impact of climate disasters, including floods. Aquifers are primarily used to mitigate the impact of droughts, so the following descriptions focus on the other three recommendations.
- Floodwater Diversion and Storage - Diverting floodwaters into wetlands, floodplains, canals, pipes, reservoirs, or other conduits helps mitigate flooding by allowing for a controlled release of water outside of residential or metropolitan areas. At least 16 states have enacted legislation since 2010 establishing intent, programs, or funds to build floodwater diversion or storage systems.
- Floodplain and Stream Restoration – Floodplains and streams not only mitigate the risk of floods but can also mitigate bank erosion and benefit local ecosystems. Floodplains store stormwater runoff, reducing the number of floods and their severity. 10 states have passed legislation to restore streams or floodplains to mitigate flood damage since 2010. 13 bills have failed in the United States Congress concerning floodplain restoration since 2010. Five more are pending.
- Low Impact Development (LID)/Green Infrastructure (GI) – LIDs and GIs mitigate the risk of floods by storing water. They tend to mimic natural hydrology and include innovations such as green roofs and permeable pavement. Most states have implemented some form of LID or GI.
At least 19 states and Puerto Rico enacted legislation in 2019 related to flood mitigation.
2019 Enacted State Legislation
||2019 HB 1148
||Appropriates $997,075 for flood hazard mitigation grants.
||2019 SB 99
||Requires a city or county, upon the next revision of its housing element, to include information identifying residential developments in hazard areas that do not have at least two emergency evacuation routes.
||2019 HB 1292
||Continues the Colorado Resiliency Office. Repeals the requirement that the office be funded solely through grant funding, making general funds available.
|2019 SB 221
||Appropriates $500,000 from the Colorado water conservation board construction fund to continue the floodplain map modernization program.
||2019 SB 1062
||Authorizes municipalities to establish climate change and coastal resiliency reserve funds that can be used to fund payments for property losses and land acquisitions due to climate change.
||2019 HB 329
||Amends the Kauai Flooding Disaster Relief Appropriation Act to include flood mitigation measures.
|2019 HB 1558
||Requires the Office of Planning to update the Hawaii 2050 Sustainability Plan using the Hawaii Climate Change Mitigation and Adaptation Initiative as guiding principles.
||2019 HB 62
||Appropriates $10 million from the Capital Development Fund to the Department of Natural Resources for implementation of flood hazard mitigation plans.
|2019 HB 142
||Appropriates $375,457,000 for capital facilities projects related to water resource management, including flood mitigation.
|2019 HB 2737
||Provides that the purposes of soil and water conservation districts include the improvement of resilience to droughts, floods, and other extreme weather.
||2019 SB 638
||Establishes a flood recovery fund to support local projects related to flood response, recovery or mitigation activities.
||2019 HB 407
||Amends growth planning and land use laws to reflect that addressing the effects of sea-level rise is a state planning and regulatory goal.
||2019 HB 428/SB 269
||Authorizes the Maryland Department of the Environment, under its existing comprehensive flood management grant program, to award grants to subdivisions that have incurred at least $1 million in infrastructure damage by a flood event that occurred on or after January 1, 2009. Requires the Governor to include in the annual state budget an appropriation of at least $5 million for the program.
|2019 HB 101
||Appropriates $5 million split between Annapolis, Ellicott City and Baltimore for projects which reduce the risk of loss of life and property from flooding. Grant funds may be used to acquire flood-prone properties, install flood warning systems, and construct flood control projects.
|2019 HB 1427
||Alters the application of certain design and siting criteria established by the Coast Smart Council to apply only to certain state and local capital projects. Extends the date the projects must comply with the criteria and the date certain local jurisdictions must develop a plan to address certain nuisance flooding. Requires the Department of Planning to develop guidelines to assist local jurisdictions in data collection.
||2019 SB 35
||Establishes the Nevada Resilience Advisory Committee and charges the group with, among other things, developing state resilience goals and formulating recommendations and policies regarding statewide mitigation, preparedness, response and recovery efforts.
||2019 SB 285
||Authorizes municipalities to create municipal development and revitalization districts as a result of a climate change emergency. Establishes the Coastal Resilience and Cultural and Historic Reserve Commission.
||2019 AB 4751
||Appropriates $3.054 million to acquire, for recreation and conservation purposes, properties throughout the state that are prone to or have incurred flood or storm damage, or that may buffer or protect other lands from such damage as part of the Blue Acres program.
|2019 SB 1073
||Authorizes counties, municipalities, and certain authorities to establish stormwater utilities and related fees and other charges.
||2019 SB 6599
||Adopts a host of measures to put the state on a path to reduce statewide greenhouse gas emissions by 85% by 2050 and net-zero emissions in all sectors of the economy.
||2019 SB 431
||Creates the Urban Flood Safety and Water Quality District in a portion of Multnomah County for purposes of managing and improving the levee system, drainage and natural areas to provide for flood safety and contribute to water quality, habitat, and landscape resiliency.
||2019 HB 5484
||Revises the definition of building height by including in special flood hazard zones those areas identified on the sea level rise map as being inundated during a one-hundred-year storm.
|2019 SB 994
||Expands the definition of the approved project to include resiliency related infrastructure projects and projects which may include state and federal infrastructures within the state.
||2019 SB 7
||Amends the existing floodplain management account to create the Texas Infrastructure Resiliency Fund, which houses four accounts: floodplain management account, Hurricane Harvey account, flood plan implementation account, and federal matching account. Also requires a report from agencies that utilize federal dollars.
|2019 SB 8
||Requires the Texas Water Development Board (TWDB), not later than September 1, 2024, to prepare and adopt a comprehensive state flood plan. Requires TWDB to designate flood planning regions corresponding to each river basin and provide technical and financial assistance to the groups.
|2019 SB 563
||Requires a state agency that uses or disburses federal money for flood research, planning, or mitigation projects to submit a report on a quarterly basis to the state Water Development Board.
|2019 HB 2345
||Creates the Institute for a Disaster Resilient Texas as a component of Texas A&M University to develop data analytics tools to support disaster planning, mitigation, response, and recovery and create and maintain web-based tools to communicate disaster risks and ways to reduce those risks.
|2019 SB 1082
||Establishes a joint interim committee to continue to study the feasibility of creating and maintaining a coastal barrier system that includes gates and barriers to prevent storm surge damage to gulf beaches or coastal ports, industry, or property.
|2019 SB 285
||Sets forth requirements for information and outreach regarding hurricane preparedness and mitigation. Requires the reports of state agency preparedness for hurricane responses to be published on the Governor's Office website.
|2019 SB 289
||Creates a Disaster Recovery Task Force to operate throughout the long-term recovery period following disasters by providing specialized assistance for communities and individuals to address financial issues, federal assistance programs, and recovery and resilience planning.
||2019 SB 1588
||Codifies an amendment to the Constitution of Virginia adopted in Nov. 2018, which enables a locality to provide by ordinance a partial exemption from real property taxes for flooding abatement, mitigation, or resiliency efforts for improved real estate that is subject to recurrent flooding.
||2019 SB 773
||Orders the approval of a Mitigation and Adaptation to Climate Change Plan by sectors. Establishes the Joint Commission on Mitigation and Adaptation to Climate Change of the Legislative Assembly.