Climate change, species extinction, water scarcity 333prices for scarce water are a serious economic problem for industry around cities,
with widely reverberating effects.
Wat er supplyfordrinking and other daily domestic uses is particularly impor-
tant in urban regions, because it requires rather clean water in an area bursting
with pollution sources. Clean water may be piped long distances into an urban
region as an ‘‘inter-basin transfer” (Thayer2003,Ghassemi2006)(San Diego,
Sydney), but that is expensive, and the process dries out and degrades the source
area. Desalinization of salt water can provide a limited amount of water, but at
considerable cost. More promising for a city is to rigorously protect natural veg-
etation around a water-supply reservoir or lake in the outer urban-region ring
(New York). This, of course, would be easier if a political/administrative perime-
tercorresponded closely with that of a dramage basin or catchment, as in the
rare case of Florida’s Water Management Districts, which have taxing authority
and regulatory power.
Using river water as a water-supply source has the advantage of usually hav-
ing ample water, but the significant disadvantage of typically being polluted,
which requires expensive water treatment for cleaning. Pollution sources tend
tobe diverse and widely distributed, and it is extremely difficult to cover a
river’s extensive drainage basin with vegetation. In consequence clean rivers
in urban regions are a rarity (Paul and Meyer2001). A water supply based on
pumping from streams may serve smaller communities, but for major cities (e.g.,
Tegucigalpa) the rate of pumping and the diverse acute pollution sources pose
limitations. Yet the presence of dirty streams and rivers also means that fresh-
waterisall around the inhabitants of urban regions. Cleaning it up provides
relatively clean water for most urban uses. Water conservation and recycling are
also potentially major clean-water sources.
Groundwateras a water-supply source is a special problem, because of potential
diverse pollution sources in an urban region (Bamako) and limited hydrologic
waterpressure. Yet a well-protected aquifer with considerable hydrologic pres-
sure can be a valuable source of drinking water, as in parts of the European
Community and Russia (Margat1994). Groundwater is also a major source for
industrial use in Northern and Central Europe, South Korea, and Japan. In con-
trast, it is extensively used for irrigated agriculture in Mediterranean areas (e.g.,
Spain, Greece), Australia, India, and parts of the USA.
Groundwater aquifers should be covered with essentially continuous vege-
tation, especially over the upper portion (Gibertet al.1994). Otherwise pollut-
ing chemicals from development or agriculture percolate into the groundwater,
which (except in limestone areas) move slowly and tend to accumulate. The
widespread impermeable surface associated with urbanization, and the rarity of
remnant wetlands and stormwater-drainage swales, sends rainwater rushing off