. Cranberries; : the national cranberry magazine. Cranberries. The crucial point of the forest influence lies not with the canopy, but with the soil. The flow of water over forest soils is practically non- existent, even in the heaviest rain. On the other hand, water in almost limitless quantities can infiltrate and flow through them. Much has been made of the forests' capacity to absorb and retain large amounts of water and pump it from the soil into the atmosphere. However, the inference that they do thereby prevent floods is erron- eous. When storm clouds are rol- ling, what is important is
. Cranberries; : the national cranberry magazine. Cranberries. The crucial point of the forest influence lies not with the canopy, but with the soil. The flow of water over forest soils is practically non- existent, even in the heaviest rain. On the other hand, water in almost limitless quantities can infiltrate and flow through them. Much has been made of the forests' capacity to absorb and retain large amounts of water and pump it from the soil into the atmosphere. However, the inference that they do thereby prevent floods is erron- eous. When storm clouds are rol- ling, what is important is not the theoretical capacity of the soil to hold water, but the degree of dryness the soil has reached since the last precipitation. Too often overlooked is the fact that floods most often occur after prolonged storm periods have already satu- rated the soils. Every added drop that infiltrates into the soil causes another drop to be ejected into a stream below. The delaying influ- ence of the forest soil has there- upon ceased. Moreover, the larger the drainage basin, the longer the time required to reach flood proportions. Hence, the forest becomes increasingly less significant as the channel storage effects of larger watersheds become more pronounced. Floods do start in small water- sheds, and earlier and more often in some than others. As the storm continues, more area becomes con- tributory in proportion to that part of the total fall entering the stormflow. The most likely areas are steep, with high precipitation and shallow soils. Where the soils are incapable of infiltrating rather than shedding water, they probably have been burned, grazed or cultivated. Be- cause water flows over them rather than through them, these soils contribute a high ratio of sediment. Sediment decreases channel capac- ity and increases flood damage because dirty water is more dam- aging than clean water. Thus, insofar as forests keep soil in place, they do lessen the prob- lems of floods. In th
Size: 986px × 2535px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcontributorumassamherstlibraries, bookspons
