Dr.-Ing. Amin Ebrahim Bakhshipour war von 2016 bis 2020 Promotionsstudent im Rahmen des dreijährigen internationalen Doktorand*innenprogramms „Environment Water“ (ENWAT) an der Universität Stuttgart. Seine herausragende Dissertation zum Thema "Optimizing hybrid decentralized systems for sustainable urban drainage infrastructures planning"wurde von Prof. Dr.-Ing. Wolfgang Nowak vom Institut für Wasser- und Umweltsystemmodellierung betreut. Die Arbeit befasst sich mit dem Entwurf und der Optimierung von Stadtentwässerungssystemen. Dies beinhaltet technische, wirtschaftliche, soziale und ökologische Herausforderungen rund um städtische Wassersysteme in Industrie- und in Entwicklungsländern. In seiner Arbeit werden praktische Lösungen für aktuelle und künftige Bewässerungsprobleme vorgeschlagen. Sie stellt einen effizienten, breiten und grundlegenden Versuch dar, die Kluft zwischen akademischen Untersuchungen und realen Bedürfnissen in der Industrie zu überbrücken.
Die Arbeit ist umfassend und deckt verschiedene Aspekte der Gestaltung und des Managements der Stadtentwässerung ab. Sie beschäftigt sich mit hydrologischen und hydraulischen Entwurfskriterien, mit mathematischer Programmierung und Optimierung und erörtert den Umgang mit verschiedenen Zielen und Randbedingungen für die Berücksichtigung von sowohl ökologischen und als auch ergebnisorientierten Kriterien (Zuverlässigkeit, Widerstandsfähigkeit und Umweltverträglichkeit) bei der Planung.
Zusammenfassung in englischer Sprache
The main objective of my thesis was to assist sustainable UDSs planning. The general aim was to develop algorithms, methods and tools that aid in the mathematical interpretation of the trending concept of decentralization. The contributions made culminate in a generic Multi-Criteria Decision-Making platform to design modern urban drainage systems with the application to stormwater management systems.
Firstly, a layout generator, namely the hanging gardens algorithm, was developed to generate all possible (de)centralized urban drainage systems for both flat and steep terrains. To form a simulation-optimization framework, an optimization engine is coupled with the proposed layout generator algorithm and with hydraulic simulation software (SWMM). The model was then applied against a real case study, a section of the city of Ahvaz. The results suggested that structural decentralization can significantly reduce the construction costs, pipe sizes and invert depths in comparison with the centralized layout; however, after a particular DC (optimal DC), more decentralization might lead to a diseconomy of scale. The optimal DC totally depends on the case study specifications and problem setup. Besides, results demonstrated that structural decentralization could increase the functional resilience in the system.
Second, a simulation-optimization framework is developed to optimize UDSs considering hybrid green-blue-gray infrastructures (HGBGIs) with different DC. The results showed that GBIs could significantly diminish the LCC of more centralized layouts. However, for the more decentralized layouts, the hybrid solutions were marginally more expensive than traditional solutions. Therefore, it can be understood that the GBIs have more impact on the more centralized network of pipes. The results also confirmed the poor functional resilience of hybrid green-blue-gray alterna-tives in comparison with traditional gray networks of pipes in facing severe rain-storms.
Finally, a MCDM platform for optimal planning of hybrid urban drainage infrastructures is presented. It can consider different centralized or decentralized strategies and encourages decision-maker engagement in all phases of the optimization to increase the buy-in to the optimization results. It has been manifested that many practical or technical concerns that usually cannot be re-garded in general optimization frameworks but are crucial for decision-makers can be man-aged within the proposed framework to (1) decrease the conflicts, (2) enrich the results of optimization with valuable experience of practitioners, and (3) increase the buy-in to the op-timization results. The results indicated that a pyramidal structure could explain the relationship between reliability, resilience and sustainability, which means resilience can be built upon reliability and sustainability can be built upon resilience. However, the life cycle costs exponentially increases in all explored scenarios, with an increase in the total sustainability. The results demonstrate the significant role of the layout configuration and degree of centralization on the optimum HGBGI.