Papers by António Chambel
Relação entre águas subterrâneas e agricultura. Quantidade e qualidade. O ciclo da água subterrân... more Relação entre águas subterrâneas e agricultura. Quantidade e qualidade. O ciclo da água subterrânea quando usada para fins agrícolas
São consideradas águas subterrâneas as águas que, numa determinada fase do ciclo hidrológico, se ... more São consideradas águas subterrâneas as águas que, numa determinada fase do ciclo hidrológico, se encontram no espaço subterrâneo, dentro das rochas e solos da crosta terrestre. O conjunto águas subterrâneas/rochas que as alojam designa-se por aquífero. Os aquíferos são definidos pela sua hidrodinâmica, ou movimento da água, pela sua hidroquímica, ou quimismo da água, pela hidrobiologia, ou biologia interna da água, e pelas características evolutivas, ou seja, a alteração das características das suas águas ao longo do tempo
Whilst hydrogeology studies the flow of water through the lithosphere, ecology studies the biolog... more Whilst hydrogeology studies the flow of water through the lithosphere, ecology studies the biologically mediated flow of energy through the biosphere. We currently lack a generic conceptual framework to examine the waterenergy interface of groundwater linked ecosystems. Eco-hydrology has emerged as a trans-disciplinary area of study over the last 2 decades in an attempt to consider water links to ecosystems more holistically. However, currently two domains are evident within this field: soil-moisture driven terrestrial systems and surface-water driven aquatic systems. Groundwater dependent ecosystems (GDEs) exist in a diverse range of habitats, spanning both aquatic and terrestrial systems, and their study encourages thinking towards a more inclusive and holistic earth-system model. Much of the previous (valuable) work on GDEs has considered individual case studies (eg Doñana wetlands) or types of habitats (in-aquifer systems), and studies have adopted a bi-disciplinary approach, linking hydrogeology to ecology, ecophysiology or hydrology. Predominantly bi-disciplinary studies have resulted in some confusing and conflicting applications of terminology. This paper proposes some clarifications for terminology, particularly groundwater dependent ecosystems and aquifer dependent ecosystems. It proposes that ecosystem water requirements should be considered in terms of hydrotopes at the landscape and ecosystem scale. Hydrotopes may be delineated in specific habitats with characteristic spatial and temporal patterns of water provision from precipitation, soil moisture, surface water, groundwater, tidal and oceanic sources. The Trigger-Transfer-Reserve-Pulse (TTRP) model of landscape ecology, is incorporated and expanded to account for the variable storage-transfer functions of different hydrological pathways. The interplay of (typically) soil-moisture/ surface water/ groundwater transfers to an ecosystem define the hydrodiversity and hydroperiodicity of an ecosystem. Special attention is given to aquifer dependent ecosystems (ADEs) in water controlled (semi-arid and arid) environments, with an illustration of hydrotope typesetting examples in Southern Africa. Semi-arid zone ADEs typically represent keystone ecosystems at ecotones with characteristic hydrotopes of biologically mediated aquifer discharge. Linear and discrete spatial discharge patterns of fractured and alluvial aquifer systems contribute to ecosystem heterogeneity and 'patchiness'. The larger (volume) and more sustained hydrodiversity of aquifer fed hydrotopes sustain relatively high productivity during seasonal periods of relative dormancy in neighbouring soil-moisture dependent hydrotopes. Both terrestrial and aquatic ADEs in these environments are believed to have greater hydrological resistance to disturbances in water inputs and contribute resilience to the surrounding ecosystem. However, ADEs have a relatively low resilience (ability to recover) following changes to the aquifer flow regime beyond natural minima and maxima, and are more vulnerable to irreversible alteration by disruption of aquifer flow. Typically ADEs subsidise neighbouring non-ADEs through trophic cascades. Linked to their smoothed hydroperiodicity, it is expected that ADEs have a lower water efficiency in primary productivity (gC.H 2 Omm -1 ) may show net mean annual productivity equivalent to their more 'flashy' episodic neighbours, who have high productivity during the shorter periods of water availability. In a nutshell -ADEs in water controlled environments have a greater hydrodiversity and characteristic smoothed, longer hydroperiod due aquifer-fed baseflow, than neighbouring hydrotopes, reliant predominantly on surface water or soil-moisture. The additional water budget available to ADEs, slowly released from aquifer reserves, effectively lubricates slower and more prolonged productivity. Whilst ADEs are typically net exporters of ecological services to surrounding non-ADEs, they tend to be lazy, inefficient and vulnerable!
The study of groundwater dependent ecosystems opened the opportunity to involve specialists of di... more The study of groundwater dependent ecosystems opened the opportunity to involve specialists of different areas of knowledge in order to obtain answers for complex interrelations between groundwater and the associated ecosystems. The actual study, carried out in two coastal lagoons of the Portuguese SW coast, showed the high dependency of the marine life and vegetation of the lagoons and associated streams discharging in the lagoons on the fresh water supply of these two lagoons and the high contribution they receive from groundwater in the dry period, which corresponds to more than half of each hydrologic year. Every year, the lagoons are artificially opened to the ocean for a few days to a few weeks, which dramatically changes the inside salinity. The sensitivity of these ecological niches is demonstrated by the strong dependence that some species that are more sensitive to high salinity waters show in relation to the entrance of freshwater resultant from the discharge of the phrea...
Quando pela primeira vez, por volta de 2010/2011 se colocou a questão da definição das áreas onde... more Quando pela primeira vez, por volta de 2010/2011 se colocou a questão da definição das áreas onde os ecossistemas estariam dependentes de águas subterrâneas, e entendendo-se por “ecossistemas dependentes de águas subterrâneas” os ecossistemas que dependem, em todo ou em parte de águas subterrâneas e que seriam irrevogavelmente afetados em caso de afetação da quantidade ou qualidade das águas subterrâneas, tornou-se necessário criar mecanismos para rapidamente se conseguirem identificar esses sistemas ecológicos. Para esse fim, foram em primeiro lugar, com base em dados de níveis freáticos de águas subterrâneas, identificadas as áreas onde as águas subterrâneas se situariam próximo da superfície do solo. Depois foram usados modelos conceptuais, onde estes existiam, para determinar as zonas onde havia hipóteses de haver ascensão de água subterrânea. Finalmente, foram identificadas áreas onde condições hidrogeológicas locais permitiriam a sustentação de ecossistemas com caraterísticas ...
In semi-arid and arid areas rock weathering is normally much less deep that in rainy areas. So, r... more In semi-arid and arid areas rock weathering is normally much less deep that in rainy areas. So, rocks tend to be more near the topographic surface. These climatic conditions also generate much less vegetation, which in all the cases clearly favours a direct observation of rock condition, fracturing or weathering. By other side, aquifers in hard rocks present specificities in relation to water presence and movement that implies a different approach when dealing with groundwater prospecting. Hard rocks are considered to have basically 3 layers of interest for hydrogeology: the weathered zone on the top, the fractured zone under the first one, and the non-fractured zone under the last one, where the possibility to get water is very low. Water is stored in both fractures and rock matrix, but moves mainly through the fractures. The capacity to transmit water is much more related with the interconnection between fractures than with the storage capacity. Even if the storage capacity is hig...
In order to turn more efficient the heating of class rooms in the lower floor of the old building... more In order to turn more efficient the heating of class rooms in the lower floor of the old building of the University of Évora (a XVI century building), five drillings were organised inside the area of the university (Figure 1). The purpose was to use the temperature differential of groundwater in relation to air, by means of a heat exchanger, and use this process to heat the rooms using less energy, turning the heating process less expensive. The wells were drilled in fractured rocks (gneisses), and the purpose was to locate them at least around 100 m one from each other, whilst trying to have a hydraulic connection in-between. From the five initial wells, four were successful in terms of productivity, but just two of them (RA1 and RA2) proved to be hydraulically connected. The wells were equipped with screens for all their drilled depth (100 m), except for the first six meters and some two or three pipes of six meters each, to allow space for the installation for submersible pumps. ...
Tiene habido muchas definiciones para el concepto de Ecosistemas Dependientes de Aguas Subterráne... more Tiene habido muchas definiciones para el concepto de Ecosistemas Dependientes de Aguas Subterráneas (EDAS, GDE en inglés), pero resumiendo son ecosistemas que usan agua subterránea en alguna parte de su ciclo de vida o por toda una generación e donde esta es crítica para la existencia de esas especies. El uso del agua subterránea no equivale necesariamente a una dependencia de las aguas subterráneas (Colvin et al. 2003). Por dependencia se entiende que el ecosistema sería significativamente alterado o mismo irreversiblemente degradado si la disponibilidad o calidad del agua subterránea fuera alterada más allá de su rango "normal" de fluctuación, o sea, son ecosistemas que dependen en el todo o en parte de las aguas subterráneas para mantener un nivel adecuado de la función del ecosistema y el mantenimiento de la composición de la comunidad (Smith et al. 2006). La dependencia de los EDAS de las aguas subterráneas es muy variable, oscilando entre parcial y con poca frecuenci...
O presente documento inclui o programa de acção e os elementos de campanha da Lista F, candidata ... more O presente documento inclui o programa de acção e os elementos de campanha da Lista F, candidata ao 3.º mandato do Conselho Geral da Universidade de Évora (2016-20)
A água é uma só, a mesmíssima água que percorre o corpo humano e de todos os outros seres vivos é... more A água é uma só, a mesmíssima água que percorre o corpo humano e de todos os outros seres vivos é a mesma que depois pode estar no solo, na atmosfera, nos rios, lagos, mares, oceanos, ou, mais escondida, no interior do Globo Terrestre, seja na parte superior da crosta, entre os poros e fraturas das rochas, seja por todo o interior do Globo, muitas vezes fazendo parte de magmas líquidos percursores das rochas ou mesmo integrando os próprios minerais das rochas. Dentro do que se consideram as “águas doces” utilizáveis porá fins humanos, a água subterrânea corresponderá a uma percentagem entre os 97 e os 98% de toda a água doce líquida disponível no Planeta, ou seja, excluindo as massas polares e os glaciares, mas incluindo todos os grandes lagos e rios de água doce do Planeta. A interligação permanente entre a água no seu todo dentro do designado “Ciclo Hidrológico” faz com que a gota de água que hoje pode ser considerada subterrânea amanhã esteja a correr num rio, desague posteriorme...
Environmental Earth Sciences, 2015
Hydrogeologist EurGeol José Martins Carvalho (BSc, PhD, DSc) gave his last lecture at the School ... more Hydrogeologist EurGeol José Martins Carvalho (BSc, PhD, DSc) gave his last lecture at the School of Engineering of Polytechnic of Porto in January 2014, bringing to a formal close an outstanding career in multidisciplinary hydrogeology teaching and practice (in Europe, Africa, Middle-East, Asia, South America) and in applied research. Nowadays, he is Emeritus Professor of the Polytechnic of Porto and Consultant Hydrogeologist. He has had a career spanning 50 years in military hydrogeology, exploration hydrogeology, environmental hydro-geology, groundwater engineering, hydrogeotechnics, urban water supply, water resources management and geothermics. This brief note aims to present the key milestones in his multifaceted professional career, acting as a geologist, a professor and a researcher of groundwater science. The essence of his long career over the last five decades was to promote the practice, teaching and research of hydrogeology to solve social problems and challenges via an environmental, sustainable and ethical approach. In his own words: ''Water is a unique resource: a drop can save a life, in war and peace''.
... 91 The Amieiro Galego sulphurous spring: characteristics and potentialities Maria Carla Loure... more ... 91 The Amieiro Galego sulphurous spring: characteristics and potentialities Maria Carla Lourenço, Elsa Cristina Ramalho 101 ... in the southern Idaho Batholith, USA: Preliminary analysis of field data and laboratory experiments Alan L Mayo, David Nelson, Brad Holdaway, David ...
São consideradas águas subterrâneas as águas que, numa determinada fase do ciclo hidrológico, se ... more São consideradas águas subterrâneas as águas que, numa determinada fase do ciclo hidrológico, se encontram no espaço subterrâneo, dentro das rochas e solos da crosta terrestre. O conjunto águas subterrâneas/rochas que as alojam designa-se por aquífero. Os aquíferos são definidos pela sua hidrodinâmica, ou movimento da água, pela sua hidroquímica, ou quimismo da água, pela hidrobiologia, ou biologia interna da água, e pelas características evolutivas, ou seja, a alteração das características das suas águas ao longo do tempo
A componente subterrânea do ciclo da água, por ser de difícil observação, constituiu sempre uma p... more A componente subterrânea do ciclo da água, por ser de difícil observação, constituiu sempre uma parte negligenciada desse mesmo ciclo. Com o enorme incremento da utilização da água principalmente na segunda metade do Século XX e com técnicas de perfuração cada vez mais eficazes na execução de captações de água subterrânea, registaram se as primeiras observações de declínio generalizado dos níveis freáticos, do declínio acentuado dos caudais de nascentes nessas áreas e do declínio acentuado também dos caudais dos rios abastecidos pelos caudais descarregados pelos aquíferos. Tal levou a consequências drásticas em muitas regiões do Globo, muito em particular nas regiões com forte stress hídrico ou onde as taxas de recarga já não conseguem equilibrar os caudais de exploração. Desse modo, até os especialistas em águas superficiais passaram a olhar para as águas subterrâneas de outro modo, como parte integrante do mesmo ciclo, e cuja afetação pode levar a consequências graves em caudais d...
Analisa-se um pouco os problemas mundiais em torno da água, concentrando-se particularmente nas á... more Analisa-se um pouco os problemas mundiais em torno da água, concentrando-se particularmente nas águas subterrâneas, na sua interação com as águas superficiais, e nos serviços da água, quer para fins humanos (consumo, indústria, agricultura), quer nos serviços prestados ao ambiente. Ao mesmo tempo, são apontados alguns casos de desastres ambientais que sucederam no passado ou ainda estão a suceder devido a intervenções humanas desajustadas à realidade ambiental, e apontadas algumas opções de gestão futura que poderão obviar algumas destas consequências
Staring from the premise that water table in aquifers tends to have a relation with a set of metr... more Staring from the premise that water table in aquifers tends to have a relation with a set of metrics or spatial variables to be derived from the topographic surface, as well as groundwater flow direction tends to be consistent with the surface streams flow direction, a new model was defined aiming to predict Static Water Level (SWL) from a set of tailored global spatial variables, using compositions of existent GIS raster standard functions. It was defined an exploratory spatial data analysis process in order to study the relation of dependent variable (Static Water Level - SWL) with a set of metrics derived from and hydrologicaly functional digital elevation model, obtained through a multi-resolution gradative interpolation method, with forced drainage. The metrics created include a new calculation of a focal convexity with a multi-radius circular focal method and a global structural convexity, derived through an inverted downstream accumulation process. Elevation and slope were al...
Hydrogeology Journal, 2019
A geostatistical methodology is developed with the aim of simulating three-dimensional grids of t... more A geostatistical methodology is developed with the aim of simulating three-dimensional grids of transmissivity. The case study is a highly heterogeneous massif rock body, mainly composed of granites and schists with distinct weathering and fracture conditions, that surrounds and is part of a former uranium mine in central Portugal. Contrasting hydraulic behaviour is given by fractured rock and a pervasively weathered rock matrix composed mainly by clay minerals. Lithology, weathering, and fracture were the geological attributes selected for simulation. Data and information were analysed in detail for their respective integration into a sequential geostatistical modelling approach. The simulation process was conditioned to local data histograms. Simulation images of transmissivity show high degrees of heterogeneity both laterally and vertically. Potential areas for high-flow propagation are restricted in number and interconnectivity is not particularly evident. Small channels, the main structures responsible for groundwater flow propagation, can be identified within the rock body.RésuméUne méthode géostatistique est développée afin de simuler des grilles de transmissivité tridimensionnelles. Le massif étudié est constitué de formations géologiques fortement hétérogènes, il est principalement composé de granites et schistes soumis à des conditions d’altération et de fracturation diverses, qui entourent et constituent partiellement une ancienne mine d’uranium dans le centre du Portugal. Les roches fracturées et une matrice rocheuse intensément altérée, majoritairement composée de minéraux argileux, confèrent un comportement hydraulique contrasté. Les attributs géologiques retenus pour la simulation étaient la lithologie, l’altération et la fracturation. Les données et les informations ont été analysées en détail en vue de leur intégration respective dans une approche par modélisation géostatistique séquentielle. Le traitement par simulation a été conditionné à des histogrammes de données locales. La visualisation des simulations de transmissivité montre de fortes hétérogénéités, autant latérales que verticales. Les secteurs potentiels de propagation de flux élevés sont peu nombreux et leur interconnexion n’est. pas spécialement évidente. De petits conduits, constituant les principales structures propageant les flux d’eau souterraine, peuvent être identifiés dans le massif.ResumenSe desarrolla una metodologa geoestadstica con el objetivo de simular cuadrículas tridimensionales de transmisividad. El estudio de caso es un macizo rocoso altamente heterogéneo, compuesto principalmente por granitos y esquistos con distintas condiciones de meteorización y fractura, que rodea y forma parte de una antigua mina de uranio en el centro de Portugal. El comportamiento hidráulico contrastante está dado por la roca fracturada y una matriz de roca meteorizada en forma generalizada compuesta principalmente por minerales arcillosos. Litología, meteorización y fractura fueron los atributos geológicos seleccionados para la simulación. Los datos y la información se analizaron en detalle para su integración respectiva en un enfoque de modelización geoestadística secuencial. El proceso de simulación se condicionó a histogramas de datos locales. Las imágenes de simulación de la transmisividad muestran altos grados de heterogeneidad tanto lateral como verticalmente. El número de áreas potenciales para la propagación de alto flujo está restringido y la interconectividad no es particularmente evidente. Los canales pequeños, las principales estructuras responsables de la propagación del flujo de agua subterránea, pueden ser identificados dentro de la masa rocosa.摘要开发了模拟导水系数的三维网络的地质统计学方法。案例研究区是主要由具有明显风化和裂隙特征的花岗岩和片岩组成的高度非均质山丘岩体,周边是葡萄牙中部的前铀矿,案例区也包括一部分前铀矿区。在裂隙和主要由粘土矿物组成的普遍风化基质中发现明显不同的水力特征。选择岩性,风化程度和裂隙作为模拟的地质属性。详细分析了各类数据和信息,并将它们集成到序贯地质统计建模方法中。模拟过程以局部数据直方图展示。导水系数的模拟图像在侧向和垂向上均显示出高度的非均质性。高流量传导的潜在区域个数得到辨识,并且互连性不是特别明显。小通道是影响地下水流传导的主要结构,可以在岩体内进行识别。ResumoUma metodologia geostatística foi desenvolvida com o objetivo de simular malhas tridimensionais de transmissividade. O caso de estudo é o de um maciço rochoso extremamente heterogéneo, maioritariamente composto por granitos e xistos com distintos graus de alteração e fracturação, localizado na envolvente a uma antiga mina de urânio situada na Zona Centro de Portugal. Neste maciço é evidente a existência de comportamentos hidráulicos distintos e contrastantes devidos a matrizes rochosas fraturadas e matrizes pervasivamente alteradas compostas maioritariamente por minerais argilosos. A litologia, o grau de alteração e a fracturação foram os atributos geológicos selecionados para simulação. Os dados e a informação disponível foram analisados em detalhe para respetiva integração de modo adequado num processo de simulação geostatística sequencial. O processo de simulação foi condicionado aos histogramas locais dos dados. Os resultados da simulação mostram imagens simuladas de transmissividade bastante…
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Papers by António Chambel