WSP09868 - Laserfiche WebLink

Home Browse Search

000658 . . ~ i [V. IJ [SUIS.') [()[\! OF RESULTS FRO~1 THE REVl FW ~ The I itcrilture search included (1) forestry abstracts, (2) water resources ahs t rdC ts, ~nd (3) envi rorunenta 1 abst racts, which covered a period of 1975 to 19R,3. Slmllll~ries from the review of selected publiclltions are pre- sented in the ,\ppendix. The numher on the left side of the publication title in the Appendix rclers t" the reference nlllnber ~'hich is also cited at the appropriate plC1ces in this section. A discllssion of results from various l"lhl ic~tions reviewed is presented in this section uncler the following sub- sections: ill SIlOW llccuTlIulation, (2) interception and evaporation of snow, (3) effects of \-;ind, (4) orientation of slope (north or south), (5) soil 1lI0istllre ~nd evapotmnspiration, (6) snowmelt and runoff, and (7) erosion, (J) Snow accumulation In Colorado, most of the stream runoff 1S produced due to snowmelt. Snow accumulation and redistribution, thus, is an important consideration in studying the effects of timber cutting on water yield. As a result of timber cutting, redistrihution of snowfall takes place. Increase in water yield due to timber cutting, as reported by lIlany authors 0, 2, 3, 4, 20, 21, 30, 31l, can be partially attributed to increases in snol\' accumulation in cut areas. Leaf (1) sununarized results of several past investigations on snow distribu- tion. Until more recent studies by Leaf in 1967, it ~os believed that reduc- tion of evaporation loss from intercepted snow on tree cro~TIS, due to cutting, I"as responsible for increased snow accumulation in cut areas. These recent studies by Leaf indicated that mechanical removal and transportation of inter- cepted snow are more important than vaporization. Several other studies following Leaf's study confirmed these findings. Patchcutting results in significant redistribution of snow 0, 3)-more in the openings and less in the uncut areas. Thus, the total change in water content in headwater basins may not significantly change (1). Patchcutting seems to produce more snow accumulations in open areas than clearcutting, The pattern of cutting may have significant impact on snow aCClllllulation and, thus, on runoff. (2) Interception and evaporation of snow During a snolvstonll, some of the snow is intercepted by trees. Inter- cepted sno"', if not blo"TI by the wind, m:-lY become cohesive and resist removal by wind (31). Portions of the intercepted snow is lost to evaporat ion and suhlimation "hile the remaining may be aCClmlulated On the ground. Evapor3tion and suhlimation losses of snow are reported bv several authors (21, 26, 27, 30, 31, 32). Timbcr cutting reduces these losses in the cut areas. I.celf (1) reports that in ccntral Colorado when 40 percent of tilt" forest is occupied by small openings, the decre~se in interception loss is almost compens'lted by the incre~se in eV<lI'Ol-ation loss [rom the Snow surface in thp. open :neas. hom tl1 i s rev iel', it appea rs tha t the evapor'Jt ion of the 51101; on tj;,~ trees is not" sign; fiem, factor. -2-