Mapping local climate zones and their associated heat risk issues in Beijing: Based on open data

Abstract

The “Urban Heat Island” (UHI) effects in cities pose great threats to heat health risks for urban dwellers, but they present great differences inside cities. Local climate zones (LCZs), with distinct surface morphologies and physical structures, can be used to better explore differences of UHI effects inside cities and can also solve their different heat risks there. However, there still existed some gaps to map LCZs and their associated heat risks in cities, due to lack of detailed urban building data. Thus, we focused on mapping LCZs and their associated heat risks in Beijing, based on open data of four urban morphology parameters, including sky view factors, permeable surface fraction, building surface fraction and building height. Seven types of land cover LCZs and eight types of artificial built LCZs were divided. In spite of only 11% of total area, artificial built types of LCZ played vital roles in local economic development. Different types of LCZ were highly related with their urban functions, and most of artificial built LCZs were located in the Capital Functional Core Area and the Urban Functional Development Area. Open low-rise and open midrise were two important artificial built types of LCZ in Beijing, due to their high value of traditional and cultural buildings. Beijing faced serious heat risks in summer, especially for artificial built type LCZs. About 6% of total area and 58% of all residents suffered heat risks in Beijing, and most of them were located in artificial built type of LCZs. Lightweight low-rise suffered the most serious heat risks, and more than 90% of its area and residents were under heat risks. Considering climate change, about 4.0~7.4 million more people would suffer heat risks in future, and the LCZ of compact high-rise was highly sensitive to future climate change in Beijing. Urban morphology, economic function, population density and heat risks existed great differences among various LCZs in Beijing, and thus different strategies should be applied to mitigate heat risks in different LCZs for future city planning.