Multifactor response
It is difficult to achieve maximum ESV and adjust all socioeconomic
factors to the optimum intervals because of the complex coupling
influence. We attempted to select several sets of factors with
significant interactions to identify which proportions could regulate
them for the purpose of maximizing ESV. As a result, “the proportion of
construction” and “population”, “1st industry
output value” and “population”, and “industrial water consumption”
and “industrial electric consumption” were chosen to analyze how they
cooperatively influence ESV.
This approach suggested that ESV is most affected by the population
(Figure 3a). The population within 4 km2 should be
controlled to be less than 20 k or approximately 120 k. In addition, ESV
dropped sharply with the increase in construction land when the
population was 50 k. In contrast, ESV declined slowly with the increase
in construction land when the population was more than 100 k, which
suggests that a relatively single distribution of construction land will
not place too much pressure on the ecosystem in densely populated
centers. However, controlling construction land still has a positive
influence on ESV. Therefore, the city center can sacrifice
nonconstruction land for infrastructure construction and population
accommodation, and it will be necessary for it to reserve ecological
space.
The surface of “1st industry output value” and
“population” showed that there were two scenarios that achieve higher
ESV (Figure 3b). One scenario was when the population was nearly 0 and
the output of the 1st industry was more than 15
million CNY. Under this scenario, the object region had a small
population but played an important role in agricultural production. The
other scenario was when the population was approximately 150 k and the
1st industry output value was less than 10 million
CNY.
Regarding energy consumption, “industrial water consumption” was
presumably the limiting factor compared with “industrial electricity
consumption” (Figure 3c). Industrial water consumption should be kept
below 15 kt if one hopes to achieve a high ESV. When industrial
electricity consumption was between 400 and 600 kw, ESV rapidly
decreased with increasing industrial water consumption. This finding
suggested that water consumption needs to be restricted and reserved in
industrial areas.