Mass movement studies in Kosi catchment,mepal — A semi quantitative approach using aerial photographs     

S. K. Subramanian  D. P. Rao 《Journal of the Indian Society of Remote Sensing》1986,14(1):61-65

An area of about 5000 sq. km. in the upper parts of river basin of Sun Kosi falling in Nepal has been studied using medium and small scale aerial photographs of two different dates. The temporal variations in relation to mass movements that occur in the study area have been demarcated. The areas which have undergone increased erosion by slope failure and gully erosion over a period of 22 years are evaluated. An attempt has been made to quantify the increase in area of mass movement taking the advantage of three dimensional model of terrain as seen in the aerial photos.  相似文献   

Sea surface temperature variability over North Indian Ocean — A study of two contrasting monsoon seasons     

M. R. Ramesh Kumar  S. Sathyendranath  N. K. Viswambharan  L. V. Gangadhara Rao 《Journal of Earth System Science》1986,95(3):435-446

Using the satellite derived sea surface temperature (SST) data for 1979 (bad monsoon) and 1983 (good monsoon), the SST variability for two contrasting monsoon seasons is studied. The study indicates that large negative anomalies off the Somali and Arabian coasts are associated with good monsoon rainfall over India. The strong monsoonal cooling in these regions can be attributed to strong low level winds and intense upwelling. The reappearance of 27°C isotherm off Somali coast in May/June coincides with the onset of southwest monsoon over India. Further, the influence of zonal anomaly of SST off Somalia Coast (SCZASST) and Central Indian Ocean Zonal Anomaly of SST (CIOZASST) with monsoon rainfall over India is brought out. The former is negatively related to the monsoon rainfall over western and central parts of India, whilst CIOZASST is positively related.  相似文献   

Base metal exploration by gravity surveys in a part of the Cuddapah basin (India)—A case study     

G Ramadass  S M Varaprasada Rao  N L Mohan 《Journal of Earth System Science》1986,95(1):131-141

A closely spaced gravity survey was conducted in the Chikativaripally area in the Cuddapah basin, Andhra Pradesh, India for base metal exploration. Analysis of the data using two-dimensional prismatic models suggest a doubly plunging folded structure in the area and also its associated mineralization.  相似文献   

Geomorphic features of a part of Cuddapah and Nellore districts,Andhra Pradesh — Using remote sensing techniques     

S. V. B. Krishna Bhagavan  K. L. Ramana Rao 《Journal of the Indian Society of Remote Sensing》1985,13(2):19-25

An area of about 1000 square kilometres in Cuddapah and Nellore districts of Andhra Pradesh is studied to bring out the different landforms and other geomorphic features, their material content and distribution, the processes that have acted and are acting in the evolution of landscape and ultimately to get an idea of the geomorphic history of the area. The data obtained during the present study is mainly through remote sensing-techniques (Landsat image and airphoto interpretation) with field checks. The study area forms a part of southeastern Cuddapah Basin and consists of structurally disturbed and deformed sedimentary sequence of varied lithology. The impor-tant rock types in the area are granites, gneisses, quartzites, shales, phyllites, limestones and dolomites. The area presently comes under semi-arid climatic zone. The different landforms recognised and mapped in the area are hog-back ridges, piedmont fans, valley fills, river built plain, abandoned channels, point bars, ’ V‘ shaped valleys, piedmont zone, colluvial plain, residual hills, besides lineaments.  相似文献   

Inferred leaf senescence of rice crop and its relationship with grain yield     

P. P. Nageswara Rao  M. V. Krishna Rao  R. S. Ayyangar 《Journal of the Indian Society of Remote Sensing》1985,13(1):1-8

The possibility of detecting change in green cover of rice crop and its relationship with the grain yield was studied using the spectral data collected by an airborne scanner. The spectral data in the form of difference in vegetation index over a 35 day interval, from the time of flowering, was observed to show good relationship between change of green cover (a measure of degree of senescence) and grain yield.  相似文献   

Acute Toxicity of Distillery Effluent on a Freshwater Fish and Three Pond Snails     

B. S. Khangarot  P. S. Rao  S. S. Shekhawat  V. S. Durve 《洁净——土壤、空气、水》1985,13(1):53-58

The LC₅₀ for 12… 96 h of a distillery waste water were determined for Lebistes reticulatus, Lymnaea luteola, Lymnaea acuminata and Viviparus bengalensis in the batch experiment with daily exchange of the medium. The sensitivity of the species increases in the given sequence with values of the LC_{50,96 h} of 10.77 to 3.72 % proportion of wastewater in the medium. Compared with this, with values of the LC_{50,48 h} of 14.06… 15.71 % after 48 h of exposure there is no significant difference in sensitivity, whereas after exposure for 12 and 24 h the sensitivity grows in the following order: V. bengalensis, L. acuminata, L. luteola, Lebistes reticulatus. Toxicity is obviously primarily determined by the sulphides; with increasing time of exposure also the suspended matter and other factors act toxically.  相似文献   

Global temperature changes: relative importance of greenhouse constituents of the atmosphere as calculated with a 1-d radiative-convective model     

M Lal  K C S Rao 《Journal of Earth System Science》1985,94(2):139-145

Most modelling endeavours concerning the CO₂-climate problem address only the question of the climatic response to increasing atmospheric carbon dioxide, while the amounts of other atmospheric gases remain fixed. But associated changes, either climatologically or anthropogenically induced, of minor atmospheric constituents can also be of significance in producing a substantial global warming. We have analysed the climatic response to changes in a number of atmospheric trace gases as they may enhance or counteract CO₂-induced warming if their abundance should change. A comparison of the increase in equilibrium global-mean surface temperature due to plausible changes in the concentration of several trace gases in the atmosphere based on our calculations with a one-dimensional radiative-convective model is presented in this paper. Our results indicate that roughly 35% of global surface warming could be due to changes in trace gases other than CO₂ and water vapour. The possible climatic consequences of the ongoing anthropogenic changes in the minor constituents of the atmosphere are also discussed.  相似文献   

Linkage between rainfall singularities and geomagnetic activity     

R. S. Reddy  K. S. Raja Rao  Bh. V. Ramana Murty 《Meteorology and Atmospheric Physics》1984,33(2-3):127-142

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Studies on the Toxicity of Some Insecticides to a Freshwater Teleost Lebistes reticulatus (PETERS)     

P. K. Gupta  V. S. Mujumdar  P. S. Rao 《洁净——土壤、空气、水》1984,12(6):629-636

In batch tests with daily exchange of the medium the toxicity of endosulfan, lindane, aldrin, chlordane, rogor and novocron is investigated during times of exposure of 12… 96 h. The mean survival periods and the LC₅₀ are determined. Toxicity increases in the following sequence (LC_50,96h) (in mg/1): novocron (22.65), rogor (18.97), chlordane (0.341), aldrin (0.017), lindane (0.0160), endosulfan (0.0027). The following safe concentrations in mg/1 are recommended: 0.0006 endosulfan, 0.0041 lindane, 0.0010 aldrin, 0.1436 chlordane, 5.4086 rogor and 7.2309 novocron.  相似文献   

Injected radiotracer techniques in hydrology     

S. M. Rao 《Journal of Earth System Science》1984,93(3):319-335

Radioactive tracers which have several advantages over conventional tracers made significant contributions to the development of the injected tracer method in hydrology. A review of the nuclear and the physico-chemical characteristics of the possible radiotracer compounds leads us to conclude that the most effective groundwater tracers are tritiated water (HTO),⁸²Br⁻ and⁵⁸Co or⁶⁰Co as a hexacyanocobaltate complex. A discussion of the various case studies in India and abroad covering the three groups of applications mentioned helps us to conclude that well established radiotracer methods with associated interpretational techniques are available for many short range studies in surface and subsurface hydrology.  相似文献