Comparative life cycle assessment and life cycle cost analysis of centralized and decentralized urban drainage systems: A case study in Zhujiang New Town, Guangzhou, China

Abstract

Rapid urbanization and global climate change are increasing the vulnerability of cities to urban flooding, thereby posing significant challenges to the design and implementation of urban drainage systems (UDS). Traditional centralized UDS have been found ineffective in mitigating the uncertainty of future flood risks. Consequently, the need to explore resilient alternatives, such as decentralized UDS, has gained importance. Of particular interest is the coupled approach of grey infrastructure (GREI) and low-impact development (LID), which merges the drainage capabilities of GREI with the versatility and sustainability of distributed green infrastructure. However, there are limited studies assessing the environmental and economic impacts of both centralized and decentralized LID-GREI UDS using integrated Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) methods. This study, using Zhujiang New Town, Guangzhou, China, as a case study, found that decentralized UDS outperformed centralized UDS from both environmental and economic perspectives, mainly due to smaller pipeline scale and lower maintenance frequency. Furthermore, though the LID-GREI UDS showcased more substantial environmental impacts and higher economic costs compared to GREI UDS, the hydrological benefits obtained from LID operation can counteract part of these environmental impacts. In a unique perspective, this study considers the payback periods for centralized and decentralized LID-GREI UDS, estimating them to be 70 and 55 years respectively, when taking economic implications and hydrologic benefits into an overall consideration. Overall, the findings underscore that the LID-GREI UDS, particularly the decentralized LID-GREI, presents a more sustainable and cost-effective strategy for mitigating pluvial flooding compared to GREI UDS. This study provides comprehensive insights into effective and cost-efficient strategies for alleviating urban flooding vulnerabilities through UDS design and implementation.