Abstract:

The social benefits of a sponge city refer to its contribution to society such that sponge city facilities contribute far more than their direct economic benefit. However, the social benefits of a sponge city are difficult to calculate objectively, which hinders people's understanding of such cities. An objective calculation of the social benefits not only reflect whether sponge city facility constructions are cost-effective, but also provides a reference for government policy making. Therefore, we developed an objective calculation method combining subjective evaluation and objective calculation. By subjectively assessing social benefits that can be objectively calculated, the evaluation scores are used to calculate other social benefits that can only be evaluated subjectively. In this study, we tested our method on the sponge city facilities on the Tianjin University's Peiyang Park Campus. The results showed that the social benefits of sponge city facilities, including rainwater garden and wetland, recessed greenspace, vegetation buffer zone and permeable pavement, were 1.0-15.5 RMB/(m²·a), grass ditch was 2.97 RMB/(m·a). Among these facilities, rainwater wetland ranking the highest and recessed greenspace the lowest. For the Peiyang Park Campus, the total social benefits of sponge city facilities, according to the total construction area, is about 2.328 million RMB per year.

Key words: sponge city, social benefits, subjective assessment, objective evaluation, monetary value