Geography Reference
In-Depth Information
budgets change and can be easily found to become increasingly serious along with
future urban expansion.
The drought effect of future urban expansion in new urban area will be more
significant than that in the original urban area (Fig.
7.29
, Panel B). The most
significant reduction of average monthly precipitation will occur in October with
11.82, 9.23, and 8.14 mm in the period of 2010-2020, 2040-2050, and 2090-2100,
respectively. Thereafter, the precipitation in new urban area starts to fall and
reaches its minimum (between 2 and 3 mm) in May. More interesting, we also find
that the more expanded urban area will weaken drought effect in new urban area.
This can be deduced from the fact that the average monthly precipitation decreases
in the periods of 2040-2050 and 2090-2100 will be smaller than that in the period
of 2010-2020. This can be explained that the enhancement of UHI effect in the
Northeast megalopolis will arouse the inflow of humid air from the Atlantic.
To investigate the effects of future urban expansion on average monthly pre-
cipitation in nonurban area, we counted the number of pixels with average monthly
precipitation changes exceeding ±1 mm (Fig.
7.28
, Panel B). The results show
that the impacts of future urban expansion on average monthly precipitation in
nonurban areas will be larger in summer than in winter. Additionally, the larger the
urban area expands, the larger area of which the average monthly precipitation will
be affected by urban expansion. For instance, the number of pixels with average
monthly precipitation changes exceeding ±1 mm in July will be 35 (covering an
area of 8.75 9 10
4
km
2
) in the period of 2090-2100, and 32 (covering an area of
8.00 9 10
4
km
2
), and 24 (covering an area of 6.00 9 10
4
km
2
) in the period of
2040-2050 and 2090-2100, respectively. It implies the area with average monthly
precipitation changes exceeding ±1 mm will spread persistently along with the
urban expansion.
7.5.3 Concluding Remarks on the Effects of Urban
Expansion in the Northeast Megalopolis, USA
A simulation-based research on the intension and scope of influences of future
urban expansion on regional climate in developed megalopolis was implemented.
The average annual and monthly temperature and precipitation change caused by
urban expansion from 1993 to 2100 were presented taking the Northeast mega-
lopolis, USA as a case study area. Some conclusions were drawn as follows:
(i)
The future urban expansion will result in the increase of the average annual
temperature, ranging from 2 to 5 C in new urban area and decrease in the
south of the Northeast megalopolis, ranging from 0.40 to 1.20 C. The
average annual precipitation in the study area will reduce by 5.75, 7.10 and
8.35 mm due to urban expansion in the period of 2010-2020, 2040-2050,
and 2090-2100, respectively. This reduction is especially severe in the
south region of the Northeast megalopolis.
