Source characterization and spatio–temporal evolution of the metal pollution in the sediments of the Basque estuaries (Bay of Biscay)

According to Water Framework Directive requirements, Member States must identify and analyze effects derived from human pressures in aquatic systems. As different kind of pressures can impact water bodies at different scales, analyses of spatio-temporal evolution of water bodies becomes essential in order to understand ecosystem responses. In this investigation, an analysis of spatio-temporal evolution of sedimentary metal pollution (Cd, Cr, Cu, Hg, Ni, Pb, Zn) in 12 Basque estuaries (Bay of Biscay) is presented. Data collected in extensive sampling surveys is the basis for the GIS-based statistical approach used. The implementation of pollution abatement measures is reflected in a long-term decontamination process, mostly evident in estuaries with highest historical sediment pollution levels. Spatial evolution is determined by either naturally occurring or human driven processes. Such spatial processes are more obviously being reflected in estuaries with lower historical sediment pollution levels.     

The future of old industrial regions in a carbon-constrained world

Even if a global agreement is achieved on climate change issues, it is likely that national policies will continue to differ. Consequently, the competitiveness of some industries could be affected and the so-called ‘carbon leakage’ effect might occur. This effect is more likely for those industries with a risk of relocation. Most of the studies that examine the carbon leakage phenomenon look at implications at the national or supra-national level, and neglect the important fact that some of the key industries affected are highly concentrated in the old industrial regions (OIRs). From a regional perspective, it is clear that these areas are affected more severely by climate policies. Using a computable general equilibrium (CGE) model, the impacts for one of the most vulnerable sectors – the iron and steel (IS) sector in the European OIR of the Basque Country (BC) – are first examined. The analysis is then replicated for the OIR of the North RhineWestphalia (NRW) region in Germany. The results show that although total effects may be diluted from a national perspective, the economic impact at the regional level may be quite large and may significantly reduce regional gross domestic product (GDP). This has broader implications for the OIRs and suggests a need to further explore policy insights for economic development and adaptation in them.     

Hydraulic conductivity characterization of a karst recharge area using water injection tests and electrical resistivity logging

Water injection tests and electrical logging are particularly useful techniques in the characterization of geological media in engineering works. In this paper these techniques in conjunction with cracks measurements obtained from drilling cores, were used in the characterization of a singular location in a karst massif. The aim of our work is to determine the hydraulic characteristics of the investigated site, as well as to establish the relationship between the data obtained by the different techniques used. Thus, electrical resistivity records and fracture data were obtained from two boreholes of 100 and 120 m depth. Hydraulic conductivity was calculated from 25 low-pressure water injection tests (LPT) carried out at different depths in both boreholes. The relationship between hydraulic conductivity and fracture frequency was not very statististically significant (R²: 0.062–0.672; σ_est: 0.61–1.575). Conversely, electrical resistivity and hydraulic conductivity had a great relationship (R²: 0.725–0.935; σ_est: 0.159–0.738), so the electrical resistivity may be related to the functionality of the fractures. Finally, the LPT is shown as a very practical tool for determining the degree of the hydraulically interconnection with the surroundings, for establishing the hydraulic conductivity profile and for obtaining a measure of soil erosionability according to the significance of the fracture washing out processes recorded.     

Rock cut stability assessment in mountainous regions

Ensuring stability of rock slopes is an essential requirement in the progress of our societies today. Rock determined to be loose or with potential for failure must be removed or restrained in some way. In our work, after doing an inventory of the instabilities that occurred in the last 5 years in the Basque Country, we analyse the different factors, in slope stability. The potential for failure is evaluated for different classes of rock mass, characterized previously by their geomechanical properties. The characterization of potential risk of each one is undertaken by considering 10 parameters that define the nature of mass rock, relative orientation and morphological features of the slope (interaction rock massif-slope) and infrastructure features (interaction rock massif-slope-infrastructure). Each of these parameters is evaluated separately and a Risk Factor (RF) is determined. The RF reaches a maximum value of 10,000 and allows to differentiate four categories of slopes; each category has its own priority. Rock mass characteristics also determine the potential damage from instability and the associated correction measures. The systematic evaluation of instabilities must allow establishing a priority in the correction measures and thus optimise the available economic resources.     

Simulating the migration of drifters deployed in the Bay of Biscay, during the Prestige crisis

A main conclusion following the oil spill from the Prestige tanker was that improvements in ocean circulation models were necessary; this was in order to predict, more accurately, the trajectories followed by the oil slicks and hence assist in fight against oil pollution operations. In this contribution, the results of the validation of a semi-empirical ocean circulation model, parameterised for the Bay of Biscay and forced with operational oceano-meteorological remote sensing observations, are shown. The model results have been validated with observations from drifting buoys, deployed in the Bay of Biscay during the crisis. The results show that the model explains a relatively large percentage of the current variability. The comparisons between the real and the estimated drifter trajectories indicate that for 3, 5 and 7 day-long trajectories, the drifter position is estimated with errors of approximately 23, 35 and 46km, respectively. The model reproduces relatively well the trajectory followed by the drifter with the shortest period (23 days).     

The effects of dredging operations on the hydrodynamics of an ebb tidal delta: Oka Estuary,northern Spain

The hydrodynamics associated with the Mundaka Sandbar are described. The sandbar (ebb tidal delta) is responsible for the formation and the quality of a “world famous” surfing wave, at the mouth of the Oka Estuary in the Urdaibai Biosphere Reserve. The primary factor controlling the shape of the sandbar is the shoreline configuration. In turn the size of the sandbar is controlled by the volume of the tidal outflow and the wave energy. Periods of tidal dominance occur during summer (associated with sandbar accretion); with mixed energy conditions during winter and wave dominance under storms (sandbar erosion).The surfing wave lost its characteristics following, intensive dredging along the estuary, combined with beach nourishment, in May 2003. Between May 2005 and April 2006, the outer part of the estuary was monitored, to understand the processes controlling recent morphological changes over the area.Recent studies undertaken in the mouths of estuaries, together with the results of the monitoring are described; these are complemented by the numerical modelling of wave hydrodynamics under medium and extreme sea states. Analyses of the wave and current survey data, combined with the modelling outputs, have demonstrated that the changes were not irreversible. As such, the natural shape of the sandbar has recovered gradually, as has the quality of the Mundaka surfing wave.     

Geomechanical characterisation of rock masses in Alpine regions: the Basque Arc (Basque-Cantabrian basin, Northern Spain)

The geomechanical characterisation of rock masses in Alpine regions is one of the main challenges currently facing rock mechanics. These rock masses, made up of very different materials and frequently tectonically disturbed, are affected by engineering works, giving rise to potentially important problems. Thus, in the Basque Country, these materials are at the cause of important fatalities occurring in recent years. In this context, we aim at characterising these materials with the ultimate purpose of predicting their behaviour. The characterisation is initially approached based on the GSI, m_i and σ_ci parameters, following the Hoek-Brown failure criterion. This information is supplemented with field and laboratory measurements, and by obtaining the RQD and RMR indices. Using the information obtained from 99 metering stations, we develop a graphic classification procedure, which allows us to distinguish materials based on their characteristics, behaviour, type and degree of associated problems, and type and effectiveness of solutions provided. Eight classes of material are established.