Electrical resistivity surveys to delineate groundwater potential aquifers in Peddavanka watershed,Anantapur District,Andhra Pradesh,India   总被引：1，自引：0，他引：1  

S.?Srinivasa GowdEmail author 《Environmental Geology》2004,46(1):118-131

Vertical electrical resistivity soundings were conducted in order to delineate groundwater potential aquifers in Peddavanka watershed, which is a catchment of about 398 km² in Anantapur District, Andhra Pradesh, India. The main lithologic units in the watershed are quartzite, limestone, shale, and alluvium. Ninety-nine vertical electrical soundings were conducted using the Schlumberger configuration, covering the entire watershed. The data were interpreted with the help of master curves and auxiliary point charts. Interpretations of VES were used to generate a top layer apparent resistivity contour map and longitudinal conductance map. Isoresistivity contour maps were prepared and interpreted in terms of resistivity and thickness of various sub-surface layers using computer software (SURFER), and isocontour diagrams depicting the depth to bedrock were prepared. Resistivity results were correlated with the existing lithology. Based on the depth to bedrock, the thickness of the saturated layer and the resistivity of the second layer, a groundwater potential map has been prepared, in which good, moderate, and poor zones are classified. The study reveals that the weathered and fractured portions in shale and limestone that occur in the southernmost and central portions of the watershed area constitute the productive water-bearing zones categorized as good groundwater potential aquifers.  相似文献   

Nature and origin of arsenic carriers in shallow aquifer sediments of Bengal Delta,India     

S.?SenguptaEmail author  P.?K.?Mukherjee  T.?Pal  S.?Shome 《Environmental Geology》2004,45(8):1071-1081

Sediments from shallow aquifers in Bengal Delta, India have been found to contain arsenic. Rivers of Ganga-Brahmaputra system, responsible for depositing these sediments in the delta, have created a store of arsenic. Geomorphological domains with different depositional styles regulate the pattern of distribution of zones with widely different content of groundwater arsenic. The high arsenic zones occur as narrow sinuous strips confined to channel deposits. A few iron-bearing clastic minerals and two post-depositional secondary products are arsenic carriers. Secondary siderite concretions have grown on the surface of the clastic carriers in variable intensity. The quantity of arsenic in all clastic carriers is in excess of what is generally expected. Excess arsenic is contributed by the element adsorbed on the concretion grown on the surface of the carriers, which adds up to the arsenic in the structure of the minerals. Variable abundance of concretions is responsible for the variable quantity of arsenic in the carriers and the sediment samples. Fe²⁺ for the growth of siderite concretions is obtained from the iron-bearing clastic carriers. The reaction involves reduction of trivalent iron to bivalent and the required electron is obtained by transformation of As³⁺ to As⁵⁺. It is suggested that oxidation of As³⁺ to As⁵⁺ is microbially mediated. In the Safe zone arsenic is retained in the carriers and groundwater arsenic is maintained below 0.05 mg/l. In the Unsafe zone sorbed arsenic is released from the carriers in the water through desorption and dissolution of concretion, thereby elevating the groundwater arsenic level to above 0.05 mg/l.  相似文献   

The impacts of global warming on farmers in Brazil and India   总被引：1，自引：0，他引：1  

Apurva Sanghi  Robert Mendelsohn   《Global Environmental Change》2008,18(4):655

How big a threat is global warming to climate-sensitive and economically important sectors such as agriculture in developing countries? How well will farmers be able to adapt to the threats of global warming? This paper attempts to shed light on these two important questions. A cross-sectional analysis is employed to estimate the climate sensitivity of agriculture in Brazil and India. Using panel data from both countries, the study measures how net farm income or property values vary with climate, and consequently, how farmers in India and Brazil react and adapt to climate. The estimated relationships are then used to predict the consequence of alternative climate scenarios. Global warming by the end of the next century could cause annual damages in Brazil between 1% and 39% and between 4% and 26% in India, although some of this effect may be potentially offset by carbon fertilization. These estimates do not factor into account climate-induced extreme weather events.  相似文献   

An overview on the seismic zonation and microzonation studies in India     

M. Yanger Walling  William K. Mohanty   《Earth》2009,96(1-2):67-91

The present study presents a review on the progressive development of the seismic zonation map of India both from official agencies and also from independent individual studies. The zonation map have been modified and updated regularly with the occurrence of major destructive earthquakes over the years in the Indian subcontinent with the addition of new data. This study discusses the criteria chosen for the progressive zonation and the major earthquakes that were responsible for retrospection of the earlier published maps. The seismic zonation maps of India have also been prepared by various independent workers by adopting different approaches to achieve the purpose of the zonation. Despite the endeavors from various sources to provide a solution for the problem of earthquake hazards in India, there were many limitations on the zonation map as it gives the picture at a regional scale mostly on the bedrock level without addressing the local site conditions. But nevertheless, the seismic zonation map gives basic guidelines for any region to know the hazard scenario and if any city or urban population is under threat from seismic point of view, further site specific seismic microzonation may be carried out. In the International scenario, the Global Seismic Hazard Assessment Program (GSHAP) in 1999 prepared a hazard map for world in terms of peak ground acceleration (PGA) with a 10% probability of exceedance in 50 years, but it turned out to be an underestimation of the hazard parameter when compared with the observed PGA. To tackle the problem of seismic hazards, there was a need to have a detail study on the local site conditions in terms of its geological, geophysical and geotechnical properties. With the advent of better instrumentation and knowledge on the mechanics of earthquakes, it was possible to identify zones of hazards at a local level and this gives rise to the study of seismic microzonation. Seismic microzonation work has been carried out in India in some of the strategic important mega cities and industrial build up that has the potential of being damaged from future earthquakes, as has been shown in the past. Though the microzonation map is not the final output map, as it can still be updated at later stage with more input data, it does provide a more realistic picture on the site specific seismic hazard.  相似文献   

Fractal analysis of quartz grain boundary sutures in a granite (Malanjkhand,Central India) — Implications to infer regional tectonics     

Sukhen Majumder  Manish A. Mamtani 《Journal of the Geological Society of India》2009,73(3):309-319

In the present paper the intensity of serration of quartz grain boundary sutures in the Palaeoproterozoic age Malanjkhand granite (Central India) is quantified using the ruler method of fractal analyses. The northern margin of the granite has proximity to the Central Indian Suture (CIS) that forms the southernmost part of Central Indian Tectonic Zone (CITZ) along which amalgamation of the northern and southern Indian shields took place. The fractal dimension (D) of the quartz sutures is calculated in 13 samples collected at varying distance from the CIS. D values are noted to increase in samples towards the CIS. This demonstrates the influence of the tectonic events along the CIS on fabric development in the Malanjkhand granite. Magmatic fabric defined by preferentially oriented feldspar laths and high-T solid-state deformation fabrics are observed in areas distant from the CIS. In contrast, mylonites and low-T fabrics such as bulging quartz grain boundaries occur in proximity to the CIS. It is inferred that the emplacement and high-T fabric development in the Malanjkhand granite was synchronous with regional accretionary processes that occurred in the region during the Palaeoproterozoic. Two different possibilities, one involving a single tectonic event and the other involving multiple tectonic events are discussed to explain the superimposition of low-T over high-T fabric due to which intensity of quartz grain boundary serration increases towards the CIS.  相似文献   

Evolution of east coast of India — A plate tectonic reconstruction     

N. K. Lal  A. Siawal  Anil K. Kaul 《Journal of the Geological Society of India》2009,73(2):249-260

The evolution of east coast of India sis discussed within the ambit of clearly identifiable four major tectonic stages which had a profound effect in shaping the tectonic grain of the east coast basins. The evolutionary process began with rift related crustal extension between India and Sri Lanka as a consequence of Africa-Antarctica rifting and development of Natal Basin. An arm of this rift led to initial extension in the Cauvery Basin and failed. Later, the India-West Australia rift propagated further in southwesterly direction initiating Mahanadi and Krishna-Godavari Basins. This extension was an oblique one with Nayudupeta high acting as pivot. The oblique extension followed by asymmetric seafloor spreading developed transpression along India-Sri Lanka and Antarctica junction, resulting in a NNW-SSE trending transcurrent fault along which Antarctica moved southward. Subsequently, entire east coast evolved through a more or less uniform post rift stage.  相似文献   

Environmental change and the informal plastic recycling networks of Kolkata     

Nicolas Schlitz 《Singapore journal of tropical geography》2020,41(3):450-467

This article introduces plastic recycling networks in Kolkata, India, as a case to illustrate the contradictory entanglement of economic and environmental change in urban informal contexts of the Global South. In light of the prevailing environmental critique of informal plastic recycling in India, this article discusses plastic recyclers’ environmental impact and contribution as well as the potential to enhance the environmental and economic performance of their business. Network and chain approaches in the emerging field of Environmental Economic Geography are combined with the notion of social metabolism to conceptualize the entanglement of environmental and economic processes as well as socio-environmental inequalities entailed in recycling networks. The analysis reveals the impact that the heterogeneity and fluctuation of plastic waste supply has on the economic organization of recycling networks, giving rise to distinct forms of governance in its intermediate and down-stream segments. Such an integrated perspective also serves to explain why environmental upgrading is hard to achieve under prevailing circumstances by plastic recyclers in Kolkata. Based on an assessment of the social and political conditions of informality under which plastic recyclers operate, the adoption of common assumptions about ecological modernization imbuing parts of Environmental Economic Geography is called into question.  相似文献   

An interpretation of wave refraction and its influence on foreshore sediment distribution     

Joevivek Vincent Jayaraj  Chandrasekar Nainarpandian  Jayangondaperumal Ramakrishnan  Thakur Vikram Chandr  Shree Purniema Krishnan 《海洋学报(英文版)》2019,38(5):151-160

To analyze the grain size and depositional environment of the foreshore sediments, a study was undertaken on wave refraction along the wide sandy beaches of central Tamil Nadu coast. The nearshore waves approach the coast at 45° during the northeast(NE) monsoon, at 135° during the southwest(SW) monsoon and at 90° during the non-monsoon or fair-weather period with a predominant wave period of 8 and 10 s. A computer based wave refraction pattern is constructed to evaluate the trajectories of shoreward propagating waves along the coast in different seasons. The convergent wave rays during NE monsoon, leads to high energy wave condition which conveys a continuous erosion at foreshore region while divergent and inept condition of rays during the SW and non-monsoon, leads to moderate and less energy waves that clearly demarcates the rebuilt beach sediments through littoral sediment transport. The role of wave refraction in foreshore deposits was understood by grain size and depositional environment analysis. The presence of fine grains with the mixed population, during the NE monsoon reveals that the high energy wave condition and sediments were derived from beach and river environment. Conversely, the presence of medium grains with uniform population, during SW and non-monsoon attested less turbulence and sediments were derived from prolong propagation of onshore-offshore wave process.These upshots are apparently correlated with the in situ beach condition. On the whole, from this study it is understood that beaches underwent erosion during the NE monsoon and restored its original condition during the SW and non-monsoon seasons that exposed the stability of the beach and nearshore condition.  相似文献   

多尺度视角下的印度地缘环境解析及对中国的启示   总被引：1，自引：0，他引：1  

葛岳静  计晶韵  黄宇 《世界地理研究》2021,30(2):223-233

在中国和印度共同崛起的背景下,随着中国“向西开放”和“一带一路”倡议的推进,中国与印度的地缘竞争日益激烈。加强对印度地缘环境解构有助于中国更好地识别地缘风险和制定有效的地缘策略。本文从地理环境、国家的地缘政治想象、地缘关系环境三个方面,从全球、区域和国家内部三个尺度来解构印度的地缘环境,并论证了印度如何在其地缘环境的基础上制定并实施本国的地缘战略：（1）在全球尺度上,凭借印度洋的地缘优势,印度建构了以印度洋为基础的全球地缘战略,追求“有声有色”的大国地位;（2）在区域尺度上,印度凭借地理结构、体量、权力和影响力的优势,构建了邻国优先和防止域外大国干涉的区域战略,谋求南亚领导地位;（3）在国家内部尺度上,印度的国家实力被内部的多样性（包括种姓制度、宗教矛盾、地方主义、党派斗争等）所肢解,如何加强统一的国家认同是印度面临的极大挑战。根据印度地缘环境的特点和中印的权力对比情况,从中国国家利益的角度出发,在南亚和印度洋地区,中国作为权力弱势方,应该加强与印度的利益共同体建构、加强区域内合作、区域互联互通和一体化建设、增强区域内的话语权和合法性;在中印边境区,中国作为权力的强势方,应该加强边境管理、防止域外势力干涉。  相似文献   

Cities within cities: intra-urban comparison of infrastructure in Mumbai,Delhi and Cape Town     

Colin McFarlane  Jonathan Silver  Yaffa Truelove 《Urban geography》2017,38(9):1393-1417

Comparison is now taken as vital to the constitution of knowledge about cities and urbanism. However, debate on comparative urbanism has been far more attentive to the merits of comparisons between cities than it has been to the potential and challenges of comparisons within cities—to what we call “Intra-Urban Comparison” (IUC). We argue that a focus on the diverse forms of urbanism located within cities may generate critical knowledge for both intra- and inter-urban comparative projects. IUCs highlight the diversity inherent in the category “city,” revealing dimensions of the urban that are central to how cities work and are experienced. We mobilise fieldwork within three cities: Mumbai, Delhi and Cape Town, and consider both how these cities have been historically understood as different urban worlds within a city, and discuss key findings from IUCs we have conducted on infrastructures. We find that IUCs can enhance comparative work both within and between cities: reconceptualising urban politics; attending to the varied and contradictory trajectories of urban life; and bringing visibility to the diverse routes through which progressive change can occur.  相似文献