Transcript Modeling Storm-Induced Inundation on the Yukon Kuskokwim Delta for Present and Future Climates Kashunuk R. 10 km 10 km Tom Ravens and Jon Allen, Univ.

Modeling Storm-Induced Inundation on the Yukon
Kuskokwim Delta for Present and Future Climates
Kashunuk R.
10 km
10 km
Tom Ravens and Jon Allen, Univ. of Alaska Anchorage
Research Goal: determine the likely
change in YK Delta ecology due to storm
surges – enhanced by sea level rise
• Tasks:
– Develop and validate a storm surge model
– Identify a number of representative storms from the past 40 years
– Model these storms and their inundation under present climate
conditions
– Re-model these storms assuming one or more sea level rise scenarios
– Compute an inundation index from each model run
– Compute an annual inundation index based on inundation indices
from selected storms
– Establish the relationship between annual index and ecological
parameters (e.g., vegetation type) under present climate
– Infer changes in ecological parameters (e.g., vegetation type) under a
future climate based on projected changes in inundation index
Storm surge modeling course grid model domain
YK Delta
Storm surge modeling –
fine scale model of YK Delta
Hooper Bay
Kashunuk River
Measured and Modeled storm surge at
coast on YK Delta
3
measurement
2.5
model
water level (m, msl)
2
1.5
1
0.5
0
-0.5
-1
11/9/2009
11/10/2009
11/11/2009
11/12/2009
date (local time)
11/13/2009
11/14/2009
Storms to study
1
Nov 74
Max surge1
(ft MLLW Hooper
Bay)
13.57
2
Oct 92
11.70
10–15
981.6
51.2 SSE
3
Oct 95
11.60
10
998.3
49.7 SE
4
Oct 96
10.78
5–10
1008.4
39.6 S
5
Nov 96
11.60
10
975.0
49.7 SE
6
Oct 04
11.83
15
975.7
43.4 SW
7
Sept 05
8
Nov 06
9
Nov 09
1
0
Nov 11
Storm
Date
1Chapman
Return
period1
(yr)
50
Min Surface
Pressure1
(mb)
978.6
Max wind1
(mph
direction)
45.6 SSW
Max surge
Kashunuk2
(Ft, MLLW)
Estimated return
period (yr, Kashunuk
River
9.6
5
11.9
15
7.6
1
et al. Storm-Induced Water Level Prediction Study for the Western Coast of Alaska, USACE. Reported surge is for
Hooper Bay. It does not include tides.
2 Calculated using ADCIRC (course grid) and DELFT3D (fine grid) models. Reported surge is for lower Kashunuk River. It does not
include tides.
15 year, 4 m
1 year, 2.5 m
5 year, 3.2 m
GMT
AK time
1 year storm inundation index
wide view
close-up
[m-days]
[m-days]
5 year storm inundation index
wide view
close-up
[m-days]
[m-days]
15 year storm inundation index
wide view
close-up
[m-days]
[m-days]
Annual Inundation Index for current climate based on a weighted average
of indices from the 1, 5, and 15 year storm (using weights of 1, 1/5, 1/15 - approximately)
Nearshore Inundation
Index dominated by
contribution of 1-year
storm
Inland Inundation
Index dominated by
contributions of 5
and 15-year storms
[m-days/yr]
Correspondence between 1-2 m-day/yr annual Inundation Index and presence of Brackish
Wet Sedge Meadow in current climate
Brackish wet sedge
meadow
1-2 m-days/yr
[m-days/yr]
Annual Inundation Index – current climate
Annual Inundation Index – future climate
1-2 m-days/yr
1-2 m-days/yr
[m-days/yr]
[m-days/yr]
7 km translation of 1-2 m-days/yr annual Inundation Index region – suggesting a
similar shift in the location of the Brackish Wet Sedge Meadow vegetation type
Conclusions
• Preliminary model validation efforts indicate that
the model works reasonably well for 1-yr storm.
• The annual inundation index was well-correlated
with vegetation type.
• The annual inundation index increased
significantly with the assumed 0.4 m sea level
rise.
• Significant shifts in vegetation are expected with
a 0.4 m sea level rise.
Future Work
• Include wind and wave action in storm surge model.
• Do additional model validation including use of aerial
images of inundation extent to calibrate overland flow
roughness.
• Study additional storms and calculate return period of
those storms at the Kashunuk River mouth.
• Analyze the relationship between annual inundation index
and vegetation type more precisely.
• Examine the relationship between inundation index and
bird/nest abundance.
• Model and analyze pond water quality.
• Model and analyze geomorphic change.
Collaborators and supporters
•
•
•
•
•
Craig Ely, John Terenzi (USGS, Alaska)
Torre Jorgenson (Ecoscience)
Raymond Chapman, Ken Eisses (USACE)
Steven Gray (USGS AK Climate Science Center)
Joel Reynolds, Karen Murphy (Western Alaska
Landscape Conservation Cooperative)
• Sarah Saalfeld (USFWS)
Questions?