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Chapter 1

Chapter 1. Foundations of . Geography. GOALS OF THIS CHAPTER Define Geography and Physical Geography Geography as an Earth Systems Science An Introduction to Systems Thinking Earth’s Reference Grid Basics of Cartography: Map Scale and Projection. GEOGRAPHY

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Chapter 1

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  1. Chapter 1 Foundations of Geography

  2. GOALS OF THIS CHAPTER Define Geography and Physical Geography Geography as an Earth Systems Science An Introduction to Systems Thinking Earth’s Reference Grid Basics of Cartography: Map Scale and Projection

  3. GEOGRAPHY • Geo (“Earth”) + Graphein (“to write”) • Geography is the study of synergistic interactions • among natural systems, geographic areas, society, • and cultural activities over space • Spatial analysis is the key to geography • The nature and character of physical space • The influence of space on Earth system processes

  4. Geography– a diverse discipline including elements of the following interrelated physical and human disciplines (Fig 1-2) PHYSICALHUMAN Cartography Geomorphology History Pedology Geology Sociology Meteorology Biology Land Use Planning Chemistry Physics Population Studies Remote Sensing Geographic Information Systems Cultural Studies Biogeochemistry Biogeography Political Science Environmental Modelling Medical Geography Sound disorganized ? Discipline held together by spatial analysis. Human and physical geographers often work together Humans are part of nature and, thus, affect and are affected by, the physical environment.

  5. What is Physical Geography ? “The spatial analysis of all the physical elements and processes that make up the environment: energy, air, water, weather, climate, landforms, soils, animals, vegetation and Earth itself.” Physical Geography is an Earth Systemsscience As a science, it employs the scientific method(Fig 1) The main concept of Earth Systems science is that: “interacting physical, chemical and biological systems produce the conditions of the whole Earth.”

  6. A Brief Introduction to Systems Thinking • System – defined(Fig 1-3, 1-5, 1-6) • “(An) interrelated set of (components) and their • attributes, linked by flows of energy and matter, as • distinct from the surrounding environment” • Energy can be transformed • A system may be open or closed • Most natural systems are open • (energy flows in and out)

  7. Earth’s Four Spheres(Fig 1-7) Atmosphere Thin, gaseous veil surrounding the Earth, held together by the force of gravity. Nitrogen, oxygen, argon, carbon dioxide, water vapour and trace gases. Hydrosphere The Earth’s waters on the surface, within the uppermost portion of The crust and in the atmosphere. Lithosphere The solid planet (soil, crust and a portion of the upper mantle) Biosphere The area in which physical and chemical factors form the context of life

  8. Sample systems: • The carbon cycle (clearly human and physical) • An ecosystem • The water cycle (global, regional, catchment) • Emerging Field in Earth Systems Science and Physical Geography: Environmental Modelling • (spatial and temporal simulation Earth’s systems)

  9. Example: A leaf (Figure 1-4) Two subsystems determine net carbon uptake Photosynthesis Inputs: sunlight, water, nutrients, carbon dioxide Inputs converted to stored chemical energy (carbohydrates) Outputs: oxygen Respiration Carbohydrates converted tocarbon dioxide, water and heat

  10. Systems Example

  11. Modelling in Physical Geography and the Earth Sciences Systems All Systems are composed of the following four elements: 1. Reservoirs 2. Processes 3. Converters 4. Interrelationships

  12. Reservoir: A repository where something is accumulated, stored and sometimes passed on to other elements in the system. Reservoirs may accumulate or diminish over time Examples: - Total mass of carbon storage in biomass in a global carbon cycle model - Number of specimens of a species in a predator/prey model

  13. Process: An ongoing activity in a system that determines the content of a reservoir over time Future contents = previous contents + all inflows - all outflows R(t+t) = R(t) + {sum of inflows - sum of outflows} PROCESS (water equivalent precipitation as snow, ice pellets or freezing rain in one day) RESERVOIR PROCESS (water-equivalent removal through melting, evaporation and sublimation and infiltration in one day)

  14. Converters: System variables that can play different roles within the system - Regulate the rates at which processes within the system operate

  15. Interrelationships between Reservoirs, Processes and Converters Snowdepth Modelling: Conceptual Model

  16. What is the point in thinking in terms of systems?

  17. Uses of System Models: 1. To understand the complex mechanisms controlling system function - Describe processes and converters - Identify mechanisms behind observed cycles and complex patterns that cannot be intuitively induced based on the simple relationships between two variables - Determine how the system maintains stability and how that stability can be jeopardized

  18. 2. “Predict” and “Validate” System Performance - Project cycles and trends - Evaluate impact of policy options and scenarios (eg. impact of greenhouse gas emission scenarios on global warming and carbon cycling) - Identify scenarios that may jeopardize or restore system stability

  19. Feedback Loops: A closed-loop circle of cause and effect in which “conditions” in one part of the system cause “results” which, in turn, alter the “original” conditions Positive feedback: Changes at one point of a feedback loop eventually amplify or reinforce the original change - Such systems tend to lose control - Example: Positive feedback to anthropogenically-induced global warming via wetlands (arguably)

  20. Negative Feedback: Changes at one point of a feedback loop eventually counteract (damp out) the original change - Such systems tend to be self-regulating and do not run out of control - Many environmental problems can be attributed to a breakdown of naturally-occurring negative feedback loops Example: High birth rate in a given species leads to higher population, which reduces resources. Higher death rates and reduced birth rates result, leading to a reduction in the population and an increase in resource availability.

  21. Steady-state Equilibrium: Systems which “level off,” so that the system reservoirs change little with time are said to have reached steady state Inputs of energy/matter equal outputs Storage is constant Dynamic System Behaviour: 1. Linear growth or decay R(t) = a + bt , where a is the value of R(t) at t=0 and b is the rate of change

  22. 2. Exponential growth or decay R(t) = R0ekt, where k is the net growth rate (positive) or decay rate (negative) of R(t) 3. Overshoot and collapse 4. Logistic growth 5. Oscillation

  23. Basic Principles of Cartography • The Spherical Earth • Incan astronomers accurately calculated the precession of the equinoxes – did they understand the Earth was spherical ? • Ancient Greece: Pythagoras (2503-2583 BP) • Aristotle proved Earth to be spherical in (2387-2325 BP) • Ancient Egypt: • Eratosthenes calculated the polar circumference (2250 BP) • England: • Newton predicted that Earth bulges slightly at equator (316 BP) • Today: Geodesy - Earth’s shape and size characterized by surveys and mathematical calculations – Geoid

  24. Latitude and Longitude Ptolemy - Divided Earth into 360, 60, 60 system (1838-1918 BP) Latitude “An angular distance north or south of the equator, measured from the centre of the Earth” Parallel “a line connecting all points along the same latitudinal angle” (eg. Arctic/Antarctic Circle, Equator, Tropic of Cancer/Capricorn) Longitude “An angular distance east or west of a point on the Earth’s surface, measured from the centre of the Earth” Meridian “a line connecting all points along the same longitude” (eg. The arbitrary prime meridian running through Greenwich) Today: Global Positioning Systems (GPS)

  25. How can latitude and longitude be represented in 2D ?

  26. Since maps are constructed in 2D, rather than on ellipsoidal geometry, projections are required (conical, azimuthal or cylindrical depending on specific needs of end-user) Map projections Two-dimensional representations of the Earth’s surface or part of the Earth’s surface Distortions of conformality, distance, direction, scale, and areaALWAYS result from this process. Some projections minimize distortions in some of these properties at the expense of maximizing errors in others. Other projections only moderately distort all of these properties.

  27. Conformality • Scale is the same in any direction at a given point • Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles. • Shape is preserved locally Equidistance Two identical lines from the centre of the projection cover the same true length in any direction Preservation of Direction Azimuths (angles from a point on a line to another point) are portrayed correctly in all directions Equal Area Areas in different regions of the map have the same proportional relationship to the same areas on the Earth’s surface

  28. Useful for navigation: All straight lines are lines of constant azimuth.

  29. Universal Transverse Mercator [UTM] World divided into 60 zones Zones numbered eastward from 1 to 60 beginning at 180 degrees west. The central meridian of each zone is given an easting of 500,000 m. For the northern hemisphere, the equator has a northing of 0 m. For the southern hemisphere, the equator has a northing of 10,000,000 m. Scale distortion within a UTM zone ranges from .9996 to 1.0003. A standard for many countries Commonly used in topographic mapping and for referencing satellite imagery.

  30. System of UTM and UPS (Polar) grid zone designations Quadrilaterals are defined by column number and row letter (I and O are omitted). The darkened area is quadrilateral 32N.

  31. UTM designed to function between 80 S and 84 N. Covers all of Canada To keep distortion to a minimum surface of globe projected down to a surface using 60 N-S strips, each 6 degrees wide. UTM grid then placed over each zone The Mercator projection is conformal. In other words, corrected compass bearings are straight lines.

  32. Conical Projections Conic projections result from projecting a spherical surface onto a cone. Conical Projection Surface Polyconic Projection: Central Median 100ºW

  33. Conical Projections Example:Albers Equal Area Conic, Origin 23N, 96W Distorts scale and distance except along standard parallels. Areas proportional and directions true in limited areas. Used in large countries with a greater E-W than N-S extent.

  34. Azimuthal Projections Azimuthal projections result from projecting a spherical surface onto a plane. Used to show air-route distances. Distances measured from centre are true. Distortion of other properties increases away from the center point. Example: Azimuthal Equidistant Projection

  35. Two Different Projections of North America The use of an appropriate projection system is dependent on the purpose and location of the region studied

  36. Cartesian Coordinate System (X,Y) Define an origin Define a positive X direction Define a positive Y direction orthogonal to X Define linear displacement from the origin in X and Y Euclidian Distance: Distance, D, between two points (X1, Y1) and (X2, Y2) can be calculated as follows:

  37. Maps, scales and projections The ratio of the image on a map to the real world is called scale For example, a scale of 1:25,000 means that 1 unit on the map represents 25,000 units on the ground. Map scales: Written scale (eg. 1:25,000) Representative fraction (eg. 1/25,000) Graphic scale - Scale remains true after enlarged/reduced The greater the denominator, the smaller the scale In other words, a large scale map (eg. 1:10,000) shows more detail and less area than a small scale map (eg. 1:1,000,000).

  38. Map Scale

  39. Calculating map scale: You have scanned a portion of a map for which the scale is known and enlarged it. How can you determine the scale of your new map ? 1. Find a similar object on each map (eg. line segment) and measure the distance on each map. 2. Let’s say the reference map has a scale of 1:24 000 and you measured a line segment distance of 65 mm. Multiply the measurement by the denominator of the scale fraction (65 x 24 000 = 1 560 000). Now you have the distance on the Earth’s surface. 3. Divide this distance by the measurement on your new map (eg. 80 mm). Your scale is 1 560 000/ 80 or 1: 19500 Is this a larger scale or smaller scale ? (Larger, just like your measurement)

  40. More mapping basics: Contour Lines A method of depicting 3-dimensional character of the terrain on a 2-dimensional map.

  41. Sample Topographic Map *NB: The U of L Library has a large collection of 1:50,000 and 1:250,000 maps produced by the Canada Centre for Mapping (Natural Resources Canada) http://imnh.isu.edu/digitalatlas/geog/basics/topo.htm

  42. Can you infer general wind direction and relative windspeed from this map ? A tight pressure gradient leads to higher wind speeds Winds blow clockwise around H pressure, counter clockwise into L pressure

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