Sustainability Evaluation of Rainwater Harvesting-Based Flood Risk Management Strategies: A Multilevel Decision-Making Framework for Arid Environments

Arid environmental regions have faced disastrous floods as a result of global climate change in the recent past, particularly the Gulf countries. For the municipalities in urban areas, flood risk management (FRM) by means of rainwater harvesting (RWH) methods is a daunting task due to multiple influencing variables, such as hydraulic capacity of drainage infrastructure, effectiveness of RWH methods, flood frequencies, and associated consequences in different land uses. The solution of this integration problem may lead to development of several possible scenarios, e.g. improved drainage infrastructure for 10-year flood, existing drainage infrastructure with green roofs for 25-year flood, etc., which have their exclusive techno-economic constraints. A multilevel decision-making framework is developed to prioritize sustainable FRM scenarios for different land uses. Firstly, screening was carried out using checklist matrix to identify potential scenarios out of 105 possible combinations. Subsequently, risk analysis is performed to identify the scenarios with an acceptable risk using fuzzy failure mode and effect analysis (fuzzy-FMEA). Finally, shortlisted scenarios are evaluated for their overall environmental, technical, and economic sustainability by means of fuzzy-based multicriteria decision-making. The implementation of the framework on Buraydah (Qassim, Saudi Arabia) revealed that ‘existing drainage system supported with green roofs and retention ponds’ is the most sustainable FRM scenario (to safely route 100-year flood) for mixed development and residential neighbourhoods, while ‘improved drainage system with retention ponds’ comes out to be the most sustainable choice for central districts.