Assessment of groundwater recharge in urban areas
In the city of Barcelona and the townships situated in the deltaic area of the Besòs River, groundwater is recognized as an aspect of urban water cycle management. There is groundwater seepage into infrastructure and buildings that in turn require drainage, a part of which is introduced into sewage...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/96291 |
| Acceso en línea: | https://hdl.handle.net/2117/96291 https://dx.doi.org/10.5821/dissertation-2117-96291 |
| Access Level: | acceso abierto |
| Palabra clave: | Aigua -- Química Aigües subterrànies Àrees temàtiques de la UPC::Enginyeria civil |
| Sumario: | In the city of Barcelona and the townships situated in the deltaic area of the Besòs River, groundwater is recognized as an aspect of urban water cycle management. There is groundwater seepage into infrastructure and buildings that in turn require drainage, a part of which is introduced into sewage systems. Sensitized by this issue, city councils have had hydrologic studies carried out to analyze its causes and to plan alternative ways of using these resources while reducing treatment costs, and minimizing the impacts that groundwater and drainage have on infrastructure and vice versa. Based on these studies, and starting in 2000 some of this has been used for municipal practices (garden irrigation and street cleaning). Subsequently, due to a drought that affected the region between April 2007 and January 2009, the government entity in charge of Catalonian water sources (ACA) aims to get greater use out of urban groundwater in this area. This requires a comprehensive understanding of the hydrogeological characteristics of the environment, the availability and quality of these resources, and the appropriate tools for proper assessment and management. This has been the framework of this thesis. Recharge is one of the most relevant aspects of water balance in aquifer systems in urban areas. Urbanization of the area alters the natural hydrological cycle and direct water recharge into aquifers by infiltration is reduced. In turn, evapotranspiration decreases and new recharge sources appear. This thesis presents, first, a methodology that allows for the quantifying of variability in space and time of the recharge in urban areas. Potential sources of recharge that have been considered are: (1) direct infiltration from rain and urban runoff, (2) losses from the sewer system, (3) losses from the water supply system, and (4) other specific sources of recharge (i.e. river infiltration, seawater intrusion, etc.). Recharge calculations are initially performed by applying analytical equations under various hypotheses. These results have been evaluated in the hydrogeological context through a numerical model of flow and transport in the whole area of study. Secondly, detection of some substances in groundwater has been analyzed. These substances and their degradation products, potentially present in recharging sources associated with urban environments, belong to so-called 'emerging organic pollutants'. These are organic chemical compounds used in the formulation of daily products for widespread use, such as pharmaceuticals, emulsions, care products and personal hygiene, household and industrial detergents, plastics, pesticides and herbicides, among others. There is relatively little known about these substances¿ introduction to and evolution in the aquifers. Organic pollutants whose evolution and behavior in the groundwater is better understood can be degraded by natural processes controlled mainly by oxidation-reduction reactions. Even in situ stimulation techniques have been developed which are able to accelerate these processes of natural attenuation of contaminated environments. A methodology is presented using an end-member mixing analysis (EMMA) and MIX to compute mixing ratios and identify hydrochemical reactions. The methodology consists of (1) identifying the potential sources of recharge, (2) characterising recharge sources and mixed water samples using hydrogeochemistry, (3) selecting chemical species to be used in the analysis and (4) calculating mixing ratios and when departures from the mixing line exist, identifying hidrochemical processes. This approach has been applied in a pilot area in the Besòs River Delta. |
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