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Subsurface stormflow from forested slopes
BOOK REVIEWS
347
sunspot cycle, is held to be inadequate to demonstrate any definite relationship, it is thought possible that the correlation coefficients of 0.30 to 0.33 obtained may improve with longer records of pressure at Marion Island. As regards the shorter term, present indications are that the upper atmosphere observations over Antarctica in the southern spring may provide the basis for forecasting the following summer rainfall over the southern sub-continents, which would clearly be of value in the problem of the regulation of the Shire River. In conclusion, it is of interest that in this present period of "quiet sun" the level of Lake Nyasa now stands higher than in any previous record, and exceptionally high levels occur similarly in the other major East African lakes. It will be of special interest to hydrologists to observe whether these lake levels will continue to rise during the coming upward phase of the sunspot cycle. F.D.
R O N A L D Z. W H I P K E Y : Subsurface Storm[tow from borested slopes. Bull. Intern. Association Sci. Hydrology. Xe Ann6e No. 2, June, 1965. Pp. 74-85. This paper is concerned with indirect runoff following rainstorms, i.e. "water that infiltrates and percolates to become ground water"; this underground, stormperiod flow, which occurs most commonly in forested areas, is referred to as "subsurface stormflow'. Undisturbed forest soil is generally covered by organic litter that protects the soil surface and keeps it permeable to water infiltration. In addition, the A and B horizons of forest soils are interlaced with roots, old root holes, animal burrows, structural channels, and so on, that provide a highly permeable medium for the rapid movement of water in all directions. So, when a relatively impermeable soil layer is reached, percolating water moves laterally to a stream, thus increasing flow during extremely wet periods. This flow is distinguished from true ground-water flow in that it flows to the stream channel before reaching the general ground-water zone. The flow under consideration is accordingly the stormperiod flow of a perched water body occurring in a highly-permeable medium. The site chosen for study is a slope typical of Allegheny Plateau. It is located in eastcentral Ohio on a sandy loam soil with a slope of 28 per cent. The vegetative cover is a 60-year-old mixed oak stand and the plot surface is covered with a 5- to 10-centimetre depth of mixed-hardwood leaf litter. The soil, classified as DeKalb sandy loam, is very permeable down to the 90-centimetre depth. The upper layer is interlaced with tree roots and decayed root channels. The plot was 17 metres long, running down-slope, and the trough pit at the lower end used for measuring the subsurface flow was 2.44 metres wide. Artificial rain from a sprinkler system was employed, and simulated rainstorms were made in August, September and October, 1963. Discharge hydrographs of outflow seepage under various storm conditions were prepared, as well as vertical hydraulic head patterns in the soil section with the aid of a multiple unit tensiometer. F.D.
7he Balletin of the International Association of Scientific Hydrology, Xe Ann6e, No. 2, June, 1965, contains the following papers: La teneur en chlore de l'eau de la nappe des sables des landes du bassin de l'Eyre. (Marc Schoelier). Equations for vapor flux as a fully turbulent diffusion process under diabatic conditions. (Wilfried Brutsaert).
347
sunspot cycle, is held to be inadequate to demonstrate any definite relationship, it is thought possible that the correlation coefficients of 0.30 to 0.33 obtained may improve with longer records of pressure at Marion Island. As regards the shorter term, present indications are that the upper atmosphere observations over Antarctica in the southern spring may provide the basis for forecasting the following summer rainfall over the southern sub-continents, which would clearly be of value in the problem of the regulation of the Shire River. In conclusion, it is of interest that in this present period of "quiet sun" the level of Lake Nyasa now stands higher than in any previous record, and exceptionally high levels occur similarly in the other major East African lakes. It will be of special interest to hydrologists to observe whether these lake levels will continue to rise during the coming upward phase of the sunspot cycle. F.D.
R O N A L D Z. W H I P K E Y : Subsurface Storm[tow from borested slopes. Bull. Intern. Association Sci. Hydrology. Xe Ann6e No. 2, June, 1965. Pp. 74-85. This paper is concerned with indirect runoff following rainstorms, i.e. "water that infiltrates and percolates to become ground water"; this underground, stormperiod flow, which occurs most commonly in forested areas, is referred to as "subsurface stormflow'. Undisturbed forest soil is generally covered by organic litter that protects the soil surface and keeps it permeable to water infiltration. In addition, the A and B horizons of forest soils are interlaced with roots, old root holes, animal burrows, structural channels, and so on, that provide a highly permeable medium for the rapid movement of water in all directions. So, when a relatively impermeable soil layer is reached, percolating water moves laterally to a stream, thus increasing flow during extremely wet periods. This flow is distinguished from true ground-water flow in that it flows to the stream channel before reaching the general ground-water zone. The flow under consideration is accordingly the stormperiod flow of a perched water body occurring in a highly-permeable medium. The site chosen for study is a slope typical of Allegheny Plateau. It is located in eastcentral Ohio on a sandy loam soil with a slope of 28 per cent. The vegetative cover is a 60-year-old mixed oak stand and the plot surface is covered with a 5- to 10-centimetre depth of mixed-hardwood leaf litter. The soil, classified as DeKalb sandy loam, is very permeable down to the 90-centimetre depth. The upper layer is interlaced with tree roots and decayed root channels. The plot was 17 metres long, running down-slope, and the trough pit at the lower end used for measuring the subsurface flow was 2.44 metres wide. Artificial rain from a sprinkler system was employed, and simulated rainstorms were made in August, September and October, 1963. Discharge hydrographs of outflow seepage under various storm conditions were prepared, as well as vertical hydraulic head patterns in the soil section with the aid of a multiple unit tensiometer. F.D.
7he Balletin of the International Association of Scientific Hydrology, Xe Ann6e, No. 2, June, 1965, contains the following papers: La teneur en chlore de l'eau de la nappe des sables des landes du bassin de l'Eyre. (Marc Schoelier). Equations for vapor flux as a fully turbulent diffusion process under diabatic conditions. (Wilfried Brutsaert).