September 14, 2012
- Why is distance so important in (urban-economic) geography?
- Distance - critical determinant of real-world, spatial relationships
- The "first law of geography": Everything is related to everything else, but near
things are more related than distant things."
- What does this mean? Why is this the case?
Human Systems and Spatial Interaction
- Spatial interaction: the movement of phenomena (people, goods, money, ideas,
etc.) between locations.
(What spatial interaction have you carried out today?) Texting a friend.
- Spatial interaction is necessary, in simple terms, because not all things are
available in all places, i.e., things are not ubiquitous, so getting something that is
available in place A to/from place B involves spatial interaction and, therefore, costs.
- What principles govern spatial interaction?
European Interaction with the World, in wealth generated by trade, 1500-1800
Relative Location & Spatial interaction and Movement.
The coloured lines describe the flow of wealth to Europe as a result of long
distance European control of trade.
Fig. 2.34 Marston et. al. p. 84
1. Ullmann postulated that spatial interaction is controlled by "three flow-
- Complementarity: these supply and demand relationship between two
places, i.e., for interaction to occur, place A must have/supply what place B
- interaction does not occur simply because places are different,
e.g., Greenland and Amazon basin
- supply location (place A) must be linked to a market (plan B),
e.g., fruits/vegetables grown in California shipped to urban markets in Canada
2. Transferability: the acceptable costs of an exchange, i.e., availability and
demand might not be linked due to the prohibitive cost ($, time)
- an expression of the mobility of a commodity
- is determined by three interrelated conditions:
- the characteristics and value of the good;
- the distance over which the good must be moved; and
- the ability of the good to bear the costs of movement
3. Intervening Opportunity
- Intervening opportunity: closer opportunities will reduce the
attractiveness of interaction with more distance alternatives, i.e., interaction is more likely with closer opportunities than with more distant opportunities (all other things
- Other Considerations
4. Distance Decay
- Distance decay: the decrease in interaction with a location as distance
from that location increases (see Fig. 3.7, p. 68)
- Related to the concept of 'the friction of distance' - the restricting effect
of distance on spatial interaction, i.e., the greater the distance, the less the interaction
between two locations
5. The Gravity Model
- Other factors, besides