Modelo de evaluación de las huellas hídrica y de carbono en la renovación del espacio urbano sensible al agua

Abstract

The main objective of this research is to develop a model for the assessment of the water and carbon footprints of infrastructures related to the urban water cycle at different scales of intervention and complexity. The results of the environmental impacts derived from the choice of the materials incorporated into the project are shown from a double perspective: that of slowing down global warming through the calculation of the carbon footprint and that of reducing the consumption of limited resources through the water footprint. Likewise, the calculation of the water footprint developed by Hoekstra and Chapagain, generally applied to the agricultural sector, is also adapted to the estimation of the water balance of urban systems with the presence of green areas. The methodology incorporates local biophysical, climatic and temporal data, together with the specific data of the project to calculate the water consumption in the re-naturalization of urban areas, which has been little explored until now. A measurable indicator of economic and environmental impacts, applicable to the construction sector, is proposed. In this way, the impact of an urban space renovation project is estimated by applying water-sensitive urban design techniques and by evaluating the nature of the materials to be incorporated in the work, the hydrological design of the project, its suitability for the urban environment and its capacity to adapt to future scenarios, evaluating in parallel the direct and indirect water and carbon footprint. The thesis is organized as follows: the concepts, methodologies and tools that have been used as a starting point of the research are presented, as well as a review of works that have addressed similar issues. Second, the objectives are described to understand the elements from which the analysis is made. Thirdly, the methodology of the investigation is presented, i. e. the process followed during the course of the investigation. Fourth, a model is defined for the calculation of water and carbon footprint indicators in infrastructure related to the supply and treatment of domestic water. Fifth, through case studies the calculation model is applied, the results are shown and the sensitivity of the calculation is analysed. Finally, a discussion and conclusions derived both from the interpretation of the data obtained and from the research process are presented. In the analysis of the results, it is worth highlighting how the case study in which water-sensitive urban design technologies are incorporated, presents higher water and carbon footprint values (increased by 2. 6 times and 1. 8 times, respectively), in relation to the materials and execution of the works than a project in which these design technologies are not applied. Instead, savings of up to 65% per year in water resources are achieved and the capacity to capture carbon produced during the use and maintenance phases is tripled. This balance means that, at the end of the life cycle, it accumulates 37% less water footprint and improves 4 times the carbon footprint.