Snow Melt - Technical Reference

Snow melt is an important phenomena that can dramatically affect the spring runoff timing and volume. Therefore, a realistic description of the snow melt process is important.

The current snow melt module is a modified degree-day method. That is, the rate of melting increases as the air temperature increases. Degree-day based methods are commonly used in hydrology because the models require limited additional data and are relatively simple to calibrate.

Energy balance methods are also widely used, but require considerably more detailed input data. Further, the energy balance methods are often layer based (i.e. multi-layered snow models) and the energy balance is often calcu­lated implicitly. Both of these factors could significantly impact the solution time.

In general, degree-day methods are most applicable in open and lightly for­ested areas. Whereas, energy balance methods are better for mountainous and densely forested areas. However, well-parameterized degree-day method, such as the one available in MIKE SHE, can usually be calibrated for all climatic conditions.