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

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

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

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

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

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

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

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

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

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

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

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

Acknowledgements Adam Winstral