INTRODUCTION TO HYDROLOGY (GEOG 3511):
HOMEWORK ASSIGNMENT 6

Instructor: Mark Williams
Telephone: 492-8830

EXERCISE 6

ENERGY BALANCE AND SNOWMELT RUNOFF CALCULATIONS

Section	Lab	Assigned	Due
012,013	Tuesday	Tuesday, Oct 16	Friday, Oct 19
011	Thursday	Thursday, Oct 18	Monday, Oct 22

• 40 possible points.
• SHOW ALL YOUR WORK.
• WRITE THE QUESTION AT THE START OF EACH ANSWER.

Energy Balance of a Snowpack

The timing and magnitude of snowmelt runoff is a direct function of the energy balance of the snowpack.

Objective

The objective here is to understand the relative contributions that different energy fluxes contribute to snowmelt runoff.

1. Calculate the cold content of a snowpack given these conditions (5 points):
   1. average snow temperature of -5 degrees C;
   2. snow depth of 2 m; and
   3. average snow density of 300 kg/m³.
2. Calculate the amount of heat added to a snowpack at 0 degrees C from 3.5 cm of rainfall with a temperature of 1 degree C (5 points).
3. Calculate the amount of water output that is produced from snowmelt on a day when the total net energy input is 150 cal/cm² (5 points).
4. Answer the following questions about radiation, given (15 points):
   • incoming solar radiation is 620 W/m²;
   • snow albedo is 0.92;
   • snow temperature is -6 degrees C;
   • incoming longwave radiation is 10% of the longwave emission from the snowpack; and
   • emissivity of snow is 0.97.
   1. net incoming shortwave radiation;
   2. longwave emission from the snowpack; and
   3. net radiation.
5. Calculate a) the amount of energy available for snowmelt and b) the depth of water equivalent melted, given these values measured every second for 10 hours (10 points):
   • net shortwave radiation is 600 W/m²;
   • net longwave radiation is -310 W/m²;
   • heat energy from rain is 50 W/m²;
   • ground heat is 50 W/m²;
   • sensible heat is 470 W/m²; and
   • latent heat is -310 W/m².