1. GIS in Water Resources Term Project Fall 2004 Michele L. Reba
The effect of changing the vegetation layer on the mass of snowcover ISNOBAL output
GIS in Water Resources
Term Project
Fall 2004
Michele L. Reba

2. Background SNOW Modeling Profound effect on water resource management
Semi-arid mountain ranges 80% of precipitation
Planning/design
Modeling
Energy balance-ISNOBAL (energy & mass balance)
Temperature Index
ISNOBAL - model is a DEM grid-based energy and mass balance model
Temperature Index- empirical relationship between air temperatures and melt rates

3. Objective
Would an improved vegetation layer better simulate the mass of snowcover generated from ISNOBAL?

4. Site Description Reynolds Creek Experimental Watershed 239 sq. km.
Elevation range:
1101m to 2241m
18 active precip. gages
12 gages sub-basins
8 snow courses
Reynolds Mountain East
0.4 sq. km.
2023 m to 2139 m
7 sites-meteorological data
2 site - eddy covariance

5. Project Plan Generate Create new ISNOBAL vegetation input images image
Run ISNOBAL
Comparisons
new veg to old veg
new veg to photos
IPW images
to ARC

6. Data Collection Differential Geographic Positioning System
Classify aspen, fir, willow, low sage, big sage, grass
Correct layer
Generalize vegetation types
Generate wind-sheltered areas

7. ISNOBAL Figure generated by Adam Winstral
Three elements that do not require vegetation image
Air temp
Vapor Pressure
Soil Temperature
Go thru numbers
Net solar Move from sky thru clouds, veg, surface

8. ISNOBAL Two multi-band images Energy and mass flux Snow conditions
Energy balance terms (Net radiation, H, LvE, G ,M)
Total Evaporation, melt, runoff, cold content
Snow conditions
Depth, density, specific mass
Surface temp. of both layers, lower layer depth
Liquid water in snowcover, liquid water saturation

9. 12 May 1986 Holds more snow mass
Larger distribution of snow due to vegetation
Isolated cells
Not as much snow as photo

10. 27 May 1986 Drifts more defined Holds more snow mass
Larger distribution of snow
Isolated cells
Western edge

11. 03 June 1986 Defined drifts Holds more snow mass
Larger distribution of snow
Large drift
Central drift
Upper drift-shape

12. Conclusions Larger distribution of snowcover More snow in drifts
Some due to vegetation differences though not all
More snow in drifts
Timing-vegetation inventory / verification
Improve vegetation layers with new aerial photography
Time lapse photography of snowcover and meltout of sub-basin

13. Acknowledgements
Adam Winstral