the largest contiguous urban green belts in the world. Only the green belt associated
with Canada’s “Golden Horseshoe” conurbation and the Sao Paulo City Green Belt
Biosphere Preserve are larger, although the latter is not actually a planned green
belt in the classic sense of the term. A proposed “European Greenbelt,” a zone link-
ing parks and preserves that would extend from the Baltic to the Mediterranean
seas through Eastern Europe, would be the largest such space in the world if it is
successfully completed. Promoters of green belts argue that they add quality to
the lives of urban dwellers, allowing them to connect with and enjoy the natural
environment, while preserving nature, in a limited way, in the urbanized setting.
It is claimed that they help to maintain both air and water quality, and of course
they provide both outdoor recreational opportunities for city residents and habitat
for wildlife.
Some scholars have criticized the green belt approach as economically
unsound, and often counterproductive. Some economists suggest that by reserving
land for the green belt in urban areas, housing prices are maintained at high levels
and the quality of housing actually suffers, because competition in the housing
market is stifled. There is some evidence to support this view, especially in
England. Moreover, while green belts have preserved a strip of land adjacent to
the main urban area, in many cases development has simply skipped over the
green belt and exploded on the other side, in the form of suburbs and satellite
towns. Critics argue that this shows that the green belt simply forced urban expan-
sion further out from the main urban center, actually increasing transportation
costs and pollution levels. Although controversial, the green belt concept in urban
planning appears to be widely accepted and applied, especially in Europe, and is
likely to be a feature of the urban landscape of the future.
Groundwater
Earth’s land surface is less than monolithically solid. The joints,faults,and
weathered rocks described elsewhere in the book allow rainwater to penetrate
the crust, sometimes to considerable depths and become groundwater. Stream
channels that intersect subsurface layers containing groundwater can add water
to or take water from the groundwater supply.
Far from being an isolatedsource of stored water,the shallowergroundwater
supplies are intimately related to the rest of thehydrologic cyclein that they are
recharged by precipitation. It should be noted that most soil moisture is distinct
from groundwater (although there are times and places at which the top of the
groundwater supply can be within the soil and so be one in the same). In that
Groundwater 163