eChapters

Atmospheric pressure is the force per unit area exerted on a surface by the weight of air above that surface in the atmosphere of earth. The gas molecules of the atmosphere are pulled towards the earth by the force of gravity and hence exert a force on earth surface. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Atmospheric pressure influences other weather elements in a significant way. Small changes in air pressure may not be felt, but they are important for bringing a change in weather. Atmospheric pressure can be calculated as the summed weight of all gas molecules between a horizontal plane and top of the atmosphere and divided by the area of the plane. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location.

Measurement of atmospheric pressure

The standard unit of pressure in the SI system is the Pascal which is the name given to one Newton per square metre (N/m²). For meteorological purposes, standard sea-level pressure is 101325 pascal (Pa). To simplify this large number, the millibar unit (mb) has been adopted, which is equal to 100 pascals. Units like kiloPascal (kPa) or hectoPascal (hPa) are also used to measure pressure. 1 kiloPascal is equal to 10 millibars and 1 hPa is 1 millibar. The standard sea-level pressure is represented as 1013.2 mb or hPa.

Soil temperature is an important environmental parameter for plant growth and development. It has direct effects on microbial growth and development, organic matter decay, seed germination, root development, and water and nutrient absorption by roots. In general, the higher the temperature the faster these processes occur. Variation in soil temperature is much more pronounced because of varying characteristics and composition of soil.

The soil gains heat by absorption of solar radiation and longwave counter radiation from the atmosphere, downward transfer of sensible heat and horizontal transfer of heat from the surroundings. On the other hand, soil loses heat by longwave radiation to the atmosphere, upward transfer of sensible heat to air when the soil surface is hotter than air and with evaporation and horizontal transfer of heat from the column to surroundings.

Temperature is the physical property of an object that quantitatively expresses the hotness or coldness. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot. When a heat transfer path between them is open, heat spontaneously flows from bodies of a higher temperature to bodies of lower temperature. If no net heat flow occurs between two objects, the objects have the same temperature which are then said to be in ‘thermal equilibrium’. Temperature plays an important role in all fields of natural and applied sciences. Most of the weather parameters are dependent on it, directly or indirectly. It has important role to play in the development and growth of all living organisms in all stages of their growth.

Atmosphere receives the heat energy from the sun and its temperature increases. Due to different amount of heat energy receipt at different places, the air temperatures at different places also vary. The variation in air temperature basically results into air motion, so as to equalise the energy content of the different regions of the earth. Thus, atmospheric temperature is one of the basic elements of weather and climate.

Sun is the prime source of energy injected into the earth’s atmosphere. The sun is the nearest star to the earth. It is a hot ball of glowing gases at the heart of the solar system. Its radiant energy is practically the only energy source to the earth. Very small and insignificant quantities of energy are available from other sources such as the interior of the earth, the moon, and other stars. Without the sun’s intense energy and heat, there would be no life on earth.

The mean distance of the sun from the earth, also known as one astronomical unit (1 AU), is approximately 1.496 × 10⁸ km, though the distance varies as the earth revolves round the sun in an elliptical orbit. At this average distance, light travels from the sun to earth in about 8 minutes and 19 seconds. The energy of the sunlight supports almost all life on earth by photosynthesis, and drives earth’s climate and weather. The minimum sun-earth distance is about 0.983 AU and the maximum is approximately 1.017 AU. The earth is at its closest point to the sun (perihelion) on around January 3 and at its farthest point (aphelion) on around July 4.

The sun makes up about 99.86% of the mass of the entire solar system. The visible disk or photosphere has a radius of 6.599 × 10⁵ km, and the solar mass is 1.989 × 10³⁰ kg. The sun is a completely gaseous body. The chemical composition (by mass) of the outer layers of sun is 71 per cent hydrogen, 26.5 per cent helium, and 2.5 per cent heavier elements like oxygen, carbon, neon, and iron among others. Since the sun is not a solid body, different parts of the sun rotate at different rates. At the equator, the sun spins once about every 25 earth days, but at its poles the sun rotates once on its axis every 36 days.

The gaseous envelope surrounding the earth is called atmosphere. Thus, atmosphere can be defined as the dynamic layer surrounding the earth above its surface containing various gases, moisture, aerosols, etc. The atmosphere is retained by earth’s gravity.

The atmosphere protects life on earth by absorbing ultraviolet solar radiation, warming the earth’s surface through heat retention and reducing temperature extremes between day and night. The common name given to the atmospheric gases used in breathing and photosynthesis is air. The atmosphere has a mass of about 5.15 × 10¹⁸ kg, three quarters of which is within about 11 km from the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The imaginary ‘Karman line’ lies at an altitude of 100 km above the mean sea level, and commonly represents the boundary between the earth’s atmosphere and outer space. The study of earth’s atmosphere and its processes is called atmospheric science or ‘aerology’. The atmosphere serves the life-system on the earth by the following activities.

Meteorology is derived from the Greek word meteoro which means above the earth’s surface; i.e., the atmosphere. The state of the atmosphere experienced at a given time, in any location on the surface of the earth is known as weather. Thus meteorology is the scientific study of the atmosphere or the weather. It is a branch of physics dealing with atmosphere and it is often quoted as the ‘physics of the lower atmosphere’. The main focus of meteorology is to understand the weather processes and forecast the weather. Solar radiation, the air mass and moisture are the three key ingredients that make up weather. The exchange of heat, moisture and momentum between the earth’s surface and the atmosphere determines the characteristic of weather. The observable weather events are known as meteorological phenomena and are defined by a set of variables called weather elements. Atmospheric temperature, atmospheric pressure, humidity, precipitation, cloudiness, wind and visibility, etc. are examples of such weather elements. The weather elements are not separate entities. They are closely related with each other and are highly variable in nature. Meteorology explains and analyses the changes of these weather elements.

Meteorology

The major subdivisions of meteorology are dynamic meteorology (or atmospheric dynamics) and physical meteorology (or atmospheric physics). The dynamic meteorology is concerned with the analysis and interpretation of the three-dimensional, time-varying, macro scale motions and energy transformations in the atmosphere. The science of dynamic meteorology is meant to develop models based on the hydrodynamic and thermodynamic equations. The physical meteorology is concerned with the processes that alter the physical properties and the chemical composition of air parcels as they move through the atmosphere.

5.1 The Need

In spite of the considerable experience and quite a few facilities available in the country, the growth of application of isotope techniques is not commensurate with India’s size, its climatic and hydrogeological diversity and the sheer range of its water resources problems.

The situation may not be unique to India and other developing countries. Australia also appears to be facing a similar problem. A recent publication [1] says ‘the limited uptake of the method may be due to a number of factors. Until relatively recently, isotope hydrology has remained a largely academic pursuit, or measurements were the domain of national atomic energy agencies. A large fraction of information lies buried in the grey literature or in arcane technical journals. Interaction with local or regional water resources agencies has been the exception rather than the rule’

India has probably a stronger case for a more effective use of isotope techniques. A large portion of groundwater occurs in hard rocks in India. Normal hydrogeological and geophysical methods cannot fully describe such groundwater regimes to effectively plan their exploitation. It is essential to apply tracer hydrology methods, especially isotope geochemical techniques, for a comprehensive understanding of the systems. The examples of Manikaran geothermal springs, seepage studies in Salal tunnel and in some dams, given in the earlier chapters come under this category. Studies on percolation tanks in basaltic terrain and on recharge processes need isotope support.

It will not be long before we would be planning to exploit very deep ground waters (>500 m), both in the hard rock terrains of peninsular India as well as in the Ganga plains to meet our ever growing need for water. We would need good understanding of the recharge processes to these deep ground waters. Isotopes will have a large role in such investigations.

Arid zone hydrology is yet another area where the potential of isotope techniques has been effectively demonstrated for the characterization of the recharge processes, both palaeo and modern, and including the role of ancient rivers.

After precipitation, run-off and surface water storage in lakes and man-made reservoirs, the next steps in the hydrological cycle are infiltration through the unsaturated zone and groundwater dynamics in the saturated zone. Well-established applications of isotopes in groundwater hydrology are

The range of isotope applications in surface water hydrology is not as wide as in groundwater hydrology as the surface waters are more easily amenable to conventional hydrological methods. Following are the areas in which isotopes have a significant role in either improving the accuracy of measurements or in providing additional information, which is otherwise not easily available.

In the last chapter, we have broadly introduced the concept of tracer hydrology and also the concepts of isotopes as tracers, their characteristics and measurement techniques. In this chapter let us see the basis of application of each group of isotope tracers, injected and environmental.

What are the different groups of isotope tracers used in hydrology and how are they classified?

“Hydrology is the science that treats the waters of the earth, their occurrence, circulation and distribution, their chemical and physical properties, and their reaction with their environment, including their relation with living things. The domain of hydrology embraces the full life history of water on the earth.” (Federal Council for Science and Technology, “Scientific Hydrology”, Washington, 1962)

This definition puts in a nutshell what is most often inadequately done before undertaking exploitation of water resources. In short, it is the scientific inputs that are likely to be missed while planning water resources management projects. It is the “full life history of water” part of the above definition that is of specific relevance to the theme of this book, Isotope Hydrology.

Conventional hydrology is strong on measurement and quantification of different parts of the hydrological cycle (Fig.1.1), be it precipitation, run-off, evaporation, transpiration, infiltration, groundwater dynamics etc. Through chemistry and isotopes, we try to understand the processes themselves in order to delineate the history of that part of the hydrological cycle that is being studied. For example, if we are measuring river flow, we would like to know the contribution of different components; base flow, rainfall run-off and snow melt, if any.

Let’s see what we know and what do not know in the conventional hydrological practice. We know surface waters evaporate, form into clouds and precipitation occurs under favourable weather conditions. What we often do not know is the source of moisture, oceanic or inland.

Abstract

Subsequent to December 26^th 2004 historical Tsunami, The Government of India has conceived a master plan for setting up Tsunami Warning System (TWS) similar to Pacific Ocean Tsunami Warning System. Concurrently, the union Govt has also initiated scientific studies through Department of Science and Technology and the significant amongst these are the

• All India Co-ordinated Programme on Tsunami disaster and risk assessment using GIS technology and
• Bilateral programme with Norway to know the know – how and capacity building in the fields of Landslides and Tsunami

As a part of this bilateral mission, the authors visited institutions connected to Geohazards and Tsunami affected areas of Norway. The article briefly narrates the salient inferences on the Tsunami scenario and the related studies in Norway.

Keywords: Landslides triggered tsunamis, Norway

Abstract

Though people belonging to different disciplines from the common citizen to top level administrators are familiar with cyclones, floods, earthquakes, landslides, droughts, etc., the tsunami which struck and devastated over 1000 km long Tamil Nadu coast was not only unexpected but also an unknown phenomenon for the people of this part of the region. The Government of Tamil Nadu, though faced with this disaster for the first time, has efficiently managed the crisis owing to clear policy directions from the top political executive of the government, the planned working of the ministers, the committed service rendered by the senior officials and the tireless efforts of district collectors and their supporting staff down the line. The immediate measures taken in search, rescue and relief operations are detailed in this paper. Also covered are the rehabilitation measures undertaken including those for orphaned children and unmarried girls and the steps adopted for the prevention of epidemics.

Keywords: Tsunami Disaster, State Administration, Relief and Rehabilitation, Tamil Nadu.

INTRODUCTION

India is traditionally vulnerable to natural disasters on account of its geo-climatic conditions. Floods, droughts, cyclones, earthquakes and landslides have been occurring regularly in some part of the country or the other. In Tamil Nadu, the unprecedented drought in 2002-03, followed by another drought of comparatively less severity in 2003-04 and the floods in the northern coastal districts in October-November, 2004 had kept the State machinery on constant alert. But the tsunami that struck the coastal districts on 26^th December, 2004 was an altogether new and nightmarish experience. It was a disaster, the like of which, had not been seen before. The suddenness and the ferocity with which the waves gushed into the habitations along the 1076 km long coast line, taking the people totally unaware, caused unprecedented damage, death and destruction and posed the greatest challenge to the State administration. However, the state faced the challenge successfully, thanks to the vision and commitment shown by the Government and the timely help rendered by a number of non-governmental organisations and groups.

Abstract

The paper deals with the roles played by the NGO’s in the relief and rescue phase of Dec, 2004 tsunami and the effective role played by NCRC -NGO Coordination and Research Centre - in the rehabilitation phase along Tamil Nadu coast by creating successful partnership with government and the public.

Keywords: The Role of NGO’s, Tsunami 2004, Relief and Rehabilitation, NGO Coordination Research Centre.

INTRODUCTION

The scale of the tsunami disaster was unprecedented and the response too was out of the ordinary. Tamil Nadu was the worst affected state in India with Nagapattinam district being the most affected with over 6000 lives lost, about 40,000 houses damaged or destroyed and 1.96 lakh people affected. Relief poured in from both government and non-governmental organizations, including the religious organizations, and the first few days witnessed heartwarming outpourings of help and support.

There were about 400 NGOs and an equal number of volunteers to help in the relief operations which included food, clothing, household utensils and bedding. With such a large scale of external support, mainly from organizations and people from outside Nagapattinam, it was not surprising that chaos and confusion marked the first few days of relief operations still. Based on the experience of some professionals experienced in disaster management, a coordination platform was created called the NGO Coordination Cell. This platform was managed by two NGOs, who had long standing field presence in Nagapattinam, viz., South Indian Federation of Fishermen Societies and SNEHA, with the mandate and support of the District Administration. The main role of this platform was to meet the field based requirements of all the relief camps with the resources and materials available with the NGOs and the Govt. The paper briefly deals with challenges faced by the NGO’s in relief and Rehabilitation of the historical Dec 2004, Tsunami.

Abstract

During natural disasters, mostly panic and curiosity lead to greater causalities. But the tsunami is such a disaster which no one have witnessed during their life time nor heard of from their ancestors. On 26, December 2004, tsunami has struck all of a sudden many South Asian coasts including the east coast of Tamil Nadu and Andhra Pradesh causing greater devastation and causalities. This historical event has taught us many lessons and the paper deals with some aspects related to tsunami from the citizen’s view point.

Keywords: Natural calamities, Tsunami mechanisms, Mitigation strategies, Citizen’s perspective.

INTRODUCTION

The tsunami that ravaged the coasts of South India had left tell tale signs that affirm the need for early warning systems as well as well-planned mitigation measures for the benefit of the affected. Over the last 12 months, since the tsunami struck the east coast of India on 26 Dec. 2004, numerous seminars, discussions, programmes and project proposals have been deliberated on various aspects that deserve attention. Government agencies, self-help groups and non-governmental organizations (NGOs) have done commendable post-tsunami work. All sections of the society have responded both emotionally and rationally to the event in an unprecedented manner. In retrospect, to the informed citizen – one who has heard about the event, read about it and discussed it with others, though not have had the ‘experience’ of the natural disaster by himself / herself - what do all these mean ? the tragedy and its aftermath. This paper documents the issues that a citizen would like to ponder over so as to understand the various dimensions of the post-tsunami activities and draw a few lessons that the tragedy had taught us. The major issues pertain to (i) the mechanisms (ii) the coastal vulnerability and the need for assessment (iii) mitigation strategies (iv) media exposition (v) communication networking and (vi) educational facilitation.

Abstract

Tsunami (2004), that struck the Tamil Nadu coast has left deep marks in the minds of the affected society. The interview conducted in the coastal villages of the tsunami affected Nagapattinam has brought out many salient societal issues like, loss of leadership, widow hood, debt grip, psychological depression etc, which warrant deeper look to bring them out from the syndrome.

Keywords: Tsunami (2004), Social issues, Nagapattinam, India

INTRODUCTION

The damages caused by tsunami (2004) along the coastlines of most of the South Asian countries are indelible not only from the minds of the coastal population but also from the heart of the entire humanity. The worst affected in the disaster are the fishing community. Many of their mechanized and un-mechanized boats and catamarans were converted to useless debris and garbages by the heartless tsunami. When their settlements themselves were swallowed even with out chewing, nothing to talk about their fishing nets which were just blown off by the ferocious tsunami. In addition, the infrastructure facilities like roads, communication systems, water and power supply were also incalculably damaged. Next to fishermen community, the affected souls were the farmers whose cultivable lands were turned into marine wet lands with swimming and tossing fishes. The Indian subcontinent was facing such onslaughts of various natural disasters periodically but our morale always stood by our side prohibiting us declaring them as national calamities for getting international aids. Specifically in this case, the central and state governments, NGOs and Voluntary Organizations have risen phenomenally to help the affected who were in need. Despite best efforts taken to provide relief and rehabilitation to the affected people, the tsunami has seedled some societal issues / syndrome, which may take long years to settle; it may not settle too. The paper discusses some of such issues gulled out through the interview conducted amongst various cross sections of the affected community.

Abstract

Ennore is an industrial region having many industries on chemicals, fertilizers, refineries etc., discharging their effluents into the Buckingham canal. Present study focuses on the impact of tsunami on water quality of Buckingham Canal segment found to the north of Chennai city, Tamil Nadu, India, in addition to the human interferences. Water samples were collected from surface and near bottom at five locations covering about 20km stretch of the Buckingham Canal during high tide on the spring tide day before (December 2004) and after (January 2005) the mega tsunami. Various water quality parameters measured were pH, Temperature, Salinity, Dissolved Oxygen, Suspended Particulate Matter, Nutrients and Chlorophyll. The maximum depth observed in the canal was 2.5m in December, whereas a shallow depth of less than 0.5m was recorded in January. The water quality analyses confirmed the incursion of saline water (upto 32ppt) into the Canal. Not much variations were observed in Dissolved Oxygen and pH. Because of the organic pollution in the canal, the water was rich in nutrients before tsunami, whereas due to the large quantity of seawater invasion, dilution had occurred after tsunami. High turbidity was observed in January 2005 indicating the tsunami induced disturbance and resuspension of the sediments from sea bed.

Keywords: Tsunami, Ennore, Tamil Nadu, Buckingham Canal.

Abstract

The mangrove wetlands form dynamic ecotones between land and sea. Mangrove wetlands are unique in terms of environment, plant and animal communities and their distribution is restricted in tropical and subtropical coastlines. They perform a number of protective and productive functions, which ensures ecological and livelihood security to the coastal communities. The role of mangroves in mitigating the impact of cyclones and storm surges is well known but only limited information is available on their role in reducing the impact of tsunami. The Pichavaram mangroves, located on the southeast coast of India in Tamil Nadu, which was hit by the 26 December 2004 tsunami, provided opportunities to understand the contribution of it in tsunami mitigation. Through a systematic field study, a comparative analysis was made on the impact of tsunami in a set of villages, one was protected by mangroves and the other lacks any vegetation surrounding it. These villages are located at more or less equal distance from the sea and situated at about same elevation. Assessment carried out with well defined indicators such as loss of lives due to forceful entry of tsunami water, damages to houses and types of houses, etc., shows that loss of lives and damage to houses were much less in the village surrounded by Pichavaram mangroves. Thus, Pichavaram mangrove wetland, which was restored with the participation of the local community, Tamil Nadu Forest Department and M.S.Swaminathan Research Foundation (MSSRF) during 1993-2004 provided great dividend during tsunami. This underlines the importance of strengthening the ecological foundation of the coastal zone with mangroves and other vegetation as one of the strategies for mitigating the impact of natural disasters in the coastal areas.

Keywords: Mangroves, Natural Disasters, Tsunami, Impact Reduction and Pichavaram.

Abstract

Coral reefs, the marine representatives of tropical forests, coupled with the sea grasses contribute considerably to the coastal productivity. Damages to these ecosystems will immediately affect the fishery productivity of the region. Due to this, the long-term ecological impact of the recent tsunami will be a serious set back to the local, national and regional economy than the immediate losses. Andaman and Nicobar reefs represent the second largest coral reef formation next to the Great Barrier Reef and are also comparable to the coral reefs of Indonesia and Philippines in terms of diversity of species and associated floral and faunal components. The recent mega – subduction of the Indian plate below the Burmese micro – plate in Andaman – Sumatra region has not only deepened the southern and uplifted the northern group of Andaman – Nicobar islands but also created a disastrous tsunami on Dec 26, 2004. While such tectonic changes are expected to cause longterm changes in the coral reefs of Andaman, Nicobar group of islands, the tsunami has damaged the coral reefs instantaneously. However, the coral reefs of the Gulf of Mannar and Palk Bay are not much affected by the tsunami by virtue of their geographic position in the shadow region of Sri Lanka.

Keywords: Indian coral reefs, Tsunami effect, Coral recovery

Abstract

The Car Nicobar Island is one of the several islands in Indian Ocean which was severally damaged by the Great tsunami on 26 December 2004. The great tsunami event caused massive devastation, in the form of loss of life and property in south and south East Asia. The objectives of the study are to assess the changes in the coastal features of the Car Nicobar Island using various indicators such as the tsunami height, run- up elevation, water flow direction, erosion, sand deposition and coastal subsidence. Andaman &Nicobar Islands are the summit of the submarine mountain range lying along the great tectonic suture zone extending from Eastern Himalaya to Sumatra and Lesser Sunda via Myanmar border and Arakan hills. The IRS P-6 satellite data has been found to be very useful in the present tsunami assessment studies. The digital analysis of the satellite data was done using the image processing software (ERDAS IMAGINE 8.4) and DTM to quantify the tsunami height (15 m), run up elevation (2-19 m), inundation (295-1203 m) and coastal responses. The settlements and coconut plantations have been severely damaged in the island, which were assessed using GIS analysis of the pre and post-tsunami satellite data.

Keywords: Tsunami, Wave Height, Run-up Elevation, Inundation, Coastal Responses, Remote Sensing, GIS.