摘要:

ABSTRACTLandsat-5 TM band 6 data of the Stockholm area were examined. Atmosphere and emissivity corrected temperatures of individual objects and different landcover categories were analysed. The results indicate good possibilities of using Landsat-5 thermal data for temperature mapping of natural surfaces.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880224

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

ABSTRACTA delta-shaped deposit 37 m wide, 50 m long and 6 m high is described. It has formed from sediment rafted to the outlet of ice-dammed Ape Lake, British Columbia by ice bergs calved from the damming glacier. They drift the length of the lake where they become grounded and trapped in outflowing waters. Sediment in the bergs is released as they melt and accumulates at an estimated rate of 1.5 m3/annum. The resulting form is composed of poorly stratified diamiction capped by an armoured, gravel surface. Except in the armour, gravel sized particles are angular and have striated surfaces. If these deltas are recognised in ancient glaciolacustrine environments, they would provide edvidence of the presence of calving glaciers and the significance of ice rafting.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880225

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

ABSTRACTThe Grand Sable Dunes and the Sleeping Bear Sand Dunes are the largest fields of active sand dunes in the Great Lakes. Both are situated along the crests of high bluffs which rise 40–90 m above the lakes and are composed of sandy glacial deposits. Annual rates of wind erosion of sand from the Grand Sable bluff face have been estimated from sand deposits interbedded with leaf litter on the forest floor adjacent to the dune field. Annual wind erosion increases linearly with slope height, reaching a maximum of almost 1 m3per m of distance along the strike of the bluff for a 90 m slope, and is concentrated in a belt along the brow of the slope. Despite the strength added to the slope by ground frost, most sand is eroded in winter. Sand, freed from the bluff by sublimation of ice, is transported into the dune field sometimes with snow sometimes without, depending on weather conditions. Groundfrost increases with distance up-slope, reaching a depth of several m at the crestslope. Frost depth is controlled by the rate of conductive heat transfer above the footslope where the ground is warmed by groundwater seepage. The annual flux of sand into the dune field for the period 1973–83 is estimated to be 6300 m3/yr. This rate of nourishment, however, varies with fluctuations in lake levels as they influence wave erosion, slumping and devegetation of the bluff.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880226

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

ABSTRACTWithin a 13 km reach of the lower course of the River Culm, Devon, UK, the river has a well-developed flood-plain which is frequently inundated at times of high flow. Detailed records of suspended sediment load obtained from upstream and downstream gauging stations indicate that approximately 28% of the upstream load may be deposited within this reach. Direct measurements of floodplain sedimentation using‘plastic grass’sediment traps evidence both macro-and microscale spatial variations in deposition which can be related to the duration of inundation, the topography of the floodplain surface and the flow velocity of the inundating water. Rates of deposition have been estimated from conveyance losses and these have been compared with data obtained from the sediment traps. Average rates of approximately 490 g m-2(0.49 mm year-1) are indicated. A comparison of the characteristics of storm and floodplain sediment indicated that conveyance losses are associated with a preferential loss of the coarser fractions, although appreciable deposition of the clay fraction also occurs.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880227

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractChemical weathering trends were detected within the silt/clay fractions of material taken from the 1750, 1852, and 1928 moraines, of Storbreen, Jotunheimen Mountains, southern Norway. In addition to being compared to each other, moraine samples were also compared to material from the 1975 terminal position of the glacier, a glacial milk sample, and nearby eolian deposits. Results from this reconnaissance study indicate that chemical weathering over∼240 years is not sufficient to be detected by changes in clay/silt ratios. However, x-ray diffraction of the<6μm fraction indicates that pyroxene is absent from materials in the top 20 cm of moraine soils, despite the local parent material being a pyroxene-granulite gneiss. Mica (a primary mineral) decreases with age while vermiculite and interstratified minerals (both secondary minerals) increase. A secondary trend, reflecting a distinction between moraine crest and moraine proximal-side base positions, emerged: in it more mica weathers directly to vermiculite on moraine crests, while at the base of moraines on the proximal side interstratified minerals are more abundant.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880228

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe water budget of Lake Naivasha, a fresh water lake at the bottom of Kenya's Rift Valley, just south of the equator at an altitude of c. 1885 m a.s.l. is discussed. It is suggested tentatively that the water budget of the lake to a large extent depends on groundwater flow to and from the lake. The latter point is very crucial, as the lake has no visible outlet. The water budget studies show that the potential evaporation is c. 2–3 times the amount of the annual precipitation over the lake. However, no studies so far have been made on the role thatSalvinia molestaMitch andCyperus papyrusL, which cover a great part of the lake, play in the water budget. This study indicates that the evaporation and transpiration from samples of the floating fernSalviniaapproximately equal the potential evaporation from a free water surface under similar conditions. Forpapyrusthe corresponding figure is about 200–250 %. The introduction ofSalviniain the 1960's has therefore hardly increased the water loss from the lake, whereas the influence ofpapyruson the water budget of the lake can not be disregarded. Nevertheless, the water budget studies and studies of the chemistry of the lake give strong support for the theory suggesting the existence of an underground outlet of the lake.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880229

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

ABSTRACTVestfonna, the second largest of the ice caps, 7895 sqkm (Schytt, 1964), on Nordaustlandet, Svalbard, is a glacier of subpolar type. To obtain understanding of the energy budget temperature measurements were carried out on the summit and near the western margin of the ice cap in summer. Variations of the cold content in the upper 10 m are calculated. Combined with the amount of the heat in ablation the magnitude of the total energy used for warming and melting the ice is obtained.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880230

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe mass balance of Storglaciären is well correlated with the summer temperature at Tarfala and at other climatic stations in northern Sweden. By using regression models, Storglaciärens net balance has been estimated back to 1878. Based on this estimate the cumulative net increase in mass from 1878 to 1910 is estimated to have been 2·1010kg. Since 1910 the mass loss has been 1.1·1011kg, or 26% of its mass in 1910.The volume change of Storglaciären has also been calculated, from comparison of maps dating from 1949,1959,1969 and 1980, all of which are based upon aerial photographs. This change is compared with the mass balance measured in the field to determine whether there are systematic errors in the field method and if so whether they are large enough to influence the annual mass balance significantly.The volume change based on the map study is in good agreement with field measurements. This means that the systematic errors in field surveys are not larger than those in the maps, which are estimated to be about±10% of the cumulative mass change over the 31-year period.

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880231

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0435-3676    

DOI:10.1080/04353676.1987.11880232

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor