Snow computations are accomplished in HEC-1 using separate, equally incremented, elevation zones within each basin. The number of elevation zones for which data must be defined is determined by specifying the base elevation of zone 1 and zone interval in the appropriate edit fields. The default values correspond to the lowest elevation and the range between the highest and lowest elevation (i.e. one elevation zone). More zones can be created by decreasing the interval, or lower elevations can be excluded from calculations by increasing the base elevation. Once the base elevation and interval are set, elevation zone data is defined by choosing the Define MA data button. The number of zones which need to be defined is automatically determined and the appropriate edit fields are unhighlighted. The elevation zone parameters are as follows:
AREA - The drainage area associated with this elevation zone.
SNOPACK - The snow pack depth.
AVEPRECIP - The normal annual precipitation in inches (mm) for this zone.
Areas for the elevation zones can be computed and supplied automatically using the Compute Areas button. The elevation fields are not part of the HEC-1 input.
Related Topics:
Editing HEC-1 Parameters
Snowmelt Simulations
Computing the Area Between Contours