An Evaluation of the Boulder Creek Local Flood
Warning System
Eve Gruntfest, Kim Carsell, and Tom Plush
Department of Geography and Environmental Studies
University of Colorado at Colorado Springs
Prepared for
Urban Drainage and Flood Control District
Boulder City/County Office of Emergency Management
May 2002
An Evaluation of the Boulder Creek Local Flood
Warning System
Eve Gruntfest, Kim Carsell, and Tom Plush
Department of Geography and Environmental Studies
University of Colorado at Colorado Springs
PO Box 7150
Colorado Springs, CO 80933
(719) 262-4058
[email protected]
Prepared for
Urban Drainage and Flood Control District and
Boulder City/County Office of Emergency Management
May 2002
Disclaimer
This report reflects the views of its authors and does not necessarily
represent the views of Urban Drainage and Flood Control District or
Boulder City/County Office of Emergency Management
TABLE OF CONTENTS
EXECUTIVE SUMMARY ........................................................................................ 1
Findings and Recommendation from Public Survey..................................... 2
Findings and Recommendations from MACS and Other Agencies.............. 7
SECTION I: LITERATURE REVIEW ..................................................................... 10
Boulder Creek Drainage Basin and Flood History........................................ 10
Integrated Warning System.......................................................................... 11
Challenges in the Warning Process ............................................................. 12
Public Response ........................................................................................ 13
SECTION II: BOULDER WARNING SYSTEM ...................................................... 16
Methodology ................................................................................................ 16
Detection Subsystem ...................................................................................16
Management Subsystem ............................................................................. 18
Warning Methods ......................................................................................... 20
SECTION III: CASE STUDIES .............................................................................. 22
Flood Control District of Maricopa County, Arizona...................................... 22
Utilities-Stormwater Department, Fort Collins, Colorado .............................. 24
Clark County Regional Flood Control District, Nevada................................. 26
SECTION IV: MACS COMMITTEE ....................................................................... 28
Methodology ................................................................................................ 28
Findings and Discussion .............................................................................. 28
Detection ........................................................................................... 28
NWS
Private Meteorologist
Stream/Rain Gauge Network
DIADVISOR
Notification of MACS Committee ....................................................... 29
Notification of Public ..........................................................................30
Public Response ............................................................................... 30
Participant Ability ............................................................................... 30
Staff Ability ........................................................................................ 30
Flow of Communication ..................................................................... 31
Concerns ........................................................................................... 31
Suggestions....................................................................................... 32
UDFCD Flood Prediction and Notification Services.......................... 32
SECTION V: RESIDENTIAL FLOODPLAIN OCCUPANT SURVEY .................... 33
Methodology ................................................................................................ 33
Survey Response Rate ................................................................................ 34
Demographic of Participants ........................................................................ 35
Participant Demographics Compared to Other Enumerations...................... 38
Findings and Discussion .............................................................................. 40
Knowledge of Location in 100-Year Floodplain ................................. 40
Knowledge and/or Retention of Flash Flood Information .................. 41
Risk Awareness................................................................................. 43
Ownership of Risk ............................................................................. 46
How to Warn About Imminent Flash Flooding ................................... 48
Overwarning vs. Underwarning ......................................................... 49
Potential Response In Flash Flood Event..........................................51
Weather And Flash Flood Information ............................................... 54
Communication Technologies .......................................................... 56
Other Noteworthy Findings................................................................ 57
SECTION VI: NON-RESIDENTIAL FLOODPLAIN OCCUPANTS........................ 58
Methodology ................................................................................................ 58
Boulder High School .................................................................................... 58
Boulder Public Library .................................................................................. 60
Millennium Harvest House Hotel .................................................................. 63
Naropa University......................................................................................... 64
CU Student Family Housing ......................................................................... 64
CU Family Housing Children’s Center.......................................................... 66
SECTION VII: SUGGESTIONS FOR FUTURE RESEARCH ................................ 69
BIBLIOGRAPHY .................................................................................................... 70
APPENDIXES.........................................................................................................
A. MACS Survey .........................................................................................I
B. Responses from MACS .........................................................................A
C. Data from Boulder Warning System Survey ...........................................a
LIST OF TABLES
SECTION I: LITERATURE REVIEW ..................................................................... 10
Table 1: Important Studies of Public Perception/Response ...................... 15
SECTION II: BOULDER WARNING SYSTEM ...................................................... 16
Table 2: HDR Messages to Boulder County
SECTION V: RESIDENTAL FLOODPLAIN OCCUPANT SURVEY ..................... 33
Table 3: Survey Mailings ........................................................................... 34
Table 4: Survey Response Rate ............................................................... 34
Table 5: Gender Division of Participants ................................................... 35
Table 6: Age Division of Participants......................................................... 35
Table 7: Tenure of Participants ................................................................. 36
Table 8: Highest Education Level Obtained by Participants...................... 37
Table 9: English Spoken By Everyone in Household ................................ 37
Table 10: University of Colorado Affiliated .................................................. 37
Table 11: Warning Study Demographic ......................................................39
Table 12: Survey Questions Used in Analysis............................................. 40
Table 13: 100-Year Floodplain Residency .................................................. 40
APPENDIX B .......................................................................................................... 78
Table 14: MACS Responses ....................................................................... 78
LIST OF FIGURES
SECTION II: Boulder Warning System ............................................................... 16
Figure 1: UDFCD ALERT Gages ................................................................ 16
Figure 2: Climb to Safety Sign.....................................................................20
SECTION III: CASE STUDIES ............................................................................... 22
Figure 3: Fort Collins 530am .......................................................................25
Figure 4: High Water Marker ....................................................................... 26
Figure 5: Clark County Billboard Advertising............................................... 27
SECTION IV: MACS COMMITTEE ....................................................................... 28
Figure 6: Confidence in Detection System .................................................. 29
Figure 7: Confidence in Public, Participant, and Staff Response ................ 31
Section V: RESIDENTAL FLOODPLAIN OCCUPANT SURVEY ......................... 33
Figure 8: General Flash Flood Knowledge .................................................. 41
Figure 9: Ready Freddy .............................................................................. 42
Figure 10: Risk Awareness .......................................................................... 44
Figure 11: Other Methods to Evaluate Knowledge of Flash Flood Risk ....... 46
Figure 12: Ownership of Flash Flood Risk ................................................... 47
Figure 13: Preferred Method of Warning ..................................................... 48
Figure 14: More Warning Preferred............................................................. 50
Figure 15: False Alarms Do Not Necessarily Reduce Confidence .............. 50
Figure 16: Potential Actions During Heavy Rain ......................................... 51
Figure 17: Potential Actions at a Flooded Intersection ................................ 52
Figure 18: Potential Actions Upon Call From OEM ..................................... 53
Figure 19: Source of Flash Flood Information ............................................. 54
Figure 20: Source of Information on Local Weather Conditions .................. 55
Figure 21: Frequency of Seeking Local Weather Conditions ...................... 55
Section VI: NON-RESIDENTAL FLOODPLAIN OCCUPANT INTERVIEWS....... 58
Figure 22: Boulder High Parents, Perceived Action in Flash Flood ............ 60
Figure 23: Potential Actions at Boulder Public Library, Flash Flood............ 62
Figure 24: Knowledge of Emergency Plans by Housing Complex .............. 66
Figure 25: CU Children’s Center Parents, Potential Action, Flash Flood .... 67
ACKNOWLEDGEMENTS
We appreciate the opportunity provided by Kevin Stewart of Urban Drainage and
Flood Control District who had the courage and perseverance to initiate and
support this research. We thank Larry Stern of the Boulder City/County Office of
Emergency Management for his encouragement, support, and inspiring
charisma.
Thanks to those who assisted with the development of the survey.
Tom Carney, CU Department Of Public Safety
Sylvia Dane, CU Natural Hazard Research And Applications Information
Center
John Handmer, Centre For Risk Community Management, RMIT
University, Australia
Ricky Martinez, CU Student Family Housing
Dennis Mileti, CU Natural Hazard Research And Applications Center
John Sorensen, Oak Ridge National Laboratory
Gilbert White, Professor Emeritus, Geography, University Of Colorado
We appreciate those who spent time providing information about their various
organizations
Luli Bevis, CU Family Housing Children’s Center
Sam Hartman, Boulder Library
Randy Heizarman, Millennium Hotel
Marsh Hilmes-Robinson, Fort Collins Stormwater Utility
Dale Hobbs And Bob Martin, Boulder Valley School District
Steve Waters, Maricopa County Flood Control District
Amy Wayne And Lisa Richie, Naropa University
Thanks to the 319 Boulder residents who participated in our survey and provided
information on their perceptions of flash floods and their flash flood preparedness
activities. Thanks also to the 21 MACS committee members who participated in
our online survey.