Preliminary Estimates of Increased Runoff from Additional High Elevation Snowfall in the Upper Colorado River Basin

Authors

  • Arlin B Super Bureau of Reclamation Denver, CO
  • Jack T McPartland Bureau of Reclamation Denver, CO

Abstract

Evaluations of winter orographic cloud seeding projects often have been based on precipitation because of difficulties associated with evaluation by streamflow at many locations.  But most sponsors are primarily interested in the amount of additional streamflow that might be expected from successful cloud seeding.  Preliminary estimates have been made of the percentage increases in streamflow that might result from increased snow water equivalent in the Upper Colorado River Basin.  This was done by fitting linear regression equations to paired streamflow and snow water equivalent observations from several mountain watersheds for which streamflow was not significantly affected by transbasin diversions or upstream regulation of flows.  The regression equations were used to predict percentage seasonal and annual streamflow enhancements for a 10 percent increase in mean April 1 snow water equivalent.  Predicted seasonal streamflow increases ranged from 6 to 21 percent, with most drainages estimated to have 10 percent or more addtitional runoff.  Possible reasons for differences in predicted streamflow are discussed.  The reasons include snow water equivalent measurements that are unrepresentative of the watersheds, variations in the geology and vegetation, and drainage slope and aspect which affect incoming solar radiation.  It is suggested that as cloud seeding technology improves, more attention should be given to targeting areas that maximize streamflow enhancement.

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Scientific Papers