Five points to consider for a more rational mitigation of flood risk:
First and foremost, decisions will vastly improve when we define AND MAKE WIDELY AVAILABLE the specific Expected Annual Cost and Present Value ($) of flood risk for every floodplain property. This is becoming increasingly easier with high resolution data/analytics/modeling. (In the US, the NFIP Risk Rating 2.0 is a very limited step that does not take full advantage of today's flood risk pricing technology and continues to substantially under- and over-price a lot of flood risk.) Note PV must incorporate reasonable estimates of future climate and landscape change. Every property-stakeholder should be encouraged to recognize their own responsibility for due diligence (i.e., understanding the PV of their flood risk and its impact on their property value), insuring, and mitigating their property-specific flood risk--as with all hazards! Second, the very definition resiliency and sustainability of any asset/property/community for flood risk means that all the necessary resources are available for timely and comprehensive recovery WHEN--NOT IF--flood damage occurs
. If an asset/property/community is subject to substantial damage and not being restored during its intended design life, then it isn't really resilient or sustainable. So there must be some sound private/public/public-private method of financing flood recovery. Potential methods include commercial insurance/reinsurance markets; government oversight; government-run insurance programs, public-private partnerships; post-disaster aid, etc. It is pretty clear that for just about any reasonably well-defined property-specific financial risk, well-regulated commercial insurance/reinsurance markets tend to provide an effective, efficient, and unbiased way to finance that financial risk.
Third, community officials should identify public mitigation and regulatory alternatives that might legitimately reduce aggregate EAC/PV--i.e., the collective cost of financing flood recovery; then determine the cost of implementing and maintaining the alternatives. This cost must include costs of preventing any adverse flood, environmental, economic, and social impacts. The officials can then pursue and optimize any reasonable measure that effectively reduces the aggregate cost of financing flood risk. Community officials should be very careful when it comes to mixing the objective of mitigating flood risk versus other public goals--such as environmental restoration and protection, development aesthetics, recreation, water supply, hydropower, etc. Dollars marked for flood risk reduction investment should only go to measures that will demonstrably reduce the PV of flood damages.
Fourth, ideally in most cases, those community property-stakeholders receiving the PV benefits of public flood risk mitigation should be the ones to largely pay for the mitigation; subsidizing and distorting flood risk should be avoided.
Fifth, where there has been past systemic discrimination in property ownership, governments should pursue measures to remedy unequitable distribution of flood financial risk. But in providing such measures governments should not continue to subsidize/distort flood risk.
Given the current variable state of technology and political commitment to rational flood risk mitigation, following these points presents more of a challenge in some communities (and parts of the world) than in others.
Robert Jacobsen P.E., M.ASCE
Baton Rouge LA
Sent: 12-27-2021 01:10 PM
From: Ebissa Gadissa
Subject: Flood control and River Engineering
How we can control floods? What are the mechanisms to control flash floods?
Ebissa Gadissa S.M.ASCE