Post on 23-Feb-2016
description
transcript
PATRICK SEJKORANOVEMBER 17 , 2009
GIS IN WATER RESOURCES
Yellowstone Fires and Their Hydrologic Effects
Yellowstone National Park 1988 Fires
1988 driest summer on record
7 major fires burned June-September 1988
3,215 km2 (36% of park) burned 485 km2 on August 20
alone!Fires extinguished in
September by rain/snow
Objectives
Did fires augment surface water runoff regimes in Yellowstone?
Hypothesis: Evapotranspiration and infiltration rates decrease in burned areas1, increasing runoff
Evaluate using runoff ratio:
Is runoff ratio post-fires higher than pre-fires?
1. Robichaud 2000
GIS DATAPark outline and Digital Elevation Map (DEM)
NHD Flowlines and USGS Gage Sites
Burn Type Raster
Compare runoff ratios between heavily burned and unaffected (control) watersheds
Before Fire After Fire
Firehole River
Boundary Creek
Firehole River(burned/experimental watershed)Baseflow 7.37 m3/s
724 km2 watershed (obtained with ArcHydro Terrain Preprocessing)
288 km NHD flowline
Drainage Density of 0.40/km
4th order stream at gage
Janua
ry
March May Jul
y
Septe
mber
Novem
ber
02468
10121416
Mean flow
Flow
(m
3/se
c)
Boundary Creek(unburned/control watershed)Baseflow 1.94 m3/s
224 km2 watershed
151 km NHD flowline
Drainage Density of 0.68/km
3rd order stream at gage
Janua
ry
March May Jul
y
Septe
mber
Novem
ber
012345678
Mean f...
Flow
(m
3/se
c)
4% 4% 1% 1
% 0%
90%
Canopy burnMixed burnNonforested burnUndifferentiated burnWaterUnburned
21%
14%
1%1%
0%
63%
Firehole River Boundary Creek
Precipitation Data Find similar precipitation events before and after 1988 fires
Obtain data from National Climactic Data Center
Interpolate rainfall across park via Spline
Pre-1988 Precipitation Event Spline raster can be used to estimate rainfall across watersheds
Zonal Statistics Tool in Spatial Analyst
July 10, 1987
July 11, 1987
September 18, 1989
0.6 cm
1.6 cm
1.6 cm
0.5 cm
1.7 cm
1.6 cmAv
erag
e Pr
ecip
itatio
n Ac
ross
Wat
ersh
eds
1.9
2
2.1
2.2
2.3
2.4
Dis
char
ge
(m3/
sec)
1.8
1.9
2
2.1
2.2
2.3
2.4
Dis
char
ge
(m3/
sec)
Boundary Creek
Pre-
Fire
Post
-Fir
eStorm Event Flow Conditions
9/9/19899/14/1989
9/19/19899/24/1989
6.8
7.3
7.8
8.3
8.8
Dis
char
ge (
m3/
s)
7/2/19877/7/1987
7/12/19877/17/1987
6.8
7.3
7.8
8.3
8.8
Dis
char
ge (
m3/
s)
Firehole River
Runoff Ratios
Boundary CreekPre-Fire RR = 1.1%Post Fire RR = 0.9%
Firehole RiverPre-Fire RR = 1.1%Post Fire RR = 0.9%
Runoff Ratio Example Calculation (Boundary Creek 9/18/1989)
These Runoff Ratios aren’t very different!
Conclusions
Runoff Ratios before and after fire are indistinguishable in burned watershed
An event’s runoff ratio same for both watershed
Suggests other factors besides landcover may influence runoff regimes Antecedent dry period, storm intensity, etc.?
Future Work
Evaluate other storm events using same methodology NEXRAD precipitation data for recent events
Similar effects for snow melt?
Questions?
Firehole River Boundary Creek
Lodgepole Pine, post disturbance
1%
Lodgepole Pine, climax
9%
Nonforested14%
Lodgepole Pine, suc-cessional
37%Engelmann
Spruce & Sub-alpine Fir, climax
2%
Douglas Fir, climax
2%
Pygmy Lodgepole
Pine36%
Lodgepole Pine, climax
25%
Nonforested5%
Lodgepole Pine, suc-cessional
66%
Engelmann Spruce & Subalpine Fir, climax
2%Pygmy Lodgepole Pine
1%
Lodgepole Pine, climax20%
Nonforested6%
Lodgepole Pine, post disturbance
38%
Lodgepole Pine, successional
34%
Engelmann Spruce & Subalpine Fir, climax
1%Pygmy Lodgepole Pine
1%
Firehole River Boundary Creek
Lodgepole Pine, post disturbance
1%
Lodgepole Pine, climax
9%
Nonforested14%
Lodgepole Pine, suc-cessional
37%Engelmann
Spruce & Sub-alpine Fir, climax
2%
Douglas Fir, climax
2%
Pygmy Lodgepole
Pine36%