Laserfiche WebLink
t <br />' projects. The idea is that using cloud seeding to increase snowfall on a mountain barrier, for example, <br />leaves less moisture for downstream areas. Some downstream water users become concerned that <br />upwind seeding projects may be "robbing" some of their water. This issue will need to be considered in <br />the design phase and some provision made for dealing with it in the operational seeding phase and <br />possibly the design phase. The extended area effects item is discussed in more detail in appendix A, <br />chapter 10. <br />' The extended area effects issue has received attention in a number of studies. Dennis (1980) reviewed <br />several projects and indicated extended area effects were tentative at best. Assessment of these effects <br />poses a major challenge given that detecting precipitation changes in intended target areas has itself <br />proven to be a formidable task. Generally, previous studies of extended area effects suggest tentative <br />effects, if any (appendix A, chapter 10). From a statistical detection standpoint, very small changes are <br />' usually not detectable in the sample sizes of most experiments. In the proposed study, detection will face <br />the same hurdles unless effects are well larger than previously thought, an unlikely possibility. If the <br />primary cloud seeding mode is propane release, the issue of reactivation of AgI (and therefore possibly <br />affecting precipitation) well downstream will not surface. Operational seeding requires that the target <br />area be seeded in all potential cases, subject to suspension criteria. This operational mode eliminates <br />extended area effects control cases. Solutions may include the monitoring of a large, currently - installed <br />' network of precipitation gauges and /or large radar - estimated, precipitation grid. Again, only large <br />changes would be detectable in such a monitoring system. The extended area effects issue will need to be <br />addressed in the operational phase evaluation plan. Extended effects in the design phase seeding are not <br />anticipated because of limited seeding for small target areas. <br />1 <br />1 <br />19 <br />