Week1: Ancillary items to FPM¶

• Video Reference

Introduction to the NFIP and Floodplain Management¶

The National Flood Insurance Program (NFIP) forms the foundation of floodplain management in the United States. Understanding its core components is essential for passing the CFM exam, which consists of 120 multiple-choice questions covering various aspects of floodplain management, with a particular focus on NFIP minimum requirements.

The Three Major Parts of the NFIP¶

The NFIP is built on three fundamental pillars (often described as "three legs" or "three pillars"):

1. Insurance

2. Mapping

3. Regulation

   

🏛️ Roles of Federal and Local Governments in the NFIP¶

Entity	Role
Federal Government	Develops policies, practices, laws, and flood insurance programs
Local Communities	Enforce regulations via building permits and inspections
Local Officials	Building officials and floodplain managers enforce compliance in their jurisdictions

• FEMA conducts Community Assistance Visits (CAV) to review local documentation.
• Local enforcement affects discount rates for flood insurance through the Community Rating System (CRS).

⚖️ Minimum and Cumulative Requirements of the NFIP¶

• Minimum Requirements:

  These are the bare minimum standards needed to comply with the NFIP.

  Similar to building codes, these ensure structures are legal and safe but represent the lowest acceptable level of protection.

• Cumulative Requirements:

  Requirements build upon one another over time—referred to as the "NFIP staircase."

  As communities develop and improve floodplain management, they add layers of regulations to provide better protection and benefits.

• The more advanced the requirements, the better the flood protection and potential lower flood insurance premiums for residents.

  | Concept | Explanation | |---------|-------------| | Minimum Requirements | Least acceptable standards to comply with NFIP regulations; equivalent to "building to code" | | Cumulative Requirements | Additional layers of rules added over time, enhancing flood protection and insurance benefits |

📜 Legislative Cornerstones Influencing the NFIP¶

Year	Act/Legislation	Key Points
1899	Navigable Stream, River, and Harbors Act	Requires congressional approval for work on navigable waters (e.g., bridges, piers)
1979	Flood Disaster Protection Act	Created FEMA
1994	National Flood Insurance Reform Act	Major reforms in flood insurance policies
2000	Disaster Mitigation Act	Requires local mitigation strategies for emergency planning (floods, hurricanes, tornadoes)
2004 & 2012	National Flood Insurance Reform Acts	Biggert-Waters Act (2012) introduced reforms including moving flood insurance to actuarial rates; subsequent reforms addressed funding and subsidy issues

• The Biggert-Waters Act aimed to reduce government subsidies for flood insurance, leading to higher premiums aligning with actual risk.
• These legislative acts illustrate a progression toward more sustainable flood risk management and financial responsibility.

💧 Forces of Water in Floodplain Management¶

Water forces affecting floodplain structures are divided into two main categories:

Force Type	Description	Examples
Hydrodynamic	Moving water forces	Waves, rivers, streams, flash floods
Hydrostatic	Standing water pressure	Water pressure on basement walls

• Hydrostatic pressure is crucial in understanding basement flooding:
  • When basements fill with water, the immediate reaction is to pump it out.
  • Pumping out water too quickly creates pressure imbalance because groundwater outside the basement walls remains high.
  • This pressure can cause cracks and water infiltration.
  • Recommendation: Lower water levels slowly and in stages to allow equilibrium and reduce damage.

Important Basement Flooding Concepts¶

• When basements fill with water, immediate pumping can create pressure imbalance
• Pumping too quickly creates pressure differential with outside groundwater
• Can cause foundation cracks and water infiltration
• Recommendation: Lower water levels slowly and in stages to allow equilibrium

Multiple Objective Management (MOM)¶

• Balances multiple community goals in floodplain management
• Considers watershed-wide impacts
• Examines environmental resources
• Balances losses vs. benefits in mitigation
• Promotes holistic and sustainable planning

⚠️ Environmental and Regulatory Considerations in Floodplain Management¶

Regulation / Agency	Role
US Army Corps of Engineers (USACE)	Responsible for wetland permitting under Section 404 of the Clean Water Act
Section 404, Clean Water Act	Regulates discharge of dredged or fill material into navigable waters and adjacent wetlands
Endangered Species Act (ESA)	Managed by US Fish and Wildlife Service and NOAA's National Marine Fisheries Service (NMFS)

• Local officials enforce Section 404 by investigating illegal dumping or dredging activities reported by citizens.
• Section 404 prohibits unauthorized discharge of materials into wetlands or navigable waters, protecting ecosystems.

Types of Flooding and Floodplains¶

Primary Types of Floodplains¶

1. Riverine - flooding that occurs along a channel
2. Coastal - flooding caused by storm surge and coastal topography
3. Shallow - flooding in flat areas with poor or no defined drainage

Riverine Flooding¶

• Occurs along channels when water overflows banks

• Features overbank flooding - the most common type of flooding in the US

• Starts in watershed tributaries and flows downstream

• May take days for flood crest to reach downstream areas after initial rainfall

• USGS and other agencies monitor river heights to warn residents

  

Coastal Flooding¶

• Caused by offshore storms (hurricanes, tropical depressions)
• Influenced by tidal cycles, coastal topography, and bathymetry
• Creates storm surge - water pushed toward shore by persistent winds and pressure changes
• Includes tsunamis generated by seismic events
• Can feature ice floe movements in larger lakes

Shallow Flooding¶

• Occurs in areas with little slope and no defined channels
• Water accumulates and spreads out, causing widespread flooding
• Often overlooked in dry-season basins or watershed recharge areas
• Cypress domes are natural depressions prone to this flooding
• Sheet flow is floodwater that spreads over large areas at relatively uniform depth

Flash Flooding¶

• Occurs in hilly/mountainous areas
• May arrive within minutes after heavy rainfall
• Also occurs in urban areas due to impervious surfaces and drainage systems

Flood Maps and Zones¶

• Base Flood Elevation (BFE): Elevation of the 100-year (1% annual chance) flood

• Special Flood Hazard Area (SFHA): Base floodplain displayed on FEMA maps (A and V zones)

• The Limit of Moderate Wave Action (LiMWA) line is crucial for determining construction requirements and flood insurance rates.

  • It represents the inland boundary of an area where 1.5-foot or greater breaking waves are expected during a 1-percent-annual-chance flood event.

  

Standard Flood Zones and Their Meanings¶

• Zone A: Base floodplain with no BFEs provided
• Zone AE: Base floodplain with BFEs provided (replaces A1-30 on newer maps)
• Zone AH: Shallow flooding in ponding areas with BFEs
• Zone AO: Shallow flooding areas with depths provided (not elevations)
• Zone A1-30: Numbered zones showing BFEs (older maps)
• Zone A99: Areas protected by levees under construction
• Zone AR: Areas where flood protection systems are being restored

V Zones (Coastal High Hazard Areas)¶

• Zone V: Coastal areas subject to high velocity wave action without BFEs

• Zone VE: Coastal high hazard areas with BFEs (replaces V1-30)

  

  

Other Zones¶

• Zone B/X (shaded): Moderate flood hazard (between 100-year and 500-year floods)

• Zone C/X (unshaded): Minimal flood hazard (above 500-year flood)

• Zone D: Undetermined but possible flood hazard

  

  

Flood Map Reading Tips¶

• Reference the map legend for interpretation
• In Zone AO, numbers indicate depth, not elevation
• In AH zones, numbers indicate BFE
• Depth less than 1 foot → Zone B (shallow flooding)
• Depth 1-3 feet → Zone AO (shallow flooding with ponding)
• Newer FIRMs use "80s zones" (e.g., AE) instead of older "numbered zones" (A1-30)

📚 Important Concepts and Clarifications¶

• 100-year flood: A flood event with a 1% chance of occurring in any given year. More common than a 500-year flood.
• 500-year flood: A flood event with a 0.2% chance of occurring in any given year; much rarer.
• The area between 100-year and 500-year floods is the moderate flood hazard zone (Zone B).
• Shallow flooding cutoff: Depths less than 1 foot fall into Zone B; depths of 2 feet or more may be classified as AO.
• Flood zones are often depicted with shading on FIRMs; gray-shaded areas often represent these shallow flood risk zones.
• Flood zones like B and C are often unshaded or lightly shaded, but their distinctions are important for insurance and planning.

Week 1: NFIP and Floodplain Management Quiz¶

1. What are the three major parts (or "pillars") of the NFIP?
   a) Insurance, Mapping, and Regulation
   b) Insurance, Recovery, and Enforcement
   c) Mapping, Monitoring, and Mitigation
   d) Development, Insurance, and Emergency Response

2. In the NFIP structure, who develops the policies and laws, and who enforces regulations?
   a) FEMA develops policies; states enforce regulations
   b) Federal government develops policies; local communities enforce regulations
   c) States develop policies; FEMA enforces regulations
   d) Local communities develop policies; federal authorities enforce regulations

3. What does the Community Rating System (CRS) affect?
   a) The level of flood insurance coverage available to homeowners
   b) The amount of disaster assistance following a flood
   c) Discount rates for flood insurance through improved floodplain management
   d) The classification of flood zones in a community

4. What is the definition of a "floodway"?
   a) Any area where flooding commonly occurs
   b) The channel of a river and adjacent land reserved to discharge the base flood without raising water levels significantly
   c) Areas protected by levees and flood control structures
   d) The entire 100-year floodplain area

5. What type of flooding is characterized by water that spreads out over a large area that does not have defined channels?
   a) Riverine flooding
   b) Flash flooding
   c) Sheet flow
   d) Overbank flooding

6. What is the difference between hydrostatic and hydrodynamic forces in flooding?
   a) Hydrostatic forces are vertical, hydrodynamic forces are horizontal
   b) Hydrostatic forces affect buildings, hydrodynamic forces affect infrastructure
   c) Hydrostatic is pressure from standing water, hydrodynamic is from moving water
   d) Hydrostatic forces occur inland, hydrodynamic forces occur in coastal areas

7. Which flood zone represents coastal areas subject to high-velocity wave action?
   a. Zone A
   b. Zone V
   c. Zone X
   d. Zone D

8. What is a correct recommendation for handling basement flooding?
   a) Pump water out as quickly as possible
   b) Lower water levels slowly in stages to allow equilibrium
   c) Add concrete walls to resist water pressure
   d) Allow basements to fill completely before pumping

9. What does the letter "E" in Zone AE indicate?
   a) Elevated risk
   b) Emergency designation
   c) Base flood elevations are provided
   d) Erosion hazard area

10. Which of the following statements about floodplain mapping is true?
    a) Zone C is at higher risk than Zone A
    b) FIRMs show precise (unrounded) BFEs
    c) FIS is less detailed than FIRMs
    d) BFEs on FIRMs are typically rounded to the nearest foot

Answer Key¶

1. a) Insurance, Mapping, and Regulation
2. b) Federal government develops policies; local communities enforce regulations
3. c) Discount rates for flood insurance through improved floodplain management
4. b) The channel of a river and adjacent land reserved to discharge the base flood without raising water levels significantly
5. c) Sheet flow
6. c) Hydrostatic is pressure from standing water, hydrodynamic is from moving water
7. b) Zone V
8. b) Lower water levels slowly in stages to allow equilibrium
9. c) Base flood elevations are provided
10. d) BFEs on FIRMs are typically rounded to the nearest foot