Liberty Lake Watershed Analysis

Brian E. Drake The University of Texas at Austin

April 24, 2007

CE394K.2 - Hydrology

Outline Geologic Formation and Background

Vegetative Zone of Influence

HEC-HMS

Geologic Formation Creek dammed by ice sheet Lake Missoula flood deposits

http://nwcreation.net/articles/missoulaflood.htm

Lake Missoula Present roughly 12,000 years ago Covered much of western Montana Volume = 530 mi3 Ice Dam = 2500 ft

http://www.pbs.org/wgbh/nova/megaflood/lake.htmlhttp://www.glaciallakemissoula.org/story.html

http://www.uwsp.edu/geo/projects/geoweb/participants/dutch/VTrips/LkPendOr.HTM

The Floods Likely multiple floods Peak flow = 386 x 106 cfs Velocity = 30-50 mph

http://www.uwsp.edu/geo/projects/geoweb/participants/dutch/VTrips/Scablands0.HTMhttp://pirlwww.lpl.arizona.edu/~turtle/photos/PTYS594A_Wash030.html

Liberty Lake Deposits

Lake and Watershed Characteristics Lake = 708 acres Watershed = 14 mi2 15 miles east of Spokane, WA

Outline Geologic Formation and Background

Vegetative Zone of Influence

HEC-HMS

Motivation Coupling hydrological/biological processes Example: Transpiration causing diel

streamflow fluctuations Improve process interactions and water

balance accuracy

(Bond et al. 2002)

Data Collection Stilling well Hourly depth records Calibrated to flow

Vegetative Water UseMay 2003 5-Day Streamflow

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

5/14 5/15 5/16 5/17 5/18 5/19 5/20 5/21

Time

Flow

(cfs

)

Measured Q

Missing Q

Baseflow

June 2003 5-Day Streamflow

0.00

0.50

1.00

1.50

2.00

2.50

3.00

6/15 6/16 6/17 6/18 6/19 6/20 6/21 6/22

Time

Flow

(cfs

)

Measured QMissing QBaseflow

July 2003 5-Day Streamflow

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

7/15 7/16 7/17 7/18 7/19 7/20 7/21

Time

Flow

(cfs

)Measured QMissing QBaseflow

Zone of Influence Transpiration Rates

2.4 – 330 ft3/acre/hr Used 120 ft3/acre/hr for

computations

Month Width of Influence, W (ft)

May 12

June 29

July 24

W

Outline Geologic Formation and Background

Vegetative Zone of Influence

HEC-HMS

Goals Gain exposure to HEC-HMS Define storm capable of causing lake

property damage Adjudicated lake elevation = 2049.51 Flooding at 2054’

Results to Date2 yr – 6 hr Storm Peak Flow = 24.4 cfs Volume = 4.9 acre-ft

100 yr – 24 hr Storm Peak Flow = 6376 cfs Volume = 871 acre-ft

Conclusions Past changes may give insight to future Diel streamflow fluctuations can be used

to quantify vegetative zone of influence Very dependent on transpiration rates MODIS Leaf Area Index (LAI)

HEC-HMS is a powerful tool for rainfall-runoff modeling Still need to determine storage-elevation

relationship

Questions?