Optimization of drinking water distribution networks: Computer-based methods and constructal design P. Bieupoude a,b,⇑ , Y. Azoumah a , P. Neveu b a LESEE-2iE, Laboratoire Energie Solaire et Economie d’Energie, Institut International d’Ingénierie de l’Eau et de l’Environnement, 01 BP 594 Ouagadougou 01, Burkina Faso b PROMES-CNRS UPR 8521, Laboratoire Procédés Matériaux et Energie Solaire, Université de Perpignan, Rambla de la thermodynamique, Tecnosud, 66100 Perpignan cedex, France article info Article history: Received 25 February 2011 Received in revised form 21 February 2012 Accepted 21 March 2012 Available online 4 May 2012 Keywords: Drinking water Pipe networks design Optimization Computer-based methods Urban systems Constructal theory abstract A well-known application of water engineering is drinking water distribution through pipe networks in urban and rural areas. The present work addresses this issue with a specific focus on the network design. First, the paper presents a brief review of computer-based design methods and shows that a significant number of efforts have been pursued. Secondly, it proposes the approach of geometric analysis of the dis- tribution networks as complementary points of the former optimization methods. Finally, an original illustrative application is proposed. The geometric and multi-scale optimization known as the constructal design is used to analytically optimize T-shaped network architectures subject to an operational water quality constraint. This illustrative application leads to the determination of an optimal geometry of the network that minimizes head losses (factor of pumping energy). Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The optimal design and management of urban networks is an interdisciplinary challenge touching environment, water, electric- ity and urban planning as noticed in many works (Christodoulou, Deligianni, Aslani, & Agathokleous, 2009; Ducrot, Le Page, Bommel, & Kuper, 2004; Kizito, Mutikanga, Ngirane-Katashaya, & Thunvik, 2009) and requires maximal computing skills (Akiba, 1982; Evatt, 1984; Ignizio, 1980; Keirstead & Shah, 2011; Miller, Hunt, Abra- ham, & Salvini, 2004; Moore & Kim, 1995). During last decades, numbers of researchers have put their interest on them in various aspects. This interest is understandable in many senses. First, these systems are huge economic infrastructures and their optimization is strongly needed in developing countries and even in western countries. Secondly, because of their very high importance, they re- quire reliable design techniques for authorities to be assisted in investment decision making. According to literature, many progresses have been made in the study of water distribution systems (WDSs) and today, they are capable of serving rural and urban communities reliably, effi- ciently, and safely, both now and in the future (Chase, Savic, & Wal- ski, 2001). Though the complexity and the size of WDS vary dramatically (from African rural areas to overpopulated cities in western countries), they have the same basic function of delivering water from sources or treatment facilities to customers (Chase et al., 2001). Technologies and researches on these systems have considerably evolved over time and through civilizations (Babbitt & Doland, 1931; Haestad methods, 1999). Today water distribution networks (WDNs) are the most known, the most well-tried and the most used systems worldwide (Chase et al., 2001) in providing water to populations. Being used for hot or cold water distribution, either for drinking water or agricultural irrigation, WDN as flow systems, are charac- terized by mechanical losses (head losses) that are factor pumping energy (Bejan & Lorente, 2007; Izquierdo, Montalvo, Pérez, & Her- rera, 2008; Tondeur & Luo, 2004), chemical and biochemical reac- tions that refer to water quality management questions (Kerneïs, Nakache, Deguin, & Feinberg, 1995). To have a thorough understanding of these phenomena, in order to optimize and well manage WDN technically, economically and socially, an important amount of researches has been pursued dur- ing the last decades on the design (optimization and modeling). Various design methods have been developed, focusing on mini- mum cost objective (Alperovits & Shamir, 1977; Simpson, Dandy, & Murphy, 1994), on reliability aspects (Bai, Pei-jun Yang, & Song, 2007; Chiplunkar, Mehndiratta, & Khanna, 1990; Fujiwara & Khang, 1990; Todini, 2000; Wechsatol, Lorente, & Bejan, 2004), and on water quality (Bieupoude, 2011; Boulos, Rossman, & Vasconcelos, 1994) which is a critical environmental question 0198-9715/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.compenvurbsys.2012.03.007 ⇑ Corresponding author at: LESEE-2iE, Laboratoire Energie Solaire et Economie d’Energie, Institut International d’Ingénierie de l’Eau et de l’Environnement, 01 BP 594 Ouagadougou 01, Burkina Faso. Tel.: +226 50 49 28 64; fax: +226 50 49 28 01. E-mail address: pascal.bieupoude@2ie-edu.org (P. Bieupoude). Computers, Environment and Urban Systems 36 (2012) 434–444 Contents lists available at SciVerse ScienceDirect Computers, Environment and Urban Systems journal homepage: www.elsevier.com/locate/compenvurbsys