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1.
The statistical relationship between the summer monsoon rainfall over all India, northwest India and peninsular India, onset dates of monsoon and the index of mid latitude, (35° to 70°N) meridional circulation at 500 hPa level over different sectors and hemisphere based on 19 years (1971–1989) data, have been examined. The results indicate that (i) the summer monsoon rainfalls over all India, northwest India and peninsular India show a significant inverse relationship with the strength of meridional index during previous January over sector 45°W to 90°E. (ii) The summer monsoon rainfalls over all India and peninsular India show a significant inverse relationship with the strength of meridional index during previous December over sector 90°E to 160°E, (iii) The summer monsoon rainfall over northwest India shows a significant direct relationship with the meridional index during previous May over sector 160°E to 45°W. Significant negative relationships are also observed between the meridional circulation indices of previous October (sector 3 and 4), previous December (sectors 1, 3 and 4), previous winter season (sector 3 and 4) and the onset dates of summer monsoon over India. The meridional circulation index thus can have some possible use for long range forecasting of monsoon rainfall over all India, northwest India and peninsular India, as well as the onset dates of monsoon.  相似文献   

2.
Except for the east coast of Andhra Pradesh, the Deccan Inter-trappean sedimentary beds of Peninsular India have been long known to yield non-marine microfauna, mainly ostracods. These have been extensively described from different localities of Madhya Pradesh, Maharashtra, Karnataka, Andhra Pradesh, Gujarat and Rajasthan states. Occurrence of mixed microfaunal association of marine, brackish water and non-marine foraminifers and ostracods is being recorded from these beds from Jhilmili, Chhindwara district, Madhya Pradesh. It comprises at least two or more planktonic foraminifer species, and one brackish water and 17 non-marine ostracod species. The brackish water ostracod, Neocyprideis raoi (Jain, 1978) has been previously recorded in great profusion from the Inter-trappean beds of Duddukuru, West Godavari District, Andhra Pradesh, which have been assigned Early Palaeocene age (Khosla and Nagori, 2002). Presence of molt stages of the bulk of non-marine and brackish water ostracods in the Inter-trappean beds of Jhilmili is suggestive that they were inhabitants of low mesohaline inland pool/lake. The planktonic foraminifers were carried to this pool/lake by a marine transgression probably from the east coast of India through the Trans Deccan Straits.  相似文献   

3.
Geoenvironmental effects of groundwater regime in Andhra Pradesh, India   总被引：4，自引：0，他引：4  
 The Indian subcontinent has the largest semi-arid tropical (SAT) area among developing nations. The State of Andhra Pradesh falls under the SAT region in India and is mostly covered by compact and hard rocks, characterized by seasonal rainfall of a highly fluctuating nature, in both space and time. As a consequence of the green revolution and an increase in industrial activity, there has been an increase in the utilization of groundwater resources during the last two decades in Andhra Pradesh. The development has also caused a number of problems, such as water table decline, decrease in well yields and seawater intrusion. Although major irrigation projects have contributed to improved agricultural production, the associated problems of waterlogging, salinization and loss of valuable bioresources have led to the gradual degradation of the land, affecting agricultural productivity. Surface water and groundwater have also been polluted in several parts of the State because of untreated discharge of effluents from the industries into nearby streams or open lands. A brief account of the overall scenario of the hydrogeological framework and geo-environmental effects on the groundwater regime in Andhra Pradesh is presented. Possible management practices and conservation methods are suggested. Received: 9 August 1999 · Accepted: 10 July 2000  相似文献   

4.
Vizianagaram–Srikakulam coastal shoreline consisting of beaches, mangrove swamps, tidal channel and mudflats is one of the vulnerable coasts in Andhra Pradesh, India. Five site-specific parameters, namely rate of geomorphology, coastal elevation, coastal slope, shoreline change and mean significant wave height, were chosen for constructing coastal vulnerability index and assessing coastal landscape vulnerability. The findings revealed a shift of 2.5 km in shoreline towards the land surface because of constant erosion and that of 1.82 km towards the sea due to accretion during 1997–2017. The rate of high erosion was found in zones IV and V, and high accretion was found in zones II and III. Coastal vulnerability index analysis revealed constant erosion along shoreline and sea level rise in the study area. Most of the coast in zone V has recorded very high vulnerability due to erosion, high slope, significant wave height and sea level rise. Erosion and accretion, significant wave height, sea level rise and slope are attributed to high vulnerability in zones III and IV. Zone II recorded moderate vulnerability. Relatively lower slope, mean sea wave height and sea level rise have made this zone moderately vulnerable. Very low vulnerability was found in zone I, and low vulnerability was recorded in zone II. Accretion, low slope and low sea level rise were found to be causative factors of lower vulnerability. Thus, zones III, IV and V should be accorded higher priorities for coastal management. The findings can be helpful in coastal land planning and management and preparing emergency plans of the coastal ecosystems.  相似文献   

5.
Unprecedented precipitation along with heavy falls occurred over many parts of India from 28th February to 2nd March 2015. Many of the stations of northwest and central India received an all time high 24 hr cumulative precipitation of March during this period. Even the national capital, New Delhi, broke all the previous historical 24 hr rainfall records of the last 100 years to the rainfall record in March 2015. Due to this event, huge loss to agricultural and horticultural crops occurred in several parts of India. In the present study, an attempt is made to understand the various meteorological features associated with this unprecedented precipitation event over India. It occurred due to the presence of an intense western disturbance (WD) over Afghanistan and neighbouring areas in the form of north–south oriented deep trough in westerlies in middle and upper tropospheric levels with its southern end deep in the Arabian Sea, which pumped huge moisture feed over Indian region. Also, there was a jet stream with core wind speed up to 160 knots that generated high positive divergence at upper tropospheric level over Indian region; along with this there was high magnitude of negative vertical velocity and velocity convergence were there at middle tropospheric level. It caused intense upward motion and forced lower levels air to rise and strengthen the lower levels cyclonic circulations (CCs)/Lows. Moreover, the induced CCs/Lows at lower tropospheric levels associated with WD were more towards south of its normal position. Additionally, there was wind confluence over central parts of India due to westerlies in association with WD and easterlies from anticyclone over north Bay of Bengal. Thus, intense WD along with wind confluence between westerlies and easterlies caused unprecedented precipitation over India during the 1st week of March 2015.  相似文献   

6.
A sediment core from Lake Barkol located in the eastern Xinjiang autonomous region, northwest China, provided a high-resolution record of environmental change covering the last ~8.6 cal ka BP. Three major climate stages, 8.6–7.1, 7.1–2.0 and from 2.0 cal ka BP to the present, were divided by grain size and the authigenic carbonate stable isotope of the lake sediment. Climatic drought during the period 7.1–4.5 cal ka BP, deduced from Lake Barkol, prevailed in the mid-Holocene climate in northern Xinjiang and northwest Mongolia. In contrast, it was wet in central Xinjiang, northwest India and the Middle East during the same period. The climatic difference between northern and southern arid central Asia demonstrates the southward shifting of the Westerlies, which indicates the potential contribution of the Siberian high in the mid-Holocene.  相似文献   

7.
Kumar  P. Vijaya  Osman  Mohammed  Mishra  P. K. 《Natural Hazards》2019,97(2):793-812
Natural Hazards - The state of undivided Andhra Pradesh, India, spent around US$ 20 million per annum on drought relief programs during the period 1998–2008. However, till date, no long-term...  相似文献   

8.
An extreme heat wave hit Egypt in summer 2015. Abnormal hot weather conditions existed over Egypt for the entire summer season. The present paper investigates the relationship between the intertropical convergence zone (ITCZ) over Africa and a scorching heat wave that existed over Egypt in summer 2015. The National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data of mean surface air temperature for the domain of Egypt for the summer season from 1948 to 2015 were used in this study. In addition, data of the daily maximum and daily minimum temperature used for the summer season of the year 2015 were also used. Time cross-section analysis of the daily operational data of geopotential height at level 500 hPa over Egypt from 1 June to 31 August 2015 was done. Moreover, the African ITCZ, both the western and the eastern ITCZ, data for summer of 2015 were used for the said period. The time series, time cross-section, anomaly, and correlation coefficient techniques were used to analyze the datasets. The results revealed that a new climate change record of heat wave over Egypt existed in summer 2015. Moreover, there is an outstanding significant positive correlation between the abrupt shift of African ITCZ position and heat wave occurrence over Egypt in summer 2015. In particular, the southerly movement of the eastern African ITCZ controls the weather over Egypt and led to the extreme heat wave in summer 2015.  相似文献   

9.
HarshGupta 《《幕》》2005,28(1):2-5
The 26th December 2004 earthquake of Mw 9.3 is the second largest earthquake ever to have been recorded.This generated a tsunami which affected several Asian countries. In India, the Andaman & Nicobar group of islands, and coastal states of Tamil Nadu, Andhra Pradesh and Kerala were severely affected. Here, we briefly provide an outline of the approach taken by India for an early warning system for mitigation of oceanogenic disasters.  相似文献   

10.
Nitrate is a common pollutant in surface water and groundwater of agricultural areas. It is essential to monitor this pollutant in groundwater, especially when it is used for drinking purposes without treatment. The present study was carried out in an intensively irrigated area which forms a part of Nalgonda district, Andhra Pradesh, India where groundwater meets all the water needs of the rural population living in this area. The objective was to assess the spatiotemporal variation in the concentration of nitrate in groundwater and soil. Based on the analysis of 496 groundwater samples collected from 45 wells over a period of 2 years from March 2008 to January 2010 by sampling every 2 months, it was observed that groundwater in 242 km2 of the total 724 km2 area had nitrate above the maximum permissible limit of 45 mg/l for drinking purposes. Nitrate concentration in groundwater showed a positive relation with potassium, chloride, and sulfate, indicating their source from fertilizers. Reasons for the high concentration of nitrate in domestic areas were the dumping of animal wastes and leakage from septic tanks. The pH of the soil samples showed that most of the area had basic soil. Apart from pH, organic carbon, available phosphorous, available potassium, ammoniacal nitrogen, and nitrate nitrogen were also analyzed in the 97 soil samples.  相似文献   

11.
This paper reports the occurrence of thorite and confirms the earlier find of radioactive zircon by Subbarao, Murali and others from syenite pegmatite in the Vinayakapuram-Kunavaram alkaline belt in the Khammam district of Andhra Pradesh, India. Thorite has also been found as residual concentrations in soil overlying the pegmatite.  相似文献   

12.
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   

13.
Information on reflected surface gravity waves from the shoreline is required for understanding the coastal hydrodynamics. We have quantified the reflected swells (frequency band 0.045–0.12 Hz) from the west and east coast of India based on the spectral wave data derived from the directional waverider buoys. Reflection coefficient, ratio of the reflected and incident spectral energy, was used to quantify the reflected waves. Influence of the seasons, cyclone, relative depth, land/sea breeze, tides and tidal current on the reflected waves were examined. For the locations off the west coast of India, seasons have large impact on the reflection coefficient and were relatively less during the monsoon season due to the increase in incident wave energy. Locations off the east coast of India show almost the same reflection coefficient throughout the year and have no significant seasonal variations. The reflection coefficient off Puducherry was higher than that for other locations due to the low incident wave energy. The reflection coefficient was low during the cyclone period, but the reflected energy during cyclone was higher than that during the normal condition due to the high incident wave energy. High-energy reflected waves show large variation with tide due to the trapping and dissipation of reflected wave by bottom friction and this effect cause low reflection in deep water location than shallow water location. The reflection coefficient decreases with increase in relative depth off west coast of India.  相似文献   

14.
The earthquake is known to be an unpredictable geophysical phenomenon. Only few seismic indicators and assumptions of earthquakes can be predicted with probable certainty. This study attempts to analyze the earthquakes over the Indo-Himalayan Border region including Bhutan, Bangladesh, Nepal, China and India during the period from 1995 to 2015. Bangladesh, Bhutan and China borders experience fewer earthquakes than Nepal and India border regions. However, Indo-China rim has inconsistency and vast range in its magnitude. Bangladesh though is a small country with respect to others, but it experiences earthquakes comparable to Bhutan. Nepal experiences highest number of earthquakes. In the last 20 years around 800 records have been observed with moment magnitude > 4.0 Richter scale, while very few records (around 10–12) have been observed for large earthquakes having moment magnitude > 6.0 Richter scale over the region. In this study adaptive neuro-fuzzy inference system has been implemented to assess the predictability of seismic moment associated with large earthquakes having the moment magnitude between 6.0 and 8.0 Richter scales using different combination of epochs, technique and membership functions. The Gaussian membership function with hybrid technique and 40 epochs is observed to be the reasonable model on the basis of the selected spatial and temporal scale. The forecast error in terms of root-mean-square error with the stopping criterion 0.001 has been observed to be 0.006 in case of large earthquakes (> 6.5 Richter scale), that is, forecast accuracy of 99.4%. The model bias of 0.6% may be due to inadequate number of large earthquakes having moment magnitude > 6.5 Richter scale over the region.  相似文献   

15.
 This study was made to assess the groundwater quality in relation to agricultural and domestic uses in a part of the Peninsular Archean granite and gneissic complex of India. Water samples were collected from the existing wells in the Niva River basin, Chittoor district, Andhra Pradesh, India and analysed for major ions. The analytical data, processed and interpreted acoording to the WHO standards, reveal that, in general, the groundwater is suitable for both agricultural and domestic uses, exept in a few locations. High concentration of nitrates were observed in some of the wells (both agricultural and domestic) that are affected by the impact of industrial effluents. Multiple regression analysis was performed and used as a positive predictive tool in understanding the chemistry of the groundwater. Received: 2 May 1996 / Accepted: 14 October 1996  相似文献   

16.
A bottom-mounted Recording Doppler Current Profiler was placed at an offshore location (depth of 34 m) in the southeast Chukchi Sea, Alaska, from July through December 2007 (UTC) with the objective of linking observed wave activity—wind-sea and swells—to their synoptic drivers. A total of 47 intervals of elevated wave state were recorded: 29 exceeding 1 m significant wave height (SWH), 16 exceeding 2 m SWH, and 3 m exceeded on two occasions; during one of those, a SWH of 4 m was observed. Detailed analysis of the two large events, including comparison with high-resolution reanalysis wind data (North America Regional Reanalysis), showed wave direction from the east, varied about 15° to the north (counterclockwise) from the wind direction, and current flow in the opposite direction (from the west). This is thought to be the influence of a strong “wind-sea” presence. Regarding classic wave limitations, although the SE Chukchi Sea is a large embayment bordered by land to the east, fetch limitations from the northeast and southeast did not appear to be a constraint for the wind speeds indicated by reanalysis. These two events appeared to be driven by winds associated with cyclonic systems that moved into the eastern Bering Sea and stalled. Examination of smaller waves associated with these events suggested that waves of 1.5 m SWH or less are likely part of another regime and can either be swell or wind-sea, moving in from the open Chukchi Sea to the northwest or through the Bering Strait to the south.  相似文献   

17.
Systematic geoelectrical investigations were carried out in a typical drought affected region of Andhra Pradesh, India, for evolving drought remedial strategies. Depth to basement maps, geoelectrical sections, and soil thickness maps were constructed. The interpreted results clearly identify locations of potential acquifer zones for soil conservation and areas artificial recharge.  相似文献   

18.
R mode factor analysis was carried out on 48 groundwater samples collected from the Chitravati river basin, a typical drought-prone area of Andhra Pradesh, India. The samples were chemically analyzed by using conventional techniques (the analyzed data have been further standardized, and eigen values and eigen vectors have been computed). The data have been put into four major factors and the subsurface geology of the region has been clearly brought out by these factors. The areas prone to salinity hazard, recharging, and nonrecharging zones have been established.  相似文献   

19.
Spectral aerosol optical depth (AOD) measurements, carried out regularly from a network of observatories spread over the Indian mainland and adjoining islands in the Bay of Bengal and Arabian Sea, are used to examine the spatio-temporal and spectral variations during the period of ICARB (March to May 2006). The AODs and the derived Ångström parameters showed considerable variations across India during the above period. While at the southern peninsular stations the AODs decreased towards May after a peak in April, in the north Indian regions they increased continuously from March to May. The Ångström coefficients suggested enhanced coarse mode loading in the north Indian regions, compared to southern India. Nevertheless, as months progressed from March to May, the dominance of coarse mode aerosols increased in the columnar aerosol size spectrum over the entire Indian mainland, maintaining the regional distinctiveness. Compared to the above, the island stations showed considerably low AODs, so too the northeastern station Dibrugarh, indicating the prevalence of cleaner environment. Long-range transport of aerosols from tshe adjoining regions leads to remarkable changes in the magnitude of the AODs and their wavelength dependencies during March to May. HYSPLIT back-trajectory analysis shows that enhanced long-range transport of aerosols, particularly from the west Asia and northwest coastal India, contributed significantly to the enhancement of AOD and in the flattening of the spectra over entire regions; if it is the peninsular regions and the island Minicoy are more impacted in April, the north Indian regions including the Indo Gangetic Plain get affected the most during May, with the AODs soaring as high as 1.0 at 500 nm. Over the islands, the Ångström exponent (α) remained significantly lower (～1) over the Arabian Sea compared to Bay of Bengal (BoB) (～1.4) as revealed by the data respectively from Minicoy and Port Blair. Occurrences of higher values of α, showing dominance of accumulation mode aerosols, over BoB are associated well with the advection, above the boundary layer, of fine particles from the east Asian region during March and April. The change in the airmass to marine in May results in a rapid decrease in α over the BoB.  相似文献   

20.
Using studies of places where heat waves are common, projected changes in heat waves in Metro Vancouver are assessed from a multi-disciplinary perspective with respect to the potential impacts of the physical change on the people and infrastructure with the intention of being better prepared for future events. Trends in maximum temperature parameters for Metro Vancouver for the past 75 years are generally not statistically significant; however, projections for 2041–2060 and 2081–2100 suggest that the region will experience such events more frequently in the future due to climate change. While Metro Vancouver, British Columbia (BC) generally does not typically experience heat waves it was strongly affected by a major heat event in July 2009, with temperature records being broken at Vancouver (≥31 °C) on the coast and at Abbotsford (≥36 °C) 65-km inland. A lack of sea breeze during this event meant that there was no cooling effect, and land surface temperatures over the downtown area approached 40 °C and excess deaths occurred. Many victims were either in the 65–74 age category, the vulnerable poor, or people with mental health issues. Because these events are rare, many buildings lack air-conditioning, and residents of Metro Vancouver under-anticipate their vulnerability. The costs of health-related impacts outweighed those related to higher electricity usage.  相似文献   

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