Gis

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Gis

  1. 1. APPLICATIONS OF REMOTE SENSING AND GIS IN CIVIL ENGINEERING,ENVIRONMENT AND NATURAL RESOURCE MANAGENEMNTDr K ElangovanAssociate ProfessorDepartment of Civil EngineeringPSG College of TechnologyCoimbatore 641 004E-Mail: ela@civ.psgtech.ac.inGEOGRAPHIC INFORMATION SYSTEMS (GIS)INTRODUCTIONGeographic Information System (GIS) is the new area with diversified applications inCivil Engineering, Geosciences, Forestry, Disaster mitigation, Environment and Ecology,Infrastructure planning, Utility mapping, Business, Mobile mapping, InformationTechnology and in many more fields. Since nearly 80% of the real world data are spatialin nature, GIS technology has been popularized overwhelmingly. It is not overestimationthat GIS will be used in day to day life within next decade. Already developed countriesuse GIS widely and it will be used in day to day activities in developing countries also innear future.Reduced cost in hardware and software in GIS made it possible to reach most of thegovernment organizations, research institutions, academic institutions and nongovernmental organizations. Although lot of data are available in paper format, if theyare not collected, stored in a structured way for visualizing the real world, then the datado not serve any purpose. But this bottleneck has been eliminated by using GIS. Mobilemapping is the new area in which dynamic GIS maps are used in cell phones to find theactual location of a person. Anyone shall find a persons exact location when the cellphone is integrated with GPS and GIS maps. This will become reality in all parts ofworld in this decade.It is important to use any tool with its background knowledge. Also GIS is a tool and ithas been used as an attractive tool nowadays. It is very much important to know thebasics of GIS and their applications. Hence to explain the concepts of GIS in a simplelanguage, this book has been attempted. Thos book covers basics of data types, databaseconcepts, map projections, errors and removal of errors, advanced analysis, web GIS,implementing a GIS project, various software and hardware requirement and advancedGIS applications. Hence any user in GIS will find this book as a catalyst to understandGIS. Also a GIS resource bank is provided which will give the users more information.Glossary consists of definition of important GIS terminology. It is advisable to read theglossary before actually going through the book, hence the readers will understand theGIS easily.1
  2. 2. Any technology is developed out of necessity and GIS is of no exception. When a largeamount of data were available for water distribution systems, road network, sewer lines,telecom lines, electricity lines, gas pipe lines, state wise population, natural resources etc,it is important to store, maintain and retrieve the data for applications. It is not possible tomanually browse through the large amount of paper records. Also even if the data isavailable in an unorganized way in the computerized environment, it is not useful. Henceif the data are referred to locations in earth surface and the data are stored in an organizedway, it is possible to retrieve and analyze the data for applications. Hence the solution isGIS and developed today into reality. Developed countries are using GIS widely in manyareas but developing countries are moving towards the development of GIS database fortheir resources.Remote sensing, aerial photography, cartography, surveying and other field instrumentsfor attribute data collection contributes to the data acquisition. Cartography, surveying,geography, geodesy contributes for mapping process. Disciplines like computer scienceand statistics, mathematics involved in processing and analyzing data . Computer scienceand mathematics involved in storing the data structure.GIS maps are intelligent. It has many advantages compared with paper map in this digitalageSpatial data means data which are referenced to earth. Maps, satellite imageries, aerialphotographs are example of spatial data. Attribute data which are attached to spatial dataare called as aspatial data or non spatial data.If these data are brought into GIS then it is stored in a standard format, it is possible toupdate, share, retrieve, manipulate and analyze quickly. Much of the time and money issaved in case of reproduction and better decisions could be madeCreation of GIS database is a time consuming job. Once the GIS database is created, theresults are obtained by simple mouse clicks. Once a GIS database is created it will beuseful for long period and updating is easy.Geographic Information System is offered as individual discipline in the name ofGeomatics, Geoinformatics and Spatial Information Technology. These programmes areoffered at UG and PG level. Much research activity is also being undertaken. This fieldhas become an individual discipline now.DefinitionGIS is a computer based technology and methodology to collect, store, manipulate,retrieve and analyze spatial data or georeferenced data.orGIS is a system of hardware, software, data, people, organization and institutionalarrangement for collecting, storing, analyzing and displaying information about the areasof earth2
  3. 3. GIS require vast amount of data. Data is converted into information. Temperature ofChennai city for a particular day is 30oand for New Delhi it is 20 o. Here 20 oand 30 oCelsius are data. But the information is that Chennai is hotter than New Delhi. GISprojects are costly because of the large data requirement from various sources. Decisionwith less information is not complete.The following questions may be asked and answers may be found using GIS in variousfields. The questions given are simple but one may ask complex question by combiningmore than one question. Many more queries can be asked for varied applicationsWhat is the perimeter of the Ooty lake?Where is the No.S1 lamp post?What is the relation between drainage and landslide?What is the area of the landuse?Where from the water comes?How many 5 star hotels are available within 3m radius of air port?What is the elevation at Coimbatore city?Where shall we dispose the nuclear waste safely?What is the relation between elevation and species diversity?What is the erosion rate in Himalayas?What is the rate of sedimentation in the Bhavani reservoir?Where shall the high income group available for my business at Chennai?Which is the direction of forest fire for the next three hour?Where do I select a site for the construction of my house?Where shall I locate the Telecom Cable near the road for this street?What is the optimum route for dumping solid waste for my city?Where does the endangered species live?What exists at this location?Where is good quality groundwater in Coimbatore district?What is the urban development pattern in Bangalore for the past 20 years?What is the shortest path between Peelamedu to Perur?What is the cost path to lay the gas pipeline form one location to other location?To perform the above questions a strong GIS database is requiredGIS has been developed due to the combination of many disciplines. The followingdisciplines contributed towards the development of GIS1. Computer Mapping2. Databases3. Computer Science4. Geography5. Remote Sensing6. Data Processing7. Mathematics and Statistics3
  4. 4. 8. Computer Aided Design(CAD)9. CartographyCHARACTERISTICS OF MAPSScale, resolution, accuracy and projection are the important component of a map.ScaleReal world features are represented in the map to scale. Graphical scale, numerical scaleare availableA map may consists of the scale of 1: 24,000. Here 1: 24,000 means 1 inch in mapsequals to 24,000 inches in ground or 1 foot in map equals to 24,000 feet on ground or 1meter in map equals to 24,000 meters in ground. No map is 100% accurate. As the mapsis the abstraction of the real world features, it consists of errors. Graphical scales are alsoused which are useful to compare the map visually with groundSmall scale map is 1:1,000,000 and large scale map is 1:500. Small scale maps showslarge area of earth surface with smaller details and large scale map shows smaller areawith more details. In India Survey of India (SOI) head quartered at Dehra Dun, isresponsible for the survey, production and distribution of maps. SOI publish maps inthree scales viz., 1:25,000, 1:50,000 and 1: 2,50,000. They are called as survey of Indiatoposheets. In western countries such maps are called as quadrangle sheets. Thesetoposheets consists of very detailed information of the countries. Presently Survey ofIndia supplies the toposheet in digital format (vector) which can be used without furtherdigitization.TYPES OF MAPSTopographical map: A map showing the surface features of the earths surface (contours,roads, rivers, houses etc) in great accuracy and detail relative to the map scale used.Thematic map: A map displaying selected kinds of information relating to specificthemes such as soil, landuse, population density, suitability for arable crops and so on)Geological maps: Maps showing rock types and geological structuresRelief maps: Maps showing contoursAgricultural maps: Maps showing crop distributionCadastral maps: Map showing land recordsNavigational charts: Maps used for sea and air routesPolitical maps: Maps with administrative boundaries of countriesCommercial maps: Maps showing the business detailsWeather maps: Maps showing temperature, pressure, rainfall, snow fall and wind speeddetails.Locations of a feature is referred in coordinate systems. Three types of coordinate systemare available . They are Cartesian coordinate system, planar coordinate system and globalcoordinate system4
  5. 5. ArcGIS (From ESRI )consists ofArcInfo , Arcview , Arc view spatial Analyst, Arcview Network Analyst, Arcview 3DAnalyst, Arcview Geostatistical Analyst.Mapinfo from mapinfo corporation, Microstation Geographics from Bentley, Geomediaform Intergraph, AutoCAD Mao 2000 form Autodesk Inc.,, GRASS form US ArmyCorps of Engineers, GRAMM++ for CSRE, IIT, Mumbai, IDRISI from Clark labs,ILWIS from ITC, Netherland, Geomatica from PCI Geomatics, Atlas GIS, CARIS,SYCADFUNDAMENTAL SPATIAL OPERATORSSearch InterpolationSearch by-regionSearch by-attributeReclassificationLocation Analysis BufferCorridorOverlayVoronoi/ThiessenTerrain Analysis Slope/Aspectcatchment/Basindrainage networkViewshedDistribution/Neighbourhood Cost/diffusion/SpreadProximityNearest neighborSpatial Analysis Multivariate analysisPattern/DispersionCentrality/ConnectednessShapeMeasurement Geometry, statistics/TopologyFollowing are some of the layers used in GISSoil, Road, Annotation, Geology , Forest, Landuse/landcover, Rail road, Sewer lineWater distribution line, Contour , Slope , Aspect, Hill shade, Parcel, FloodVillage, city and other administrative boundaries ,Pollution areaBore well/open well, Route map for rail,air,water, Telecom line, Electricity lineCrops, Groundwater potential area, Geomorphology ,Groundwater level, Places ofworship, Hotels, drainage, hops etc5
  6. 6. Remote sensing and GIS technology is useful in the following fields.1. Protection of environment2. Water resources management3. Urban planning and transportation planning4. Watershed management5. Surveying6. Coastal zone management7. Natural disaster management8. Terrain characterization and evaluation9. Infrastructure10. Utilities11. Agriculture12. Forestry13. Geosciences14. Demography15. Biodiversity16. Wildlife etc.,INTERNET GISInternet GIS is useful to share information through world wide web without owning aGIS software. Arc IMS, Autodesk Map Guide Server, MapXtreme Java and GeomediaWeb Map. Environmental authorities publish data regarding pollution in the web andgeneral public is using the data for their development. Spatial query could be asked as inthe GIS and maps and tabular information are displayed in the web. Sensors capable ofobtaining information about weather, water quality and air quality are made available torecord the information and they are connected with Internet GIS. These data are updatedfor every 10 seconds and public could the information regarding weather, water qualityand air quality can be obtained through Internet GIS as real time dataREMOTE SENSINGRemote sensing means acquiring information about objects without having in physicalcontact with the object. Human eye is an example for remote sensing device. Like thissatellites revolving at higher orbit take images of earth at various spectral and spatialresolution.Aerial photography was the first remote sensing data, providing visual imagery oflandscape on film. In recent decades, sophisticated electronics and high tech sensors havebeen developed that gather data from various parts of electromagnetic spectrum that areinvisible to human eye.Remote sensing satellites take images in the visible and infrared regions ofelectromagnetic spectrum (EMR). Everything in nature has its own unique distribution of6
  7. 7. reflected, emitted and absorbed radiation. These energies are different for differentobjects. At temperature above absolute zero every objects radiate electromagnetic energy.Electromagnetic spectrum is a dynamic form of energy that propagates as wave motionat a velocity of 3x1010cm/sec.Two types of remote sensing are there based on the source of light used. Active remotesensing means passing known source of light to the ground and recording the reflectedradiation. Radar satellites employ this method. But most of the satellites working basedon passive remote sensing principle. Here solar energy is the source. When the solarenergy reaches the earth part of it is reflected back in the atmosphere itself, some part isreflected by the ground objects and some part is refracted. Sensors in the satellite recordsthe energy at various spectral levels. Charge coupled devices (CCDs) are used to sensethe energy.Radiation form the sun, when incident upon the earths surface, transmitted into thesurface or absorbed and emitted by the surface. The EMR, on interaction, experiences anumber of changes in magnitude, direction, wavelength, polarization and phase. Thesechanges are detected by the remote sensor and enable the interpreter to obtain usefulinformation on the object of interest. The remotely sensed data contain both spatialinformation (size, shape and orientation) and spectral information (tone, color andspectral signature).The interaction of EMR with atmosphere is important. The information carried by EMRreflected/emitted by the earths surface is modified while traversing through theatmosphere The atmospheric constituents scatter and absorb the radiation . Rayleighscattering, Mie scattering and non selective scattering are caused by air molecules, smokeand clouds respectively. The phenomenon of refraction in the atmosphere also affects theEMR. Ozone, CO2 and water vapour absorb the EMR passing through atmosphere incertain spectral bands.Electromagnetic Energy SpectrumElectromagnetic spectrum is expressed as wavelength of energy ranging from very short(cosmic ray on the left) to very long (television and radio waves on the right). Visiblelight is the very narrow portion of the electromagnetic spectrum meaning that human eyesee only a small part of that spectrum whereas remote sensing equipment can obtaininformation from much greater portion of the spectrum. Each portion on the spectrumhas particular advantage in remote sensing..Middle range of electromagnetic spectrum contain wavelengths that are visible to thehuman eye (visual) ranging from blue to red. Ordinary camera film is sensitive to thisspectrum producing standard aerial photography. Electronics and some films capture nextlarger wavelength just outside the visual, called the near infrared. The near infraredreveals information that are not available in the visible spectrum, such as plant health andstress. Visual infra red can show damaged vegetation before it is apparent to the observer7
  8. 8. on the ground. Thermal infrared sensors detect very small temperature differences anddisplay themes on imagery Warmer water is brighter than cooler land. This is useful inthermal pollution monitoring. For example industrial effluent can be analysed in terms ofheat characteristics. Urban heat sources can be detected, easily and landscape thermalmapping can reveal geologic and vegetation differences. Thermal data is important in firefighting.Radar microwave data are long wave, producing land and water information muchdifferent from that of the visual region of the spectrum. Radar is useful in penetratingcloud cover, and can help to map topography in humid cloud covered tropical regionwhere aerial photography has been unsatisfactory. It can also detect some types ofvegetation and can detect subtle geologic features such as faults. Microwave is useful insome oceanographic application, such as oil spill mapping and monitoring sea icedistribution.Some of the remote sensing satellite available for resource management are given in thefollowing table with their characteristics.Mision Country Launch Imaging Mode Resolution(m)Landsat 1,2,3,4,5 USA 1972, 7578,82,84MSSTM7930SPOT1,2,3 France 1986,90,93PANHRV1020IRS 1A&1B India 1988, 91 LISSI&II 72 (LISS I)36 (LISS II)IPS P2 India 1994 LISS II 37x32IRC 1C/IRS 1DIndia 1995/97 LISS IIIWiFSPAN23.5 (VNIR)69 (MIR)188 (WiFS)5.8 (PAN)NOAA –910,11,12,14,15USA 1985,8688,91,9497AVHRR 1100 kmADEOS NASDA/Japan 97 MSSPAN816TERRA-ASTER USA/Japan 98 MSS 15IKONOS SpaceImaging,USA99 PANMSS0.823.2KOMPSAT KARI, SouthKorea2000 PAN 6.6EROS A1 Israel 2000 PAN 1.8Quickbird2 Earthwatch,USA2001 PANMSS0.612.44Orb View 3 OrbImage, USA 2002 PANMSS1/248
  9. 9. Resolution Of ImagesResolution is defined as the ability of the system to render the information at the smallestdiscretely separable quantity in terms of distance (spatial), spectral, temporal andradiometricSpatial Resolution: Scanners spatial resolution is the minimum size of the groundsegment sensed at any instant.Spectral resolution: It is a measure of both the discreteness of the band widths of thesensor and the sensitivity of the sensor to distinguish between grey levelsRadiometric resolution: Dividing the total range (B to W) of the signal output into a largenumber of just discriminable levels so as to be able to distinguish ground featuresdiffering only slightly in radiance or reflectanceTemporal resolution: Repetivity of the satellitesVisual Image InterpretationAn interpreter study remotely sensed data and attempts through logical process to detect,identify, measure and evaluate the significance of environmental and cultural objects,patterns and spatial relationships. It is an information extraction process. For this purposehard copy of black and white and color images are used.Size and ShapeNumerous components of the environment can be identified by their shape. Size of theobjects like length, breadth and area are important in image interpretation . A play groundmay be in oval shape. Regular arrangement of square shape may be indication ofagricultural field.The approximate size of objects can be judged by comparisons with familiar features(e.g. road) in the same scene.ToneDifferent objects emit or reflect different wavelengths and intensity of radiant energy.Such differences are recorded and are useful for discriminating the objects. A denseforest is represented in darker tone while a paddy field is represented in lighter tone.PatternRepetitive pattern of both natural and cultural features are quite common, which isfortunate because much image interpretation is aimed at the mapping and analysis ofrelatively complex features rather than the more basic units of which they may becomposed. Such features are farms and orchards, alluvial valleys and coastal plains.Texture9
  10. 10. Texture is an important image characteristic closely associated with tone in the sense thatit is a quality that permits two areas of the same overall tone to be differentiated on thebasis of micro tonal patterns. Common textures are smooth, rippled, mottled, lineated andirregular. Two rock units may have two units may have the same tone but differenttextures. Deciduous forest may have coarser texture while coniferous forest may havefine texture.SiteAt an advanced stage in image interpretation, the location of an object with respect toterrain features of other objects may be helpful in refining the identification andclassification of certain picture contents. For example, the combination of one or two tallchimneys, a large central building, conveyors, cooling towers and solid fuel piles point tothe correct identification of a thermal power station.ResolutionImageries posses different types of resolution and they should be considered whileinterpretation.Stereoscopic AppearanceWhen the same feature is photographed from two different positions with overlapbetween successive images, an apparently solid model of the feature can be seen under astereoscope. Such a model is termed a stereo model and the three dimensional view itprovides can aid interpretation. This valuable information can not be obtained from asingle imagery. Stereo images are used for large scale mapping and used for the selectionof suitable sites for infrastructure projects.GROUND TRUTHGround truth refers to any verification of mapped data against true ground conditions.Digital Image ProcessingCommonly available Satellite Image Processing Softwares areERDAS IMAGINE, ENVI, EASI/PACE, ER MAPPER, IDRISI, ILWIS, GRAMM++IDRISI, ILWIS and GRAMM++ consists of both image processing and GIS component.Remotely sensed data is available in CD ROM, magnetic tape and in floppy diskette.A digital remotely sensed image is typically composed of picture elements (pixels)located at the intersection of each row i and column j in each k bands of imagery. Digital10
  11. 11. imageries are in raster format. Associated with each pixels a number known as DigitalNumber (DN) or Brightness Value (BV) that depicts the average radiance of a relativelysmall area within a scene. A smaller number indicates low average radiance from the areaand high number is an indicator of high radiant properties of the area. When representedas numbers, brightness can be added, subtracted, multiplied, divided and in generalsubject to statistical manipulations that are not possible if an image if presented only asphotograph. Nowadays due to the availability of advanced and cheapest hardwares andsoftwares, digital image processing is widely used rather than visual interpretation byphotograph.IMAGE RECTIFICATIONThis involves the initial processing of raw image data to correct for geometric distortion,to calibrate the data radiometrically and to eliminate noise present in the data. This is apre processing operation.Image EnhancementIt involves techniques for increasing the visual distinction between features in a scene.New image is created from the original image to obtain more information form theimage. The operations are level slicing, contrast stretching, spatial filtering edgeenhancement, spectral ratioing, principal component analysis and intensity - hue -saturation color space transformations.Image ClassificationThis operation is to replace visual analysis of the data with quantitative techniques forautomating the identification of features in a scene. This involves the analysis ofmultispectal image data and the application of statistically based decision rules fordetermining the land cover ideality of each pixel in an image. Unsupervisecd andsupervised classification methods are adopted.Supervised ClassificationSupervised Classification is a technique for the computer-assisted interpretation ofremotely sensed imagery. The operator trains the computer to look for surface featureswith similar reflectance characteristics to a set of examples of known interpretationwithin the image. These areas are known as training sites.Unsupervised ClassificationUnsupervised Classification is a technique for the computer-assisted interpretation ofremotely sensed imagery. The computer routine does this by identifying typical patternsin the reflectance data. These patterns are then identified by undertaking site visits to afew selected examples to determine their interpretation. Because of the mathematicaltechnique used in this process, the patterns are usually referred to as clusters.11
  12. 12. SITE SELECTION FOR GROUNDWATER POTRENTIAL ZONES:A case study has been carried out for the parts of Bhavani river basin and data werecollected from various sources and shown in the Table.Sl.No Nature of Data Source of Data1Survey of India toposheets(SOI)Survey of India, Guindy, Chennai2 Hydrological soil groupTamilnadu Agriculture university,Coimbatore3 Ground water level details PWD , Coimbatore4 Rainfall details PWD, Salem5 Geological data Institute of Remote Sensing, ChennaiThe methodology applied in to demarcate groundwater recharge potential zones isshow in the following figure12BASE MAP CREATIONGEO REFERENCINGDIGITIZATIONPREPARATION OF THEMATIC LAYERS(Soil Type, Geology, Geomorphology, Lineament, Water Level)CRITERIA DEFINITIONCOMPOSITE RANKINGWEIGHTED INDEX OVERLAYMAPGROUNDWATER PROSPECTSMAP
  13. 13. The following Figure shows the zones for groundwater explorationThe following Figure shows the classified map for various crops of parts of PAP project.IRS 1D LISS III imagery was processes and classified data was used to study the cropwater requirement13
  14. 14. SITE SELECTION FOR SOLID WASTE DISPOSALSite selection for solid waste disposal for Coimbatore was carried out in GIS and shownin following FigureUrban development has brought forth several maladies and suffering to human kind,besides bringing economic and cultural development in its fold. Due to pressure ofurbanization most of the cities are growing and some times they develop beyond theplanned limits. Generally the unplanned area of the city contains a quarter of the totalpopulation where the spatial information is missing. At present no efficient system isavailable for solid waste management in Coimbatore Corporation, though the corporationadministration now taking a few steps to manage the solid wastes. In this direction, anattempt has been made to optimize the route and also finding a favorable site for disposalof solid wastes using GIS & GPS for Coimbatore Corporation.LANDSLIDE HAZARD ZONATION FOR NILGIRI REGIONSeveral different themes like land use, drainage, soil and outcrop, lineament,slope, etc. were obtained and weightages were assigned to each theme. Based onweightages assigned, the entire study area is divided into 5 classes [Very High, High,Moderate, Low and very Low]. From the map obtained by weighted overlay and thearithmetic overlay map, the Landslide Hazard Zonation (LHZ) is thus created. The road14
  15. 15. network map is overlaid with slope and land use map to identify sites, where mitigationworks to be taken on priority basis.15

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