Incorporating Climate Change, Risk, and Resilience into Hydrologic Design

Procedures for Transportation Infrastructure

Roger Kilgore, Kilgore Consulting and Management Brian Beucler, Robert Kafalenos, Joe Krolak, and Cynthia Nurmi,

Federal Highway Administration George Herrmann, Desert Sky Engineering

Wilbert O. Thomas, Jr., Michael Baker International David Thompson, Thompson Hydrologics

NAS Conference September 16-18, 2015

Washington, DC

Why do we care? Floods have destructive power!

Hydraulic Engineering Circular 17 (HEC-17)

Title: Highways in the River Environment- Floodplains, Extreme Events, Risk, and Resilience. Part of FHWA’s anticipated implementation plan for the Federal Flood Risk Management Standard. Intent: Best available and actionable engineering and scientific data and approaches.

Table of Contents

1. Introduction 2. Federal Floodplain Policy 3. Riverine Flood Events 4. Risk and Resilience 5. Climate Change 6. Analysis Framework 7. Case Studies

Chapter 3: Riverine Flood Events

What is an extreme flood event?

Nonstationarity

Watershed changes Climate change “Natural variability”

Hydrologic Methods: Statistical

100

where:

0.52 0.24

Q100 = estimate of the 100-year peak, ft3/s

Can this approach accommodate watershed or climate changes? Can climate models provide precipitation?

A = watershed drainage area, mi2

P = mean annual precipitation, in

Hydrologic Methods: Rainfall Runoff

Q=CiA where:

Q = estimated peak discharge, ft3/s C = runoff coefficient, dimensionless i = average rainfall intensity, in/h A = watershed drainage area, acres Same questions…different answers…

Chapter 4: Risk and Resilience

Risk: Combined effect of consequence and probability of failure. Resilience: “adapt” “recover” from failure. Examine “What is failure” Violation of a standard or criteria Delay or inconvenience Property/infrastructure damage Loss of life

Consequences to Action and No Action

No Trend in Floods HO

Trend in Floods HA

Do Not Adapt

1-α β Type II Error (under-prepare)

Adapt α Type I Error (over-invest)

1-β

Chapter 5: Climate Change

Future projections (models and scenarios) Precipitation: average annual versus 1 hour 50 year event. Data sources

Chapter 6: Analysis Framework

Levels of effort Recommended steps Best available and actionable data and methods.

Chapter 7: Case Studies

Examples to illustrate concepts Lessons learned: Cumulative

conservativism Approach to

uncertainty What is important?

T h a n k y o u

RKilgore@KCMwater.com