October, 2012

October, 2012   ||  Volume 16 No.4


Review Article

Global warming-Present status of research and future strategies

Umesh Chandra Kulshrestha

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067 INDIA (Email:umeshkulshrestha@gmail.com)

Increased fossil fuel combustion, land use changes and deforestation are contributing significant amount of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and other greenhouse gases (GHGs) into the atmosphere. This has resulted in an increase of 0.6 0C in global mean surface temperature since the 19th century. Estimates show that at the present rate of GHG increase, this will further increase up to 1.4 0C - 5.8 0C by 2100. Surprisingly, in the past 100 years, the average temperatures in the Arctic region have increased at almost twice the global rate. It is estimated that combined effect of present increase in CO2, N2O and CH4 would lead to an increase of atmospheric heating by 2.3 W m-2. Calculations show that due to aerosol effect, the observed increase in global mean surface temperature over the industrial era is lesser by 40% of that expected from observed increase in concentrations of major GHGs. A significant part of heating is attributed to absolute nature of black carbon (BC) which contributes radiative forcing of the order of 0.3 to 0.5 W m-2. At the same time, BC and other absorbing aerosols are reported to cause the dimming effect at the rate of ~6 W m-2 per decade over India. However, aerosol radiative forcing calculations have huge uncertainties which need to be corrected. Scientific evidences show that due to global warming, Indian region will experience severe consequences such as increased number of extreme events, sea level rise, melting of glaciers etc. Although per capita GHG emissions of India are very low, the total emissions, however, place India at 4th rank. It is to be noted that Indian initiatives to control GHG emissions and to share emission data with global community are highly appreciable. However, there is a great need of taking measures to control GHG emissions through mitigation and adaptation techniques. It is realized that Clean Development Mechanism (CDM) is the best adaptation option for developing countries to participate in emission reduction strategies.


Electrical Resistivity Logging for Assessing Nature of Foundation at Kaiga Nuclear Power Plant

R K Kamble*, G A Panvalkar and S. Bhowmick

Central Water & Power Research Station, Khdakwasla, Pune-411024
E-mail: rkkamble@gmail.com, Fax: 020-24381004

The electrical resistivity logging technique is required for assessing the nature of foundation of large power projects. The parameters determined by electrical logging serve as essential input for the design of foundation. The construction of units 3 and 4 of Kaiga Nuclear Power Plant (KNPP) was founded on granitic gneiss of lower and middle Dharwar group overlain by laterites and humus soil. Assessment on nature of the sub-surface formation was required for the design of the foundation on critical structures like turbo-generator and reactor buildings of KNPP. This paper deals with potential of electrical resistivity logging in assessing the nature of the foundation strata at KNPP and its utility of providing parameters for deciding design of the foundation of the structure.


Delineating uneven bedrock topography by Continuous Seismic Refraction Study
Ch. Subba Rao and M.S. Chaudhari
Central Water and Power Research Station, Khadakwasla, Pune 411024

For designing and deciding the level of foundation for heavy civil structures, information on depth to rock and its quality are pertinent. Information on rock quality and its topography can be obtained from boreholes at discrete locations. However, information gathered covers a small volume around the hole. Interpolation of geological information between boreholes in areas of uneven weathering could be erroneous and misleading. Continuous seismic refraction study along with the information from a few boreholes can overcome these limitations and provide the required information reliably. The efficacy of the method is illustrated through a study conducted at Indira Gandhi Center for Atomic Research (IGCAR), Tamil Nadu. Continuous refraction study was carried out along 24 line km in the form of 20 m grid in two mutually perpendicular directions to decipher subsurface stratigraphy including rock topography, to infer its quality and to check anisotropy in rock velocities, if any. Special efforts were made to ensure good coupling of explosives with dry sand in shot holes and also of geophones with loose sand on surface, for generating and efficient recording of seismic waves in windy conditions near the sea coast.
Seismic depth sections revealed two to three layers viz., loose sand, compact sand/ weathered rock and good quality charnockite rock. The rock topography was very uneven indicating differential weathering pattern. The depth to rock varied from 5.9m to 25.8m and the rock velocity ranged between 4000 m/sec and 5800 m/sec, which for charnockite rock indicated good quality. However, a few zones in bedrock having lower wave velocity (< 3500 m/sec), corresponding to inferior quality rock, were inferred and their lateral extent delineated. The seismic velocities obtained in the two mutually perpendicular directions were comparable and did not show any anisotropy in rock. The study showed that at the sites with uneven weathering, only boreholes at discrete locations are not enough to define rock topography and quality precisely. Instead, continuous seismic refraction study in conjunction with limited borehole data provided optimum coverage economically.

Extreme hydro-meteorological Events and urban development

U. S. De1 and Sikandar M. Jamadar 2
1. Visiting faculty, Maharashtra Institute of Technology, Pune and Department of Environmental Science, University of Pune. E-mail: udayshankarde@gmail.com.
2. India Meteorological Department, Pune. E-mail: smjamadar@gmail.com


Extreme weather events in particular heavy rains and floods cause huge losses to economic growth of the country. India receives nearly 4000 billion M3 water from rains and snowfall annually. However, it shows great seasonal and spatial variability and is concentrated in the summer monsoon season.
Even during the summer monsoon season, short (1-2 days) spells of extreme rainfall can exceed even monthly normal rainfall (of the station), and cause natural hazards, which can turn into a disaster. These disasters are increasing affecting adversely major urban areas. The area and persons affected by floods may increase due to reasons such as deforestation, urbanization and population growth (IPCC AR-4). An analysis of recent data (1998-2007) of Disastrous Weather Events (DWE) (IMD) indicated 34 cases of heavy rains, 71 cases of severe floods, 70 cases of moderate floods, 30 cases of cloud bursts, 88 cases of flash floods over the Indian region. We discuss the important features reported in the recent decade- damage, economic losses and lives lost in these disastrous events.
The paper presents some of these aspects and stresses the need for a sustainable way of development for cities, balancing the needs of various stake holders vis-à-vis the environment.

Studies on Coastal Geomorphology along Visakhapatnam to Bhimunipatnam, East Coast of India
M. Jagannadha Rao, Greeshma Gireesh A.G., P. Avatharam1, N.C. Anil2 and T. Karuna Karudu
Delta Studies Institute, 1Dept of Geology, 2Dept. of Geo-Engineering,
Andhra University, Visakhapatnam.

An attempt has been made to study and record the diverse coastal geomorphic features along Visakhapatnam – Bhimunipatnam coast. The study area is marked by geomorphic features resulted from various coastal and land ward processes. The geomorphic units under different heads namely, features formed by present day wave action, features formed due to sea level oscillations and features formed by rock and sea water interaction have been presented. The influence of sea level oscillations and land and sea interaction forms a diverse coastal geomorphology along the coast. The details of features such as beach, dune system, inter tidal deposits, red sediments, wave cut platform, marine terrace, sea stack, sea cave, serpent hood structures, promontories, wind gap and natural bridge have been recorded and the formation as well as significance of their occurrence are presented. The coastal geomorphology of the study area clearly established not only the sea level oscillations but also variations in climatic conditions in this part of the coast.


A Study of Aerosol Distribution over Indian Region based on Satellite Retrieved Data
G Sheshu Kumar, B Padma Kumari #, and C V V Bhadram
Center for Earth, Atmosphere & Weather Modification Technologies,
3 floor, ECE Building, Jawaharlal Nehru Technological University, Kukatpally, Hyderabad-85
#Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pashan, Pune-8
Corresponding author’s e-mail: bhadramcvv@gmail.com

Atmospheric aerosols play a major role in climate change. However, aerosol measurements, particularly their vertical distribution, are sparse over Indian region. Data from Vertical distribution of aerosols obtained from space-borne Lidars such as CALIPSO (Cloud-Aerosol and Infrared Pathfinder Satellite Observation) has been used to study the properties of pollution aerosols, dust aerosols and biomass burning aerosols on randomly selected days over Indian region in the pre-monsoon and monsoon seasons of 2009
The first case study describes the presence of dust aerosols as retrieved by CALIPSO over central India on 18 March 2009. It is observed that thick layer of aerosols is present up to a height of 5km across India extending from south to north. It is also interesting to observe that the aerosols are being lifted along the slopes of Himalayas. In the second study on a monsoon day, the strong westerly winds with patches of upward and downward vertical winds give a good insight to understand the weather conditions on 22 June 2009.
A significant variation in the vertical distribution of aerosols is seen from day to night. During day maximum total attenuated backscatter is at 2-3 km and during night the maximum is at 4 km. Dust and polluted dust aerosols are dominating during both day and night. The year 2009 being a bad monsoon year, the presence of high aerosol levels up to a height of ~ 4 km is clearly seen. MODIS derived Aerosol Optical Depth (AOD) also confirms high aerosol loading ranging from 0.4 to 1 µm.

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