  During the epidemics of COVID-19, the whole world is experiencing a serious
crisis on public health and economy. Understanding human mobility during the
pandemic helps one to design intervention strategies and resilience measures.
The widely used Bike Sharing System (BSS) can characterize the activities of
urban dwellers over time & space in big cities but is rarely reported in
epidemiological research. In this paper, we present a human mobility analyzing
framework} based on BSS data, which examines the spatiotemporal characteristics
of share bike users, detects the key time nodes of different pandemic stages,
and demonstrats the evolution of human mobility due to the onset of the
COVID-19 threat and administrative restrictions. We assessed the net impact of
the pandemic by using the result of co-location analysis between share bike
usage and POIs (Point Of Interest). Our results show the pandemic reduced the
overall bike usage by 64.8%, then an average increase (15.9%) in share bike
usage appeared afterwards, suggesting that productive and residential
activities have partially recovered but far from the ordinary days. These
findings could be a reference for epidemiological researches and inform
policymaking in the context of the current COVID-19 outbreak and other epidemic
events at city-scale.
