یک مدل چارچوبی TOPSIS فازی برای رتبه بندی تامین آب پایدار A Fuzzy TOPSIS model Framework for Ranking Sustainable Water Supply Alternatives

1 Introduction Water is recognized as a commodity fundamental to health but scarce, and achieving adequate water delivery to the public can be an overwhelming task anywhere in the world, especially when characterized by increasing population, urbanization and industrialization, as in developing countries especially. Yoe 2002, described associated problems with urban water supplies in achieving sustainability as a wicked task, since no answer can exactly be termed right, hence a compromise situation or solution is usually opted for. This is because the problem of uncertainty and human rationality is encapsulated in all wicked problems (Khisty and Mohammadi 2001). The renaissance to non-conventional or alternative water supply options are recognized as ecofriendly and sustainable, and their integration globally such as, reclaimed water, grey water, black water, rain water harvesting (RWH), desalination, borehole water, water importation, into water supply schemes is intrinsic. Hence exploring these pathways usually borders on the ‘soft path’ approach which suggest a combination of supply options that is usually not technology driven and viable, especially in new urban areas where no central infrastructure pre-exist. These systems undoubtedly can limit demand for fresh water resources, diversify water source, boost reliability of access to resource, and minimize volume of waste water discharged into the environment. These supply options over time, have undergone and undertaken diverse research patterns (Ukpong and Agunwamba 2012; Mara 2004; Dolnicar 2009; Contard and Gouvello 2013; Chowdhury and Rahman 2008; Kanakoudis et al. 2011; Angelakis and Gikas 2014). However the numerous difficulty, rigor, variability of criteria, and uncertainty encountered/ interplay during the decision making process for the best or appropriate supply option endears our employ of multi-criteria decision making approach (MCDA), a decision support tool in overcoming these shortcomings. Fuzzy TOPSIS (technique for order preference by similarity to ideal solution), is a MCDA approach, employed in this study for the first time in alternative water supply option, with consideration of the socio-cultural input in its analysis, a fundamental aspect of sustainability, to evaluate the preferred water supply alternative in the eastern Niger delta of Nigeria, based on economic, technical, environmental and socio-cultural criteria. This region is endowed with water resources including over 2200 mm of annual rainfall, but yet faced with gross inadequacies in water supply, evidenced by the proliferation of water vendors, a clear indication that supply are below acceptable levels. This condition is prevalent in most other parts of the country (Sule et al. 2010). (Okoli et al. 2010) identified major alternative sources of water in the region to be boreholes, wells and ground water.