Laserfiche WebLink
<br />Accumulated evidence from a number of projects indicates that seeding under <br />favorable conditions should increase seasonal precipitation 10 to 15 <br />percent. However, there is also evidence that orographic precipitation can be <br />decreased under certain conditions, emphasizing the importance of having a <br />well-defined and verified physical hypothesis, reacting to seeding <br />opportunities with a timely recognition and response system, and employing <br />seeding delivery systems that can target the seeding material accurately. <br /> <br />The encouraging evidence about the potential for wintertime orographic <br />snowpack augmentation is largely based on statistical indications from past <br />projects. However, limited physical data from previous experiments have <br />provided insight into natural precipitation processes and their potential for <br />modification. A physical analysis of data collected during the last two years <br />of the Colorado River Basin Pilot Project, conducted from 1970 to 1975, has <br />been used to develop a winter orographic storm structure qIOdel and an <br />assessment of its seeding potential. The general features of this model are <br />consistent with storms observed in Washington and California as well as those <br />in Colorado, Utah, and Wyoming. Results of previous programs suggest that <br />locally produced moist orographic clouds that are not associated with large- <br />scale disturbances constitute a second class of seedable conditions. Further <br />elaboration and verification of these concepts are required to establish a <br />sound physical foundation for modification hypotheses, their operational <br />implementation, and their extension to other locations. The Colorado River <br />Basin Project was established in part to satisfy this requirement. <br /> <br />The Colorado River Basin Project is an experiment designed to conJ:l.rm the <br />effectiveness of the promising Rocky Mountain orographic cloud seeding <br />technique and to demonstrate its applicability in water resource management in <br />the Colorado River Basin. A randomized seeding experiment will be conducted <br />in one or the six high-potential areas to determine the magnitude and location <br />of precipitation increases resulting from seeding operations over several <br />winter seasons. The San Juan Mountains in southwestern Colorado are <br />tentatively identified for this core project. Expanded application of the <br />technology to the other five major-water-yield areas of the Colorado River <br />Basin will depend on the results of the core project; the completion of <br />transferability studies in the other potential areas; and an evaluation or the <br />social, legal, economic, and environmental acceptability or the program. <br />These societal interests are being addressed through interactions with state <br />agencies, local organizations, and citizens in the area. <br /> <br />Recent advances in measurement capabilities have strengthened confidence <br />in our ability to obtain the required physical insight, as many of the new <br />measurement techniques are particularly well-suited to investigating winter <br />orographic cloud systems. It is no longer necessary to rely on indirecc <br />indices or physical conditions, an approa~~ whi~~ has proved to be inaccurate <br />and misleading. It is now possible to reinforce the statistical evaluation of <br />~~periments by documenting the chain of physical events. The Colorado River <br />Basin Project is based on this philosophy. <br /> <br />- 19 - <br />