286 Gathering the pieces
Just as for the riverside cities, these coastal donut geometries are good indi-
cators of how the urban region is structured and how it works. The directional
river flow, tilted land surfaces, and stream flows as described above are evident.
In addition, along the coast the land commonly tilts and streams flow toward
thesea. Water from the urban area pollutes a harbor or bay, especially one with
limited circulation. Irrespective, pollution normally extends into the near-shore
area beyond the coastline, where polluted water is then spread by currents or
wind particularly in one direction along the coast.
A coastal microclimate, often extending inland 5 km (3 mi) or more, brings
haze or fog, on- or off-shore breezes, and cooler or warmer conditions, which
change seasonally according to the temperature difference between seawater and
land. Coastlines in an urban region are usually lined with recreational resort
development, and protected natural areas along the coast tend to be small and
ever-threatened by human activities. Also coastal cities commonly have a ‘‘flat-
tened semicircle” major highway around them for through travel and transport
along the coast.
Onshore winds and storms and waves threaten and periodically damage
coastal areas. Low-lying areas where river meets sea, especially around bays,
formerly were largely wetlands, but today often much urbanized. Flooding from
coastal storms, particularly at high tide, tends to cover these low areas. Ironically,
theriver brings floodwaters from inland storms to the same low areas.
In addition, thedirection of prevailing windsindicates much about a region.
Downwind of a metro area, considerable air pollution (and sometimes a bit
more rain) is common, so recent development may be more on the upwind side.
Wind direction is critical in locating airports and flight patterns, and reducing
hazards such as a sudden large pollutant release from a nuclear power plant.
Furthermore the upwind side of an urban region is strongly influenced by condi-
tions in the adjoining region, from eroded-soil particulates to wildfire, industrial
pollution, or cooling by a large lake or forested area. In short, the flattened side
of the donut, as well as the central slice, indentation, and prevailing wind,
provide considerable insight into pattern, process, ecology, and planning in an
urban region. The following represent variations on the coastal city theme:Coastal city without a prominent bay.Barcelona, Toronto, Chicago, Rabat
(Morocco), Algiers
Coastal city with a prominent bay.Buenos Aires, San Diego, Marseilles,
Lagos, Helsinki, Guayaquil (Ecuador), Tampa (USA), Lisbon
Coastal city with islands providing partial storm-protection.Kuala Lumpur,
Boston, Port Moresby (Papua New Guinea), Stockhom, Seoul