Resumen
Extreme precipitation poses significant threats to economic development and social security. In order to tackle this formidable issue, the Chinese government has invested substantial investments to promote the ?sponge city? project. However, extreme precipitation in Zhengzhou on 21 July 2021 proved that this effort fell far short of its goal, highlighting the difficulty in relying solely on the government to respond to severe disasters. Collaborations between the public and the government have become essential for effectively managing extreme precipitation risk. However, bridging the gap between the public and the government remains a challenging task in China. Interestingly, an Online Collaborative Document (OCD) emerged without any financial investment from the government yet went on to save countless lives. The key lies in that the OCD greatly promoted the cooperation between spontaneous volunteering and official response. This study aims to explain how an OCD encourages effective collaboration between spontaneous volunteering and official responses in tackling extreme precipitation risk. This study employs the method of the case study about the extreme precipitation and analyzes the directed survey on the spontaneous volunteers, grassroots government officials, and affected individuals who used the OCD. Additionally, a variety of data collection techniques, including focus groups and one-on-one interviews, are used to examine the relevant information. This study explores how the OCD eliminated the paradox of collaboration between spontaneous volunteering and the official response thereby fostering coordination between them.