Optimal design of urban sewer systems
- Autores: Juan Saldarriaga
- Directores de la Tesis: Pedro Luis Iglesias Rey (dir. tes.)
- Lectura: En la Universitat Politècnica de València ( España ) en 2024
- Idioma: inglés
- Tribunal Calificador de la Tesis: Dragan A. Savic (presid.), Francisco Javier Martínez Solano (secret.), Orazio Giustolisi (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería del Agua y Medioambiental por la Universitat Politècnica de València
- Menciones:
- Internacional
- Calificación: Sobresaliente Cum Laude
- Materias:
- Enlaces
- Tesis en acceso abierto en: RiuNet
- Resumen
Urban drainage systems, also known as sewer systems, have the purpose of draining both rainwater and wastewater from our cities. These systems are one of the different civil infrastructures that allow the proper functioning of modern cities. Stormwater systems are responsible for moving the rainwater that falls in the city safely and in a reasonable time, without allowing flooding, to the natural receiving bodies located downstream. On the other hand, wastewater systems are designed to collect sewage from domestic, industrial, and commercial sources and transport it safely to a wastewater treatment plant before sending it definitively to a receiving body or to a reuse system, if available. Both types of sewer systems, but particularly wastewater systems, have an extensive impact on public health with implications for the viability of a city.
The existing urban drainage infrastructure presents new challenges to urban hydraulic engineering. On the one hand, stormwater systems, in addition to being subjected to aging problems with deterioration of materials and soil settlement, are facing serious problems caused by climate change. In many cities this phenomenon is implying radical changes in urban hydrology; intensities and frequencies of rainfall events are increasing so that the existing systems, which were designed for different hydrological conditions, are running out of capacity, increasing the frequency of urban flooding with its consequences on safety and human health. On the other hand, wastewater systems also present engineering challenges due to problems of increasing population density in cities, lack of resilience to external events such as earthquakes, and water quality problems in receiving waters within urban areas, in groundwater, and natural water currents. These systems are also affected by the deterioration of materials and soil settlement problems.
Now, a different problem is the non-existence of urban drainage systems in many cities of the world, particularly in those located in developing countries. In the vast majority of these cases, the lack of sewers is caused by the high cost of this infrastructure, making its construction unfeasible for local governments. In addition, the growth of urban areas in these countries exacerbates the problem. Not only does the necessary infrastructure become larger and more complex, but the public health problems associated with the lack of environmental sanitation increase. Therefore, the challenge for modern urban water engineering is to achieve greater access to this essential service. One way to solve this is by lowering the construction and operating costs of drainage systems, making them financially viable while maintaining their resilience and safety. This will help meet Sustainable Development Goal No. 6 Clean Water and Sanitation.
Considering the above, the aim of this thesis was to propose a methodology that would lead to the minimum cost design of conventional sewer networks, maintaining their resilience and ease of operation, while complying with all the hydraulic, constructive, and operational restrictions that, according to international empirical experience, are appropriate to guarantee a correct behavior of the drainage system.
The optimized design of a sewer network is composed of two mutually dependent parts: the layout selection and the hydraulic design. In this thesis, the two problems were solved separately from a mathematical point of view, maintaining their interdependence through an iterative process. For a given layout, which could be random for a first iteration, the hydraulic design problem was solved as a shortest path problem using the Bellman-Ford algorithm that guarantees the global minimum cost for that layout. The problem is model as a directed graph in which the nodes represent the combination of diameters and invert elevations at every manhole, and the arcs represent the diameter and upstream and downstream invert elevation of a specific pi
