Spatial Interaction / Migration NOTES

Part A: Spatial Interaction (Human Geography, pp.66-84)

Spatial interaction means the movement of peoples, ideas, and commodities within and between areas. Such movements and exchanges are designed to achieve effective integration between different points of human activity.

Model for Interaction (Edward Ullman, 1912-1976)

Spatial interaction is effectively controlled by:

·  complementarity—for two places to interact, one place must have a supply of an item for which there is an effective demand in another (e.g. seasonal fruits from California to Ontario);

·  transferability—acceptable costs of an exchange in value, distance measured in cost and time, and ability to bear the costs of movement (e.g. new road allows a forest to be logged);

·  intervening opportunity—supply close at hand will limit exchange with complementary areas at greater distance (e.g. sand obtained from nearby moraine and not from Sahara desert).

Measuring Interaction

Distance decay describes the decline of an activity or function with increasing distance from its point of origin—near destinations have a disproportionate pull over more distant points in movements of commodities or people. Friction of distance can be reduced by lowered costs or increased ease of flow (e.g. expressways expand the area of potential interaction).

Gravity Model (Henry Carey, 1793-1879)

Newton’s law of universal gravitation states that any two objects attract each other with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.

Carey modeled that the interaction (I) between two places, i and j, can be analogous to the law of gravity.

Exchanges between any set of two cities, A and B, can therefore be quickly estimated.

Large cities also have a greater drawing power for individuals than smaller ones—the breaking point is the boundary marking the outer edge of a cities’ trade area (Reilly, 1931).

Chapter 3 Discussion Questions KUBY and Barron’s CGU4U

  1. Firstly, define each term in Chapter 3 and find an example for each. This will help to answer Qs 2-12.
  2. Spatial diffusion
  3. Relocation diffusion
  4. Expansion diffusion
  5. Contagious effect
  6. Hierarchical diffusion
  7. Distance decay effect
  8. Barriers to diffusion
  1. What is the newest, coolest trend among high school students today? Where did it originate? How did it get here? How long did it take? What percent have adopted it already?
  1. Can you think of anything that you adopted very early in the S-curve? Anything in which you were a late adopter or non-adopter? (Hint: see fig. 3.2 in Kuby)
  1. Have we manipulated your impressions of the diffusion of AIDS through our selective choice to map AIDS rates in metropolitan areas? (Act 3.1)
  1. Does the diffusion of AIDS in the U.S. follow an S-curve pattern? (Act 3.3)
  1. Would other diseases diffuse according to the same time-space pattern as AIDS?
  1. How do you suppose AIDS would have spread 150 years ago?
  1. Name some other phenomena that diffuse hierarchically?
  1. Name some other phenomena that diffuse contagiously?
  1. What characteristics determine whether a phenomenon will diffuse hierarchically or contagiously?
  1. If you were a marketing manager for a company (e.g., an athletic shoe company or a music label), how could you apply your knowledge of spatial diffusion?
  1. What other professions besides marketing and disease control might benefit from knowledge of diffusion?