Post-Fire Runoff Parameter Recovery and Highway Protection after

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Post-Fire Runoff Parameter
Recovery and Highway Protection
after the Waldo Canyon Fire
Rich Ommert, P.E., CFM - RESPEC
Tony Tran, P.E., - RESPEC
CASFM 2015
September 23, 2015
PRESENTATION OVERVIEW
PART I. INITIAL RESPONSE TO WALDO CANYON FIRE
•
•
•
•
•
Multiple Agency Efforts to Reduce Flooding Threat
Post-Fire Watershed Characteristics
Improvements Implemented
August 2013 Waldo Canyon Flood Triggered Emergency Response
Emergency Response and Assessment
PART II. POST-FIRE RECOVERY HYDROLOGY AND
PARAMETER DEVELOPMENT
•
•
•
Rainfall
Sediment Movement and Bulking Factor
Runoff Curve Number (RCN) Recovery
PART III. MOVING FORWARD
•
•
•
Rainfall Monitoring
Evaluating Risk
Additional Improvements
CONCLUSION
PART I. INITIAL RESPONSE
Fire Statistics
•
•
•
•
Burned 18,247 Acres
Insurance Claims of $454 M
2nd Most Destructive Fire in Colorado
$5.5M+ State and Federal Funds for
Flood Work Repairs
Multi Agency Response: CUSP, RosgenWARSS, CDOT, Local Government
Photo Source: Wikipedia.org
Post-Fire Watershed Characteristics
Increased runoff immediately after the fire is affected
by several factors including the Soil Burn Severity. There
are three levels of burn severity as shown below.
Large areas in the upper watershed burned at a high
severity.
Photo Source: BAER Report
Post-Fire Mitigation Efforts (MM 291-298)
SEDIMENT AND BULKED FLOWS ARE AN
ON-GOING CHALLENGE
Sand Gulch (MM 291.5)
Wellington Gulch (MM 291.9)
SEDIMENT AND BULKED FLOWS ARE AN
ON-GOING CHALLENGE
Fern Gulch (MM 292.6)
Cascade (MM 293.7)
Williams Canyon
(MM 297.8)
AUGUST 9, 2013 FLOOD





Major Flooding and Damage
1 Fatality
Downstream ramp and bridge damage
Federal Disaster
Emergency Contracting
Radar Source:
Iowa Environmental Mesonet (IEM)
WALDO CANYON (MM 296.5)
•
Waldo Canyon: Post-Fire Improvements
•
Waldo Canyon: Post 2013 Flood Improvements (Bulked Flow = 2355 cfs)
April 2014
June 2014
RAINBOW FALLS (MM 297.2)
POST 2013 FLOOD
March
2014
June2015
Post 2013 Flood Response and
Assessment
• Increased monitoring of the corridor for rainfall and coordinated with the
National Weather Service (NWS) to monitor for Flash Flood Warnings
• Gate Closure Systems and Signage
• This worked but at a high cost of manpower
• Understanding the post 2013 flood hydrology:
– Recommended improved conveyance at Waldo Canyon Crossing.
– Sediment and debris capture to reduce impacts to downstream community.
– Channel and Trail repair at Rainbow Falls.
Understanding the post-fire recovery hydrology to
better evaluate future improvements
ADVANCE WARNING NETWORK
• Cameras & Closure
Gates Operational
• Camera feeds available
on Cotrip.org
PART II.
POST-FIRE RECOVERY HYDROLOGY AND
PARAMETER DEVELOPMENT
• Post-Fire Recovery Hydrology Analysis
– Rainfall
– Increased Sediment  Bulking Factor
– Runoff Curve Number (RCN) Recovery
HYDROLOGY OVERVIEW
•
•
•
•
HEC-HMS Model
SCS Runoff Curve Number (RCN) Loss Method and UH
1 hr Rainfall depth over a 1 hr Storm Distribution
USGS Resources
• Sediment Bulking Factor
• Runoff Curve Number (RCN) Recovery
RCN
Q
As watershed heals
RCN
Q
NOAA COLORADO SPRINGS DCM 5/2014
1-hr Rainfall Depths (in)
2-year
1.19
5-year
1.50
10-year
1.75
25-year
2.00
50-year 100-year
2.25
2.52
RAINFALL: STORM CLASSIFICATION
• Collect rainfall data
• Classify the frequency of storms
based on rainfall intensity and/or
depth and duration
Colorado Springs DCM
INTENSITY (in/hr)
*NOAA Atlas 14 Point Precipitation Frequency
Estimates:
Manitou Springs CO
Duration
5-min
10-min
15min
30-min
60-min
2-hr
3-hr
6-hr
12-hr
24-hr
1
0.231
0.339
0.413
0.594
0.763
0.931
1.03
1.22
1.45
1.71
Average Recurrence Interval (years)
2
5
10
0.276
0.354
0.423
0.405
0.519
0.619
0.494
0.633
0.755
0.71
0.912
1.09
0.894
1.14
1.36
1.08
1.36
1.64
1.17
1.47
1.77
1.38
1.73
2.1
1.67
2.11
2.57
1.99
2.54
3.08
100
0.689
1.01
1.23
1.78
2.33
2.88
3.23
3.92
4.74
5.58
*NOAA only uses a minimum record period of 30-years for frequency analysis
RAINFALL: AUGUST 9TH 2013 FLOOD
Storm Intensity and Duration
• August 9th, 2013 rainfall intensity - Lower Waldo Gauge
• Max rainfall intensity of 1.3” in 20 minutes, 5:30-5:50 PM
• Equivalent rainfall intensity of 3.9”/ hr for 20 minutes
• Storm Frequency: 10-25 year event (4% - 10% annual chance occurrence)
1.6
Cumulative Rainfall (in)
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0
10
20
30
Time (min)
40
50
60
SEDIMENT MOVEMENT & BULKING FACTOR
Summary of USGS Estimated Erosion from Debris Flows
Pour Point
Description
A
B
C
E
F
H
K
Sand Gulch
Wellington Gulch
Fern Gulch
Cascade
Marygreen Pines
Waldo Canyon
Williams Canyon
Drainage
Area
(mi2)
1.12
1.74
0.35
0.77
0.19
1.78
2.63
2-year/1-hour precipitation
1.14 in
Probability
Volume
(%)
(yd3)
6
20,928
48
53,628
45
10,595
54
22,236
1
2,354
31
51,012
32
81,096
• Volume and Probability of
Sediment loads are
dependent on :
10-year/1-hour precipitation 25-year/1-hour precipitation
1.65Moderate
in
1.89soil
in
1.
to high
Probability
Volume
Probability
Volume
burn
severity
(%)
(yd3)
(%)
(yd3)
13 2. Slopes
26,160> 30% 18
28,776
69
68,016
78
73,248
3.
Soil
properties
67
13,080
76
14,388
74
2
53
54
27,468
2,878
62,784
100,716
82
3
63
64
30,084
3,270
69,324
109,872
• Bulking Factor to account
for sediment entrained
flows (USGS)
SEDIMENT MOVEMENT & BULKING FACTOR
RCN RECOVERY: CURVE CALIBRATION
TC Calibration
1.2
e^(-t/TC)
1
TC=1
0.8
TC=2
0.6
TC=3
0.4
TC=4
TC=5
0.2
0
(Source: USGS)
0
2
4
6
8
Year Post-Fire
• Pre-Fire RCN
• Calibrated major storm to existing infrastructure capacity
• Little to zero runoff for minor event
• Post-Fire RCN  BAER Burn Severity / USGS Recommended RCN
• Decay coefficient “TC” Calibration
• HIGH TC  Flatter slope, Slower Recovery
• LOW TC  Steeper slope, Faster Recovery
10
12
Upper Waldo Canyon
Post-Fire Recovery RCN Calibration
Waldo Stream
Gauge Installed
March 2014
95
July 19, 2014
Qp Actual = 32.0 cfs
UW Qp Unbulked = 31.9 cfs, CN = 80.8
UW Qp Bulked = 22.7 cfs, CN = 79.5
90
Waldo Stream Gauge
Upper Waldo Gage Bulked
Weighted Gage Bulked
April 16-20, 2015
WT Qp Unbulked = 15.0 cfs, CN = 79
Weighted Runoff Curve Number
85
Waldo Gage Bulked
Upper Waldo Gauge Unbulked
Weighted Gague Unbulked
May 9, 2015
W Qp UnBulked = 36.0 cfs, CN = 77.8
W Qp Bulked = 25.5 cfs, CN = 76.0
80
Waldo Gauge Unbulked
USGS Theoretical Recovery Curve
CALIBRATION  TC = 3.5
April 16-20, 2015
UW Qp Unbulked = 15.2 cfs, CN = 78.5
UW Qp Bulked = 10.4 cfs, CN = 77.0
(1.5 Bulked Factor Used)
75
April 16-20, 2015
WT Qp Bulked = 9.4 cfs, CN = 76.0
70
May 17-19, 2015
WT Qp UnBulked = 29.2 cfs, CN = 74.8
WT Qp Bulked = 18.9 cfs, CN = 69.5
65
April 16-20, 2015
W Qp UnBulked = 15.0 cfs, CN = 73.0
W Qp Bulked = 10.8 cfs, CN = 70.5
RCN RECOVERY CURVE
60
0
1
2
3
4
5
6
7
8
9
10
Year Post-Fire
11
12
13
14
15
16
17
18
19
20
Calibrated Event : July 19, 2014
Calibrated Event : April 16-20, 2015
Burn Severity RCN Recovery Curve
100
High Burn Severity
Post-Fire (2012) RCN = 98
95
90% Recovery Moderate to High Burn
High Burn Severity, CN = 67.0
Moderate Burn Severity, CN = 66.4
Low Burn Severity, CN = 65.7
High Burn Recovery Curve
Moderate Burn Recovery Curve
Low Burn Recovery Curve
Runoff Curve Number
90
90% Recovery
Moderate Burn Severity
85
Low Burn Severity
80
75
70
Pre-Fire RCN = 63.5
65
60
2012
BAER Estimated Vegetative
Recovery Period 5-7 years
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
Year
2023
2024
2025
2026
2027
2028
2029
2030
2031
August 9th, 2013
Bob Jarrett, USGS Paleohydrologist
Q= 1,800 cfs
RESPEC Bulked
Q = 1,500 cfs
(pre-fire 100 cfs)
PART III.
MOVING FORWARD
Understanding the post-fire recovery hydrology to
better evaluate future improvements
•
•
•
•
Vegetation Recovery
Rainfall monitoring
Evaluate Risk
Additional Improvements
VEGETATION RECOVERY
USGS 2014 vs 2012 Post-Fire Vegetation Recovery
• Re-vegetation has an impact on the peak flows  RCN recovery
• Green areas are additional growth in 2014
Legend
2012 Soil Burn Severity
<all other values>
LAYER
_UNBURNED
Soil Burn Severity
_LOW
_MODERATE
_HIGH
RAINFALL MONITORING
US 24/WALDO CANYON BURN CORRIDOR EMERGENCY REPSPONSE PLAN
LIVE RADAR
WEATHER MONITORING
Date
Initials
Williams Canyon Abv
Mouth Near Manitou
Springs, CO
Station: 7103100
Waldo Canyon Abv
Mouth Near Manitou
Springs, CO
Station: 07100750
Live Camera
Live Camera
Lower Waldo Canyon Met
Abv Manitou, CO
Station:385241104560101
Fountain Creek at
Cascade, CO Station:
07100300
Sand Gulch Met Station
Upper Waldo Canyon Met
Abv Chipita Park, CO
Abv Cascade, CO
Station: 385653104583101
Station: 385449104565501
Live Camera
Daily
5-Day
Daily
5-Day
Daily
5-Day
Daily
5-Day
Daily
5-Day
Daily
5-Day
Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative Cumulative
5/1/2015
5/2/2015
5/3/2015
5/4/2015
KMP
KMP
KMP
KMP
0.02
0.00
0.00
0.01
2.00
1.21
0.00
0.01
0.03
0.00
0.11
0.28
0.89
0.05
0.11
0.28
0.00
0.00
0.07
0.28
0.56
0.00
0.07
0.28
0.01
0.01
0.16
0.33
1.28
0.13
0.16
0.33
0.00
0.00
0.12
0.36
1.69
0.98
0.12
0.36
0.04
0.00
0.20
0.19
1.61
1.06
0.20
0.19
5/5/2015
5/6/2015
5/7/2015
KMP
KMP
AJL
0.00
0.00
0.00
0.03
0.01
0.01
1.68
0.04
0.03
2.10
2.11
2.14
1.61
0.04
0.04
1.96
2.00
2.04
1.38
0.08
0.04
1.89
1.96
1.99
1.34
0.07
0.04
1.82
1.89
1.93
0.95
0.12
0.04
1.38
1.46
1.50
5/8/2015
AJL
0.01
0.02
5/9/2015
AJL
1.45
1.46
5/10/2015
AJL
0.90
2.36
5/11/2015
AJL
0.84
3.20
5/12/2015
AJL
0.03
3.23
5/13/2015
AJL
0.25
3.47
5/14/2015
AJL
0.03
2.05
5/15/2015
AJL
0.01
1.16
5/16/2015
AJL
0.05
0.37
5/17/2015
AJL
0.05
0.39
5/18/2015
THT
0.31
0.45
5/19/2015
THT
0.98
1.40
5/20/2015
THT
0.49
1.88
5/21/2015
THT
0.32
2.15
5/22/2015
THT
0.30
2.40
5/23/2015
THT
0.26
2.35
5/24/2015
THT
0.18
1.55
5/25/2015
THT
0.12
1.18
5/26/2015
THT
0.05
0.91
5/27/2015
THT
0.03
0.64
5/28/2015
THT
0.01
0.39
5/29/2015
THT
0.00
0.21
5/30/2015
THT
0.01
0.10
5/31/2015
THT
0.00
0.05
** box turns red when 5-day cummulative > 1.0" **
5-DAY CUMULATIVE RAINFALL COMMENTS
Waldo Canyon Gauge: Low intensity storm for 12.5 hours with average intensity =
0.12. Max 1 hr intensity = 0.96 in/hr, min 1 hr intensity = 0.0 in/hr
FFW 2:06 pm to 4:00 pm
1.03
3.06
1.03
3.00
0.84
2.67
0.71
2.52
0.51
Waldo Canyon Gauge: Low intensity storm for 5 hours and 20 minutes with
1.81 average intensity = 0.12. Max 1 hr intensity = 0.48 in/hr, min 1 hr intensity = 0.12
0.95
0.79
0.40
0.12
0.11
0.06
0.00
0.15
0.04
0.57
2.00
0.14
0.20
0.38
0.10
0.06
0.06
0.05
0.00
0.00
0.09
0.00
0.17
3.73
2.84
3.20
3.29
2.37
1.48
0.69
0.44
0.36
0.82
2.76
2.90
2.95
3.29
2.82
0.88
0.80
0.65
0.27
0.17
0.20
0.14
0.26
1.61
1.42
0.16
0.07
0.12
0.04
0.00
0.12
0.00
0.59
1.85
0.08
0.20
0.35
0.12
0.04
0.08
0.04
0.00
0.00
0.04
0.00
0.11
4.33
4.14
4.26
4.29
3.38
1.81
0.39
0.35
0.28
0.75
2.56
2.64
2.72
3.07
2.60
0.79
0.79
0.63
0.28
0.16
0.16
0.08
0.15
0.97
0.61
0.01
0.04
0.18
0.04
0.00
0.21
0.05
0.66
1.51
0.10
0.25
0.37
0.19
0.07
0.07
0.06
0.01
0.00
0.04
0.00
0.13
3.31
2.54
2.47
2.47
1.81
0.88
0.27
0.47
0.48
0.96
2.43
2.53
2.57
2.89
2.42
0.98
0.95
0.76
0.40
0.21
0.18
0.11
0.18
0.24
1.18
0.00
0.00
0.28
0.03
0.00
0.08
0.04
0.40
0.82
0.04
0.16
0.35
0.16
0.04
0.16
0.12
0.00
0.00
0.11
0.00
0.04
2.40
2.24
2.17
2.13
1.70
1.49
0.31
0.39
0.43
0.55
1.34
1.38
1.46
1.77
1.53
0.75
0.87
0.83
0.48
0.32
0.39
0.23
0.15
0.16
0.90
0.32
0.00
0.11
0.04
0.00
0.16
0.08
0.47
0.71
0.04
0.04
0.08
0.04
0.04
0.04
0.04
0.00
0.00
0.04
0.03
0.04
1.78
1.73
1.93
1.89
1.49
1.37
0.47
0.31
0.39
0.75
1.42
1.46
1.34
1.34
0.91
0.24
0.24
0.24
0.16
0.12
0.12
0.11
0.11
FFW 4:43 am to 7:45 am, 1:16 pm to 3:15 pm, 4:20 pm to 7:15 pm
Lower Waldo Canyon Gauge: Low intensity storm for 8.5 hours with average
FFW 6:22 am to 9:15 am
EVALUATING RISK
10-year Storm Event and Probability
ADDITIONAL IMPROVEMENTS
PROPOSED ALTERNATIVES TO IMPROVE CONVEYANCE
ADDITIONAL
SEDIMENT BASINS
CONCLUSION
• Forest fires create a significant change in the watershed
characteristics.
• As a result the watershed attempts to rebalance causing
debris flows and increased peaks
• An initial comprehensive approach can significantly reduce the
impacts downstream.
• Watershed stabilization
• Improved conveyance
• Sediment conveyance and deposition at identified locations
• On-going monitoring and identifying areas that require
additional improvements and evaluate risk to refine protection
to nearby and downstream users.
Questions?
[email protected]
[email protected]
www.respec.com

Post-Fire Runoff Parameter Recovery and Highway Protection after

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