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A long-term hydrogeochemical data set is used in this study to evaluate the water quality and hydrogeochemical evolution of shallow groundwater in a Quaternary deposit. A multivariate statistical method, hierarchical cluster analysis (HCA), is applied to overcome the problem of a large number of data points in the integration, interpretation and representation of the results. HCA is applied to a subgroup of the hydrogeochemical data set to evaluate their usefulness to classify the groundwater bodies. This subgroup consists of 27 groundwater wells and 15 variables [pH, total dissolved solids, electrical conductivity (EC), Na + , Ca 2+ , Mg 2+ , K, HCO 3 − , Cl − , SO 4 2− , Fe, Mn, NH 4 , NO 3 − and SiO 2 ]. Only 12 chemical variables were used for the analysis. Four clusters have been identified: C1–C4, with two main prevalent facies, Na–HCO 3 and Ca–HCO 3 . The hydrogeochemical evolution of shallow groundwater is governed by the processes of precipitation, weathering, dissolution and ion exchange.

Quaternary strata in China mainly comprise continental deposits in a variety of depositional settings. The continental Quaternary in temperate northern China consists mainly of eolian and fluvio-lacustrine deposits; that in subtropical southern China, mainly of vermiculated red soils, cave/fissure deposits, and fluvio-lacustrine deposits; and that in the alpine Tibetan Plateau, mainly of fluvio-lacustrine and piedmont deposits. The marine Quaternary in China consists of detrital deposits and biogenic reef deposits. The integration of biostratigraphy, magnetostratigraphy, climatostratigraphy and an astronomically calibrated chronology has led to the establishment of high-precision climatochronostratigraphic timescales for the detrital marine Quaternary in the South China Sea and the loess-paleosol sequence in the Chinese Loess Plateau. Extremely high-precision 230 Th dating has provided a high-precision absolute age model for cave stalagmites over the past 640000 years as well as high-resolution oxygen isotope records representing orbital- to suborbital-scale climate changes. By combining magnetic stratigraphy and biostratigraphy, robust chronostratigraphic frameworks for non-eolian continental Quaternary deposits on the scale of Quaternary geomagnetic polarities have been established. The continental Pleistocene Series consists, from oldest to youngest, of the Nihewanian Stage of the Lower Pleistocene, the Zhoukoudianian Stage of the Middle Pleistocene, and the Salawusuan Stage of the Upper Pleistocene. Stages of the continental Holocene Series have not yet been established. This review summarizes recent developments in the Quaternary chronostratigraphy of representative Quaternary strata and associated faunas, and then proposes an integrative chronostratigraphic framework and a stratigraphic correlation scheme for Quaternary continental strata in China. In the near-future, it is hoped to establish not only a Chinese continental Quaternary climatochronostratigraphic chart on the scale of glacial-interglacial cycles but also a Quaternary integrative chronostratigraphic chart including both continental and marine strata in China.

The young water fraction (Fyw*), defined as the fraction of catchment outflow with transit times of less than 2–3 months, is increasingly used in hydrological studies that exploit the potential of isotope tracers. The use of this new metric in catchment intercomparison studies is helpful to understand and conceptualize the relevant processes controlling catchment functioning. Previous studies have shown surprising evidence that mountainous catchments worldwide yield low Fyw*. These low values have been partially explained by isolated hydrological processes, including deep vertical infiltration and long groundwater flow paths. However, a thorough framework illustrating the relevant mechanisms leading to a low Fyw* in mountainous catchments is missing. The main aim of this paper is to give an overview of what drives Fyw* variations according to elevation, thus clarifying why it generally decreases at high elevation. For this purpose, we assembled a data set of 27 study catchments, located in both Switzerland and Italy, for which we calculateFyw*. We assume that this decrease can be explained by the groundwater storage potential, quantified by the areal extent of Quaternary deposits over a catchment (Fqd), and the low-flow duration (LFD) throughout the period of isotope sampling (PoS). In snow-dominated systems, LFD is strictly related to the snowpack persistence, quantified through the mean fractional snow cover area (FSCA). The drivers are related to the catchment storage contribution to the stream that we quantify by applying a cutting-edge baseflow separation method to the discharge time series of the study sites and by estimating the mean baseflow fraction (Fbf) over the PoS. Our results suggest that Quaternary deposits could play a role in modulating Fyw* elevation gradients via their capacity to store groundwater, but subsequent confirmation with further, more detailed geological information is necessary. LFD indicates the proportion of PoS in which the stream is sustained and dominated by stored water coming from the catchment storage. Accordingly, our results reveal that the increase of LFD at high elevations, to a large extent driven by the persistence of winter snowpacks and the simultaneous lack of a liquid water input to the catchments, results in lower Fyw*. In our data set, Fbf reveals a strong complementarity with Fyw*, suggesting that the latter could be estimated as Fyw*≃1-Fbf for catchments without stable water isotope measurements. As a conclusion, we develop a perceptual model that integrates all the results of our analysis into a framework for how hydrological processes control Fyw* according to elevation. This lays the foundations for an improvement of the theory-driven models.

The DRASTIC method is one of the most widely used groundwater vulnerability assessment techniques. In areas where the main useful aquifers are covered with an extra layer of diverse sediments, a further modification of the DRASTIC method is required for a more precise vulnerability estimation. In this article, the DRASTIC method was improved in areas characterized by a layer of diverse Quaternary deposits remarkably influencing the infiltration conditions. Three parameters were modified: (1) the D-parameter was adjusted to consider the overlying Quaternary deposits that, in some cases, make the aquifer confined, (2) the S-parameter was replaced by the Quaternary sediment-type parameter to assess the hydraulic characteristics of the highly variable deposits, and (3) the I-parameter was replaced by the thickness of the Quaternary deposits parameter to describe the distance from the ground surface to the main useful aquifer. The original and modified DRASTIC methodology was applied in an area with glacial sediments in Central Estonia. Comparing the results using the original and the modified DRASTIC method to a former Estonian groundwater vulnerability method showed that the DRASTIC method was significantly improved and could, thus, be successfully applied in other areas characterized by a heterogenous Quaternary sediment cover.

Tectonic deformation along the External Dinarides fold-and-thrust belt is slow, with transpressional crustal strain redistributed along multiple faults. Some of these faults reach the surface along the NE Adriatic coast as part of the strike-slip Dinaric Fault System (DFS). This work uses new high-resolution sub-bottom seismic data to characterize the geodynamic significance of active surface deformation in the offshore sector of the Kvarner area, Croatia. Seismic profiles reveal gentle folding in early Quaternary strata that is associated with contractional deformation in the Rijeka Bay; yet, active faults are documented only in narrow zones along the DFS, and specifically in the Vinodol and Velebit channels. Fault Mechanism Solutions (FMS) confirm that a strike-slip tectonic regime exists in the study area, but the strike of surface faults and FMS data are discrepant, probably as a result of strain dissipation along (creeping? ) faults whose geodynamic response differs from deep-rooted seismogenic structures. This differing geodynamic response causes important caveats when linking surface deformation to deeper seismogenic structures which are, offshore Kvarner, either blind structures or currently deforming under distinct stress conditions to near-surface faults. Crucially, this work presents the first geological evidence for active faulting along the DFS in Croatia, a piece of information deemed critical for future geohazard assessments.

Small communities living in mountainous terrain in Hubei province are often affected by landslides. Previous studies by the China Geological Survey focused on the 1:100 000 scale. Therefore, a more detailed assessment, especially at the community level, is urgently required by local governments for risk management. In this study, we conducted a more detailed semiquantitative landslide and risk assessment at the community level using a scale of 1:10 000. We applied the probabilistic method to assess landslide spatial, temporal, and size probabilities, while the hazard and risk assessment were considered for four return periods (5, 10, 20, and 50 years) and two size scenarios (landslide volume). The spatial probability from susceptibility mapping with an accuracy of 84 % indicates that the major controlling factors are Quaternary deposits and weathered eluvium from Ordovician limestones. This study revealed that most building areas in hazard maps are at the foot of major slopes with very high hazard probabilities, and therefore we computed the potential loss of life and property for each slope. The results reveal that 1530 people and USD 18 million worth of property were at risk of landslides within a 50-year return period and a landslide volume of 50 000 m3. The longer the return period is, the higher the hazard probability is. Compared with the classic inverse gamma and power law distribution of landslide magnitude and frequency, the function by the ordinary least squares method is more suitable for landslide size probability analysis of the study area. According to these methods, the proposed procedure of landslide risk assessment proves more useful than the existing data from the 1:100 000 scale in western Hubei, China.

The Jiti–Khuji Diana interfluve of the Himalayan piedmont zone has been considered to reanalyse the tectonic character of the Main Boundary Thrust (MBT) and Main Frontal Thrust (MFT), which are two major east–west trending structural units of the Himalayan orogen. The MBT marks a tectonic boundary between the Lesser and sub-Himalayan sequences (Gansser, Geology of Himalayas, Wiley Interscience, New York, 1964), while the MFT is the youngest deforming front that carries the Siwalik Group of rocks over the Quaternary deposits (Yin, Earth Sci Rev 76:1–131, https://doi.org/10.1016/j.earscirev.2005.05.004 , 2006). This area is dissected by three main steams of the Jaldhaka system, i.e. rivers Jiti, Khuji Diana, and Thaljhora; amongst which the Thalhjora flows from east to west and the other two rivers flow roughly from NNE to SSW. Thaljhora and Chalsa fault scarps are observed, respectively, at and near the MBT and MFT. The present research focuses on significance of active Thaljhora and Chalsa fault scarps, which represent the monocline faults that deformed the geomorphic landscape. The displacement along these faults have formed a synform that uplifted over time and formed river terraces by incision processes of rivers. The analysis of morphometric indices confirms the recent neotectonic activities going on in the region. The deformed landforms, emerged as terrace and Doon-shaped valley, are observed between the Jiti fault (MBT) and Chalsa scarp (MFT). The doon-shaped valley is developed as a flat-lying surface situated between the Jiti fault and Thaljhora scarp. This study has deciphered the application of morphometric indices to study the active neotectonics.

This paper discusses the geological and hydrogeological features of Quaternary deposits in Tianjin as well as the geohazards related to groundwater hydrology in this region. The soft soil deposits, comprising silt, sand, silty clay and clay, are composed of four aquifer groups. In the first aquifer group, one phreatic aquifer and two confined aquifers have relationships with underground construction in the urban area. These three aquifers are separated by two aquitards and collectively form a multi-aquifer system. During geotechnical construction, potential geohazards present are related to the groundwater, which include water-in-rushing, quicksand and piping hazards. To prevent the aforementioned geohazards, dewatering is conducted; however, groundwater pumping may result in large settlements of the surrounding ground. To reduce pumping-induced settlement, the dewatering–waterproofing system has been adopted. According to the characteristics of the subsoil, excavation depth and the surrounding environment, the dewatering system can be divided into five patterns. In the first four patterns, when pumping is conducted in the excavation pit, the groundwater head in the adjacent aquifers outside the pit decreases due to the leakage effect of the aquitards located between the aquifers. In the fifth pattern, waterproof curtain has cut off the aquifers completely and dewatering in the pit cannot result in settlement around excavation pit. To avoid geohazards related to groundwater hydrology, countermeasures recommended include construction of an effective waterproof curtain, selection of a reasonable excavation dewatering pattern and withdrawal of required groundwater.

Colluvial landslides develop in loose Quaternary deposits, with deformation generally being progressive and crack development dominant in the sliding mass surface layer. With the Tanjiawan landslide in the Three Gorges Reservoir (China) as a case study, field investigations, deformation monitoring, and groundwater level monitoring data were integrated to analyze the landslide deformation characteristics and elucidate the influence of cracks on its deformation. We used numerical simulations, including the finite element and discrete element methods, for investigating the progressive deformation mechanism of rainfall-triggered landslides in the accumulation layer and predicting the failure process. The results indicated that crack formation instigated a preferential seepage channel in the shallow layer of the sliding mass, rainfall infiltration along cracks generated water pressure, and the landslide gradually morphed from a stable into a “step-like” progressive deformation state. Preferential flow inside the cracks effectively elevated the groundwater level within the landslide, and either the number or depth of cracks significantly affected the groundwater seepage field, thereby influencing slide stability. Geological conditions controlled the deformation and failure processes of each landslide section. The uplifted bedrock on the right side blocked the sliding process of the rear sliding mass, and the middle and front sliding masses moved faster but the sliding distance was shorter. The deformation trend is deformation, crack formation, preferential flow occurrence, crack extension, and deformation. The ultimate cause of failure was a steep rise in groundwater level following short duration heavy rainfall or long duration light rainfall.

Increasing evidence has emerged that Mn derived from drinking water could be a health risk, especially for children. This study aimed to provide more information on the variation in Mn concentrations in well water and factors that affect manganese concentrations in groundwater in the natural environment. The geochemical data consisted of analyses of single water samples (n = 5311) that were taken only once and data from monitoring sites where water samples (n = 4607) were repeatedly taken and analyzed annually from the same wells. In addition, the well-specific results from six wells at monitoring sites were described in detail. We obtained the data on water samples from the groundwater database of Geological Survey of Finland. In single samples, Mn concentrations varied from < 0.02 µg/l to 5800 µg/l in bedrock well waters and up to 6560 µg/l in Quaternary deposit well waters. Results from single water samples from bedrock wells and Quaternary deposit wells indicated that the dissolved oxygen content has an inverse association with the Mn concentration. When the dissolved oxygen O2 levels were lower, the Mn concentrations were higher. No clear association was found between the Mn concentration and the pH or depth of the well for single samples. Part of Mn was particle bound, because total Mn was higher than soluble Mn in most measured samples. In the monitoring survey, large variation in Mn concentrations was found in bedrock well water in Kemijärvi, 114–352 µg/l, and in dug well water in Hämeenkoski, 8.77–2640 µg/l. Seasonal and spatial variability in Mn concentrations in water samples from two bedrock wells was large at monitoring sites in northern Finland. Variability in the Mn concentrations in groundwater can be large, even in the same area. These data suggest that single measurements of the Mn concentration from a water source may not reveal the Mn status, and measurement of both the total and soluble Mn concentrations may be recommended.