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31.
Abstract Suspended sediment concentrations in the meltwater of Pindari Glacier were determined at regular intervals in four ablation seasons. The late ablation periods (September 1994 and October 1995) were characterized by a reduced level of sediment concentration, while the sampling periods of early ablation (May 1994 and July 1995) showed very high concentrations of suspended sediment in the meltwater. Grain size distribution shows the dominance of medium and coarse silt fractions of the mean size of the suspended sediments between 4.35 and 5.82 ø. Clay size constitutes about 7% of the total size population. The majority of the samples are poorly sorted, symmetrically to finely skewed and mesokurtic in nature. The grain shows texture of mechanical and chemical origin, in which mechanical texture is predominant on most of the grains. It was observed that the grains were mostly subangular to subrounded in shape with variable size ranges. Bulk sediment chemistry consists mostly (>70%) of the five elements, Si, Al, K, Fe and Mg. Iron (Fe) and Mn are dominant heavy metals and sediments show the elemental abundance in the order of Fe > Mn > Zn > Cu > Ni > Pb. The Chemical Index of Alteration (CIA) of suspended sediments (57) is relatively higher than in the case of average unweathered upper continental crust (~50) indicating a higher degree of weathering due to glacier grinding and crushing action. Quartz is the most dominant mineral, followed by mica, illite, feldspar and kaolinite. 相似文献
32.
Abstract: The Lower Cambrian Nagaur Sandstone (Marwar Supergroup) has yielded trace fossils Treptichnus, Cruziana, serially repeated Rusophycus, Diplichnites, Monomorphichnus, Bergaueria, arthropod swimming traces and leap frogging marks of Cruziana ichnofacies. This ichnofossils assemblage is dominantly preserved in fine to medium grained red sandstone beds of the Mohra Member (Nagaur Sandstone). The presence of graded rip-up clasts, current ripples, dune cross-stratification with mud drapes and tidal bundles indicates a subtidal paleoenvironment for the deposition of Nagaur Sandstone Formation, which is corroborated by the Cruziana ichnofacies trace fossil assemblage. 相似文献
33.
34.
Birendra P. SINGH 《地球学报》2009,30(Z1):79-80
Cambrian trace fossils and worm like impressions are described herein from the three stratigraphic units of Tal Group of rocks exposed along the track from Maldeota to Dhaulagiri in Gopi-Chand-Ka Mahal sec-tion, Mussoorie syncline. The upper 10 m thick sand-stone succession (Arenaceous Member) of Deo-Ka- Tibba Formation (lower Tal Group) contains high den-sity and low diversity Skolithos pipe rock. The Sko-lithos pipe rock in sandstone succession of Arenaceous Member (Deo-Ka-Tibba Formation) indicates shallow marine condition under sand shifting environment of deposition. Higher in the succession, in calcareous Member (Deo-Ka-Tibba Formation), Cruziana ichno-facies occurs in association with Monomorphichnus, Planolites and Paleophycus. 相似文献
35.
Thirteen equations based on the mass-transfer method for determining free water evaporation were expressed in seven generalized equations. These seven equations were then compared with pan evaporation at four climatological stations in north-western Ontario, Canada. The comparisons were based on monthly evaporation. Equations were compared by calibrating them on the entire data sets as well as by calibrating on part of the data and then verifying them on the remainder of the data. The results of comparison showed that all equations were in reasonable agreement with observed evaporation, and that the effect of wind velocity on monthly evaporation was marginal. However, when an equation with parameters obtained at one site was applied to compute evaporation at another site, the computed evaporation was not in good agreement with observed values. © 1997 by John Wiley & Sons, Ltd. 相似文献
36.
Vertical movement of snowmelt water through snowpacks is modelled by applying the kinematic wave theory. Analytical solutions are obtained for moisture flux, particle velocity, time history and velocity of meltwater front and total moisture content for a single melt event assuming that the melt rate is constant. These solutions are extended to the case involving more than one event. © 1997 by John Wiley & Sons Ltd. 相似文献
37.
V. P. SINGH 《水文研究》1997,11(6):587-626
Since the development of the entropy theory by Shannon in the late 1940s and of the principle of maximum entropy (POME) by Jaynes in the late 1950s there has been a proliferation of applications of entropy in a wide spectrum of areas, including hydrological and environmental sciences. The real impetus to entropy-based hydrological modelling was provided by Amorocho and Espildora in 1972. A great variety of entropy applications in hydrology and water resources have since been reported, and new applications continue to unfold. This paper reviews the recent contributions on entropy applications in hydrology and water resources, discusses the usefulness and versatility of the entropy concept, and reflects on the strengths and limitations of this concept. The paper concludes with comments on its implications in developing countries. © 1997 by John Wiley & Sons, Ltd. 相似文献
38.
V. P. SINGH 《水文研究》1996,10(7):955-969
Error equations for the kinematic-wave and diffusion-wave approximations were derived under simplified conditions for space-independent flows occurring on infiltrating planes or channels. These equations specify error as a function of time in the flow hydrograph. The kinematic-wave, diffusion wave and dynamic-wave solutions were parameterized through a dimensionless parameter γ which is dependent on the initial conditions. This parameter reflects the effect of initial flow depth, channel-bed slope, lateral inflow and channel roughness when the initial condition is non-vanishing; and it reflects the effect of bed slope, channel roughness, lateral inflow and infiltration when the initial condition is vanishing. The error equations were found to be the Riccati equation. 相似文献
39.
Karakoram Himalaya(KH) has continental climatic conditions and possesses largest concentration of glaciers outside the polar regions. The melt water from these glaciers is a major contributor to the Indus river. In this study, various methods have been used to estimate the ice volume in the Karakoram Range of glaciers such as Coregistration of Optically Sensed Images and Correlation(COSI-Corr) method and Area-Volume relations. Landsat 8 satellite data has been used to generate the ice displacement, velocity and thickness map. Our study for 558 Karakoram glaciers revealed that the average ice thickness in Karakoram is 90 m. Ground Penetrating Radar(GPR) survey has been conducted in one of the KH glacier i.e. Saser La glacier and the collected GPR data is used for the validation of satellite derived thickness map. GPR measured glacier thickness values are found comparable with satellite estimated values with RMSE of 4.3 m. The total ice volume of the Karakoram glaciers is estimated to be 1607±19 km3(1473±17 Gt), which is equivalent to 1473±17 km3 of water equivalent. Present study also covers the analysis of glacier surface displacement, velocity and ice thickness values with reference to glacier mean slope. 相似文献
40.
Abstract The distributed parameter model ANSWERS was used to predict runoff and soil loss from three agricultural watersheds in the arid zone of India. Model input parameters such as landform, drainage, soil and land use/land cover were derived from Landsat Thematic Mapper false colour composites and limited ground truth. The model predicted hydrographs and sediment graphs within acceptable limits. ANSWERS underpredicted the total soil loss by factors of 2.6 to 3.6. Reasons for these results are discussed. 相似文献