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M. Ramakrishna Reddy N. Janardhana Raju Y. Venkatarami Reddy T. V. K. Reddy 《Environmental Geology》2000,39(3-4):342-352
Intensive application of surface water in command areas of irrigation projects is creating water logging problems, and the
increase of groundwater usage in agriculture, industry and domestic purposes (through indiscriminate sinking of wells) is
causing continuous depletion of water levels, drying up of wells and quality problems. Thus the protect aquifers to yield
water continuously at economical cost, the management of water resources is essential. Integrated geological, hydrological
(surface and groundwater) and geochemical aspects have been studied for the development and management of water resources
in drought-prone Cuddapah district. The main lithological units are crystallines, quartzites, shales and limestones. About
91 000 ha of land in the Cuddapah district is irrigated by canal water. A registered ayacut of about 47 000 ha is irrigated
by 1368 minor irrigation tanks. A total of 503 spring channels are identified in the entire district originating from the
rivers/streams, which has the capacity of irrigating about 8700 ha. The average seasonal rise in groundwater level is 7.32 m
in quartzites, 5.35 m in crystallines, 3.82 m in shales, 2.50 m in limestones and 2.11 m in alluvium. Large quantities of
groundwater are available in the mining areas which can be utilised and managed properly by the irrigation department/cultivators
for the irrigation practices. Groundwater assessment studies revealed that 584 million m3 of groundwater is available for future irrigation in the district. From the chemical analysis, the quality of groundwater
in various rock units is within the permissible limits for irrigation and domestic purposes, but at a few places the specific
conductance, chloride and fluoride contents are high. This may be due to untreated effluents, improper drainage system and/or
the application of fertilisers.
Received: 10 June 1998 · Accepted: 15 November 1998 相似文献
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Botanical and geochemical exploration studies at the seruwila copper-magnetite prospect in Sri Lanka
R.R. Brooks A.J.M. Baker R.S. Ramakrishna D.E. Ryan 《Journal of Geochemical Exploration》1985,24(2):223-235
Geobotanical, biogeochemical and geochemical studies were carried out over the Seruwila copper-magnetite prospect near Trincomalee in Sri Lanka. Soil and plant samples were collected along a 180-m transect across the ore body near a gossanous outcrop at Kollan Kulam. Eighteen elements were determined in plant foliage and soil samples. The data showed that in the soils, the concentrations of the ore elements copper and iron and of the pathfinders Ca, Co, Mg, Mn, Mo, Ni and P, were highly indicative of the position of the ore body as determined by a drilling programme.Plant mapping showed that only two species (Glycosmis mauritiana and Pterospermum canescens) were sufficiently ubiquitous to be of use for biogeochemical prospecting in this area. Neither species had a foliar copper content related to Cu levels in the soils, but G. mauritiana had P levels which related well to the position of the ore body and to the concentrations of Fe, Cu and pathfinders in the soils.Principal components and factor analysis of the biogeochemical and geochemical data showed that most of the variance in the plant-soil system was accounted for by the concentrations of ore elements in the soils. It is concluded that the data will be of use for further geochemical and botanical exploration studies in the region or in other genetically similar ore occurrences in South Asia. 相似文献
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Modeling the interannual variability and trends in gross and net primary productivity of tropical forests from 1982 to 1999 总被引：1，自引：0，他引：1
Kazuhito Ichii Hirofumi Hashimoto Ramakrishna Nemani Michael White 《Global and Planetary Change》2005,48(4):314
The role of tropical ecosystems in global carbon cycling is uncertain, at least partially due to an incomplete understanding of climatic forcings of carbon fluxes. To reduce this uncertainty, we simulated and analyzed 1982–1999 Amazonian, African, and Asian carbon fluxes using the Biome-BGC prognostic carbon cycle model driven by National Centers for Environmental Prediction reanalysis daily climate data. We first characterized the individual contribution of temperature, precipitation, radiation, and vapor pressure deficit to interannual variations in carbon fluxes and then calculated trends in gross primary productivity (GPP) and net primary productivity (NPP). In tropical ecosystems, variations in solar radiation and, to a lesser extent, temperature and precipitation, explained most interannual variation in GPP. On the other hand, temperature followed by solar radiation primarily determined variation in NPP. Tropical GPP gradually increased in response to increasing atmospheric CO2. Confirming earlier studies, changes in solar radiation played a dominant role in CO2 uptake over the Amazon relative to other tropical regions. Model results showed negligible impacts from variations and trends in precipitation or vapor pressure deficits on CO2 uptake. 相似文献
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B. S. Gera S. P. Singal Neeraj Saxena Y. S. Ramakrishna 《Journal of Earth System Science》1996,105(3):261-272
A monostatic sodar was set up at Jodhpur, near the western end of the monsoon trough, to investigate the atmospheric boundary
layer dynamics. A 30 m instrumented tower was also located close to the sodar antenna. Data were collected from June to August
during the monsoon period of 1990, as also from July 1992 to September 1993.
Thermal plumes, surface-based stable layers (both flat or short spiky top and tall spiky top), elevated/multi-layers with
or without undulations and dot echo structures were seen; however, erosion of the morning inversion layer in the form of a
rising layer with growing thermal plumes under it was rarely seen, and that too only during the winter period. The observed
structure of the stable layer with tall spikes and its depth have been found to be correlated with the intensity of the monsoon
spell; the dot echoes have been found to be correlated with the approach of a monsoon depression near Jodhpur; and the elevated/multilayers
have been attributed to the formation of a subsidence (shear instability). 相似文献
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The projected response of coniferous forests to a climatic change scenario of doubled atmospheric CO2, air temperature of +4 °C, and +10% precipitation was studied using a computer simulation model of forest ecosystem processes. A topographically complex forested region of Montana was simulated to study regional climate change induced forest responses. In general, increases of 10–20% in LAI, and 20–30% in evapotranspiration (ET) and photosynthesis (PSN) were projected. Snowpack duration decreased by 19–69 days depending on location, and growing season length increased proportionally. However, hydrologic outflow, primarily fed by snowmelt in this region, was projected to decrease by as much as 30%, which could virtually dry up rivers and irrigation water in the future.To understand the simulated forest responses, and explore the extent to which these results might apply continentally, seasonal hydrologic partitioning between outflow and ET, PSN, respiration, and net primary production (NPP) were simulated for two contrasting climates of Jacksonville, Florida (hot, wet) and Missoula, Montana (cold, dry). Three forest responses were studied sequentially from; climate change alone, addition of CO2 induced tree physiological responses of-30% stomatal conductance and +30% photosynthetic rates, and finally with a reequilibration of forest leaf area index (LAI), derived by a hydrologic equilibrium theory. NPP was projected to increase 88%, and ET 10%, in Missoula, MT, yet dcrease 5% and 16% respectively for Jacksonville, FL, emphasizing the contrasting forest responses possible with future climatic change. 相似文献
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Ramu Dandi A. Chowdary Jasti S. Ramakrishna S. S. V. S. Kumar O. S. R. U. B. 《Theoretical and Applied Climatology》2018,132(1-2):465-478
Theoretical and Applied Climatology - Realistic simulation of large-scale circulation patterns associated with El Niño-Southern Oscillation (ENSO) is vital in coupled models in order to... 相似文献
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