SNOW HYDROLOGY (GEOG 4321): HOMEWORK ASSIGNMENT 10

Instuctor: Mark Williams
Telephone: 492-8830

Homework 10

• Assigned March 30
• Due April 4, 5 pm
• There are 40 possible points.

Meltwater Flow through Snow (10 points)

Explain why understanding meltwater flow through snow is so difficult to understand from first principles. Include these words in your answer: preferential flowpaths, grain size, capillary flow, gravitational flow, intrinsic permeability. 2 pages max.

Ablation Stakes (20 points)

You have the following results from snow surveys in an alpine basin in Colorado during one summer season. Survey dates are about two weeks apart.

Daily Ablation is the average lowering of the snow surface in the interval preceding the date recorded.

The area of the basin is 2 km².

Snowmelt started on May 15.

Sampling Date	Density	Ablation	Snowcover
----	kg/m3	cm	%
May 15	390	0.0	93
June 1	400	2.0	92
June 15	420	1.5	95
July 1	450	2.2	90
July 15	500	3.0	85
July 31	510	4.2	50
Aug. 15	520	4.5	28
Sep. 1	540	4.3	15
Sep. 15	550	3.0	7
Sep. 30	550	2.1	3

1. How much water has been produced by snowmelt in the basin during the summer.
2. Graph the changes in density, ablation rates, snow-covered area and water production change during the sampled period.
3. Briefly, account for these changes.

Martinec-Rango Snowmelt Runoff Melt (SRM) (10 points)

Lets calculate the amount of snowmelt from the basin above for the time period 15 May to 1 June.

Remember, SRM calculates basin-wide snowmelt using this formula:

Our data are as follows:

• C = 60%, the basin runoff coefficient
• a = 0.5 cm per degree C per day, the degree day factor
• T = 200 degree C day, the number of degree days
• S = 0.91, ratio of SCA to total basin area
• P = 0.0, the amount of new precipitation
• A = 2 km², the area of the basin.

Be sure and show the starting equation and all your work.

How does the amount of snowmelt calculated using the SRM compare to using ablation states?