Abstract
In this paper, long (>40 years) hourly tide gauge records from the North Atlantic are analyzed. A new time series clustering approach which combines Bayesian methodology, extreme value theory, and classification techniques is adopted for the analysis of the regional variability of sea-level extremes. The tide gauge records are clustered on the basis of their corresponding predictive distributions for 25-, 50-, and 100-year return values. The results of the cluster analysis show a clear distinction between the higher latitude stations for which the return values are largest and the remaining locations. This distinction reflects in the U.S. east coast the transition between the Scottian shelf and Gulf of Maine area and the mid-Atlantic Bight area. For the stations at lower latitudes the results show a grouping based on return levels that is not a function of geographical proximity but reflects local effects in extreme sea levels associated with the specific location of each tide gauge.

Abstract
Radon is a naturally occurring radioactive noble gas generated within mineral grains of uranium bearing rocks by alpha decay from radium. The Amram tunnel (A. Bloch Geophysical Observatory) is a particularly suitable location for the investigation of radon variability. Located in the arid environment of the Arava desert, near Elat, the 170 m tunnel that constitutes the observatory enables radon monitoring in a desert environment and under fairly stable environmental conditions. The analysis of the temporal variability of continuous measurements of radon and environmental parameters at the Amram tunnel over a period of several years shows a complex temporal pattern characterized by non-stationary and multiscale features. Radon concentrations exhibit multiyear variability in the form of a increasing trend of similar to 1000 Bq m(-3) yr(-1) in the mean and much larger trends up to similar to 2500 Bq m(-3) yr(-1) in the maximum radon levels. Radon concentrations also display strong seasonal patterns, with maxima in summer and minima in winter, ranging from 2.5 kBq m(-3) in winter to 35 kBq m(-3) in summer. Intraseasonal variability is characterized by very large radon anomalies, with sharp increases of more than 20 kBq m(-3) relative to the base level, that occur in spring and summer and last for several days. Daily periodic variability with maxima around midnight appears also in spring and summer, being absent in the cold months. Radon variability at seasonal, intraseasonal and daily timescales is associated with the air temperature outside the tunnel, specifically the temperature gradient between the external environment and the more stable environment inside the tunnel where the measurements are performed.

Abstract
This work introduces the coastal geo-engineering issues for a suitable selection and geomaterial characterisation of quarries. The development of the research had two main phases: (i) the field survey, applied cartography and inspection of maritime structures and (ii) the geological and geotechnical quarry assessment. This study reports results from the second phase which comprises the evaluation of quarries and the identification of potential areas for the extraction of armourstone with quality and availability to supply maritime structures. It was proposed a zoning of the NW Portugal region and taken into account some features like the land use, urban and settlement plans, geological setting, geotechnical and geomechanical description/typification of the rock masses. 459 quarries were identified, georeferenced and distributed in a total area of 14.010km2. More than 200 sites were selected, characterised and included in the GIS database project with interactive support (e.g. hyperlinks for the datasheets, photos or essential information). A total area of 4,1% was calculated, including relevant geological conditions and comprising existent quarries (active/inactive) or new places (suitable or predictable areas). A multidisciplinary perspective must be adopted providing a cost-effective method useful to the incorporation of important concepts (durability and integrity) in geo-monitoring coastal plans and highlighting GIS coastal projects.

Abstract
This study presents the results of a multidisciplinary approach, using hydrogeochemical, isotopic and ecotoxicological analyses, performed to assess the nature and suitability for use of Paranhos and Salgueiros spring waters (Porto city, NW Portugal). Based on the surface activities located along the course of the springs, 23 water samples were collected. All the samples were analysed for major element concentrations. The isotopic techniques employed included delta(2)H, delta(18)O and (3)H. Standard acute bioassays with Daphnia magna were also performed. The hydrogeochemical analyses showed a nitrate and sulphate-enriched composition for these groundwaters, resulting mainly from urban drainage and sewer leakage. In the ecotoxicological analyses, no significant mortality was observed in any of the tests performed. The results obtained in this study suggest that Porto urban groundwater could be suitable for irrigation uses.

Abstract
The Porto settlement (Northwest Portugal, Iberian Peninsula) was originally built in the twelfth century and has been developed on granitic hill slopes of the Douro riverside, being one of the oldest cities in Europe. In the urban area of Porto, the second most important city of the Portuguese mainland, there is a population of about 216,000 inhabitants. This study highlights the importance of urban speleological mapping applied to groundwater and geo-engineering studies. All the water that flows from the so-called Paranhos or Arca D'Agua springs is captured by catchwork galleries and their utilization date back around 1120 AD. Paranhos spring galleries catchworks (c. 3,3 km extension and a -21m below ground level) was one of the main water supplies to Porto City for more than six centuries and, nowadays, these waters are still appropriate for irrigation uses. Topographical, geological, geophysical and hydrogeological data were collected and interpreted, allowing the definition of a hydrogeotechnical zoning. All these features were mapped and overlaid using GIS mapping techniques. This multidisciplinary approach offers a good potential for reliable urban speleological and geo-engineering studies of Arca D'Agua site.

Abstract
A new approach to gas leakage detection in high pressure distribution networks is proposed, where the pipeline is modelled as a Linear Parameter Varying (LPV) System driven by the source node mass flow with the pressure as the scheduling parameter, and the system output as the mass flow at the offtake. Using a recently proposed successive approximations LPV system subspace identification algorithm, the pipeline is thus identified from operational data. The leak is detected using a Kalman filter where the fault is treated as an augmented state. The effectiveness of this method is illustrated with an example with a mixture of real and simulated data.