Sustainable Urban Water Management System in Palomino, Colombia

Abstract

This master thesis is an attempt to contribute to the understanding of urban water systems through the use of the urban metabolism (UM) framework. By developing steady-state models with STAN, a software used for material flow analysis (MFA), the urban water flows are quantified and analyzed as they enter the system boundary and are transformed by anthropogenic processes. Such a model has been applied to a specific urban water system in the town of Palomino, Colombia, to research the main barriers and opportunities for a sustainable urban water system. The area under study corresponds to a system boundary of 4.83 km2, and the analysis was performed for the year 2015. A detailed examination of Palomino’s water system was established based on primary data collection through survey processes, mapping, and semi-structured interviews. Based on the qualitative and quantitative characteristics of the water system, a conceptual urban water metabolism (UWM) model was created to identify the critical flows of the water system through a monthly (31-day) analysis based on fourteen scenarios, each including four variables: Touristic season, Hours without electricity per month, Percentage of water losses due to pipelines leaks, and Percentage of water losses due to user’s behavior. Subsequently, a definition of sustainable urban water management system (SUWMS) was generated based on a literature review and an industrial ecology perspective, wherein the system is analyzed using a holistic, system thinking approach. Guided by the SUWMS definition and the local conditions of Palomino’s urban water system, various sustainable water technologies and initiatives are introduced as a set of potential solutions to shift the current water system towards a SUWMS. Finally, the potential of the sustainable water supply technique of rainwater harvesting to influence the current UWM of Palomino was assessed by identifying changes in the UWM for three key years: 1969, a year of extreme rainfall; 1997, a year of El Niño phenomenon characterized by extreme drought, and 1987, a year of ‘standard’ precipitation. The analysis was based on a critical scenario with the highest water losses and water demand. The rainwater harvesting collection capacity was determined by a storage capacity of 2000 L per household, while taking into account water consumption (water demand) per household between rain events on a monthly basis analysis. This condition implied that, even though the analysis was based on steady-state modeling, a semi-dynamic analysis was performed based on the variations of the stored rainwater volume (∆V) between the time intervals determined by the rain events per month (∆t). One of the most significant results is that the applied methodology proved to be successful in terms of understanding water systems—not by the traditional approach of modeling based on average values, but rather by using scenarios that explain the variations and dynamics in the water systems. The changes in the UWM are then understood by the use of signals (e.g. positive and negative values) to determine the metabolic changes and water needs of the urban systems. This methodology could be applied in a larger context, especially in developing countries that have limited data to undertake a statistical analysis.