57 research outputs found
Seawater intrusion and coastal groundwater resources management. Examples from two Mediterranean regions: Catalonia and Sardinia
Seawater intrusion is a natural phenomenon that allows the encroachment of saline water into aquifers. Nevertheless, many human actions along the coastline, in particular groundwater withdrawal, enhance this process and finally cause the salinization of groundwater resources. Here we review the hydrogeological basis of seawater intrusion and describe specific cases in Catalonia and Sardinia, as examples of environmental problems and water management actions. We emphasize the origin of salinization and the hydrogeological details of each case, as well as the solutions that have been implemented to prevent groundwater salinization
Presència i distribució espacial de concentracions anormals d'ió nitrat a les aigües subterrànies dels aqüífers del Baix Fluvià (Alt Empordà)
Presentem una caracterització de la
distribució espacial de la contaminació
per nitrats en els aqüífers de la plana del
baix Fluvià. En concret, els valors de
concentració més elevats s’han observat a l’aqüífer superficial, on sobrepassen, amb escreix, els límits de potabilitat
aconsellats pel RD 1138/1990. L’àrea
més afectada ocupa part dels termes
municipals de Vilamacolum i Torroella
de Fluvià, en els quals hi predominen
concentracions que oscil·len entre 50 i
200 mg × L–1. Els focus de contaminació
són de tipus puntual i difús.
Documentada la presència anormal
de nitrats en aquest aqüífer, es planteja
el correcte maneig agrícola, en vistes a
una doble finalitat: d’una banda, contribuir a la planificació d’unes bones pràctiques agrícoles tenint en compte la relació entre volums de reg i aportacions
de nitrogen; d’altra banda, preveure
una progressiva recuperació de la qualitat de l’aqüífer, a partir de l’ús de tecnologies que integrin la ubicació d’unes
zones favorables on es pugui maximitzar l’extracció del recurs contaminat, i
la ubicació d’uns sòls aptes per a l’aplicació d’aquest recurs, amb uns criteris
agronòmics coherents.Presentamos una caracterización de
la distribución espacial de la contaminación por nitratos en los acuíferos de la
llanura del baix Fluvià. En concreto, los
valores de concentración más elevados
se han observado en el acuífero superficial, donde sobrepasan, con creces, los
límites de potabilidad aconsejados por
el RD 1138/1990. El área más afectada
ocupa parte de los términos municipales de Vilamacolum y Torroella de Fluvià, en los cuales predominan concentraciones que oscilan entre 50 y 200 mg
× L–1. Los focos de contaminación son
de tipo puntual y difuso.
Documentada la presencia anormal
de nitratos en este acuífero, se plantea
el correcto manejo agrícola, en vistas a
una doble finalidad: por un lado, contribuir a la planificación de unas buenas prácticas agrícolas teniendo en cuenta
la relación entre volúmenes de riego y
aportaciones de nitrógeno; por otro
lado, prever una progresiva recuperación de la calidad del acuífero, a partir
de usar tecnologías que integren la ubicación de unas zonas favorables donde
se pueda maximizar la extracción del
recurso contaminado, y la ubicación de
unos suelos aptos para la aplicación de
este recurso, con unos criterios agronómicos coherentes.A characterisation of spatial distribution of the nitrate groundwater contamination in the baix Fluvià plain is
presented. Specially, the highest values
have been found in the upper aquifer,
where the critical values specified by
RD 1138/1990 for drinking water are
clearly surpassed in some cases. The
worse afeected areas are the municipalities of Vilamacolum and Torroella de
Fluvià where concentrations between
50 and 200 meq × l–1 are dominant. The
contamination comes from both point
and non-point sources.
After documenting the abnormal
amounts of nitrate in such aquifer the
next issue is good agricultural management. This has two aims. Firstly, to contribute to the planning of good agricultural practices taking the relationship between amount of irrigation water and
inputs of nitrogen into account. Secondly, to try to recover the aquifer
progressively using technologies capable of integrating the setting of favourable areas where the polluted
resource could be withdranw and other spots where there are soils suitable for
the application of such resource, all
with coherent agronomic criteria
Presència i distribució espacial de concentracions anormals d'ió nitrat a les aigües subterrànies dels aqüífers del Baix Fluvià (Alt Empordà)
A genealogical critique of Beauchamp and Childress' for principles approach to medical ethics
<bold>Part Three</bold> examines the development of Beauchamp and Childress 'four principles' approach to medical ethics from the 1<super> st</super> to the 6<super>th</super> Editions of <italic>Principles of Biomedical Ethics,</italic> arguing that it has, thanks to changes in the authors' conception of philosophical moral theory, been able to productively incorporate the views of many of its critics over this time; that it is also able to incorporate features of different ethical approaches such as virtue ethics, narrative ethics and ethics of care; and that, properly understood, it continues to provide a good framework both for moral reflection in medicine and the provision of concrete action-guides. The thesis concludes by considering this view of the four principles in the light of the earlier sections' approach, and attempting to demonstrate further demonstrate their value through two case-studies.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Identificación de flujos entre acuíferos a nivel regional en base a datos hidroquímicos (Alt Empordà, NE España)
A escala regional, los flujos de agua subterránea entre formaciones hidrogeológicas condicionan su ba lance hídrico y, con él, su régimen de explotación. En este estudio se caracteriza la dinámica hidrogeológica a nivel regional de la depresión del Alt Empordà (Girona, NE España) en base a datos hidroquímicos, con el objetivo de identificar flujos de agua subterránea entre las formaciones que constituyen la zona de recarga (relieves circundantes) y la depresión. En este sistema, el ión sulfato resulta un trazador adecuado para identificar los procesos hidroquímicos y de mezcla que acontecen en este zona. Los datos presentados sugieren que la presencia de sulfato, y por consiguiente la recarga, se debe a aportaciones de flujos profundos, en algunos casos desde las unidades geológicas inferiores, ajenos a la recarga local por precipitación desde la superficie.At a regional scale, groundwater flow between aquifer systems controls their water budget and, therefore, its exploitation regime. This study characterizes the hydrogeology at a regional level of the Alt Empordà Basin (Girona, NE Spain). Our goal consists in recognizing recharge flowpaths, based on hydrochemical data, between the aquifer systems located in the ranges (recharge) areas and these within the basin. Sulfate stands as an appropriate tracer to identify hydrochemical as well as mixing processes and, therefore, recharge relationships. Field data suggest that sulfate occurrence is related to deep groundwater fluxes unrelated to the local rainfall recharge.Universidad Nacional de La Plat
Nitrate pollution of groundwater; all right…, but nothing else?
Contamination from agricultural sources and, in particular, nitrate pollution, is one of the main concerns in groundwater management. However, this type of pollution entails the entrance of other substances into the aquifer, as well as it may promote other processes. In this study, we deal with hydrochemical and isotopic analysis of groundwater samples from four distinct zones in Catalonia (NE Spain), which include 5 different aquifer types, to investigate the influence of fertilization on the overall hydrochemical composition of groundwater. Results indicate that intense fertilizer application, causing high nitrate pollution in aquifers, also homogenize the contents of the major dissolved ions (i.e.; Cl(-), SO4(2-), Ca(2+), Na(+), K(+), and Mg(2+)). Thus, when groundwater in igneous and sedimentary aquifers is compared, significant differences are observed under natural conditions for Cl(-), Na(+) and Ca(2+) (with p-values ranging from <0.001 to 0.038), and when high nitrate concentrations occur, these differences are reduced (most p-values ranged between 0.054 and 0.978). Moreover, positive linear relationships between nitrate and some ions are found indicating the magnitude of the fertilization impact on groundwater hydrochemistry (with R(2) values of 0.490, 0.609 and 0.470, for SO4(2-), Ca(2+) and Cl(-), respectively). Nevertheless, the increasing concentration of specific ions is not only attributed to agricultural pollution, but to their enhancing effect upon the biogeochemical processes that control water-rock interactions. Such results raise awareness that these processes should be evaluated in advance in order to assess an adequate groundwater resources management.Peer ReviewedPostprint (author's final draft
Digitise This! A Quick and Easy Remote Sensing Method to Monitor the Daily Extent of Dredge Plumes
Technological advancements in remote sensing and GIS have improved natural resource managers’ abilities to monitor large-scale disturbances. In a time where many processes are heading towards automation, this study has regressed to simple techniques to bridge a gap found in the advancement of technology. The near-daily monitoring of dredge plume extent is common practice using Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and associated algorithms to predict the total suspended solids (TSS) concentration in the surface waters originating from floods and dredge plumes. Unfortunately, these methods cannot determine the difference between dredge plume and benthic features in shallow, clear water. This case study at Barrow Island, Western Australia, uses hand digitising to demonstrate the ability of human interpretation to determine this difference with a level of confidence and compares the method to contemporary TSS methods. Hand digitising was quick, cheap and required very little training of staff to complete. Results of ANOSIM R statistics show remote sensing derived TSS provided similar spatial results if they were thresholded to at least 3 mg L-1. However, remote sensing derived TSS consistently provided false-positive readings of shallow benthic features as Plume with a threshold up to TSS of 6 mg L-1, and began providing false-negatives (excluding actual plume) at a threshold as low as 4 mg L-1. Semi-automated processes that estimate plume concentration and distinguish between plumes and shallow benthic features without the arbitrary nature of human interpretation would be preferred as a plume monitoring method. However, at this stage, the hand digitising method is very useful and is more accurate at determining plume boundaries over shallow benthic features and is accessible to all levels of management with basic training
Twenty-three unsolved problems in hydrology (UPH) – a community perspective
This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales.
Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come
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