eChapters

Abstract

Traditionally remote sensing technology has been widely used in the mapping and change detection of vegetation features. Of late research has shown that remote sensing technology can be successfully employed for retrieval of biophysical parameters of vegetation, either by statistical techniques or by employing radiative transfer models (RTMs). This paper gives an introduction to leaf and canopy RTMs, especially about PROSAIL, which is the most commonly used model. It reviews different techniques for inverting RTM models, their merits and performance comparison. The main techniques briefly described are iterative optimization, look-up table, artificial neural network, genetic algorithm and support vector machine. At the end, it gives examples of applications which use canopy biophysical parameters retrieved by inverting RTM.

Keywords: Radiative transfer, PROSAIL, Inversion, Vegetation

1.0 Introduction

Accurate quantitative estimation of vegetation biophysical variables is useful for a large variety of agricultural, ecological, and meteorological applications (Houborg et al., 2007). The spatial and temporal distribution of these variables are important inputs into models quantifying the exchange of energy and matter between the land surface and the atmosphere, developing better yield prediction models and detecting abiotic stresses at regional scales. Among the many vegetation characteristics leaf area index, leaf chlorophyll content and leaf water content are of prime importance (Bacour et al., 2006; Houborg et al., 2007).

Abstract

In the present study an integrated remote sensing and Geographical Information System (GIS) based methodology is adopted for demarcating the groundwater prospective zones and identification of artificial recharge sites in the Peddavanka watershed, Andhra Pradesh. In this study Shuttle Radar Topograhic Mission (SRTM) digital elevation model (DEM) with spatial resolution of 90 m and Indian Remote Sensing Satellite (IRS-1A), Linear Imaging Self Scanner (LISS- III) satellite data along with other field and collateral data on geology and well inventory have been utilized to generating the Drainage, Slope, Lineaments and Hydro geomorphology of the study area, which are an essential prerequisites for demarcating water resources and identification of recharge sites. Spatial data integration and analyses are carried out in GIS environment.

Keywords : DEM, Drainage, Hydrogeomorphology, Groundwater prospective zones, Remote sensing, GIS

1.0 Introduction

Groundwater is an important natural resource in arid and semi- arid regions, because most of the places surface water resources are scarce and some places it’s totally absent particularly in hard rock areas. Because in hard rock terrains availability of groundwater is of limited extent and its occurrence is essentially confined to fractured and weathered zones (Saraf and choudhury 1998, Sankar 2002). In these areas groundwater recharge depends on rainfall only. For understanding rainfall recharge mechanism and groundwater management in the watersheds level, first we have to understand the morphometric parameters in the watershed level.

Abstract

Land development in urbanized watersheds poses a potential of increasing storm runoff rates, and therefore increasing the risk of flooding in the downstream areas of a watershed. To investigate the impact of change in land use practices on the watershed hydrology, an hydrological analysis was conducted on Little Kitten Creek watershed located near Manhattan city of Riley county, Kansas, USA. Prior to development, land use types in the watershed included woodland, pasture, and fallow land. However, rapid development has occurred in the watershed in the last ten years. Post development land use practices include commercial development, residential housing, and conservation (woodland and grasslands). Data collected and analyzed included digital elevation model (DEM) of study site, stream network and soil data using ArcGIS (ESRI, 2006) and Arc-Hydro Software (Maidment, 2000). Watershed characteristics such as slopes, channel length, circularity ratios, and drainage density were also computed. The delineated watershed boundary, stream segments and soil data layers were over laid to produce soil maps. Time of concentration (Tc) was determined for the pre and post development conditions in the watershed using seven different methods. The time of concentration values computed using Kerby, Federal Aviation Agency, Kinematic Wave and NRCS (SCS) methods found more reasonable compared to the remaining three methods used.

These computed time of concentration values were observed to be shorter for the post-development condition when compared to the pre-development condition of the watershed. The reduced time of concentration in the post development condition is attributed to increase in percentage of impervious areas due to increased residential development in the watershed; therefore increased rates of runoff in the watershed are expected.

Keywords: Rezoning, Time of Concentration, DEM, Kinematic Wave, Drainage density, Circularity ratio.

Abstract

Conventional wisdom holds that variability in rainfall represents a significant variability of agriculture production. But urbanization of the cities on one hand and climate change on theother hand areaffecting the agriculture. Surprisingly, there have been very few analyses exploring the link between rainfall variability and urbanization on agriculture production. Therefore an attempt is made in this paper to know the affect of rainfall variability and urbanisation on the cropping area. For this purposeNDVI analysis is carried out in the catchments of Osmansagar and Himayathsagar Reservoirs by using the medium to high spatial resolution multi spectral data provided by remote sensing satellites, such as Landsat TM, IRS-1C/1D LISS-III and IRS-P6 LISS-III has been used for the years1989, 1994, 1998, 2002 and 2008 for Kharif season, 1975, 1990, 1994, 1998, 2003 and 2008 for rabi season which is collected from NRSC (National Remote Sensing Centre). From this analysis it is found that the increment is more in rabi season compared to kharif season due to the increment of non-monsoon rainfall intensities and ground water withdrawal structures. The increased utilization of the groundwater is causing the reduction of inflows to the reservoirs in the recent years because whatever the rainfall that occurs in the catchment, first utilised for meeting the depleted soil moisture and ground water consequently reducing the surface runoff.

Keywords : Climate change, Urbanisation, Inflows, Cropping area, NDVI

Abstract

The rapid development and integration of spatial technologies viz., Geographical Information System (GIS), Remote Sensing (RS) along with Global Positioning Systems (GPS) provide functional alternatives to revolutionize the conventional entomological approaches like surveillance, spatial/temporal distribution of insect populations, pest distribution mapping and predictive modeling. Application of these technologies for insect problems is well established in the fields of forest, range land, medical and agricultural entomology elsewhere. Nevertheless, in India its field relevance in agricultural entomology is still limited owing to lack of proven field prototype studies and collaborative efforts among stakeholders. It’s time to gain real momentum to integrate these progressive technologies to formulate sustainable integrated pest management programs.

Key words: GIS, Remote Sensing, Insect Populations, Field Applications

Abstract

Carrying out effective and sustainable agriculture has become an important issue in recent years. A key to this is the usage of modern technologies for precision agriculture. Recent technological developments allowed envisioning sensor devices with distributed ambient sensory network, which could be a potential technology for monitoring various natural phenomena (weather parameters, soil moisture, etc.) at micro level. As more and more agricultural data are virtually being harvested along with the crops and are being collected/ stored in databases, the same can be used in productive decision making if appropriate data mining techniques are developed/applied. As a case study for this, an experiment was conducted with four consecutive agricultural (Kharif and Rabi) seasons in a semi-arid region of India to understand the crop-weather-environment-pest/diseases relations using wireless sensory and field-level surveillance data on closely related and interdependent pest/disease dynamics of groundnut crop. Association rule and multivariate regression mining techniques/algorithms were propose developed /tailor-made to turn the data into useful information/ knowledge/relations/trends to know crop-weather- environment-pest/disease continuum. These findings have been used for development of prediction models (cumulative and non-cumulative) followed by a web based pest/disease decision support system.

Keywords : Data Mining, Pest/Disease Management, Precession Protection, Wireless Sensor Networks

Abstract

Remote sensing is the art and science of obtaining information about an object or phenomenon without having any contact with the object concerned. Geographical information system is a tool to create, manage, retrieve and query spatial databases. Remote sensing in conjunction with Geographical Information System (GIS) has wide applications in all spheres of life and especially in agriculture. Specifically, this paper reveals some of the applications of remote sensing and GIS in the field of crop condition assessment viz., crop type classification, crop stress detection, crop yield estimation and pest and disease monitoring.

Keywords : Remote Sensing, GIS, Yield Forecasting, Crop Stress, Pest and Disease Monitoring

1.0 Introduction

Remote sensing is the art and science of obtaining information about an object or phenomenon without there being any physical contact. The information is so collected using a device called a sensor. The sensors are mounted on a platform at an advantageous position. Accordingly the remote sensing is called ground based (sensor is hand held or mounted on mast), air borne (sensor is on a balloon or aero plane) or space borne (sensor is mounted on a satellite). The basic principle in remote sensing is that each and every object has unique reflecting property like human thumb impression and when the solar energy is falling on an object a part of it gets reflected, which carries the information about the object. The reflected light is converted in to reflection percentage of incoming solar radiation. This percentage of reflection can be used to work out the vegetation indices which are surrogate measure of crop condition.

Geographical Information System (GIS) is software system which enable Collection of large volume of data with spatial relation Integration of data from different source is possible Analyze such data for our requirement Present the data in different formats (maps, table and reports)

Abstract

The present study discusses the cropping pattern changes in Andhra Pradesh agriculture will leads to crop diversification and crop concentration using with Geographical Information System (GIS). Crop data were compiled for the triennium ending period 1980-81, 1990-91, 2000-01 and 2004-05 from various statistical abstracts of Andhra Pradesh. For measuring the crop diversification indices, we have used the Herfindahle index and for crop specialization is measured by using the Location quotient method. The level of crop diversification in the some districts of the state in the eighties is very high. However with the advent of green revolution, there had been a moderate crop unification or crop concentration in the eighties. This trend of crop unification is found to be reversed after 1990-91, though the magnitude of the change is not very striking. The crop diversification is observed to differ across the districts. The level of crop diversification is high in the agricultural backward regions of Rayalaseema and Telangana districts and low in the agriculturally progressive Coastal Andhra districts. During the period 1990-91 to 2004-05, the major trends in crop concentration are increase in the concentration of rice in the districts where it is popularly grown and decline in the concentration of coarse cereal crops, pulses and oilseeds. The concentration of spice crops and fruits and vegetables are also on an increasing trend, which they are popularly grown in their respective districts.

Keywords : Cropping Pattern, Diversification, Location Quotient, Andhra Pradesh, GIS

Abstract

Food security to the increasing population on one side and the increasing export of food grains on the other side has lead to the immediate attention on to raise the food production in our country. The decreasing land availability for agriculture due to the increased degraded lands and use of agricultural lands for non agricultural purposes has still worsened the situation. In order to match with the food requirement from decreasing agricultural lands, Indian agriculture has been pushed towards indiscriminate use of farm inputs exploiting the non renewable natural resources without any concern to the environmental ill effects leading to further degrading of the situation. Even though the concept of sustainability is age old, the importance is felt recently. Sustainable use of resources at farm level can magnify the effect of conserving non renewable resources and reducing ill effects on the environment at state level and to the country. Sustained farm production is a key to manage our resources and environment. Adoption of new information technologies with the conventional agronomic practices to increase farm production is made inevitable due to our past experience. The advancement in the technology tools like Remote Sensing, Geographic Information System, Global Positioning System and Decision Support Systems have paved way for better and effective management of crop production at farm level. 46 Geospatial Technologies for Natural Resources Management

A systematic approach of management involving advanced technologies and conventional agronomic practices through understanding the factors like soil variability, weather parameters and crops that contribute for the sustainable farm production is need of the hour. The spatial and temporal variability of the farm production parameters are to be studied and mapped in relation to historical data of the farm for successful site specific management. Site specific management tools may improve decisions related to site conditions, thereby reducing the aspect of uncertainty in the management system. This approach of farm management using advanced technologies viz., Remote Sensing, Geographic Information System, Global Positioning System, Variable rate technology, crop production modeling and Decision Support System can enable sustainable farm production with beneficial effect on the environment in future.

Keywords : Remote sensing, GIS, Sustainable Farm production, Site Specific Management

Abstract

Soil Resource Appraisal helps in characterizing the existing land resources, assessing their suitability for various land uses and then helping the user to prepare a rational land use plan suitable for the integrated development of the area. Application of Remote Sensing (RS) and Geographical Information System (GIS) helps not only in the characterization of the resource base, but also in the generation of various thematic maps and preparation of land use and action plans for effective implementation of various developmental plans at farm level.

Keywords : Soil Resource Appraisal, Land Use Plan, Farm level Developmental Plans

1.0 Introduction

A thorough knowledge and understanding of soils is basic to the development and management of agricultural resources. About 100 years ago, man began systematic study of soils in the field and tried to separate, classify and map their geographic distri­bution. Today we have sufficient knowledge about soils; however the characterisation, classification and mapping of soils is still tedious, time consuming and costly affair. Therefore the need for adopting new and more rapid and accurate methods of mapping soils has resulted in the use of satellite images with image interpretation techniques for soil survey and map­ping.

In India for the country as a whole, soil and other land resources information is available at 1:1 M scale, which was generated from the state level mapping done at 1:250,000 scale under the Soil Resources Mapping Project of India during the period from 1986 to 1995. This information is of general nature and useful for planning on a wide canvas and not particularly useful for farm or watershed level planning in the country. For site-specific needs and for developmental works at watershed level, we need detailed farm level database at 1:10,000 scale. Once this type of information is generated at village/watershed level, this will be useful for identifying site specific constraints, generation of area and site specific agro technologies, land-use options based on soil site suitability assessment, wasteland identification, identification of prime farm lands and farm clusters for zoning and Strategic planning, preparation of farm level development plans by line departments and proactive advice and technology transfer to farmers.

Abstract

The ever increasing population in India and the world, impeding threats from the climate change scenario and the increasing demand for land resources from the industrial sector calls for improved resource efficiency. The production strategies are changing from input intensive to integrated resource management strategies. The shift is towards adopting the precision farming technologies like addressing the site specific variability and crop needs. Remote sensing technology coupled with GIS has been recognized as reliable tool in agriculture to guide application of fertilizer, pesticides and other farm inputs. With precision farming, technologies such as grid soil sampling, remote sensing, on- the-go sensing, and electronic yield monitoring help farmers gather very detailed information about the heterogeneous makeup of a farm field. Site specific applications means application of required input only where it is required rather than entire fields or adjusting application rates accordingly. This chapter discussed the input management based on the time of intervention - Input management prior to crop sowing, in season crop management and end of the season.

Keywords : Management zones, soil variability and Remote Sensing

1.0 Overview

Natural resources sustain life and are critical for economic development of nations. In developing countries like India where more than half the population is rural, economic development is inextricably linked with agricultural development. In these countries, the food and livelihoods security of the poor are critically associated with access to the services provided by the natural resources - land, soil, water, biodiversity and climate resources. The natural resources are finite, and with increasing population, economic growth, urbanization, and demands for food and other agricultural commodities, these are being increasingly strained. As a result, the productive capacity of the natural resource base is shrinking and deteriorating. Sustaining the productive capacity of natural resources for future generations, while meeting the food and other demands of the growing populations, is the major development challenge of the twenty first century.

In India, during the last forty years the net sown area under agriculture has remained nearly constant at 141 million ha. In the same period, the population has more than doubled (from 541 million in 1970 to 1186 million in 2010) and per capita income grew by more than 3.5 times (from Rs 14824 in 1970 to Rs 53331 in 2010). As available land resources for agriculture are finite, increases in agricultural production to meet the growing demands of the population have to come from intensification of agriculture on the same lands. As a result, the quality of soils on these lands is gradually deteriorating both at the farm and ecosystem levels. The major threats to soil quality come from loss of organic carbon, erosion, nutrient imbalance, compaction, salinization, water-logging, decline in soil bio-diversity, urbanization, and contamination with heavy metals. More than 100 million ha of the total cultivated land of 141 million ha is stated to be under some form of soil degradation.

Similarly, utilizable fresh water resources of India are finite at about 1123 billion cubic meters (BSM), of which about 690 BCM are from surface water resources and 433 BCM are from groundwater. This supply is shared among multiple uses: human and animal consumption, agriculture, urban uses, industry and for provision of environmental services. The total water demand in 2010 is estimated at 710 BCM and is projected to increase to 1180 BCM by 2050. Several parts of India are already facing severe water shortages as a result of the growing demand for water. The quality of water resources is also impacted by agricultural intensification and development, and is increasingly a matter of concern. By the year 2050, when population is expected to stabilize, the shortages will only intensify. The country as whole can be on the verge of becoming a water scarce country, with nearly all the presently estimated utilizable water resources being put to use.

Biodiversity natural resources refer to the abundance of different species and ecosystems in nature. These resources are the primary sources of present and future productive agriculture and human well being, as they provide the basic resources for use in breeding crops and livestock, soil formation and structure, soil fertility, nutrient cycling and the provision of water services. India is among the 12 mega diversity regions of the world. It is known to have more than 18,000 species of higher plants including, 160 major and minor crop species and 325 of their wild relatives. Increasing pressure from human population growth, agricultural intensification, urbanization, pollution and degradation of land, soil and water resources are having a negative impact on the plant, animal and microbial biodiversity resources of the country and their productivity.

17.1 Introduction

It is well known fact that planners as well as end users have to consider any resources as technology from economic point of view. Therefore, it is important to have techno – economic analysis of each energy source option. In the feasibility study of particular energy option, three tier judgment approaches is required, which include technical feasibility, economical viability and social acceptability. Hence in the rural energy planning programme one has to considered techno socio economic analysis of an individual energy option. Since in integrated rural energy planning, locally available energy resources are used, presuming that it is socially recognized. Hence in the IREP project, the need and scope of techno economic analysis in terms of economic analysis of different technical feasible options, before between “economic” and “finical” analysis should be kept in mind. An economic analysis is needed to verify that a particular energy source will provide “net benefit” to society as a whole, before its final integration in the energy context, while a financial analysis integrated in the energy practices. In simple words, a financial analysis is concerned with goods and services, money inflow and outflows and the transfer of payments. An economic analysis also considers the social benefits and costs of goods and services which are not traded in a market.

16.1 Fuel Cell

Fuel cell is an electrochemical device that convert chemical energy of a reaction directly into electrical energy. The basic physical structure of a fuel cell consists of an electrolyte layer in contact with a porous anode and cathode on either side. A schematic representation of a fuel cell with the reactant or product gases and the ion conduction flow directions through the cell is shown in Fig. 16.1

15.1 Introduction

The oceans cover 71% of the earth’s surface and it acts a natural collector and store of solar energy. On an average day, 60 million sq. km. of tropical seas absorb an amount of solar radiation equivalent in heat content to about 245 billion barrels of oil, if this energy could be trapped, large scale renewable source becomes available especially for tropical countries. The energy available in the ocean is clean, continuous throughout the year and renewable.

Renewable energy contribution to the available energy resources is very important to the country as it is presently facing an energy resources crunch. Out of the total installed capacity of approximately 370.106 GW as on March 2020, Renewable Power Plants including hydro-electric plant contribute 35.86 % of total installed capacity. However, with the present increase in demand, more attention is required to extract the renewable sources so that at least 50 to 60 % share for the total energy requirement by the renewable energy sources.

There are various forms of ocean energy such as Ocean Thermal Energy Conversion (OTEC), Wave Energy, Tidal Energy, Salinity Gradient Energy, Offshore Wind Energy, Marine Currents, Marine Biomass Conversion. Among these, the first three forms are likely to be technically viable for the future.

More recently Ministry of New and Renewable Energy (MNRE), Government of India hasdeclared Ocean Energy as renewable energy, and clarified to all the stakeholders that energy produced using various forms of ocean energy such as tidal, wave, ocean thermal energy conversion among others shall be considered as renewable energy.

MNRE reported that, the total identified potential of tidal energy is about 8000 - 9000 MW, with about 7000 MW in the Gulf of Cambay in Gujarat, about 1200 MW in Gulf of Kutch and less than 100 MW in Sundarbans. Primary estimates of wave energy potential along Indian coast are about 5 – 15 MW/m, so that theoretical estimates are around 40 – 60 GW. Ocean Thermal Energy Conversion (OTEC) has a theoretical potential of 180,000 MW in India subject to suitable technological evolution. As of date, there is not any installed Ocean Energy capacity in India.

14.1 Introduction

Hydro-electric power is electricity produced by the movement of fresh water from rivers and lakes. Gravity causes water to flow downwards and this downward motion of water contains kinetic energy, that can be converted into mechanical energy, and then from mechanical energy into electrical energy in hydro-electric power stations. (“Hydro” comes from the Greek word hydra, meaning water). At a good site hydro-electricity can generate very cost-effective electricity.

13.1 Introduction

Geothermal energy is the nature-based heat generated from within the earth. Underneath the earth’s relatively thin crust, temperature range from 1000 to 4000°C & in some areas, pressures exceed 138 MPa is available. Geothermal energy is most likely generated from radioactive thorium, potassium and uranium dispersed evenly throughout the earth’s interior which produce heat as part of the decaying process. This process generates enough heating, keep the core of the earth at temperature approaching 400°C. Composed primarily of molten nickel & iron, the core is thought to be surrounded by a layer of molten rock, the mantle at approximately 100°C. Nine major crustal plates float on the mantle & currents in the mantle cause the plates to drift, colliding in some areas and diverting in others. When two continental plates converge a complex series of chemicals in the form of molten magna rises in the earth’s crust and depending upon its magnitude, it may break the crust and reach at the earth surface. Volcano, hot spring, geysers & fumaroles are natural geothermal resources near the surface and perhaps where economic drilling operations can tap their heat and pressure.

12.1 General

The term “biomass” generally refers to renewable organic matter generated by plants through photosynthesis. Materials having organic combustible matter is also referred under biomass. Biomass is an important fuel source in our overall energy scenario. Biomass is produced through chemical storage of solar energy in plants and other organic matter as a result of photosynthesis. During this process conversion of solar energy in sugar and starch, which are energy rich compounds takes place. The chemical reaction of photosynthesis can be written as:

6CO₂ + 6H₂ O + sun light → C₆ H₁₂ O₆ + 6O₂ + 636_kcal

It indicates that the storage of 636 kcal is associated with the transfer of 72 gm carbon into organic matter. Biomass can be directly utilized as fuel or can be converted through different routes into useful forms of fuel. In fact, biomass is a source of five useful agents, which start with `F’ like Food, Fodder, Fuel, Fiber and Fertilizer. Further, biomass has many advantages like.

11.1 General

Biogas is generated through a process of anaerobic digestion of organic materials. The materials normally used are human and animal waste, crop residues, agro-industrial waste and other biomass in a combination with water. Biogas production technology contributes in following ways:

(a)It provides a better and cheaper fuel for cooking, lighting and for power generation.

(b)It produces good quality, enriched manure to improve soil fertility.

(c)It provides and effective and convenient ways for sanitary disposal of human excreta, improving the hygienic conditions.

(d)It generates social benefits such as reducing burden on forest for meeting cooking fuel by cutting of tree for fuelwood, reduction in the drudgery of women and children etc.

(e)As a smokeless domestic fuel, it reduces the incidence of eye and lung disease.

(f)It also helps in generation of productive employment.

The biogas technology is primarily based on fermentation of cellulosic rich organic matter under anaerobic conditions. The methane producing bacteria become more active after the creation of anaerobic conditions, thus, the gas produced become rich in methane & carbon dioxide, beside traces of hydrogen sulphide, ammonia, oxygen, water vapour etc. depending on the feed material and other conditions. For burning of gas, it is necessary that methane contents should be more than 50 per cent. The complete knowledge of process of methane production including its chemistry, physiology, bio-chemistry, micro-biology and bacteriology has been studied over years in many parts of the world. The culture and isolation of microbes under various environmental conditions have been successfully experimented to improve rate of reaction. The conditions, under which cattle dung, organic wastes, bushes, weeds etc. will produce methane, can be understood through chemistry of fermentation.

10.1 Introduction

Winds are the motion of air around the Earth. This movement in air is caused by the uneven heating of the planet’s surface by the sun. The idea of using wind as a form of power is not new. The traditional applications of wind were primarily as sources of kinetic energy for rural, agricultural and a limited number of industrial uses such as pumping water and grinding grain.

Presently wind energy can be used for two major applications, such as wind mills for pumping water for drinking as well as for irrigation purposes and second application is as aero-generator for electricity generation for domestic and industrial uses. In addition to this, presently wind energy battery charger are also available, which can store energy for lights, radio communication, hospital equipment and to power various emergencyrelated equipment.

The wind energy has an enormous resource, but the problems of utilizing the winds are many and varied. Wind energy is very diffuse in nature and local topographical features significantly alter the prevailing winds, thus leading to the extremely site specific nature of wind energy.

Scientists have estimated that as much as 10% of the world’s electricity could be prepared by wind generators by the middle of 21 century. India has estimated wind power potential of 40,000 MW. India now, ranks fourth in the world in wind power generation.

The world’s largest wind farms are in California (USA), where wind turbines can generate power up to about 1120 MW. The first wind mill used as source of electric power was built in Denmark in 1890.

9.1 Introduction

Basically, for heating or cooling the space using solar energy, the solar energy is to be collected, stored and distributed properly in the space to be heated or removed from the space to be cooled. There are two basic approaches for solar houses, there are:

(a)Active solar house technology

(b)Passive solar house technology

In active approach, the solar energy is collected and stored in some separate solar energy collector and then energy is distributed in the space where heating is to be done using electrically operated pumps and fans coupled with radiator etc. The storage of solar energy in active solar house may be in the form of storage as sensible heat or storage as latent heat or chemical heat storage. As per requirement of heating the size of solar collector and storage system be decided. Generally, the active concepts of solar houses are used for heating purpose. Active concept can also be used for space cooling applications. Solar vapor compression and absorption system can be used for this purpose, essentially, this includes incorporation of solar heat collectors, thermal storage system, auxiliary heat supply system (to compensate intermittent nature of sun energy) and control systems. Further, there are three ways of solar space heating i.e. solar air systems, solar liquid systems and solar heat pump systems.

8.1 Introduction

Solar energy can be directly converted into electrical energy. Energy conversion devices which are used to convert sun light into electricity by use of the photovoltaic effect are called solar cells. The advantages of solar cells are:

1.They are reliable, convenient and durable.

2.It is green, sustainable and pollution free technology.

3.Directly solar radiation can be converted into electricity (conversion of global solar light by flat plate photovoltaic).

4.Maintenance cost is quite low therefore suitable even in isolated and remote area, since no moving parts are involved.

5.Solar cells are quite compatible with almost all environments, respond instantaneously with solar radiation.

6.Considerable expected lifetime i.e. 20 years or even more.

7.1 Introduction

A greenhouse is quasi-permanent structure, covered with a transparent or translucent material, ranging from simple homemade designs to sophisticated pre-g\fabricated structures, wherein the environment could be modified suitable for propagation or growing of plants. Materials used to construct a greenhouse frame may be wood, bamboo and steel or even aluminum. Covering can be glass or various rigid or flexible plastic materials. Depending on the covering material, different terminology have been used in the context of greenhouse structures as mentioned below:

Glasshouse: A greenhouse with glass as the covering material is called glasshouse

Polyhouse: It is a greenhouse with polyethylene as the covering material.

6.1. Introduction

Solar crop drying has been demonstrated to be cost effective and an effective alternative to traditional and mechanical drying systems, especially in location with god sunshine during the harvest season. Considerable energy savings can be made with open sun drying since the source of energy is free and sustainable. However, this method of drying is extremely weather dependent and has the problems of contamination, infestation, microbial attacks, etc., thus affecting the product quality. Additionally, the drying time required for a given commodity can be quite long and results in post-harvest losses. Solar drying of agricultural products in enclosed structures by natural convection is an attractive way of reducing post harvest losses and low quality of dried products associated with traditional sun-drying methods. The crop is vulnerable to damage due to hostile weather conditions. The crop is also susceptible to re-absorption of moisture, if it is kept on the ground during periods of no sun, which reduces its quality. This type of problem can be solved by solar dryer. Many dryers have been developed and used to dry agricultural product in order to improve shelf life .Most of these either use expensive sources of energy such as electricity or combination of solar energy and some other form of energy which is not cost effective and dependent on regular supply of fuel.

Principally, drying requires temperature for removing moisture from product, air flow rate to remove moisture from drying chamber and optimum relative humidity within the drying chamber to allow fast drying. These all three requirements for drying can easily be achieved from solar energy. Solar drying is one of the direct applications of solar heat, which involves removal of moisture from the products through the application of solar energy. The removal of moisture requires only low temperature heating, which can be met easily by absorbing solar energy by the surface. This increases the temperature of the air inside the dryer. The moisture produced from the drying product is usually carried out along with the exhaust air. The characteristic of solar energy is good for the drying at low temperature i.e. high flow rates with low temperature rise. The intermittent nature of solar radiation can not affect the drying performance at low temperature. Further, solar energy is available at the site of use and saves transportation cost.

5.1 Introduction

Energy in the form of heat is one of the main energy requirements in domestic, agricultural, industrial and commercial sector of our economy. From an enduse point of view, solar thermal energy finds its application in these areas. Solar thermal energy devices convert radiant energy of the sun into thermal energy for different productive works. In fact, solar energy consists of infrared radiation, it is characteristics of infrared radiation that whenever it falls on any object, it converts into thermal heat energy.

The conversion of sun light into thermal energy is easily or conveniently achieved by means of a metallic or plastic cover, painted black with ordinary black board paint or having selected coating over it and covered with one- or double-glazing cover for transmitting solar radiation inside it. This metallic cover is known as absorber, below it either channels or pipes or passages for allowing entry of water or air are provided, through which heat energy is transferred to working medium either air or water. The absorber plate is covered with suitable thickness of insulating material on its back or sides for preventing loss of heat from the absorber plate. This complete system is enclosed in an airtight box. When exposed to solar radiations, the blackened metallic surface absorbs solar energy and converts into heat. This heat could be used for cooking of food, heating of water and air, evaporation of moisture form the grains etc. In fact, absorber works on the principle of black body, which absorbs maximum and a good absorber, is a good emitter. Hence generated heat could be utilized for different applications.

4.1 Introduction

Heat is energy which flows due to difference in temperature. Whereas energy is stored heat. Therefore, when the heat energy transfer is completed. It is stored in the form of potential or kinetic energy, in general as internal energy. Heat as energy is measured in terms of observed changes in other forms of energy & other physical properties. A heat transfer analysis is required for estimating the size, the efficiency and cost of the equipment necessary to transfer a specified amount of heat in a given time. It is well known fact that the size of a solar collector or a heat exchanger depends not so much on the amount of heat to be transmitted but rather on the rate at which heat is to be transferred under given conditions.

4.2 Modes of Heat Transfer

Heat is transferred from one body to another in three possible ways, conduction, convection, and radiation.

3.1 The Sun

The Sun is a star. It is a huge, spinning, glowing sphere of hot gas. It appears so much larger and brighter than the other stars because we are so close to it. The Sun is the center of our Solar System and contains most of the mass in the Solar System. All of the planets in our Solar System, including Earth, orbit around the Sun. In sun the energy generation is a multi-step process of thermo-nuclear fusion reactions. In the thermo nuclear fusion hydrogen (four protons) combines to form helium (one helium nucleus). The mass of the helium nucleus is less than that of four hydrogen protons and mass having been lost in the reaction is converted to energy. The reaction is represented as

2.1 Introduction

The name thermodynamics stems from the Greek words therme (heat) and dynamis (power), which is most descriptive of the early efforts to convert heat into power. It may be defined as the science that deals with the relations among heat, work and properties of a system. Today, thermodynamics is broadly interpreted to include all aspects of energy and energy transformations, including power generation, refrigeration, and relationships among the properties of matter. It is viewed as the science of energy, and thermal engineering is concerned with making the best use of available energy resources.

Thermodynamics basically entails four laws or axioms known as Zeroth, First, Second and Third law of thermodynamics.

The zeroth law deals with thermal equilibrium and establishes a concept of temperature.

The first law pertains to the conservation of energy and introduces the concept of internal energy.

The second law indicates the limit of converting heat into work and introduces the concept of entropy.

The third law defines the absolute zero of entropy.

The concept of energy was introduced by Newton in the field of mechanics during generalizing the hypothesis of kinetic and potential energies. Energy may be defined as the capacity to do work and it is a scalar quantity. It cannot be seen or observed. Its presence can, however, be felt by the properties of the system. There occurs a change in one or more properties of the system in case of energy transfer. The absolute value of energy of a system is difficult to measure, whereas the energy change is rather easy to calculate. Energy follows the conservation law, one of the most fundamental laws of nature, which simply states that during an interaction, energy can change its form from one form to another but the total amount of energy remains constant, that is, energy cannot be created or destroyed only form can be changed.

1.1 General

Renewable technologies are considered to be clean sources of energy. The optimal use of these resources minimize environmental impacts, produce minimum secondary wastes, and are sustainable based on current and future economic and social needs. Sustainable development requires methods and tools to measure and compare human activities’ and its environmental impacts for various products. Renewable energy sources (RES), which include biomass, hydropower, geothermal, solar, wind, and marine energies, supply 14% of the world’s total energy demand. Renewable resources refer to primary, domestic, and clean or inexhaustible energy resources. Large-scale hydropower energy supplies 20 % of the global electricity need. Wind power in coastal and other windy regions is a promising source of energy.

Renewable energy resources can make a decisive contribution to the economic, social and sustainable development of rural regions in developing countries, yet the consumption of fossil fuels is dramatically increasing along with improvements in the quality of life, the industrialization of developing nations, and the increase of the world’s population. It has long been recognized that excessive consumption of fossil fuel leads not only to a diminishing fossil fuel reserves more quickly, but also has a significant adverse impact on the environment. Such impacts result in increased health risks and the threat of global climate change. Changes to improve environmental conditions are becoming more politically acceptable globally, especially in developed countries. Society is slowly moving towards seeking more sustainable production methods, minimizing waste, reducing air pollution from vehicles, generating distributed energy, conserving of native forests, and reducing greenhouse gas emissions. Increasing consumption of fossil fuel to meet out current energy demands, however, has sounded alarms over regarding potential energy crisis. This has generated a resurgence of interest in promoting renewable alternatives to meet the developing world’s growing energy needs. Excessive use of fossil fuels has caused global warming from carbon dioxide emissions, therefore, promoting renewable forms of clean energy is eagerly required. To monitor the level of these greenhouse gas emissions, an agreement that has fulfills the objectives of the Kyoto Protocol was create with overall pollution prevention targets.

The science of agrometeorology has great practical utility in protection against, or avoidance of adverse climate risks of crop production. Agrometeorological information can be used in efficient land use planning, determining suitable crops for a region, risk analysis of climate hazards and profit calculations in farming, production and harvest forecasts, and in adoption of farming methods and choice of farm machinery. Meteorological instruments are the equipments used to sample the state of the atmosphere at a given time. Meteorology does not use much laboratory equipments but relies more on field-mode in situ observation and remote sensing equipments. Rain was one of the first weather parameter to be measured historically. Two other accurately measured weather-related variables are wind and humidity.

An agrometeorological observatory or station is a place where all the necessary instruments and structures are installed and maintained to observe and record the weather parameters at stipulated time interval.

Many aspects of the global climate are changing rapidly. Evidence for changes in the climate system abounds, from the top of the atmosphere to the depths of the oceans. The climate system is the highly complex system consisting of five major components; the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere, and the interactions among them. The climate system evolves in time under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations and human-induced forcings such as the changing composition of the atmosphere and land-use.

The term ‘climate variability’ is often used to denote deviations of climatic statistics over a given period of time (e.g., a month, season or year) from the long-term statistics relating to the corresponding calendar period. In this sense, climate variability is measured by those deviations, which are usually termed anomalies.

‘Climate change’ refers to a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Climate change may be due to natural internal processes or external forcings, or due to persistent anthropogenic changes in the composition of the atmosphere or in land use. The United Nation’s Framework Convention on Climate Change (UNFCCC) defines ‘climate change’ as ‘a change of climate behaviour which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods’. The UNFCCC thus makes a distinction between ‘climate change’ attributable to human activities altering the atmospheric composition, and ‘climate variability’ attributable to natural causes. Climate change is a long-term shift in weather conditions measured by changes in temperature, precipitation, wind, snow cover, and other indicators. It can involve both changes in average conditions and changes in variability, including, for example, changes in extreme conditions.

A key difference between climate variability and change is in persistence of ‘anomalous’ conditions. In other words, events that are used to be rare occur more frequently, or vice versa. Occasionally, an event or sequence of events occurs that has never been recorded before, such as the exceptional tsunami in the Indian Ocean in 2004 or hurricane season in the Atlantic in 2005. Yet even that could be a part of natural climate variability. If such a season does not recur within the next 30 years, by looking back it could be called as an exceptional year, but not a ‘climate change’. Only a persistent series of unusual events taken in the context of regional climate parameters can suggest that a potential change in climate has occurred.

Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. Weather forecasts are made by collecting quantitative data about the past and current state of the atmosphere on a given place and using scientific understanding of atmospheric processes to project how the atmosphere will evolve on that place. Weather warnings are important forecasts because they are used to protect life and property. Forecasts based on temperature and precipitation is important to agriculture.

Agricultural production is highly dependent on weather, climate and water availability, and is adversely affected by weather and climate related disasters. In many developing countries where rainfed agriculture is the norm, a good rainy season means good crop production, enhanced food security and a healthy economy. Failure of rains and occurrence of natural disasters such as floods and droughts can lead to crop failures, food insecurity, famine, loss of property and life, mass migration, and negative national economic growth (Sivakumar, 2006).

Farming in many parts of the world, especially in the arid and semiarid regions is risky, because climate is highly variable. In some developing countries as much as 80% of the variability in agricultural production is due to the variability in weather conditions. This production variability in agriculture has immediate and important macroeconomic impacts. A timely seasonal forecast of favourable conditions could permit farmers to adjust cropping patterns and input use in order to benefit fully from these conditions. Also, a timely forecast could give the marketing system and downstream users, such as the food processing industry, time to prepare for a bountiful harvest (Arndt et al., 2000). It is important to remember that under rainfed conditions, even a less reliable, but earlier forecast may be more valuable than an accurate but late forecast (Mjelde et al., 1998).

Different crops are grown over a wide range of agroecosystems. Though the crops are raised in varied climates, ranging from very hot to very cold, and very wet to very dry, across temperate, tropical and semiarid zones, they are very sensitive to climate. The crop production is dependent on climatic parameters like rainfall, light, temperature, relative humidity and carbon dioxide concentration. Each kind of cultivated crop plants has its own optimum growth requirements. Breeding and selection of new cultivars have allowed for a greater adaptability to less favourable growing conditions than was possible in the past, but the inherent climatic requirements of a specific kind of crop have not changed materially.

CLIMATIC NORMALS FOR CROPS

Crop management is very much about managing climate risk so as to have financially viable and sustainable agricultural systems. Professor Henry Nix of the Australian National University posed three questions that need to be addressed when considering what crop can be grown where (Nix, 1981).

1. For any given crop which areas offer the greatest biophysical advantages?
2. For any given area which crops offer the greatest advantages?
3. For any given crop and area how much productivity be raised and sustained?

A weather hazard is an extreme weather event that threatens people or property. There are various weather hazards that affect agricultural productions. These hazards vary from one climatic zone to another and occur at different times, although some regions are more vulnerable to certain hazards than other. These weather hazards depend on the latitude of the place on the world map. These hazards affect crops and agricultural productivity negatively if they are not checked. Every agricultural zone has one particular hazard that is associated with it and in most cases affects the crop productions and reduces the annual crop yield. Weather hazards include cyclones, droughts, f loods, hailstorms, heat-waves and cold-waves.

The hazard is distinguished from an extreme event and a disaster. An extreme event is simply an unusual event; it does not necessarily cause harm. A disaster is an event that does cause harm in significant amounts. Weather hazards are often called as natural hazards. The natural hazards become natural disasters when people’s lives and livelihoods are destroyed.

Hydrologic hazards are the result of either excess or a severe lack of water, i.e., flood or drought. Hydrometeorological hazard is a process or phenomenon of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage. Human and material losses caused by natural disasters are a major obstacle to sustainable development. By issuing accurate forecasts and warnings in a form that is readily understood and by educating people about how to prepare against such hazards, before they become disasters, lives and property can be protected.

The word ‘monsoon’ is derived from the Arabic word mawsim meaning season. The Arabs during their travel towards India recognised that by June strong southwesterly winds commence over the Arabian Sea and bring a lot of rains to the subcontinent. The term was first used in English in British India and neighbouring countries to refer to the big seasonal winds blowing from the Bay of Bengal and Arabian Sea in the southwest bringing heavy rainfall to the area. In the Indian subcontinent, monsoon is one of the oldest weather observations, an economically important weather pattern over June through September every year, and the most anticipated weather event and unique weather phenomenon. Due to its effects on agriculture, flora and fauna, and other economic, social, and environmental effects, a monsoon is keenly followed and studied. It has significant impact on the overall well-being of subcontinent residents.

The term ‘monsoon’ is customarily used in India to refer to the rainy season during the northern hemisphere summer from June to September and is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea. Now the term monsoon has been broadened to include almost all of the phenomena associated with the annual weather cycle within the tropical and subtropical land regions of the earth.

Intergovernmental Panel on Climate Change (IPCC) describes monsoon as a tropical and subtropical seasonal reversal in both the surface winds and associated precipitation, caused by differential heating between a continental-scale land mass and the adjacent ocean. India Meteorological Department defines it as the seasonal reversals of the wind direction along the shores of the Indian Ocean, especially in the Arabian Sea, that blow from the southwest during one half of the year and from the northeast during the other half.

The definitions include major wind systems that change direction seasonally. The cyclic change of wind and rain can be separated into the summer monsoon period characterised by warm and humid southwest winds, and the winter monsoon period characterised by dry and cool northeast winds. In fact, monsoon systems are a major feature of the general circulation of the atmosphere in subtropical latitudes of most regions of the world.

Precipitation is water in liquid or solid forms, falling on to the earth. In other words, precipitation is the deposition of atmospheric moisture on earth. Formation of clouds does not mean precipitation. Precipitation involves condensation, growth of hygroscopic nuclei, cooling of nuclei at different stages and their fall on to the earth’s surface. There may be several clouds but no precipitation. If the cloud particles are too small and remain suspended in the sky, they may not fall on the earth. Under certain conditions, water particles formed tend to fall but do not reach the surface since they get evaporated on the way. Only when the cloud droplets or ice crystals grow to certain size and can no more remain floating due to buoyancy of air, do they fall as precipitation.

Precipitation is the major source of water to all the living organisms on the earth. All the water sources on the earth depend on precipitation only.

FORMS OF PRECIPITATION

Precipitation form is the state that the moisture is in, i.e., liquid, freezing, or frozen (solid). Different forms of precipitation may occur together, such as mixed rain and snow; but such an occurrence is simply a mixture of forms, not a separate form of precipitation. Because atmospheric conditions vary greatly both geographically and seasonally, several different forms of precipitation are possible. All forms of precipitation are collectively termed hydrometeors. Hydrometeors have been classified into 50 specific types. Out of these precipitation forms, only rain (liquid form) and snow (solid form) make significant contribution to total precipitation. In many parts of the world, the term rainfall is used interchangeably with precipitation.

Clouds are visible mass of little drops of water or frozen crystals suspended in the atmosphere above the surface of the earth. The World Meteorological Organisation defined cloud as a visible aggregate of minute particles of water or ice or both, in the free air. This aggregate may include larger particles of water or ice and particles such as those present in fumes, smoke or dust.

Clouds are the most important form of suspended water droplets caused by condensation. The typical size of these water droplets and ice crystals range from less than 1 µm to 50 µm. When surrounded by billions of other droplets or crystals, they become visible as clouds. In the atmosphere sufficient moisture is required to allow condensation to take place. Then, moisture needs a suitable surface upon which it can condense. In free air, condensation begins on hygroscopic nuclei such as aerosols. These are microscopic particles and include dust, smoke, salts and chemical compounds. Nuclei range in size from 0.001 µm radius to over 10 µm. On an average, oceanic air contains one million condensation nuclei per litre and land air holds some 5 or 6 millions. On hygroscopic particles such as sea salts, condensation can begin before the air is saturated. Supersaturation in clouds rarely exceeds one per cent. On average, clouds contain only four per cent of the total water in the atmosphere at any one time. Almost all clouds exist in the troposphere, although the tops of some severe thunderstorms occasionally extend to the stratosphere. Clouds move along with the wind and remain stationary in calm winds. They grow vertically and horizontally, depending on the temperature of the cloud and its ambient temperature. They may dissipate or precipitate. Under favourable atmospheric conditions, they burst and fall as rain. Clouds are essential to the earth-atmosphere system. They complete the following functions.

Water is the only substance that exists in the atmosphere in all the three phases, i.e., solid, liquid and gas. The moisture on the earth’s surface is in a constant phase change. The moisture content of the atmosphere is about 0.035% of all fresh water. The atmosphere receives its supply of moisture from the earth’s surface through evaporation from oceans, lakes, rivers, damp soil, etc. and through transpiration from vegetation. Water vapour is the gaseous state of water and is invisible.

The amount of water vapour present in the atmosphere is called atmospheric moisture or humidity. It is a measure of the amount of water vapour dissolved in the air, not including any liquid water or ice falling through the air. While humidity itself is a climate variable, it also interacts strongly with other climate variables. The humidity is affected by winds and by rainfall. Moisture content is determined by the local rate of evaporation, air temperature and the horizontal transport of moisture. Humidity indicates the likelihood of precipitation, dew or fog. It also plays a major role in the heat budget and the weather phenomenon of the atmosphere.

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.

NATURE AND PROPERTIES OF SOLAR RADIATION

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.

A big layer of air called the atmosphere surrounds the earth. The air within this layer moves from place to place when it warms up or cools down. This moving air is known as wind. In other words, air in motion is called wind. Winds move moisture and heat around the world and also produce much of our weather.

The strength of the wind can vary enormously. Sometimes air moves slowly and the wind is barely noticeable. When the weather is clear there may be a gentle breeze. When the wind is still very light, but it can be felt and there may be rustlings by leaves. At other times, the air can move very quickly and become a gale or hurricane, blowing down trees and damaging electric poles and buildings.

Winds are part of a global air circulation system that acts to balance temperature and pressure around the world. Different parts of the world receive different amounts of heat from the sun. This differential heating in turn results in differences in temperature and air pressure around the world, which drives the world’s winds.

As equatorial areas are heated most, the air above them warms and rises as it becomes lighter than the surrounding air, causing an area of low pressure. In cooler areas, the air sinks because it is heavier and results in an area of high pressure. Winds will blow as air is squashed out by the sinking cold air and drawn in under the rising warm air. Any difference in temperature like this will always cause a difference in air pressure, and therefore winds will blow. These movements result in a global wind pattern, with air moving between different areas around the world and also at different heights in the atmosphere. Colder air from the poles tends to sink and move towards the equator closer to the surface of the earth. In contrast, warm air from the equator rises and moves towards the poles high in the atmosphere because it is lighter.

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 inf luences 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.

FACTORS AFFECTING ATMOSPHERIC PRESSURE

Air pressure never remains constant. Air pressure is greatly influenced by air temperature, altitude, water vapour presence in the air, rotation of earth, etc. However, these factors are not independent of each other in affecting the atmospheric pressure.

Temperature: Hot air expands and exerts low pressure. Cold air contracts and exerts high pressure. Thus, increase in temperature decreases the air pressure. Places nearer to equator experience low pressure due to prevalence of high temperature. The air being cold and heavy throughout the year a high pressure belt is created in both polar regions.

Altitude: Pressure varies smoothly from the earth’s surface to the top of the mesosphere. The pressure depends on the density or mass of the air. The density of air depends on its temperature. The density of air decreases with increase in height so the pressure also decreases with increase in height. At low altitudes above the sea level, the pressure decreases by about 1.2 kPa for every 100 metres.

Water vapour: Water vapour content of air is low in cold areas than that in dry areas. Hence, moist air of high temperature in dry areas exerts less pressure compared to cold air.

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

The atmosphere protects life on earth by absorbing ultraviolet solar radiation, warming the 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 of 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 earth’s 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’.

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.

8.1 INTRODUCTION

To implement a good GIS project, a well structured project design and management are essential. Well planned project will give fruitful result within the stipulated time. Project not completed in time will not incur more cost and also the time delay will add negative value to the project. Hence all the elements in project planning and implementation should be considered to have a desired result. Some of the issues are also present in GIS and they will be rectified in the next decade.

8.2 PROBLEM IDENTIFICATION

Any project is coming into reality due to necessity. If water scarcity is more in a hard rock region with sufficient rainfall, it is important to augment groundwater resource using rain water harvesting structures. It is important to build water harvesting structures like check dam, percolation pond in suitable locations so that groundwater recharge will be more. Hence a problem is identified and the project work may be carried out by a government or private organisation and the result is given to the government to implement the project. Likewise many area may require a project in GIS environment for planning. Once a project is created any development taking place can be added and GIS database is updated.

7.1 INTRODUCTION

Web technology revolutionised information technology and GIS of no exception. Analysis of maps available in internet through remote personal computer is called as web GIS. The term web is GIS synonymous with the term internet GIS. Most of the software vendors in the field of GIS have developed their GIS compatible to internet. The advantage of internet GIS is no need to own a GIS software in the personal computer. Maps available in a web site can be analysed for GIS functions as one could do with GIS in standalone personal computer. Applications of web GIS is not limited. Most of the governmental agencies, business people and others put their data in their server and the data could be analysed spatially for the users requirement. Internet mapping is simple, cost effective and reach vast audience.

Internet GIS is useful in field like civil engineering, government organisations, forestry, environment, goescience, utility planning etc.

6.1 INTRODUCTION

Besides simple analysis, GIS is useful to do advanced analysis like network analysis, spatial analysis, 3D analysis and modeling. Different softwares are available to perform such analysis and the above mentioned analysis is done in separate modules of the softwares.

6.2 NETWORK ANALYSIS

Network consists of well connected linear features. Roads, railway line, water distribution system, sewer line, streams are some of the examples of networks. These networks consists of nodes and arcs with designated directions and connection with other linear features. Networks are topology based with attributes for the flow of objects like traffic. Road network will be considered for explaining network analysis.

Road map is digitised with nodes and arcs. Signals, accidents are represented as points. Road is represented as line and two or more roads intersect at nodes. Attributes are added to the nodes and lines. Dynamic segmentation model is used for network analysis. It is built on lines of network. In road network analysis, attributes for travel time, one way street, two way street, right turn, impedance are added to the nodes and arcs. A link is the line running between two nodes. Link impedance is the cost of passing through the link. Travel time is different in links in cities due to varying traffic at different locations. Time taken to pass through a known length of link may give the cost but the travel time in a link is not uniform because of varying speed designated in the link as 20 km per hour and 30 km per hour. Hence it is important to consider the length of link and also the travel time. If the speed limit is 20 miles per hour for a length of 2 miles, then the travel time is 6 minutes (2/20x60 minutes). Also tuning in the network is considered. A road may have a maximum of 12 possible turns excluding U turns. There are right turn, left turn, straight way for each road. Also U turn is possible. This turning takes different time depending on the signal. Straight way takes less time but left and right turn may require some more time. If signals is available then signal time should also be taken into account. Fig 6.1 show the possible turns in a road.

5.1 INTRODUCTION

A GIS database without single error is reliable for decision making. There are various possible sources of errors in GIS. If an error is not removed during scanning, the final output will also have that error. Besides whatever the work has been carried on wrongly scanned map it will add to errors because the source map itself's erroneous. This is like garbage in garbage out proverb. If wrong data is taken for analysis it will only result in wrong output. Hence it is important to remove error at every stage of GIS work. It is important to locate the sources of errors so that due care may be taken while handling a project.

5.2 ORIGINAL SOURCES OF ERRORS

All the equipments which give attributed data and spatial data will give errors. Before going to field or before collecting data all the related instruments should be calibrated properly. Also the instrument should not cross the permissible error. Besides these while using data from diversified sources errors pertaining to those instruments are mixed to give a different result. When very good accuracy is desired data should be collected from high end equipments. Even if one adds the data from a comparbly less accurate instrument to the data of many accurate instrument is then the result obtained finally will not reliable enough. Global Positioning System (GPS) is available with mm accuracy to meters accuracy. Also surveying with suitable map projection and datum is important; otherwise the result will be wrong. Survey instruments posses some inaccuracy and when a person is using it he should have the accuracy over the instrumental like rain gauge, water level recorders which give attributed data which should be checked for instrumental inaccuracies and method of data collection before using it. Likewise satellite and aerial sensors miss some data and some error are inherent. Such errors should be removed before moving ahead. Errors are resulted due to map reduction, enlargement, data editing and computation method adopted. At the same mapping instruments also possess inaccuracies. When after certain interval a person is going for survey, the registered object may have been changed. Many new features might have come up. Hence the established control points are changed and if the wrongly placed control points are taken for survey then the result itself will be wrong. If proper resolution is not available in the instruments, then the instruments may not capture the minute details which are required.

4.1 INTRODUCTION

Database management system is a computer program to store, search, manipulate retrieve and give the result. Vast amount of spatial data are available and it is necessary to arrange them, store them for retrieval and analysis. Attribute data adds intelligent to GIS. Without database, a GIS will be just a Cad software. Cad softwares do not have database. GIS softwares have their own databases besides it has the potential to link with external database like Oracle, MS Access, MS Excel, Informix, INGRESS, Sybase and dbase. The data available in paper has to be digitally stored in a proper order. Previously the data were stored in a a flat file format where the data was stored without any structure. But to search and retrieve and analyse the database, database structures were developed. There are of 4 types of database structures namely Hierarchical, Network, Relational database and Object orientation.

Tables are made of rows and columns. Rows represent a map feature. Columns represents characteristic of map feature. Row is called a record or a tupule column is a field or an item. Table 4.1 is a table where rows 1, 2 and 3 represent the locations with the soil types. A column soil type represents various soil types.

3.1 INTRODUCTION

Geographic Information System handles large volumes of data. It is important to know the nature of data, instruments from which the data is collected and represented in computers. GIS data is either spatial or aspatial. Data is an important component in GIS. Digital data are available for some projects. but for many projects, input data may not be available. Now-a-days, data is supplied by many government, private organizations and also available on internet. If data for a particular project is not available, then the user has to collect the data from satellite imageries, GPS and other instruments and maps from various sources.

Spatial Data

All locations in the earth surface are spatial data. Location of a city, location of a river, location of a lake are represented in earth by their latitude or longitude in global coordinate system or as x,y coordinate in Cartesian coordinate system. Spatial data consists of location, shape and size in earth. A village boundary is represented as a polygon in map. The village is having certain shape of irregular polygon with definite area. As all these are mappable , they are called as spatial data. But name of the village, revenue of a village and description about a village and called as non-spatial or aspatial data.