FEMA Standards for Substantial Improvement / Substantial Damage Determinations

FEMA, 2010. Substantial Improvement / Substantial Damage Desk Reference, Federal Emergency Management Agency, Washington, DC

When buildings undergo repair or improvement, it is an opportunity for local floodplain
management programs to reduce flood damage to existing structures. More than 21,000 communities
participate in the National Flood Insurance Program (NFIP), which is managed by
the Federal Emergency Management Agency (FEMA). To participate in the NFIP, communities
must adopt and enforce regulations and codes that apply to new development in Special Flood
Hazard Areas (SFHAs). Local floodplain management regulations and codes contain minimum
NFIP requirements that apply not only to new structures, but also to existing structures which
are “substantially improved (SI)” or “substantially damaged (SD).”
Enforcing the SI/SD requirements is a very important part of a community’s floodplain management
responsibilities. There are many factors that local officials will need to consider and
several scenarios they may encounter while implementing the SI/SD requirements. This Desk
Reference provides practical guidance and suggested procedures to implement the NFIP requirements
for SI/SD.
This Desk Reference provides guidance on the minimum requirements of the NFIP regulations.
State or locally-adopted requirements that are more restrictive take precedence (often referred
to as “exceeding the NFIP minimums” or “higher standards”).

Who has to pay for the MRGO Closure and Wetlands Restoration?

Most Corps of Engineers wetlands projects require the state or other non-federal sponsor to pay for part of the cost. This is both a cost-sharing measure and a measure to make sure that the state really needs the project – without a match, state politicians would demand unlimited projects from the Corps as economic development. Louisiana generally tries to avoid paying the match on projects, but unless Congress passes a law waiving the match on specific projects, the state has to pay for what has been done and nothing new will be done until the state pay’s the necessary match. This dispute arises from the push to close the Mississippi River Gulf Outlet canal after Hurricane Katrina.

A Comprehensive Restoration Plan for the Gulf of Mexico

The Trustees have reached a settlement with BP to resolve BP’s liability for natural resource injuries from the Deepwater Horizon oil spill. Under this settlement, BP will pay up to $8.8 billion for restoration.

Based on our thorough assessment of impacts to the Gulf’s natural resources, we selected the comprehensive, integrated ecosystem restoration approach for restoration implementation. This approach is outlined in the comprehensive restoration plan, which will allocate funds from the settlement for restoration over the next 15 years.

Introduction to FEMA’s National Flood Insurance Program (August 2016)

CRS – Congressional Research Service Paper: Introduction to FEMA’s National Flood Insurance Program (August 2016)


The NFIP was established by the National Flood Insurance Act of 1968 (NFIA, 42 U.S.C. §4001 et seq.), and was most recently reauthorized by the Biggert-Waters Flood Insurance Reform Act of 2012 (Title II of P.L. 112-141). The general purpose of the NFIP is both to offer primary flood insurance to properties with significant flood risk, and to reduce flood risk through the adoption of floodplain management standards.

Suburban sprawl and poor preparation worsened flood damage in Louisiana

Suburban sprawl and poor preparation worsened flood damage in Louisiana

An excellent post by Professor Craig Colten on the events leading to the August 2016 flood:

Reports of flooding in Louisiana may conjure up images of Hurricane Katrina, but these rivers are completely separated from the Mississippi River, and these floods posed no threat to New Orleans. Nonetheless, based on my experience studying risk and resilience in this region, I see parallels between the damage of current flooding and the damage caused by Katrina. In both cases, human decisions magnified the consequences of extreme natural events. Planning and permitting enabled development in areas that had experienced repeat floods, and agencies had failed to complete projects designed to mitigate flood damage before the storms hit.

FEMA Proposes New Rules On Elevation for Rebuilding After Flooding

44 CFR Part 9 – Updates to Floodplain Management and Protection of Wetlands Regulations To Implement Executive Order 13690 and the Federal Flood Risk Management Standard; Proposed Rule

Executive Summary

The Federal Emergency Management Agency (FEMA) is proposing to amend 44 CFR part 9 “Floodplain Management and Protection of Wetlands” and issue a supplementary policy to implement the Federal Flood Risk Management Standard (FFRMS) that was established by Executive Order 13690.

Louisiana Flood of 1983 – Suing the State for Causing Flooding

The mayor of Walker, a small town near Baton Rouge that flooded in the August 2016 flood, wants to sue the State of Louisiana for flooding caused by the recent expansion of federal highway I12. (While the Federal Department of Transportation funds highway construction, the designed and construction is done by the state and its contractors.) A class action lawsuit was filed against the State after the 1983 flood, alleging that a different stretch of I12 blocked the drainage for a group of homeowners and caused them to flood. The plaintiffs were successful and won a sizable verdict against the state. Unfortunately, in Louisiana, there is no way to enforce a state court judgment against the State, so the plaintiffs were never able to collect the judgment.

FEMA Resources for Flood Resilient Construction

(original link)

Flood Resistant Provisions of the 2015 International Codes® (May 2015)

This document is a compilation of flood resistant provisions, prepared by the Federal Emergency Management Agency (FEMA), of the 2015 I-Codes (IBC, IRC, IEBC, IMC, IPC, IFGC, IFC, ISPSC, IPSDC, ICC-PC). Also included, as a separate document, is a summary of changes from the 2012 I-Codes.

What is a 100/500/1000 year rain event?

See Also: What is a 100/500/1000-Year Flood Event?


Hershfield, D.M., 1961. Rainfall Frequency Atlas of the United States, Technical Paper No. 40. Weather Bureau, US Department of Commerce, Washington, DC.

This started the 100 year rain event system. Although it was never intended to be about flooding, the notion of a 100 year event was later incorporated into the NFIP when it was passed in 1968.