4. Environmental self-Conservation and
self-Recovery Index (ECRI)
4.1 purpose
ECRI focuses on natural capacity in comparison with human activities. It has used for setting targets under the environmental plan such as “manage emission within three times as much as self-purification”. Based on this aspects, Chiba City set targets under Environmental Basic Plan: absorbed NO2 rate for total emission, fixed CO2 rate for emission, rate of controlled flowing groundwater for total rainfall.
4.2 content
ECRI is consist of six indices: Air self-purification, Climate mitigation, GHG gas reduction, Flood control, Water circulation conservation, and Soil erosion reduction(table 5).
Air self-purification is indicated by NO2 absorption Heat mitigation is caught up by evapo-transpiration from plants, which are mainly mitigated local heat pollution. GHG gas reduction is represented by plants Carbon accumulation. Flood control is presented by the cut of maximum flow on rivers. Water circulation conservation is indicated by rainwater sinking into soil. Soil erosion reduction counts the function of plants effect reducing soil erosion.
4.3 method
First each values by 1km mesh are calculated, and summarized by city level. Next, based on mean and standard deviation between cities, each standardized indices are led. ECRI in all Japan’s cities has been calculated.
Figure 10 Heat mitigation (1987)