B.A. Geography Practical and Viva Voce Preparation Notes

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B.A. Geography Practical and Viva Voce Preparation Notes

These notes are prepared specifically for a B.A. student preparing for a Geography Practical Examination and the associated Oral Examination (Viva Voce), drawing exclusively from the provided source excerpts. The content focuses on key definitions, methodologies, and concepts likely to be questioned in a viva.

Part I: Map Scale (Chapter 2)

1. Definition and Importance of Scale

  • The scale is an essential element of all types of maps.
  • If a network of lines and polygons does not carry a scale, it is simply called a “sketch”.
  • A map scale provides the ratio of distances between two points on the map and the corresponding distance between the same two points on the ground.

2. Methods of Expressing Scale

There are at least three ways to express the relationship between map distance and ground distance:

  1. Statement of Scale: Indicated as a written statement, e.g., “1 cm represents 10 km”.
    • Limitation: If the map is reduced or enlarged, the scale becomes redundant and requires recalculation.
  2. Representative Fraction (R.F.): Shows the relationship between map distance and ground distance in units of length.
    • Numerator: The number above the line (e.g., ‘1’ in 1:50,000), representing map distance.
    • Denominator: The number below the line (e.g., ‘50,000’ in 1:50,000), representing ground distance.
    • Universal Nature: The use of units makes R.F. the most versatile and universally acceptable method.
  3. Graphical or Bar Scale: Uses a line bar with primary and secondary divisions marked with distances (e.g., kilometres or miles).
    • Major Advantage: Unlike the Statement of Scale, the graphical scale stands valid even when the map is reduced or enlarged.

3. Systems of Measurement

Scales are expressed using systems of measurement, primarily:

  • Metric System: Used in India and many countries (e.g., kilometre, metre, centimetre).
  • English System: Prevalent in the UK and USA (e.g., mile, furlong, yard, foot).

Part II: Geographical Coordinates and Time (Chapter 3)

1. Geographical Grid

  • The Geographical Grid is a network of intersecting imaginary lines drawn on a globe or map to locate various places.
  • The lines include parallels of latitude (horizontal, East-West) and meridians of longitude (vertical, North-South).
  • Latitudes and longitudes are commonly referred to as geographical coordinates.

2. Parallels of Latitude

  • Definition: Angular distance of a point north or south of the Equator. Lines of latitude are parallel to each other.
  • Equator (0°): The line drawn midway between the poles. It is the largest circle and a great circle, dividing the globe into two equal halves.
  • All parallels other than the equator are small circles and get smaller towards the poles. The poles are $90^{\circ}\text{N}$ and $90^{\circ}\text{S}$.

3. Meridians of Longitude

  • Definition: Angular distance of a point east or west of the Prime (Greenwich) Meridian.
  • Characteristics: Meridians are semi-circles that converge at the poles. They are all equal in length.
  • Prime Meridian (0°): Passes through the Greenwich observatory (near London) and is adopted as the reference longitude by international agreement.
  • Longitudes vary from 0° to 180° eastward and westward of the Prime Meridian.

4. Longitude and Time

  • The earth rotates from west to east over its axis.
  • The earth rotates $360^{\circ}$ in 24 hours. The sun traverses $15^{\circ}$ of longitudes per hour or one degree of longitude in every four minutes of time.
  • Time increases when moving from west to east, and decreases with westward movement.
  • Standard Time: The local time at the central meridian of a country is taken as the standard time to maintain uniformity.
    • Indian Standard Time (IST): Calculated from $82^{\circ}30’$ E meridian. IST is plus 5.30 hours from the GMT.
  • International Date Line (IDL): Located approximately at the $180^{\circ}$ line of longitude, where there is a difference in days.

Part III: Map Projections (Chapter 4)

1. Map Projection Fundamentals

  • Definition: The system of transferring the graticule (network of parallels and meridians) of latitude and longitude on a plane surface.
  • Graticule: The network of parallels (horizontal lines) and meridians (vertical lines).
  • Need: Necessary because the globe is a non-developable surface; transferring it to a flat surface inevitably introduces distortion.

2. Global Properties and Classification

No projection can maintain all global properties simultaneously. The basic properties to be preserved are:

  1. Distance
  2. Shape (Orthomorphic Projection)
  3. Size or Area (Equal Area or Homolographic Projection)
  4. Direction (Azimuthal or True-Bearing Projection)

Classification by Developable Surface:

  • Cylindrical Projections: Uses a cylindrical developable surface touching the globe (often at the equator).
  • Conical Projections: Uses a cone wrapped around the globe.
  • Zenithal/Azimuthal Projections: Directly obtained on a plane surface that touches the globe at a single point (often a pole).

3. Mercator’s Projection (Key Example)

  • Type: An orthomorphic projection (correct shape is maintained).
  • Key Property: Maintains correct directions. A straight line joining any two points on it gives a Laxodrome or Rhumb line (constant bearing), making it very useful for navigation purposes.
  • Limitation: There is greater exaggeration of scale along the parallels and meridians in high latitudes, leading to highly exaggerated sizes of countries near the poles (e.g., Greenland).

Part IV: Topographical Maps (Chapter 5)

1. Introduction

  • Topographical Maps are also known as general purpose maps.
  • They are drawn at relatively large scales (e.g., 1:250,000, 1:50,000, 1:25,000) and show detailed natural (relief, water bodies) and cultural (settlements, transportation) features.
  • In India, these maps are prepared and published by the Survey of India.

2. Relief Representation

  • Relief (elevation and depression) is predominantly shown using contours and spot heights.
  • Contours: Imaginary lines joining all points of equal elevation or altitude above mean sea level.
  • Contour Interval (V.I.): The vertical distance between two successive contours, usually constant for a given map.
  • Horizontal Equivalent (H.E.): The horizontal distance between two successive contours. It is large when the slope is gentler and small when the slope is steeper.

3. Contour Spacing and Landforms

  • Steep Slope: Contours are closely spaced.
  • Gentle Slope: Contours are widely spaced.
  • Vertical Slope (Cliff/Waterfall): Two or more contour lines merge with each other.
  • V-Shaped Valley: Contours are V-shaped, with the ‘V’ pointing upriver (towards the higher ground, with the innermost contour having the lowest value).
  • Spur: A tongue of land projecting from higher ground, represented by V-shaped contours where the ‘V’ arms point to the higher ground and the apex points to the lower ground.

4. Map Interpretation

Topographical sheets are usually interpreted under five main heads:

  1. Marginal Information (scale, sheet number, location, grid references).
  2. Relief and Drainage (hills, valleys, general slope direction, river patterns).
  3. Land Use (natural vegetation, agricultural, wasteland).
  4. Means of Transport and Communication (roads, railways, post offices).
  5. Human Settlement (types and patterns: Compact, Scattered, Linear, Circular).

Part V: Remote Sensing (Chapter 6)

1. Definition and Energy

  • Remote Sensing: The process of acquiring and measuring information about objects/phenomena by a sensor that is not in physical contact with the objects under study.
  • Energy Source: The Sun is the most important energy source used.
  • EMR Spectrum: Energy propagates as Electromagnetic Radiation (EMR). Remote sensing primarily uses the visible, infrared, and microwave regions.

2. Sensors and Satellite Orbits

  • Sensor: A device that receives EMR and converts it into a signal (photographic or digital image).
  • Photographic Sensor (Camera): Records images at an instance of exposure (Analogue).
  • Non-Photographic Sensor (Scanner): Obtains images bit-by-bit (Digital).
    • Whiskbroom Scanners: Use a rotating mirror and a single detector.
    • Pushbroom Scanners: Use a linear array of multiple detectors.
  • Sun-Synchronous Satellites (e.g., IRS series): Low altitude (700–900 km), used for Earth Resources Applications, high/fine resolution.
  • Geostationary Satellites (e.g., INSAT series): High altitude (36,000 km), used for Weather monitoring and Telecommunication, coarse resolution.

3. Sensor Resolutions

  1. Spatial Resolution: The capability of the sensor to distinguish two close-spaced object surfaces as two different object surfaces.
  2. Spectral Resolution: The sensing and recording power of the sensor in different bands of EMR.
  3. Radiometric Resolution: The capability of the sensor to discriminate between two targets.

4. Elements of Visual Interpretation (Viva Keywords)

Visual interpretation involves identifying objects based on image and terrain characteristics:

  • Tone or Colour: Depends on the reflected energy. Healthy vegetation reflects strongly in the infrared and appears bright red in a standard False Colour Composite (FCC). Clear water absorbs much radiation and appears in dark tone or black colour.
  • Texture: Minor variations in tone or colour (e.g., dense residential areas show fine texture; low-density areas show coarse texture).
  • Shape: General form and configuration (e.g., railway lines are distinct due to long continuous linearity).
  • Shadow: Gives clues about the object’s height, but can hide features underneath.
  • Association: Relationship between objects and their surroundings (e.g., an educational institution being near a residential area).

Viva Metaphor Summary:

Preparing for your Geography practical and viva is like being a cartographer interpreting a landscape. The Scale is your magnifying glass—it tells you how much the world has shrunk so you know if you are measuring an inch on the map or a mile on the ground. Projections are your drafting table, necessary to flatten the round Earth, but causing inevitable compromises in shape or size. Finally, Remote Sensing and Topographical Maps are your field guides, providing detailed visual clues (like contour spacing or a building’s color signature) that help you identify the natural and human features without needing to physically walk the entire terrain.

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