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<br />000113 <br /> <br />"The comparison of seasonal erosion rates and amounts <br />suggests that the snowpack has relatively little direct <br />effect on alpine geomorphic processes. Comparatively <br />little sediment movement is produced by the action of snow <br />glide and creep over the ground surface, by avalanches or <br />by overland flow from snowmelt. Stream channel processes <br />are more obviously responsive to the seasonal snowpack, <br />since most alpine streamflow derives from snowmelt, but are <br />relatively unimportant in the alpine area of the San Juan <br />Mountains. By extension, this conclusion implies that the <br />30 percent increase which might be produced by operational <br />cloud seeding should have little immediate, direct effect <br />on alpine erosion rates." [14, p. 145J (In this study, <br />the 30 percent increase considered by Caine exceeds the <br />normally accepted "concensus increase" of 10 to 15 percent.) <br /> <br />Concerns have been expressed about the delay in snowpack meltout <br />in the spring as a result of increased precipitation. Climatic <br />and meteorological investigations in both the maritime-influenced <br />Sierra Nevada and the continental Rocky Mountains disclosed that <br />temporary delays in snowpack meltout could occur as a result of 10 to <br />15 percent increases in snowfall. However, it is believed that snow- <br />melt extension would occur in protected areas, those that serve as snow <br />traps, and those in which permanent snowbanks or glaciers exist. One <br />of the San Juan Ecology project studies included development of a snow <br />cover recession model for two study basins. The model illustrated that <br />only a small area actually experienced an extended period of snow <br />cover. In discussing the effect of a 15 percent increase in snowfall <br />in the two San Juan study basins, the report concluded: "On only <br />1 percent of the William Forks Lakes catchment is the delay in seasonal <br />melting likely to be of more than 7 days, while only 3 percent of the <br />E1 Dorado Lake Basin would be similarly affected." [14, p. 179J <br /> <br />Snowpack meltout dates must be monitored during a demonstration seeding <br />program in cooperation with resource management agencies to determine <br />if snowmelt delay causes significant and adverse effects on the envi- <br />ronment and human activities. This objective can be accomplished by <br />informal observation and reporting networks in addition to formal <br />monitoring techniques. <br /> <br />The PrOject Skywater FES states: "In research studies aimed at identi- <br />fying avalanche triggering effects, the effect of relatively small <br />incremental increases in snowfall have been masked by the more pro- <br />nounced i nfl uences of wi nd, temperature, rate of snowfa 11, etc." <br />[4, pp. 3-30J A 1977 analysis by Howell states: <br /> <br />"The relation between snowpack augmentation and avalanche <br />hazard is greatly complicated by other factors affecting <br />the release of avalanches and affecting the prediction, <br />warning, and application of countermeasures that mitigate <br />this hazard. In chutes where they seldom run, avalanches <br />occur under rare conditions of recognizably high avalanche <br /> <br />16 <br />