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Introduction and Application of GIS

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Fundamentals of GIS
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Introduction and Application of GIS

  1. 1. Introduction and Application of GIS Prepared by Prof. S. G. Taji Dept. of Civil Engineering S.R.E.S’s College of Engineering, Kopargaon Content Beyond Syllabus 18/09/2017
  2. 2. Geographic Information Systems (GIS)  There are a number of definitions of GIS  GIS is much more than a container of maps in digital form”.  A GIS is a system (hardware + database engine) that is designed to efficiently, assemble, store, update, analyze, manipulate, and display geographically referenced information (data identified by their locations).
  3. 3.  GEOGRAPHIC  implies that locations of the data items are known, or can be calculated, in terms of Geographic coordinates (Latitude, Longitude)  INFORMATION  implies that the data in a GIS are organized to yield useful knowledge, often as colored maps and images, but also as statistical graphics, tables, and various on-screen responses to interactive queries.  SYSTEM  implies that a GIS is made up from several inter-related and linked components with different functions. Thus, GIS have functional capabilities for data capture, input, manipulation, transformation, visualization, combinations, query, analysis, modeling and output.
  4. 4. Key Component of GIS
  5. 5.  Hardware  Computer  Digitizer and Scanner  Printer/Plotter  Software  GIS software provides the functions and tools needed to store, analyze, and display geographic information.  Tools for entering and manipulating geographic information such as addresses or political boundaries  A database management system (DBMS)  Tools that create intelligent digital maps you can analyze, query for more information, or print for presentation  An easy-to-use graphical user interface (GUI)
  6. 6.  GIS software, allows you to interactively work with spatial data  There are a number of Geographical Information Systems (GIS) (or GIS software) available today:  Web-based GIS  Geobrowser: Google Earth  Desktop GIS: ArcGIS  QGIS
  7. 7.  Web-based GIS  Web-based GIS, or WebGIS, are online GIS applications which in most cases are excellent data visualisation tools  Geobrowser: Google Earth  Geobrowser can be understood as an Internet Explorer for geographic information  The biggest difference between the World Wide Web and the geographic web however is that everything within the latter is spatially referenced.  Google Earth is the most popular geobrowser available
  8. 8.  Desktop GIS: ArcGIS  A desktop GIS is a mapping software that needs to be installed onto and runs on a personal computer.  we will use ArcGIS, which is developed by ESRI  ArcGIS is what ESRI refer to as a suite of products which can be tailored to your need. ArcGIS is used for a vast range of activities, covering both commercial and educational uses.
  9. 9. QGIS  Quantum GIS developed in 2002 and undergone significant development.  It is open source software which is freely available  QGIS runs on Windows, various Linux distributions, Unix, Mac OS X, and Android.  Features of QGIS include;  Importing data from multiple sources  Digitizing  Editing  Geoprocessing  Raster processing
  10. 10.  Data:-  GIS incorporates geographical features with tabular data in order to map, analyze, and assess real-world problems.  Data that is in some way referenced to locations on the earth. Attribute data can be generally defined as additional information about each of the spatial features.  Geographic data and related tabular data can be produced by digitizing images from aerial photographs or published maps.  An example of this would be college. The actual location of the College is the spatial data.  Additional data such as the College name, specialization, capacity would make up the attribute data.
  11. 11.  People  GIS users range from technical specialists who design and maintain the system to those who use it to help them perform their everyday work.  Methods  A successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization
  12. 12. Co-ordinate systems  Geographic Coordinates - such as latitude and longitude  These are usually referred by degrees, minutes, and seconds, e.g. 56°27'40" and 116°11'25".  Map Projection - Coordinates are measured in metres,  e.g. Universe Transverse Mercator (UTM) e.g. 545,000.000 and 6,453,254.000  normally reference to a central meridian. Eastings refer to X coordinates while Northings refer to Y coordinates.
  13. 13. GEOGRAPHIC COORDINATE SYSTEMS  The geocentric coordinate system is not a map projection.  The earth is modelled as a sphere or spheroid in a right handed X,Y,Z system.  The X-axis points to the prime meridian, the Y-axis points 90 degrees away in the equatorial plane, and the Z-axis points in the direction of the North Pole.
  14. 14.  Equator is imaginary line which split Earth Horizontally in two parts i.e. It separates North and South pole from the centre.  Meridian is imaginary line which split Earth vertically in two parts (it runs through Greenwich, England). i.e. It separates Western and South Hemisphere.
  15. 15.  Latitude and longitude are imaginary (unreal) lines drawn on maps to easily locate places on the Earth.  Latitude is distance north or south of the equator  Longitude is distance east or west of the prime meridian  Both are measured from the center of earth in terms of the 360 degrees (symbolized by °) of a circle.  In the spherical system, horizontal lines, or east– west lines, are lines of equal latitude, or parallels.  Vertical lines, or north–south lines, are lines of equal longitude, or meridians.
  16. 16. CHARACTERIZING GEOGRAPHIC FEATURES  All geographic features on the earth's surface can be characterized as one of three basic feature types:  Point data exists when a feature is associated with a single location in space.  Ex. well, a weather station, etc.  Linear data exists when a feature's location is described by a string of spatial coordinates.  Ex. rivers, roads, pipelines, etc.  Areal data exists when a feature is described by a closed string of spatial coordinates  Commonly referred to as a polygon.  Ex. forest stands, soil classification areas, administrative boundaries, and climate zones, etc.
  17. 17. GIS DATA TYPES  Accordingly, GIS technology utilizes two basic types of data 1. Spatial Data - Describes the absolute and relative location of geographic features. 2. Attribute data - Describes characteristics of the spatial features  The coordinate location of a watershed would be spatial data, while the characteristics of that watershed, e.g. catchment area , type of soil, elevations, etc., would be attribute data.
  18. 18. Spatial Data  Traditionally spatial data has been stored and presented in the form of a map.  Three basic types of spatial data models have evolved for storing geographic data digitally. These are referred to as: 1. Raster 2. Vector
  19. 19. 1) Raster • Data is classified as “continuous” (such as in an image), or “thematic” (where each cell denotes a feature type. • Stores images as rows and columns of numbers with a Digital Value/Number (DN) for each cell • Units are usually represented as square grid cells that are uniform in size • Numerous data formats (TIFF, GIF, ERDAS img, CAD Drawings, etc)
  20. 20. 2) Vector  Allows user to specify specific spatial locations  It not broken up into discrete grid squares  information about points, lines, and polygons is encoded and stored as a collection of x & y coordinates.  Numerous data formats- SHP, KML, GNT, etc. point 1,6 2,5 5,4 4,1 7,10 5,9 4,7 6,6 8,6 9,8 li ne polygon 2,2 5 10 5 10 as geometric objects: points, lines, polygons
  21. 21. Importance of Layers in GIS • Geographic data = Representation of reality • Reality is complex. • GIS utilizes a layer approach • Each layer only includes information about one type of phenomenon. • Data layers must be aligned with one another
  22. 22. Modeling Geospatial Reality Real World Vector Model Raster Model
  23. 23. Coding Vector GIS Reality Vector Mode Model of Reality
  24. 24. Coding Vector GIS Polygon I Polygon node II Polygon III Polygon V Polygon IV node A node B node C E node F node G node D Reality Vector Mode Model of Reality
  25. 25. Coding Raster GIS Data Reality Raster Mode Model of Reality
  26. 26. Coding Raster GIS Data Reality Raster Mode Model of Reality 1 1 1 1 2 3 4 4 1 1 1 2 2 3 4 4 1 2 2 2 3 3 4 4 2 2 2 3 3 4 4 4 3 3 3 3 5 5 5 5 1 1 1 1 6 5 5 5 1 1 1 1 1 5 5 5 1 1 1 1 1 1 5 5
  27. 27. Remote Sensing • Remotely-Sensed data is one of the most important sources of data for GIS. • RS means - Acquiring data from a distance • Usually uses electromagnetic energy – sunlight, radar, laser • Originally captured on photographic film • Recent platforms utilize digital sensors
  28. 28. Early Remote Sensing Platforms
  29. 29. What kinds of devices collect the data? • Aircraft – High altitude – Low altitude Geosynchronous Orbit • Spacecraft: – Landsat – SPOT – Weather satellites – GeoEye-1 when the satellite moves at the same speed as the spinning earth – results in the camera staying over the same spot of the earth
  30. 30. Application of GIS in Hydrology I. Surface Water Hydrology  Data Required :  Terrain  Digital elevation models  Slope and aspect  Watersheds and sub-catchments  Drainage network  Soil • Permeability • Layer depth • Soil textural and Soil water content •Precipitation & climate •Rain-gauge data •Gauge locations & context •Statistics(e.g., intensity, duration) •Temperature •Evaporation & transpiration
  31. 31.  Analysis of Data & Final Output :  Watershed Management  Terrain modeling  Flow modeling  Debris flow probability  Flood Management  Flood plain delineation  Channel characteristics  Inundation modeling  Infrastructure analysis  Risk modeling and mitigation
  32. 32. II. Groundwater Modeling  Data Required :  Weather  Topography  Land cover type  Water levels and geologic data from no. of groundwater wells  Analysis & Output  Ground water model  Groundwater development and  Artificial recharge sites
  33. 33. Example  Project Planning for a Storage Structure  In this example, a dam is proposed to be constructed across a river, for which the following information may be required: i. Watershed area contributing to the project site ii. Reservoir surface area and volume, given the height of the dam iii. Villages that may be inundated under reservoir
  34. 34.  For the above, the following themes may be stored in a GIS:  Elevation contours of the watershed area, including the project site o For this, DEM is required  Satellite image derived land-use map of the watershed o For this, Satellite images which shows land use/land cover data is required  Village boundary map, showing location of habitation clusters o For this, digital map which shows village boundaries and other important structure is required
  35. 35.  Using the above data, one may obtain desired in information as follows: i. Watershed area may be found by using the elevation contour data, and using a suitable GIS software that has a tool to delineate the watershed boundary. ii. Once the boundary is identified, the area calculation tool may be used in the GIS software to calculate the watershed area. iii. Reservoir surface area can similarly found using the area calculation tool.
  36. 36. iv. Volume calculation tool of the GIS software may be used to find out the storage volume, which is the space between a plane at the reservoir surface and the reservoir bottom. v. By overlying the reservoir extent over the village boundary map and the locations of habitation clusters one may identify the villages that are likely to be inundated once the reservoir comes up. vi. The area of the cultivable village farms that would be submerged may also be similarly identified, as it would be required to pay compensation for the loss to the villagers.
  37. 37. Any Questions……??

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