Hydrogeological research in coastal areas has gained considerable attention over the last decades due to increasing stresses on fresh groundwater resources. Fundamental groundwater flow and solute transport analyses remain essential for a concise understanding of the governing processes that lead to salinisation of fresh groundwater resources. However, the challenge of modern research is the application and quantification of these processes in real world cases. In this context, deltaic areas are amongst the most difficult study areas as they often have a complex groundwater salinity distribution. The Wadden Sea area in the northern part of the Netherlands is an example of such an area.

We quantified salt water intrusion and salinisation of groundwater flow systems in two representative case studies in the Wadden Sea area, using the density dependent groundwater flow and transport code M0CDENS3D. The results indicate that sea-level rise and autonomous processes will cause severe salinisation in the future, especially in the low polder areas close to the sea. In addition, we show that enhanced land subsidence due to salt exploitation accelerates this process. Salinisation can be mitigated to some extent by raising surface water levels in polders and by creating saline groundwater collection areas that maintain a low controlled water level.

3D basin modelling is used to investigate the history of maturation and hydrocarbon generation on the main platforms in the northwestern part of the offshore area of the Netherlands. The study area covers the Cleaverbank and Elbow Spit Platforms. Recently compiled maps and data are used to build the input geological model. An updated and refined palaeo water depth curve and newly refined sediment water interface temperatures (SWIT) are used in the simulation. Basal heat flow is calculated using tectonic models. Two main source rock intervals are defined in the model, Westphalian coal seams and pre-Westphalian shales, which include Namurian and Dinantian successions. The modelling shows that the pre-Westphalian source rocks entered the hydrocarbon generation window in the Late Carboniferous. In the southern and central parts of the study area, the Namurian started producing gas in the Permian. In the north, the Dinantian source rocks appear to be immature. Lower Westphalian sediments started generating gas during the Upper Triassic. Gas generation from Westphalian coal seams increased during the Paleogene and continues in present-day. This late generation of gas from Westphalian coal seams is a likely source for gas accumulations in the area.

Westphalian coals might have produced early nitrogen prior to or during the main gas generation occurrence in the Paleogene. Namurian shales may be a source of late nitrogen after reaching maximum gas generating phase in the Triassic. Temperatures reached during the Mid Jurassic were sufficiently high to allow the release of non-organic nitrogen from Namurian shales.

Subsidence caused by extraction of hydrocarbons and solution salt mining is a sensitive issue in the Netherlands. An extensive legal, technical and organisational framework is in place to ensure a high probability that such subsidence will stay within predefined limits. The key question is: how much subsidence is acceptable and at which rate? And: how can it be reliably assured that (future) subsidence will stay within these limits?

To address the issue for the Wadden Sea area, the concept of ‘effective subsidence capacity’ is used. To determine the ‘effective subsidence capacity’, the maximum volumetric rate of relative sea-level rise, that can be accommodated in the long term, without environmental harm, is established first. The volume of sediment that can be transported and deposited by nature into the tidal basin where the subsidence is expected, ultimately determines this ‘limit of acceptable average subsidence rate’. The capability of the tidal basins to ‘capture’ sediment over the lunar cycle period of 18.6 years is the overall rate-determining step. Effective subsidence capacity is then the maximum average subsidence rate available for planning of human activities. It is obtained by subtracting the subsidence volume rate ‘consumed’ by natural relative subsidence in the area (sealevel rise plus natural shallow compaction) from the total long-term acceptable subsidence volume rate limit.

In the operational procedure for mining companies, six-years-average expectation values of subsidence rates are used to calculate the maximum allowable production rates. This is done under the provision that production will be reduced or halted if the expected or actual subsidence rate (natural + man induced) is likely to exceed the limit of acceptable subsidence. Monitoring and management schemes ensure that predicted (6-year average) and actual (18.6-year average) subsidence rates stay within the limit of acceptable subsidence rate and that no damage is caused to the protected nature. A GPS based early warning system is used for early detection of unexpected behaviour. In support of SSM (State Supervision of Mines, the government regulator), TNO-AGE (an independent government advisory group) applies an independent Bayesian statistical analysis of all data, as they become available, to calculate the probability of scenario's under which future subsidence will exceed the defined limits. It is external to the operator's annual measurement and control loop and ensures that preventive actions can be taken in time in case such scenarios emerge.

Regular communication keeps the authorities and the general public informed on the use of the effective subsidence capacity to demonstrate that the actual average subsidence rate stays strictly within the defined bounds and that, from a scientific point of view, there is no reasonable doubt that damage to the tidal system will not occur now or in the future.

Present study provides a review of the latest results on fluvial and aeolian landscape evolution in Hungary achieved by our team during the last 20 years.

– The Hungarian river terrace system and its chronology was described with special emphasise on the novel threshold concept. A revised terrace system was created by the compilation of novel terrace chronology and MIS data. Evolution of river terraces was not only governed by climatic factors but tectonic ones too. Incision rate of the Danube, and uplift rate of the Transdanubian Range (TR) was around 0.1-0.3 mm/a in the marginal zones of the TR (mostly based on the published U-series data) and was above 1 mm/a in its axial zone (based on 3He exposure age dating of strath terraces).

– According to a detailed geomorphological investigation of the different channel-planform morphologies in the Middle Tisza region and Sajó-Hernád alluvial fan, six phases of river pattern change and four incision periods were detected during the last 20,000 years.

– Wind polished rock surfaces dated by in situ produced cosmogenic 10Be suggest that deflation was active in Hungary as early as 1.5 Ma ago. According to these exposure age data, Pleistocene denudation rate of the study area (Balaton Highland) was 40-80 m/Ma.

– In sand covered areas the alternations of wind-blown layers and buried fossil soils provide information about climate and environment changes. In this study, periods of sand movement were mostly determined by optically stimulated luminescence (OSL) dating methods and five aeolian sand accumulation periods were recognised during the last 25 000 years.

– A new loess stratigraphical view was elaborated using the most recent dating methods (luminescence, AAR). The lower part of Mende Upper (MF1-2) pedokomplex is suggested to represent the last interglacial period (MIS 5e). During the last interglacial/glacial period (MIS 5 - MIS 2) several soil-forming periods existed but the preservation of these paleosoils is variable depending on their paleogeomorphological position.

Exploration in a mature basin requires a detailed classification and standardisation of rock stratigraphy to adequately comprehend the depositional history and prospect architecture. The pre-Quaternary Stratigraphic Nomenclature of the Netherlands compiled by Van Adrichem Boogaert & Kouwe in 1993 provided a consistent framework for use by the Dutch geological community. Over the past twenty years, new biostratigraphic techniques and continued exploration in the Netherlands have provided additional stratigraphic information. Based on this information the Late Jurassic lithostratigraphy in particular, shows significant inaccuracies. The Callovian-Ryazanian strata from the northern offshore of the Netherlands' territorial waters, termed the Central Graben Subgroup and Scruff Group, reveal a complex sedimentary history. The combination of non-marine to shallow marine lateral facies changes, repetitive log and facies characteristics in time, sea-level and climate change, salt tectonics and structural compartmentalisation hamper straightforward seismic interpretation and log correlation. Recognition of three genetic sequences by Abbink et al. in 2006 enabled an improved reconstruction of the geological history. Further improvements in refinement and reliability of the stratigraphy together with new information on the facies and ages of the successions and about the subsequent tectonostratigraphic development of the northern Dutch offshore area form the basis of the present revision. As a result, earlier lithostratigraphic models have been changed and new lithostratigraphic relationships and names are introduced in this paper.

Large conglomerate lenses occur in a fine-grained siliciclastic succession of the Singhbhum craton, eastern India. They overlie an Archaean orthogneiss, from which they are separated by a palaeosol. Neither the conglomerates nor the directly overlying rocks have been dated, but the conglomerate unit is assumed to have also an Archaean age. The conglomerate lenses occur within a succession of pelitic and mafic schists, and the depositional environment of this conglomerate/schist unit had not been clarified thus far. On the basis of a combination of the vertical and horizontal distribution of the conglomerates, their stratigraphic position and analysis of their sedimentological characteristics and the sedimentological context, it is concluded that the succession must have developed in a fluvial lowland environment where volcanic input contributed significantly to the sediment accumulation.

In this study, seismic stratigraphic criteria have been used to characterise the evolution of the Southern North Sea (SNS) shelf-delta system that progressively filled the Southern North Sea basin during Plio-Pleistocene times. Based on the prograding and down-stepping architecture of the shelf-delta sequence it is inferred that deposition occurred during a time of high sediment supply and overall sea-level lowering. During this time the delta slopes failed several times, creating at least 30 internally coherent Mass Transport Deposits (MTDs) mainly grouped in common areas, affecting the same clinoform set and partially sharing the basal shear surface (groups of MTDs). The most important features of the studied MTDs are 1) the dominance of brittle deformation; 2) the small amount of material removal from the headwall domain (lack of completely depleted areas above the basal shear surface); and 3) the lack of an emergent toe domain above the un-failed sediment located basinward, although proper confining geometries for the MTD are not detected. Therefore, the studied MTDs can neither be classified as frontally confined nor as frontally emergent but they are a new intermediate type of submarine landslides which has not been described before. These characteristics suggest that the mass movement ceased relatively soon after initiation of failure. Incisions on top of the MTDs suggest the presence of erosive flows. These flows were probably generated due to a concentration of the drainage in the negative morphology the failure event left behind in the upper sector of the slope. The stronger progradational character of the reflections on top of MTDs confirms a concentration of drainage after the erosional phase too.

The interplay between high sediment supply and constant or even decreasing accommodation space (caused by constant or decreasing sea-level) is supposed to be the main precondition for slope instability for most of the MTDs in this study area. Slope failures themselves can also be considered a preconditioning factor by the creation of local very high sedimentation rates (see groups of MTDs). Salt-induced seismicity and storm waves' effect superimposed on high frequency sea level fall are considered the most important triggering factors.

In July 2007 an important archaeological find was made in the Op de Schans loess pit near Kesselt (Belgian Limburg) immediately to the west of the Dutch city of Maastricht. During an archaeological rescue dig, three Lower Palaeolithic artefacts were recovered from the infill of an ancient erosion gully: a bifacial side-scraper, an atypical biface and a cortical flake. Typologically, the artefacts can be classified as Acheulean. In this region, harbouring several such brickyard pits, these are the oldest artefacts yet found, prompting further investigations into the stratigraphic position of the archaeological layer. The Op de Schans pit, which has yielded several Middle Palaeolithic occupation horizons, is located in the middle of an ancient sediment trap. Because of this exceptional geomorphologic situation, multiple ancient sediments have been preserved which elsewhere were entirely removed during subsequent erosion phases. Here five separate loess beds with intercalated interglacial palaeosols are present, overlying the deposits of the River Maas (Meuse). This sequence has been used as a hypothetical framework for elaborating a chronostratigraphic model. The archaeological level in question, discovered at the base of a subsequently infilled erosion gully, can most likely be chronostratigraphically dated to around the start of Marine Isotope Stage 10 (MIS 10), in the era of the Pottenberg discordance (approx. 390 ka). However, the possibility cannot be excluded that the gully in which the artefacts were found dates from an early phase of MIS 12 (approx. 480 ka). The age may in fact be greater still, as the artefacts have been eroded out of their original, primary context and subsequently deposited in the gully. Hypothetically, they may even have been taken up from the Maas loam of the Kesselt Maas terrace (MIS 13) that here is situated directly below the archaeological horizon. This would make the maximum age of the artefacts recovered from the gully around 500 ka.

In 1992, the well L9-7, drilled by the Nederlandse Aardolie Maatschappij (NAM) unexpectedly found a thick previously unknown sandstone interval with excellent reservoir characteristics in the Middle Buntsandstein (Triassic) of the Dutch Northern Offshore: the ‘Fat Sand’. A follow-up well, L9-8, found this reservoir gas-bearing in an accumulation that turned out have recoverable reserves of circa 1 Tcf of gas distributed over several fault compartments. This serendipitous discovery led to a frantic period in NAM's office trying to understand the setting of this local sand development and, most importantly, assess follow-up potential; could this sand be present elsewhere in a trapping configuration? The local depocentre in which the Fat Sand accumulated is considered to be caused by local extension along a strongly listric fault soling out on the top of the Zechstein Salt. This supra-salt fault seems to be caused by early east-west extension in the Dutch northern offshore. The shape of the fault plane was strongly influenced by the presence of the nearby Zechstein Salt, and by early salt flow, which was also triggered by E-W extension.

Aeolian dust deposits can be considered as one of the most important archives of past climatic changes. Alternating loess and paleosol strata display variations of the dust load in the Pleistocene atmosphere. By using the observations of recent dust storms, we are able to employ Late Pleistocene stratigraphic datasets (with accurate chronological framework) and detailed granulometric data for making conclusions on the atmospheric dust load in the past. Age-depths models, created from the absolute age data and stratigraphic interpretation, allow us to calculate sedimentation rates and dust fluxes, while grain-size specifies the dry-deposition velocity, i.e. the atmospheric residence time of mineral particles. Thus, the dust concentration can be expressed as the quotient of the dust flux and gravitational settling velocity. Recent observations helped to clarify the mechanisms behind aeolian sedimentation and the physical background of this process has nowadays been well established. Based on these two, main contrasting sedimentary modes of dust transport and deposition can be recognised: the short suspension episodes of the coarse (silt and very fine sand) fraction and the long-range transport of a fine (clay and fine silt) component. Using parametric curve fitting the basic statistical properties of these two sediment populations can be revealed for Pleistocene aeolian dust deposits, as it has been done for loess in Hungary. As we do not have adequate information on the magnitude and frequency of the Pleistocene dust storms, conclusions could only be made on the magnitude of continuous background dust load. The dust concentration can be set in the range between 1100 and 2750 μg/m3. These values are mostly higher than modern dust concentrations, even in arid regions. Another interesting proxy of past atmospheric conditions could be the visibility, being proportional to the dust concentration. According to the known empirical dust concentration – visibility equations, its value is around 6.5 to 26 kilometres.

Loess deposits in the Vojvodina region, northern Serbia, are among the oldest and most complete loess-paleosol sequences in Europe to date. These thick sequences contain a detailed paleoclimatic record from the late Early Pleistocene. Based on the correlation of detailed magnetic susceptibility (MS) records from Vojvodina with the Chinese loess record and deep-sea isotope stratigraphy we here reconfirm and expand on a stratigraphic model of the Vojvodinian loess-paleosol chronostratigraphic sequence following the Chinese loess stratigraphic system.

Variations in MS, dust accumulation rates, and the intensity of pedogenesis demonstrate evidence for a Middle Pleistocene climatic and environmental transition. The onset of loess deposition in Vojvodina also indicates a direct link between dust generation in Europe and that in the interior of Eurasia since the Early Pleistocene. The youngest part of the Early Pleistocene and oldest part of the Middle Pleistocene is characterised by relatively uniform dust accumulation and soil formation rates as well as relatively high magnetic susceptibility values. In contrast, the last five interglacial-glacial cycles are characterised by sharp environmental differences between high dust accumulation rates during the glacials and low rates observed during soil development. The data presented in this study demonstrate the great potential of Vovjodina's loess archives for accurate reconstruction of continental Eurasian Pleistocene climatic and environmental evolution.

Geothermal low enthalpy heat in non-magmatic areas can be produced by pumping hot water from aquifers at large depth (>1 km). Key parameters for aquifer performance are temperature, depth, thickness and permeability. Geothermal exploration in the Netherlands can benefit considerably from the wealth of oil and gas data; in many cases hydrocarbon reservoirs form the lateral equivalent of geothermal aquifers. In the past decades subsurface oil and gas data have been used to develop 3D models of the subsurface structure. These models have been used as a starting point for the mapping of geothermal reservoir geometries and its properties. A workflow was developed to map aquifer properties on a regional scale. Transmissivity maps and underlying uncertainty have been obtained for 20 geothermal aquifers. Of particular importance is to take into account corrections for maximum burial depth and the assessment of uncertainties. The mapping of transmissivity and temperature shows favorable aquifer conditions in the northern part of the Netherlands (Rotliegend aquifers), while in the western and southern parts of the Netherlands aquifers of the Triassic and Upper Cretaceous / Jurassic have high prospectivity. Despite the high transmissivity of the Cenozoic aquifers, the limited depth and temperature reduce the prospective geothermal area significantly.

The results show a considerable remaining uncertainty of transmissivity values, due to lack of data and heterogeneous spatial data distribution. In part these uncertainties may be significantly reduced by adding well test results and facies parameters for the map interpolation in future work. For underexplored areas this bears a significant risk, but it can also result in much higher flowrates than originally expected, representing an upside in project performance.

Reconstruction of a complete Quaternary record of climatic changes in the northeastern Qinghai-Tibetan Plateau is not well obtained, because of high relief and extensive surface erosion. In this study, two long cores obtained from thick loess deposits in the region, both contain clear alternations of loess and paleosols, indicating distinct climate changes during the Quaternary. The palaeomagnetic stratigraphy and optically stimulated luminescence dating indicate that the loess deposition began approximately 2.0 Ma ago, with continuous accumulation until the Holocene. Dust accumulation rates in this region are much higher than those in the central Chinese Loess Plateau, suggesting an extended dust source and/or robust transport agent. Variations of magnetic susceptibility of the loess are a good proxy index of warm/wet and cold/dry alternations and are correlated with the intensity of pedogensis. The magnetic susceptibility record reveals that a relatively cold/dry climate dominated the northeastern Qinghai-Tibetan Plateau in the Quaternary, punctuated by warm/wet phases. A stepwise strengthening of the plateau summer monsoon, with a significant strengthening at around 1200-1000 ka and at least 7 phases of strengthening of the plateau summer monsoon in the past 800 ka are interpreted from the core data. The cores provide evidence that strengthened warm/wet climates occurred at around 80-130, 190-250, 290-340, 385-420, 500-625, 690-720 and 755-780 ka, which may correlate to warm/wet phases in the Qinghai-Tibetan Plateau. The palaeoclimate changes probably were regulated by the glacial-interglacial alternations.

A resource assessment methodology has been developed to designate prospective high permeable clastic aquifers and to assess the amount of potential geothermal energy in the Netherlands. It builds from the wealth of deep subsurface data from oil and gas exploration and production which is publicly and digitally available. In the resource assessment various performance indicator maps have been produced for direct heat applications (greenhouse and spatial heating). These maps are based on detailed mapping of depth, thickness, porosity, permeability, temperature and transmissivity (methodology presented in other papers in this NJG issue). In the resource assessment analysis 14 lithostratigraphic units (clastic aquifers) have been considered, ranging in age from the Permian to the Cenozoic. Performance maps have been made which include a) the expected doublet power (MWth) to be retrieved; b) the number of houses or hectares that can be heated from one doublet; and c) a potential indicator map, which provides insight in subsurface suitability for specific applications from a techno-economic perspective. To obtain a nationwide overview of the resource potential in terms of recoverable geothermal energy, a progressive filtering approach was used from total heat content of the reservoirs (Heat In Place – HIP) via the heat that can potentially be recovered (Potential Recovery Heat – PRH) to energy maps taking into account a techno-economic performance evaluation (Recoverable Heat – RH). Results show that the HIP is approximately 820,000 PJ which is significantly more than previous estimates of around 90,000 PJ. This considerable increase in geothermal energy potential is the result of accurate geological mapping of key reservoir properties and the development of state-of-the-art techno-economic performance assessment tools that performs Monte Carlo simulation. Moreover, for the previous estimates boundary conditions were set with the aim to compare the geothermal potential between different EU countries (Rijkers & Van Doorn, 1997). Taking into account techno-economic aspects, the RH is in the order of 85,000 PJ. This is equivalent to ~70% of the ultimate recoverable gas of the Slochteren Gas field. In total over 400 maps have been created or used as input for the resource assessment. Together, they provide comprehensive information for geothermal energy development from various stakeholder perspectives. The maps can be interactively assessed in the web-based portal ThermoGIS (www.thermogis.nl). This application complements existing subsurface information systems available in the Netherlands and supports the geothermal community in assessing the feasibility of a geothermal system on a regional scale.

In a ~60 m long record reflecting the period from 284 ka to 27 ka we analysed grain size distributions (GSD), organic carbon content, and aquatic pollen assemblages at 1-cm increments. The 4768-points time series show with ~60 yr resolution the dynamic history of Lake Fúquene (2540 m alt., 4° N lat.) of the northern Andes during two full interglacial-glacial cycles. GSD show proportions of clay, fine silt, coarse silt, and sand evidencing the location of the sediment source (proximal vs distal) in relation to the drilling site, and available energy to transport sediments in the catchment area. Loss-on-ignition (LOI) values reflect estimates of the abundance of organic matter (OM) in the sediments. Aquatic pollen were grouped into assemblages characteristic of deep water, shallow water, swamp, and wet lake shore environments, reflecting a hydrological gradient sensitive for lake level changes.

The End-Member Modelling Algorithm (EMMA) showed that 4 end-members (EMs) explain an optimal proportion (70%) of the observed variation. EMMA is able to unmix GSD of lacustrine sediments in a genetically meaningful way allowing EMs to be interpreted in past depositional and environmental settings. Most unexplained variability is located in the fraction of coarse sediment. OM content was estimated on the basis of LOI data and formed a fifth EM that mainly indicates presence of peat. Changes concur with submillennial-scale variability established in other proxies from this record (Groot et al., 2011). Periods with distinct sediment compositions are 284-243 ka (mainly MIS 8), 243-201 ka (mainly MIS 7), 201-179 ka (mainly MIS 7/6 transition), 179-133 ka (mainly MIS 6), 133-111 ka, (mainly MIS 5e) 111-87 ka (mainly MIS 5d-5b), 87-79 ka (mainly MIS 5a), 79-62 ka (mainly MIS 4), and 62-27 ka (MIS 3) showing sedimentological regimes are climate driven.

In this paper we present a probabilistic fast model for performance assessment of geothermal doublets for direct heat applications. It is a simple yet versatile and multipurpose tool. It can be well applied in better understanding the sensitivity of performance to key subsurface parameters and depth trends therein, and for assessing the probability of success for geothermal projects under technical and financial constraints.

The underlying algorithms deliver a sensible accuracy given the uncertainties associated with geothermal projects at exploration state. A public release of the software, available under the name of DoubletCalc, is easy to handle and requires a limited set of input parameters. Thanks to an open source code, DoubletCalc can be implemented in other software applications and extended as it has been implemented for the integration into the national geothermal information system in the Netherlands (ThermoGIS, 2011).

Apart from its application for site assessments, the tool can be integrated into automated workflows processing faster representations of key aquifer properties and capable to produce indicative maps for predicted doublet power, economic feasibility and prediction of cumulative amount of heat that can be recovered. These capabilities are specifically important for decision support for policymakers while assessing the effects of particular insurance schemes and funding mechanisms.

DoubletCalc cannot and is not intended to substitute geologic exploration approaches. As exploration measures, such as seismic surveys are cost intensive, DoubletCalc can be used to focus geothermal exploration on areas and sites where an enhanced probability of success can be expected.

Soft rock pediments developed in South Moravia in some places as early as the Tertiary, in other places as late as the Pleistocene. Depending on local environmental factors the pediments developed either due to backwearing or downwearing. The most suitable conditions for the evolution of the Pleistocene pediments were during transitional periods between warm and cold climate phases and especially during periglacial conditions between cold and warm periods in the Middle and Late Pleistocene. In agricultural landscapes, the studied relief features continue to develop also at present.