A multi-criteria decision analysis framework for sustainable rainwater harvesting systems in Ibadan, Nigeria
Siddall, Omolara Oyewumi
PublisherUniversity of Wolverhampton
MetadataShow full item record
The approach to water management worldwide is currently in transition, with a shift fromcentralised infrastructures to greater consideration of decentralised technologies, such asrainwater harvesting (R WH). Initiated by recognition of drivers, including water demand,increasing risk of ground-water pollution and flooding, the value of R WH is filtering acrossthe academic-policy boundary. However, in Nigeria, implementation of sustainable watermanagement (SWM), such as R WH systems, is inefficient social, environmental andtechnical barriers, concerns and knowledge gaps exist, which currently restrict its widespreadutilisation. This inefficiency contributes to water scarcity, water-borne diseases, and loss oflives and property due to flooding. Meanwhile, several RWH technologies have beendeveloped to improve SWM through both demand and storm-water management. Suchtechnologies involve the use of storage tanks, surface water reservoirs and ground-waterrecharge pits as storage systems.A framework was developed to assess the significance and extent of water managementproblems, match the problems with existing RWH-based solutions and develop a robustready-to-use multi-criteria analysis tool that can quantify the costs and benefits ofimplementing several RWH-based storage systems. The methodology adopted was the mixedmethod approach, involving a detailed literature review, followed by a questionnaire surveyof 1067 household respondents, 135 Nigerian Architects and Civil Engineers and focus groupdiscussion with Stakeholders. A total of 1042 sets of data were collected through aquestionnaire survey and analysed using SPSS, Excel and selected statistical methods toderive weightings of the attributes for the tool. Following this, three case studies wereselected to collect data for hydrological modelling using the RainCycle model. From theresults it is found that the most important barrier constraining sustainable R WH regime inIbadan was obsolete and insufficient operational equipment, followed by poor renumerationof water corporation staff and misuse of available funds. In addition, the measure ofimportance of storage capacity was established, with the highest score of 4.5 which reflectsthe general inadequacy of storage as a major barrier to the adoption of RWH as a sustainablewater management method. Further, respondents' major health hazards associated withdrinking contaminated water was established. A larger proportion (61.2%) of respondentschose prevalence of typhoid fever; some have a prevalence of diarrhea (19.4%), while few ofrespondents ' water sources is free from water-borne diseases (2 .3%).The tool developed is an integrated platform of related evaluation techniques, includingWhole Life Cycle Cost Analysis and Multi-Attribute Utility Theory. The tool uses dataincluding cost and quantities of materials for building a RWH storage system and quantifiesthe cost and benefits of alternative RWH-based systems that can improve projectmanagement. This tool is novel, given its integration of the analytical techniques mentionedabove and application for selecting the most appropriate RWH-based SWM systems. Theimplementation of the tool is envisaged to provide an objective platform for thequantification of the costs and benefits of RWH-based systems prior to implementation.