Abstract
Urbanization in Mediterranean climate zones intensifies stormwater runoff challenges, including flooding, water quality degradation, and groundwater depletion. Decentralized green infrastructure (GI) such as permeable pavements and rain gardens offers sustainable solutions, but their economic viability remains underexplored in these regions. This study conducts a comprehensive cost-benefit analysis (CBA) of permeable pavements and rain gardens for decentralized stormwater management in a representative Mediterranean city (Valencia, Spain). Using life-cycle costing and benefit transfer methods, we evaluate capital and maintenance costs against benefits including flood damage reduction, water quality improvement, groundwater recharge, heat island mitigation, and carbon sequestration. Over a 30-year analysis period, results indicate net present values (NPV) of €2.1 million for permeable pavements and €1.8 million for rain gardens per hectare of treated catchment, with benefit-cost ratios of 2.4 and 2.1, respectively. Sensitivity analyses confirm robustness under varying discount rates and benefit valuations. The findings demonstrate that both GI types are economically favorable for Mediterranean climates, with permeable pavements offering superior stormwater volume reduction and rain gardens providing enhanced water quality benefits. Policy recommendations include targeted subsidies to promote GI adoption in water-scarce regions.
Keywords
green infrastructure, cost-benefit analysis, permeable pavements, rain gardens, stormwater management, Mediterranean climate, decentralized systems, urban hydrology