Economics in time, space, and footprints 59summer tourism, street trees, flood frequency, flood heights and damage, scour-
ing of streams/rivers, fish populations and recreation, and stormwater pollu-
tants carried into water bodies. The economic effects of an extensive loss of the
greenspace resource are too widespread and uncertain at present, and into the
future, to confidently estimate. Many other resources in the urban region fall
into this category.
Whereas the preceding discussion focuses on resource protection and pollu-
tion avoidance and minimization, many of the same points apply to restoration,
mitigation, and compensation for sites or areas already degraded by pollution
and human overuse (Salvesen1994,Cuperuset al.2001,Formanet al.2003).
Restorationis a return to some previous state, which in the urban region typi-
cally means to semi-natural vegetation with little pollution.Mitigationmeans to
minimize the effects of, which can be accomplished in many ways.Compensation,
where mitigation seems impossible, means to provide benefits off-site equivalent
tothelosses on-site. A significant reduction in pollutant input and human usage,
plus clean up of the accumulated pollutants, is usually assumed in restoration
and mitigation projects.
Economics in time, space, and footprints
An important range of factors affecting urban region economics are
presented in three categories: (1) time, stability, and sustainability; (2) spatial
arrangement; and (3) ecological footprints.
Time, stability, and sustainability
Occasionally over pre-history and history cities have been wiped off the
map by wars, ‘‘natural” disasters, or climate change. Now greenhouse-gas buildup
with an expected 0.5 to 5+ m sea-level rise may eliminate more. Nevertheless
most urban regions are nearly permanent, and are especially suitable for long-
termthinking and action. The concepts of uncertainty, adaptability, and stability
are all focused on the long term rather than short term. These are familiar to
industries that expect to persist. The time period is decades or human genera-
tions, exactly the time period usually considered for sustainability.
Stability
Numerous solutions for issues such as uncertainty, surprises, flexibility,
adaptability, and stability exist and have been proposed. Methods of analysis are
equivalently diverse, from simple comparisons of options based on principles and
distinctive features on the land to computer simulation modeling of complex sys-
tems (biological and/or social) with uncertainty levels, spatial remote-sensing/GIS