Aerial photographs for operational streamflow forecasting in the Colorado Rockies

A method is developed for predicting and simulating the snowmelt runoff hydrograph by using aerial photographs taken vertically, then measuring, piece-meal, the percent of the basin covered with snow on the total basin. The procedure is developed by means of empirical correlations between snow cover depletion and runoff. In addition the application is made to daily simulation of streamflow depletion-runoff relationship and can be used effectively as a basis for advanced estimates of residual volume of flow during the remainder of the snowmelt season. Photographs are taken at about 10 day intervals, with a scale of 500 feet to the inch. The confines of the basin are divided into elevation zones and totals are derived from tabulations where the snow cover depletions are summarized. Relationships between the several variables are determined by multiple regression correlations solved by electronic computer procedures.