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The Dobson wave refraction programme, modified to incorporate bottom frictional attenuation, is being tested for its universal applicability for prediction of nearshore wave heights. An investigation has been undertaken to test the applicability of this programme for the prediction of wave heights over a gently sloping, wide continental shelf. The study has been carried out in the shelf waters off Alleppey, situated along the southwest coast of India. The measured wave height at a nearshore point and the computed wave height at the same point are compared. The application of Spearman's rank correlation and Wilcoxon's matched-pairs signed-ranks test has indicated that there is a high degree of correlation between the measured and predicted heights. Since similar results have been obtained by Bryant (1979) for steep shelf waters of Australia, it may be concluded that the programme can be used in different coastal waters irrespective of the nature of the shelf gradient, but subject to other limitations of the programme. 相似文献
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Probability distribution of shallow water wave heights, obtained from a pressure type recorder, are examined. It is tested with the theoretical distributions of (a) Rayleigh, (b) Weibull, (c) Gluhovski, (d) Ibrageemov and (e) Goda. The best fit is shown by the Gluhovski probability density function with a correlation coefficient greater than 0.8. The functions of Weibull, Ibrageemov and Goda fit only half of the tested cases. The role of wave steepness in the wave height distribution is found to be negligible. 相似文献
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Stable isotope composition of precipitation from Pamba River basin, Kerala, India, is evaluated to understand the role of spatial and temporal variations on rainwater isotope characteristics. Physiographically different locations in the basin showed strong spatial and temporal variations. δ 18O varied from ?7.63 to ?1.75 ‰ in the lowlands; from ?9.32 to ?1.94 ‰ in the midlands and from ?11.6 to ?4.00 ‰ in the highlands. Local Meteoric Water Lines (LMWL) for the three regions were determined separately and an overall LMWL for the whole of the basin was found to be δ 2H = 6.6 (±0.4) δ 18 O+10.4 (±2.0). Altitude effect was evident for the basin (0.1 ‰ for δ 18O and 0.8 ‰ for δ 2H per 100 m elevation), while the amount effect was weak. The precipitation formed from the marine moisture supplied at a steady rate, without much isotopic evolution in this period may have masked the possible depletion of heavier isotopes with increasing rainfall. Consistently high d-excess values showed the influence of recycled vapour, despite the prevailing high relative humidity. The oceanic and continental vapour source origins for the south-west and north-east monsoons were clearly noted in the precipitation in the basin. Rayleigh distillation model showed about 30% rainout of the monsoon vapour mass in the basin. 相似文献
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Manivannan Ramachandran Chidambaram Sabarathinam Karmegam Ulaganthan Anandhan Paluchamy Manikandan Sivaji Shahul Hameed 《Arabian Journal of Geosciences》2012,5(3):433-439
The accurate information through water quality analysis, scientific study on F ? distribution in groundwater and geochemical knowledge with spatial information on geology and climate are necessary to understand the source/cause, type and level of F ? contamination. The Dindigul district is a hard-rock terrain and marked as one of the fluoride-rich area in Tamilnadu due to occurrence of various rock types including fluoride-bearing minerals. The F ? content of groundwater can thus originate from the dissolution of fluoride-bearing minerals in the bed rock. Eighty-six representative groundwater samples from Dindigul district was collected during two different seasons. Samples were analysed for F ?, other major cations and anions. The study area is chiefly composed of hornblende biotite gneiss and charnockite, apart from this untreated tannery effluents also let from many places in the study area. Geographical Information System technique was adopted to study the sources of F ?, and it was found that F ? in the study is mainly attributed to geogenic source. 相似文献
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N. P. Kurian K. Rajith T. S. Shahul Hameed L. Sheela Nair M. V. Ramana Murthy S. Arjun V. R. Shamji 《Natural Hazards》2009,49(2):325-345
Wind waves in the innershelf of the south-central Kerala coast, south-west India were measured at four locations during different
seasons. Simultaneously, numerical models were developed to simulate the wave and sediment transport regime of the innershelf.
Strong monsoonal influence is seen in the wave characteristics with greater amplitudes, lower periods and switch-over from
SW to SWW–W direction. The net annual longshore sediment transport is southerly in the innershelf and northerly in the surf
zone. These counter-directional transports are linked by seasonally reversing the cross-shore transports. In the locations
where the transports in the longshore and cross-shore directions are balanced, stable beaches prevail. Erosion/accretion tendency
prevails in locations where these transports are not balanced. The southern and northern parts of the coast where onshore
transports are predominant could be accreting zones. The erosion/accretion pattern deduced from the sediment transport model
corresponds well with the long-term erosion/accretion trend for this coast. 相似文献
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The responses of a sandy beach to the southwest monsoonal waves are studied based on biweekly observations. The onslaught
of the first spell of monsoonal breakers causes maximum erosion in the sub-aerial section of the beach. However, further spells
of high breakers do not affect this zone significantly. The erosion in the sub-aerial zone is followed by accretion in the
nearshore zone and vice versa. Whereas the sub-aerial zone has a net erosion the total section of the beach including the
nearshore zone shows near equilibrium condition. It is concluded that in spite of erosion or accretion of the sub-aerial zone,
equilibrium conditions may be found in the total section of the beach. 相似文献
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In this paper, we argue that the politics of aid in Sri Lanka 'after' the 2004 Indian Ocean tsunami accentuated what we call the 'politics of purification'– the fragmented ethnic politics of territoriality – in Sri Lanka's east. The politics of purification entail geographical imaginations of a nation as 'the same people living in the same place'. We illustrate this with a case study on Muslim geographies in Kalmunai Divisional Secretariat division, on the coast of Ampara District, southeast Sri Lanka, where the politics of relocating Muslim families from the buffer zone created the conditions for the geographical imaginations of the politics of purification to play out. At the same time, our study indicates the antinomies of purification and the political fragmentation of Muslim geographies. 相似文献
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