Anàlisi multidisciplinària de l'estat de l'aigua a la depressió de la Selva

Consultable des del TDXA portada: Institut de Ciència i Tecnologia AmbientalsTítol obtingut de la portada digitalitzadaLa gestió dels recursos hídrics ha esdevingut un element determinant en el desenvolupament territorial, en el que cal preservar el subministrament pels diferents usos antròpics, tradicionals o emergents, i alhora mantenir la qualitat ambiental del medi. El nivell assolit de qualitat ambiental, definit per l'estat hidrològic dels recursos superficials i subterranis i l'estat dels ecosistemes associats, és l'indicador final de l'eficiència en la gestió i la seva sostenibilitat. En aquest context s'ha desenvolupat aquesta tesi doctoral, titulada "Anàlisi multidisciplinària de l'estat de l'aigua a la depressió de la Selva", amb la finalitat d'assolir un coneixement exhaustiu de l'estat en què es troba l'aigua en aquesta zona, a través de la integració de dades de tipus hidrogeològic, hidroquímic, biològic i social, i proposar criteris per a una gestió apropiada de l'aigua. En aquest sentit, el contingut de la tesi comprèn un estudi hidrogeològic de la depressió de la Selva amb els objectius de caracteritzar la hidrodinàmica general del sistema, identificar i avaluar els sistemes de flux i finalment, determinar la possibilitat, en quantitat i qualitat, de satisfer la demanda actual a partir dels recursos subterranis existents. Seguidament, s'ha realitzat un estudi de la qualitat ecològica dels cursos fluvials d'aquesta zona identificant les pressions i els impactes que els afecten. Finalment, s'ha realitzat un exercici de participació pública per a definir diferents escenaris de futur en la gestió de l'aigua a la depressió, i per a identificar-ne les fortaleses i debilitats al comparar-los amb la disponibilitat de recursos hídrics descrita en els apartats anteriors. A partir d'aquests estudis s'han pogut destacar, d'una banda, aspectes positius en la hidrologia local, com el fet que, els recursos dels nivells aqüífers profunds permeten cobrir les necessitats dels usos actuals, sense afectar negativament el sistema. Els resultats d'aquesta tesi han permès definir els sistemes de flux i la seva hidrodinàmica a la depressió de la Selva, els quals recolzen la conclusió anterior. D'altra banda però, s'han identificat aspectes negatius relacionats amb la qualitat de l'aigua. En primer lloc, hi ha les deficiències de qualitat de tipus natural que presenten les aigües dels pous situats en els punts propers a les fractures principals de la depressió. Si bé els nivells aqüífers que exploten aquests pous són els que presenten millors recuperacions, les concentracions de fluorurs, i en alguns casos d'arsènic, poden suposar limitacions en l'ús de les seves aigües, i en aquest sentit, del volum total d'aigua disponible. En segon lloc, hi ha els problemes de qualitat d'origen antròpic, que evidencien mancances en la gestió de l'aigua. D'una banda, el fet que els aqüífers presentin problemes de contaminació per nitrats limita la disponibilitat d'aigua per a alguns usos, com l'abastament domèstic. Dins aquest grup també destaquen els impactes detectats en els cursos fluvials causats per una sobreexplotació dels aqüífers al·luvials i l'abocament d'aigües residuals (tractades o no). Ambdós casos suggereixen que la gestió portada a terme fins a l'actualitat, en relació a aquests aspectes, no ha estat la més apropiada. Així si, tal i com es destaca en l'exercici de participació pública realitzat, es preveu un creixement de l'ús del territori, del nombre d'habitants de la zona, i dels usos industrials, caldrà plantejar-se alternatives de gestió de l'aigua per assolir un nivell adient de sostenibilitat, tant pel que respecta a l'abastament com en la depuració, atès que aquestes noves activitats suposaran noves pressions sobre el territori, podent-se agreujar encara més els problemes identificats.Water management has become a determinant element for land planning. This management has to deal with the preservation of traditional and new water uses, as well as with environmental protection. In this context, environmental quality levels, defined by the hydrological surface and ground water status and the ecological status of the ecosystems associated, are indicators of water management and sustainability efficiency. In this context, the main aim of this dissertation is to achieve a complete knowledge of the «status of the water» in the Selva basin, in NE Catalonia, through the study of its water resources availability, its hydrochemical quality, and to check whether water management is conducted under sustainability principles. To attain these goals, this work presents a classical hydrogeological study of the area, an evaluation of the ecological status of freshwater ecosystems and, finally, an appraisal of future scenarios of water management and its associated uncertainties. First of all, the hydrogeological study has determined the main hydrogeological units of the area and their hydrodynamic relationships, the main recharge areas, and the existing flow systems. This study shows that, even though ground water recharge seems to satisfy present water extraction in the Selva basin, its low quality jeopardizes its use for human consumption as well as for some industrial applications. The study of the ecological status of streams in the Selva basin also considers surface-ground water interaction and human impacts upon the riparian area. The best ecological status is found on the uppermost stream reaches of this area, and the value of the indicators diminishes as riparian areas and water quality worsen downstream. Ground water exploitation, treated and non-treated waste water dumping and hydromorphological alterations of stream channels are the main impacts observed in the area. The last part of this dissertation deals with the interviews to different social actors involved in water management or its use in the Selva basin. In each interview, opinions on possible future scenarios were sought, as a means to identify opportunities, deficiencies and conflicts in water resources management. Those interviews show that the most demanding water-consuming activities will increase in this area in a near future, raising therefore the total water demand. However, these agents also consider that water uses and distribution will improve, which implies a most efficient use of present water resources. Nonetheless, this represents a paradox since despite water savings, the increase of water demand will represent a larger stress on the hydrological system. Based on these data and knowledge, we shall question whether a sustainable management is now taking place in the study area and which are the short-term prospects. Impacts related to human activities such as high nitrate concentrations related to excess pig manure application as fertilizer, or overexploitation of the shallow alluvial aquifer, show significant deficiencies in the water resources management in the Selva basin, which keeps it far from sustainability. Future development plans might increase the pressures of human needs upon water resources, even though better efficiency on water use and distribution can be achieved. Therefore, alternative management strategies must be defined for these areas, especially on ground water exploitation and its quality to fulfill potential water demand and prevent further deterioration of the hydrological and ecological systems

L’ús de dades reals per a la realització de pràctiques basades en l'aprenentatge cooperatiu (Pràctiques d'hidrogeologia )

Pràctiques d’hidrogeologia realitzades per Anna Menció i Domingo, dins aquesta assignatura que forma part del mòdul obligatori de Bases científiques del medi natural del segon curs del grau en Ciències Ambientals

L’ús de dades reals per a la realització de pràctiques basades en l'aprenentatge cooperatiu (Pràcitques d'hidrogeologia )

Pràctiques d’hidrogeologia realitzades per Anna Menció i Domingo, dins aquesta assignatura que forma part del mòdul obligatori de Bases científiques del medi natural del segon curs del grau en Ciències Ambientals

Determinación de sistemas de flujo regionales y locales en las depresiones tectónicas del Baix Empordà y La Selva (NE de España) en base a datos hidroquímicos e isotópicos

The Baix Empordà-Selva-Gavarres aquifer system is related to the fault set that created the tectonic basins of Empordà and Selva areas (NE Spain) during the Neogene. In this work, we describe groundwater hydrogeological, hydrochemical and isotopical (3H, δD, δ18O, and the 87Sr/86Sr ratio) characteristics of this system in order to illustrate the relevance of fault zones in groundwater flow-paths and the recharge. In that way, we identify two flow systems, with distinct hydrochemistry and isotopes. A local flow system originates at the Gavarres Range, and it flows towards the basins of the Baix Empordà and Selva, with an approximate residence time of 20 years. Additionally, a regional flow system has only been identified in the Selva basin. This one is related to the main fault zones, as preferential flow paths. Its recharge is located in mountain ranges with higher altitudes, namely the Transversal and Guilleries Ranges, with residence times larger than 50 years. Isotopical data has also shown mixing processes between both flow systems and rainfall recharge while multivariate statistical analysis of principal components has shown the main processes that control hydrochemistry of each flow system

Hydrochemical processes in the alluvial aquifer of the Gwydir River (northern New South Wales, Australia)

The hydrochemistry of the Narrabri Formation, the shallow aquifer system of the alluvial fan of the Gwydir River (NSW, Australia), is analyzed to better understand the hydrogeological processes involved in aquifer recharge, and to set up future management options that preserve the quantity and quality of water resources. Results show that groundwater hydrochemistry in this alluvial aquifer is mainly controlled by silicate weathering and cation exchange. However, salt remobilization in specific sedimentary layers within this alluvial fan deposit may locally increase groundwater salinity. Mixing between stream leakage and aquifer groundwater controls the hydrochemistry of water resources and produces a decrease in its salinity, which is beneficial for human usesThis study was conducted during the stay of the first author at Macquarie University as a visitor researcher. Its content is related to the goals of the Spanish Government research project CGL-2011-29975-C04-0

Diagnosi ambiental de la riera de Santa Coloma entre Santa Coloma de Farners i Riudarenes

A l'actualitat trobem nombrosos sistemes aquàtics alterats per diferents efectes d'origen antropogènic. Per tal d'evitar i/o disminuir aquests efectes va sorgir la Directiva Marc de l'Aigua (2000/60/CE) essent aquest un dels seus objectius. Aquest article descriu el funcionament hidrogeològic i l'estat ecològic de la riera de Santa Coloma, afluent de la Tordera (NE Catalunya), des de pràcticament el seu inici a Santa Coloma de Farners (Girona) fins a Riudarenes (Girona). S'intenta establir les possibles influències del funcionament hidrogeològic en l'estat ecològic a partir de dades piezomètriques, de cabal, fisicoquímiques i biològiques. Per aquesta última part s'han utilitzat indicadors biològics com l'índex d'hàbitat fluvial (IHF), avaluant l'hàbitat físic; l'índex de Qualitat del Bosc de Ribera (QBR), per determinar la qualitat ecològica de la zona de ribera; l'índex Biological Monitorig Working Party per a conques internes de Catalunya (BMWPC), per avaluar les diferents famílies de macroinvertebrats que hi viuen i l'índex ECOSTRIMED, una síntesi dels dos índex anteriors.En la actualidad encontramos numerosos sistemas acuáticos alterados por diferentes efectos de origen antropogénico. Para intentar evitar y/o disminuir estos efectos surgió la Directiva Marc del Agua (2000/60/CE) siendo este uno de sus objetivos. Este artículo describe el funcionamiento hidrogeológico y el estado de la riera de Santa Coloma, afluente de la Tordera (NE Catalunya), desde prácticamente su inicio en Santa Coloma de Farners (Girona) hasta Riudarenes (Girona). Se intenta establecer las posibles influencias del funcionamiento hidrogeológico en el estado ecológico a partir de datos piezométricos, de caudal, fisicoquímicos y biológicos. Para esta última parte se han utilizado indicadores biológicos como el índice de hábitat fluvial (IHF), evaluando el hábitat físico; el índice de Calidad del Bosque de Ribera (QBR), para determinar la calidad ecológica de la zona de ribera; el índice Biological Monitorig Working Party para cuencas internas de Catalunya (BMWPC), para evaluar las diferentes familias de macroinvertebrados que viven y el índice ECOSTRIMED, una síntesis de los dos índice anteriores.Nowadays there are several water systems affected by anthropogenic actions. In order to avoid or minimize these effects came up the Water Framework Directive (2000/60/EC) being one of its objectives. This article describes the hydrogeological behaviour and the ecological status of the Santa Coloma River, a tributary of Tordera River (NE Spain), from near the headwaters in Santa Coloma de Farners (Girona) to Riudarenes (Girona). We try to establish the potential influences of the hydrogeological system in the ecological status of the river from potentiometric data, stream flow, physicochemical and biological parameters. For this last part have been used as biological indicators the river habitat index (IHF), evaluating the physical habitat; the quality index forest bank (QBR), to determine the ecological quality of riparian zone; the Biological index Monitorig Working Party for the inner basins of Catalonia (BMWPC) to evaluate the different families of macroinvertebrates; and the ECOSTRIMED index, a synthesis of the two previous rates

Isotope and microbiome data provide complementary information to identify natural nitrate attenuation processes in groundwater

Natural attenuation processes alleviate the impact of fertilization practices on groundwater resources. Therefore, identifying the occurrence of denitrification has become a requirement for water quality management. Several approaches are useful for this purpose, such as isotopic and microbiological methods, each of them providing distinct but complementary information about denitrification reactions, attenuation rates and their occurrence in the aquifer. In this paper, we investigate the contribution of both approaches to describe denitrification in a consolidated rock aquifer (limestone and marls), with a porosity related to fracture networks located in the northeastern sector of the Osona basin (NE Spain). Isotopic methods indicated the origin of nitrate (fertilization using manure) and that denitrification occurred, reaching a reduction of near 25% of the nitrate mass in groundwater. The studied area could be divided in two zones with distinct agricultural pressures and, consequently, nitrate concentrations in groundwater. Denitrification occurred in both zones and at different levels, indicating that attenuation processes took place all along the whole hydrogeological unit, and that the observed levels could be attributed to a larger flow path or, in a minor extent, to mixing processes that mask the actual denitrification rates. Microbiological data showed a correlation between denitrifier genes and the isotopic composition. However, the groundwater microbiome and the distribution of denitrifying bacteria did not reveal a major influence on the denitrification level observed by isotopic methods. This focuses the interest of microbiological analysis to identify functional genes within the bacteria present in the aquife

Towards the understanding of antibiotic occurrence and transport in groundwater: Findings from the Baix Fluvià alluvial aquifer (NE Catalonia, Spain)

Antibiotics are an increasing focus of interest due to their high detection frequency in the environment. However, their presence in water bodies is not regulated by environmental policies. This field study investigates, for the first time, the occurrence, behavior and fate of a selection of 53 antibiotics, including up to 10 chemical groups, in an alluvial aquifer originated from manure application in an agricultural region using hydrogeological, hydrochemical and isotopic approaches. Up to 11 antibiotics were found in groundwater corresponding to 4 different chemical groups: fluoroquinolones, macrolides, quinolones and sulfonamides. In surface water, only 5 different antibiotics from 2 chemical groups: fluoroquinolones and sulfonamides, were quantified. The most frequent antibiotics were sulfamethoxazole and ciprofloxacin. Concentrations of antibiotics were in the order of ng/L, with maximum concentrations of 300 ng/L in groundwater. Hydrochemistry and isotopic data and geostatistics confirmed the spatial trend observed for nitrates, where nitrate concentrations tend to be higher in the margin areas of the study area, and lower concentrations are found nearby the river. On the other hand, no clear continuous spatial concentration trend of antibiotics was observed in the aquifer, supported by the short spatial correlation found in the variograms. This indicates that the physical-chemical properties and processes of each antibiotic (mainly, sorption and degradation), and other environmental issues, such as a patchy diffuse input and the manure antibiotic content itself, play an important role in their spatial distribution in groundwater. A discussion on the estimation of the antibiotic sorption parameter reveals the difficulties of describing such phenomena. Furthermore, retardation factors will extend over several orders of magnitude, which highly affects the movement of individual antibiotics within the aquifer. To summarize, this study points out the difficulties associated with antibiotic research in groundwater in order to define water resources quality management strategies and environmental regulation

Groundwater dependence of coastal lagoons: the case of La Pletera salt marshes (NE Catalonia

Coastal wetlands are among the most productive ecosystems of the world, playing an important role in coastal defense and wildlife conservation. These ecosystems, however, are usually affected by human activities, which may cause a loss and degradation of their ecological status, a decline of their biodiversity, an alteration of their ecological functioning, and a limitation of their ecosystem services. La Pletera salt marshes (NE Spain) are located in a region mainly dominated by agriculture and tourism activities. Part of these wetlands and lagoons has been affected by an incomplete construction of an urban development and in this moment is the focus of a Life+ project, whose aim is to restore this protected area. Several studies have analyzed the role of hydrological regime in nutrients, phytoplankton and zooplankton in this area, however, the role of groundwater was never considered as a relevant factor in the lagoon dynamics, and its influence is still unknown. In this study, the hydrogeological dynamics in La Pletera salt marshes has been analyzed, as a basis to set sustainable management guidelines for this area. In order to determine their dependence on groundwater resources, monthly hydrochemical (with major ions and nutrients) and isotopic (δ18OH2O and δD) campaigns have been conducted, from November 2014 to October 2015. In particular, groundwater from six wells, surface water from two nearby streams and three permanent lagoons, and sea water was considered in these surveys. Taking into account the meteorological data and the water levels in the lagoons, the General Lake Model has been conducted to determine, not only evaporation and rainfall occurring in the lagoons, but also the total inflows and outflows. In addition, the Gonfiantini isotopic model, together with equilibrium chemical-speciation/mass transfer models, has been used to analyze the evaporation and the physicochemical processes affecting the lagoons. Results show that during the dry season groundwater inputs may account for 15–80% of the water in La Pletera lagoons. Besides, water salinity depends on two main processes: 1) mixing of fresh and sea water occurring within the lagoons or in the aquifer; and 2) evaporation. According to the obtained results, the goal of preserving La Pletera lagoons and their salinity conditions implies maintaining groundwater fluxes towards the ocean, and also the hydraulic connectivity of these lagoons with the aquiferThis study has been funded by the projects CGL2014-57215-C4-2-R and CGL2016-76024-R of the Spanish Government, the European Community LIFE 13 NAT/ES/001001 project, and the University of Girona fund MPCUdG2016/061

Multi-isotopic and compositional exploration of factors controlling nitrate pollution

In Catalonia, according to the nitrate directive (91/676/EU), nine areas have been declared as vulnerable to nitrate pollution from agricultural sources (Decret 283/1998 and Decret 479/2004). Five of these areas have been studied coupling hydro chemical data with a multi-isotopic approach (Vitòria et al. 2005, Otero et al. 2007, Puig et al. 2007), in an ongoing research project looking for an integrated application of classical hydrochemistry data, with a comprehensive isotopic characterisation (δ15N and δ18O of dissolved nitrate, δ34S and δ18O of dissolved sulphate, δ13C of dissolved inorganic carbon, and δD and δ18O of water). Within this general frame, the contribution presented explores compositional ways of: (i) distinguish agrochemicals and manure N pollution, (ii) quantify natural attenuation of nitrate (denitrification), and identify possible controlling factors.To achieve this two-fold goal, the following techniques have been used. Separate biplots of each suite of data show that each studied region has a distinct δ34S and pH signatures, but they are homogeneous with regard to NO3- related variables. Also, the geochemical variables were projected onto the compositional directions associated with the possible denitrification reactions in each region. The resulting balances can be plot together with some isotopes, to assess their likelihood of occurrenceGeologische Vereinigung; Institut d’Estadística de Catalunya; International Association for Mathematical Geology; Càtedra Lluís Santaló d’Aplicacions de la Matemàtica; Generalitat de Catalunya, Departament d’Innovació, Universitats i Recerca; Ministerio de Educación y Ciencia; Ingenio 2010