Laserfiche WebLink
<br /> <br />O[l2th!'~ <br /> <br />. <br /> <br />. <br /> <br />percolating water leaves the watershed through porous strata and may supply <br /> <br /> <br />a well miles away without ever appearing as streamflow. In other places, the <br /> <br /> <br />total storage capacity may be so limited that streams are dry a week after <br /> <br />rain ceases. In some places, water percolates to deep groundwater, and the <br /> <br />extra percolation under forest may suffice to hold up minimum flows. <br /> <br />Results, to date, confirm that forest cover does serve to reduce the <br /> <br />range between high and low flows. This effect is caused primarily by the <br />reduction of peak discharges. <br />Snowmelt.--The retardation of snowmelt under forest was not questioned <br /> <br />because it is a common observation. The question was, does this retardation <br /> <br />of melt show up in streamflow? The answer is that it has on the watersheds <br /> <br />where the effect has been tested. Both at Wagon Wheel Gap and more recently <br /> <br />at Fool Creek in the Colorado Rockies snowmelt has been rapid after clear- <br /> <br />cutting and peak flows have been earlier. In neither of these instances was <br /> <br />flow from forested watersheds especially prolonged as compared to cutover <br />watersheds. <br /> <br />The role of forest cover in relation to snow accumulation and melting has <br /> <br />received a great deal of attention since 1909, and especially since 1935. It <br />is recognized that all forests consist of various arrangements of trees and <br /> <br />openings. Maximum total snowfall is received by the largest openings, but <br /> <br />because these are unshaded, some snow melts during the winter and some is <br /> <br />blown to more sheltered locations. The openings with maximum depths of snow <br /> <br />in the spring are those that receive shade and wind protection. Thus openings <br /> <br />on south aspects must be smaller than those on north aspects to have the <br /> <br />- 3 - <br /> <br />