Laserfiche WebLink
<br />~ <br />-J <br />~ <br />00 <br /> <br />Weather Modification As a Source of Supply <br /> <br />Each of the alternative means of supply discussed thus far has involved the <br /> <br />use of water which occurs under natural conditions. Another possible alternative <br /> <br />is to attempt to increase the amount of water available to EET's by enhancing <br /> <br />precipitation through weather modification. For the purposes of this assess- <br /> <br />ment, winter orographic cloud seeding is the only technique that was examined <br /> <br />since experimental results exist for no other precipitation enhancement techniques <br /> <br />in the Upper Basin. <br /> <br />Over the past two decades, several experiments in winter orographic weather <br /> <br />modification have been ponducted in the Upper Colorado River Basin. These experi- <br /> <br />ments indicate that for an entire experimental period (which typically involved <br /> <br />several seasons). significant increases in precipitation (i.e., snowpack) were <br /> <br />experienced for those orographic clouds with the proper characteristics for <br /> <br />seeding. The overall potential for increased precipitation depends upon the <br /> <br />frequency and duration of the proper kind of cloud systems in any particular <br /> <br />area. <br /> <br />Estimates derived from the experiments in the Upper Basin indicate that <br /> <br />precipitation ranged between 105 and l20 percent of what would have occurred <br /> <br />naturally. <br /> <br />Operationally, orographic cloud seeding is still a developing technology <br /> <br />with a number of uncertainties. However, most scientists actively involved in <br /> <br />cloud seeding research are of the opinion that wintertime orographic weather <br /> <br />modification has developed to a scientifically acceptable degree and that <br /> <br />operational programs could be successfully implemented. <br /> <br />Using a conservative estimate, it is conceivable that an operational area- <br /> <br />wide Upper Basin wintertime orographic cloud seeding program could increase <br /> <br />precipitation by lO percent above what would have otherwise occurred. In turn, <br /> <br />this could increase the aggregate yield of Upper Basin rivers on an average <br /> <br />cxiii <br />