The International Association of Hydrogeologists (IAH): reflecting on 60 years of contributions to groundwater science and water management

The 60th anniversary of the founding of the International Association of Hydrogeologists (IAH) is an important milestone that allows pause for reflection on how the association has evolved over the years and the contributions it has made to groundwater science and water management. IAH was founded in 1956 at the 20th International Geological Congress and developed rapidly during the 1980s and 1990s in response to a growing global interest in groundwater mapping and in sound approaches to resource protection and sustainable aquifer management. Incorporated in 2000, IAH has now secured its position as the world’s leading international association specialising in groundwater with over 4,100 members in 131 countries. Much credit for this success must go to members, past and present, whose individual efforts and collaboration with sister institutions are documented here. These members have shaped the association’s goals and contributed selflessly to its scientific programmes, publications and educational and charitable activities. Looking ahead to the next 60 years, it is essential that IAH does not rest on past achievements but listens and adjusts to the needs of members while continuing to pursue its mission of furthering the understanding, wise use and protection of groundwater resources throughout the world.     

Geochemical tracing and hydrogeochemical modelling of water–rock interactions during salinization of alluvial groundwater (Upper Rhine Valley,France)

In the southern Upper Rhine Valley, groundwater has undergone intensive saline pollution caused by the infiltration of mining brines, a consequence of potash extraction carried out during the 20th century. Major and trace elements along with Sr and U isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect conservative mixing between saline waters resulting from the dissolution of waste heaps and one or more unpolluted end-members. The results imply the occurrence of interactions between host rocks and polluted waters, and they suggest that cationic exchange mechanisms are the primary controlling process. A coupled hydrogeochemical model has been developed with the numerical code KIRMAT, which demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process controlling the geochemical evolution of the groundwater. The model requires only a small amount of montmorillonite (between 0.75% and 2.25%), which is in agreement with the observed mineralogical composition of the aquifer. The model also proves that a small contribution of calcite precipitation/dissolution takes places whereas other secondary mineral precipitation or host rock mineral dissolution do not play a significant role in the geochemical signature of the studied groundwater samples. Application of the model demonstrates that it is necessary to consider the pollution history to explain the important Cl, Na and Ca concentration modifications in groundwater samples taken over 2 km downstream of waste heaps. Additionally, the model shows that the rapidity of the cationic exchange reactions insures a reversibility of the cation fixation on clays in the aquifer.     

The geographic distribution of Sr isotopes from surface waters and soil extracts over the island of Bornholm (Denmark) – A base for provenance studies in archaeology and agriculture

In this paper we report the Sr isotope signatures, and Sr, Al and Na concentrations of 30 surface waters (lakes/ponds and rivers/creeks) and 19 soil sample extracts from the island of Bornholm (Denmark) and present a categorized ⁸⁷Sr/⁸⁶Sr value distribution map that may serve as a base for provenance studies, including archaeological migration and authenticity proof for particular food products. The Sr isotopic compositions of surface waters range from ⁸⁷Sr/⁸⁶Sr = 0.7097–0.7281 (average 0.7175 ± 0.0049; 1σ), whereas 0.1 M HNO₃, 0.05 M HNO₃, and 0.01 M CaCl₂ soil extracts range from ⁸⁷Sr/⁸⁶Sr = 0.7095–0.7197 and define somewhat lower but statistically indistinguishable averages of 0.7125 ± 0.003 (1s). These compositions are lower than the values expected from the Precambrian granitoid basement (⁸⁷Sr/⁸⁶Sr = 0.758–0.944), and from the overlying, mainly clastic Paleozoic sediments. Combined Sr isotope composition vs. Sr, Na and Al concentration relationships of soil extracts imply that lowering of the isotopic composition of leachable Sr on Bornholm results as a consequence of significant admixture to this fraction of Sr deposited as marine salts (aerosols), and that rainwater only has a minor influence on the Sr budget of the surface waters. Positively correlated Al/Na and [1/Sr] vs. ⁸⁷Sr/⁸⁶Sr relationships in soil extracts and surface waters indicate that the surface run-off on Bornholm is characterized by two predominant sources, namely marine aerosols (sea salts) with high Sr and low ⁸⁷Sr/⁸⁶Sr values, and a source with lower [Sr] delivering radiogenic Sr to the surface waters, which we equate with Sr leached from the products of mineral weathering (soils).A feasibility study for using Sr isotopic compositions of surface waters and soil extracts as a proxy for bioavailable Sr signatures was performed with a few samples collected in the vicinity of the eleventh century AD Ndr. Grødbygård cemetery site in SW Bornholm, from where Sr isotope compositions of modern fauna samples and tooth enamel of humans buried in the cemetery have been reported. Waters and soil extracts studied herein from around this site range from ⁸⁷Sr/⁸⁶Sr = 0.7104–0.7166 and correspond to Sr compositions extracted from snail shells in this area which span a range of ⁸⁷Sr/⁸⁶Sr = 0.7095–0.7160. Some human tooth enamel is characterized by more radiogenic values (⁸⁷Sr/⁸⁶Sr up to 0.718) which points to a possible provenance of these humans from the granite–gneiss terrain in the north of the island and/or to immigration of these humans in their childhood from other places (for example from mainland Sweden) to Bornholm. If the total compositional range of ⁸⁷Sr/⁸⁶Sr = 0.709–0.718 (n = 44) recorded in human enamel from the Ndr. Grødbygård site is considered representative for the variation of bioavailable Sr on Bornholm, then our soil leachate and surface water data entirely covers this range. We therefore propose that the combination of Sr isotope analyses of surface waters and soil leachates are an easy, fast and relatively cost efficient way to characterize a local bioavailable ⁸⁷Sr/⁸⁶Sr signature, and consequently propose that the overall average of ⁸⁷Sr/⁸⁶Sr = 0.7153 ± 0.0048 (1σ; n = 50) can be taken as a band for bioavailable Sr fractions suitable to discriminate between local and non-local signatures in provenance studies in the field of archaeology and for food and plant authenticity control in agricultural applications.     

Model of hydrological behaviour of the anthropized semiarid wetland of Las Tablas de Daimiel National Park (Spain) based on surface water–groundwater interactions

Las Tablas de Daimiel National Park (TDNP) in Spain is one of the most important semiarid wetlands of the Mediterranean area. The inversion of the regional groundwater flow, primarily due to overexploitation and inadequate aquifer management, has led to degradation. The system has turned from a groundwater discharge zone into a recharge zone, and has remained mostly dry since the 1980s. High heterogeneity and complexity, enhanced by anthropogenic management action, hampers prediction of the surface–groundwater system response to flooding events. This study analyses these interactions and provides empirical evidence to define a conceptual model of flooding-infiltration-groundwater dynamics through the application of a few simple analysis tools to basic hydrological data. Relevant surface water–groundwater interactions are mainly localized in the left (west) margin of TDNP, as confirmed by the fast responses to flooding observed in the hydrochemic, hydrodynamic and isotopic data. During drying periods, small artificial and/or low-flow natural floods are followed by infiltration of evaporated poor-quality ponding water into saline low-permeability layers. The results allow an improved understanding of the hydrological behaviour essential to support efficient management practices. The relative simplicity of the methodology allows for its application in other similar complex groundwater-linked wetlands where detailed knowledge of local geology is still absent.     

Numerical simulation of the effect of heavy groundwater abstraction on groundwater–surface water interaction in Langat Basin, Selangor, Malaysia

The paper aims at evaluating the interaction between ground and surface water along the Langat River in Malaysia through the development of a numerical simulation. Malaysia has been experiencing a rapid economic growth since the last few decades, driven by many factors such as agriculture, industry, and the like. The demand for water in these sectors has increased so tremendously that surface water has been utilized in conjunction to groundwater. Approximately 18,184 m³ of water per day is obtained from the aquifer to supply to the steel factory. There are also workshops, petroleum stations, and houses in the area thus causing the water quantity and quality to degrade. In terms of quantity, the pumping activity has altered the interaction between the groundwater and surface water. Therefore, a numerical model was proposed and two aquifer layers were simulated, with the first layer being approximately >20 m in depth and the second layer >100 m. The recharge estimated from the tank model was input into the groundwater modeling. The effects of the surface water to the aquifer were included in the simulation by defining the river conductance, river bed, and river level. The calibrated model (error about 0.9 m) was achieved and applied to predict the flow pattern in its natural state without the pumping and with the pumping states. As a result, in the first scenario, the stream was in an effluent condition influenced by the groundwater from the northeast to the west. A hyporheic flow occurred and was observed from the contour map. The flow system was changed in the second scenario when the pumping activity was included in the simulation. The groundwater lost its original function but received leakage from the stream near the pumping sites. The findings of this study will help the local authorities and other researchers to understand the aquifer system in the area and assist in the preparation of a sustainable groundwater management.     

A case-study of complex gas–water–rock–pollutants interactions in shallow groundwater: Šalek Valley (Slovenia)

The complex geochemical interactions in the groundwater of the industrial area of Šalek Valley (Slovenia) between natural and anthropogenic fluids were studied by means of major (Ca, Mg, Na, K, HCO₃ ⁻, Cl⁻ and SO₄ ²⁻) and trace elements’ (As , Cd, Cu, Pb, Zn, Hg, Se and V) abundances, geochemical classification and statistical analysis of data. Cation abundances indicate mixing between a dolomitic end-member and an evaporitic or geothermal end-member. Anion abundances indicate mixing between bicarbonate waters and either sulphate-enriched waters (suggesting hydrothermalism) or chlorine-rich waters. Principal component analysis (PCA) allowed the extraction of seven factors, which describe, respectively: water–rock interaction mainly on dolomitic rocks; redox conditions of water; Cd–Zn enrichment in chlorine-rich waters (probably from industrial wastes); hydrothermal conditions in waters close to major faults; Pb and Cu pollution; V and K enrichments, indicating their common organic source; the role of partial pressure of CO₂ dissolved in water, which is highest in three wells with bubbling gases. Average underground discharge rates of solutes from the Valley range between 0.09 t/a (V) and 1.8 × 104 t/a (HCO₃ ⁻) and indicate how natural fluids can significantly contribute to the levels of elements in the environment, in addition to the amount of elements released by human activities.     

Permafrost and groundwater settings at the site of “Kraton-3” peaceful underground nuclear explosion (Yakutia), from TEM data

Geological and geophysical interpretation of TEM data has revealed changes to the subsurface from the “Kraton-3” peaceful underground nuclear explosion (PUNE). The explosion was conducted on 24 August 1978 at a depth of 577 m in Middle Cambrian limestone on the eastern periphery of the Tunguska basin (Western Yakutia). The site is located in an area of 100 to 300 m thick permafrost and pressurized aquifers with Na-Ca-Cl brines (up to 400 g/l TDS) and cryopegs. The “Kraton-3” epicenter is only 160 m away from a fault emerging along the Markha River.TEM responses collected at 22 stations along three profiles image a layered-earth background resistivity pattern. The highly resistive uppermost layer, ~ 150–200 m thick, consists of perennially frozen ice-rich rocks. Dry permafrost on watersheds of the Markha right side reaches 1200 ohm?m, while the hypsometrically lower frozen ground along the fault is 10 to 40 times less resistive. That is exactly the place of the PUNE epicenter, and the resistivity lows may record permafrost degradation and taliks (unfrozen layers).The layers below are conductive and correspond to Upper Cambrian and Middle Cambrian (I) aquifers with brines. The top of the Upper Cambrian aquifer along the central profile is highly variable in depth, especially along the fault on the river left bank. The data indicate a local groundwater anomaly above the explosion: the Middle Cambrian I brines, which show up as a conductor in the resistivity pattern, become ~ 300 m shallower, most likely rising along the rubble chimney above the UNE containment cavity; the lateral extent of the anomaly reaches 400 m. There may exist paths for mass and heat transport maintained by pressurized brines in the system “containment cavity–rubble chimney–fault zone–ground surface”.     

Mössbauer studies of marine and fresh water manganese nodules

Practically identical Mössbauer spectra have been obtained for 40 ferromanganese nodules from a wide variety of marine and fresh-water locations. None of the nodules examined contains more than one weight percent Fe²⁺, so no more than a few percent of the total iron in these nodules can be Fe²⁺. Most of the iron is present as Fe³⁺ in paramagnetic or superparamagnetic oxide phases, although hysteresis loops show the presence of small amounts of ferromagnetic phases not detected by the Mössbauer technique.     

REE and trace element patterns from organic-rich rocks of the Ediacaran–Cambrian transitional interval

It has been established that important changes in the marine environment and the biosphere occurred during the Cambrian. However, the relationships between the so-called “Cambrian Explosion” and the concomitant environmental changes are not yet fully understood. This study presents new geochemical data from the black shale successions from different facies belts of the Yangtze Platform in South China. Variations in the concentrations of REE and trace elements (varying Ce/Ce*, Th/U, V/Sc, and V/Cr ratios) in kerogen as well as in bulk rocks from different depositional environments along a transect from platform to basin indicate two oxidation events, which led to the oxygenation of the water column in shallow-marine environments and euxinic conditions (weak correlation between TOC, V, U, and Mo) in the deeper sea. During the first oxidation event in the late Terreneuvian, anoxic conditions in bottom waters rapidly changed to euxinic conditions. Subsequently, the second oxidation event during the early Epoch 2 of the Cambrian led to oxic–suboxic conditions in deeper seawater.     

Focused groundwater discharge of phosphorus to a eutrophic seepage lake (Lake Væng, Denmark): implications for lake ecological state and restoration

A study on Lake Væng in Denmark demonstrates a high potential for loading of phosphorous via groundwater to seepage lakes. Groundwater discharges are displayed as an important source of phosphorous to a lake due to: (1) high concentrations in the aquifer just below the lake, and (2) the main flow paths through the aquifer–lakebed interface either being overland flow through a seepage face, or focused in zones with very high discharge rates. In-lake springs have measured discharge of up to 7.45 m³ per m² of lakebed per day. These findings were based on seepage meter measurements at 18 locations, stable isotope (δ¹⁸O) analyses, temperature profiles and mapping of ice cover distribution. Groundwater–lake interaction was modelled with a 2D conceptual flow model (MODFLOW) with hydrogeology interpreted from catchment multi electrode profiling, on-lake ground-penetrating radar, well logging and borehole data. Discharge was found to be much focused and opposite to expected increase away from the shoreline. The average total phosphorus concentration in discharging groundwater sampled just beneath the lakebed was 0.162 mg TP/l and thereby well over freshwater ecological thresholds (0.043–0.612, median = 0.117 mg TP/l). The study illustrates a direct link between groundwater and lake chemistry.     

Re-evaluating the US Geological Survey’s pumping tests (1967) in the Punjab region of Pakistan for use in groundwater studies

In 1967, the US Geological Survey (USGS) published the results of 141 pumping tests carried out throughout the Pakistani Punjab to establish representative hydraulic parameters of its large aquifer. Many authors have since concluded that the USGS had over-estimated the horizontal hydraulic conductivity (k _r) by 25–100 %, leaving vertical anisotropy and aquifer depth unresolved. No test wells have ever been drilled below 450 m to reach the base of the aquifer, although petroleum explorations mention depths between 1,500 and 4,500 m. After comparison and re-evaluation of all related papers, this study concludes that the USGS interpretation was correct, that its hydraulic values still stand without change, and that the USGS’s applied distance drawdown interpretation is valid to prevent influence of partial penetration on the results. This study also uniquely resolved vertical anisotropy and aquifer thickness by using early- and late-time drawdowns separately and proper scaling of the coordinates, which has often been omitted. With appropriate scaling, all interpretations match the data. The representative hydraulic aquifer values are: k _r?=?65 m/d, vertical anisotropy k _r/k _z?=?25 and aquifer depth 500–1,500 m. The conclusion is that these values can be used, at least as first estimates, for groundwater studies in the Pakistani Punjab.     

In situ and laboratory treatment tests for lowering of excess manganese and iron in drinking water sourced from river–groundwater interaction

Manganese and iron are essential nutrients at low doses. However, long-term exposure in high doses may be harmful. Human activities and natural sources are responsible for manganese and iron contamination in water. This study aimed to investigate the source of high manganese and iron contents in shallow groundwater, where the groundwater is used for drinking purpose, and to decrease the excess manganese and iron from shallow groundwater. Based on the on-site analytical results taken from the wells in the study area, iron contents in water samples varied between 30 and 200 μg/L, which were under the allowable limits of Turkish Drinking Water Standards (TDWS) (Water intended for human consumption, http://rega.basbakanlik.gov.tr/eskiler/2005/02/20050217-3.htm, 2005). However, manganese levels varied from 30 to 248 μg/L, which some of them are higher than the allowable limits of TDWS (Water intended for human consumption, http://rega.basbakanlik.gov.tr/eskiler/2005/02/20050217-3.htm, 2005) (50 μg/L), and EPA (http://water.epa.gov/drink/contaminants/index.cfm, 2006) (50 μg/L). The source of excess manganese is originated mainly from geogenic source besides Porsuk River interaction in shallow aquifer in the specific section of the study area. To decrease high manganese content from the well water and reservoir water, laboratory and in situ treatment tests were applied. Among these tests, chlorination, associated with filtration (by fine sand, active carbon and zeolite) and the use of different filtration procedures by cation exchange resin were determined as the most effective methods, which was not previously applied on-site as a combinative approaches to reduce the excess manganese in water.     

The conspicuous red “impact” layer of the Fish Clay at Højerup (Stevns Klint,Denmark)

The marine Cretaceous-Paleogene boundary (KPB) section at Højerup-Fish Clay consists of a very thin red smectite-rich carbonate-poor (“impact”) layer overlain by a thick black marl. Similar red layers are found in the KPB sections at Agost in Spain and El Kef in Tunisia.Smectite of the red layer of the KPB section at Højerup is probably detrital and redeposited from adjacent coastal or marine areas. This clay mineral is likely mixed with a small amount of smectite derived from impact glasses. Most of the microspherules and nano-size glasses of the red layer at Højerup are probably detrital and simultaneously redeposited with smectite. The deposition of the red layer occurred for several decades to a century at most.     

Distal “impact” layers and global acidification of ocean water at the Cretaceous-Paleogene boundary (KPB)

The KPB sections at Højerup in Denmark, Agost and Caravaca in Spain and El Kef in Tunisia and (elsewhere in the world) consists of a very thin reddish biogenic calcite-poor smectite-rich “impact” layer overlain by a thicker smectite-rich marl. The massive amount of impact-generated atmospheric CO₂ at KPB would have accumulated globally in the ocean surface, leading to acidification and CaCO₃ undersaturation. These chemical changes would have induced a low biocalcification of calcareous plankton and a high dissolution of their shells. The biocalcification/dissolution crises may have played a significant role for the low abundance of biogenic calcite in the “impact” layer of the marine boundary clays at Højerup, Agost, Caravaca and El Kef (and elsewhere in the world). Experimental data and observations indicate that the deposition of the “impact” layer probably lasted only a few decades at most.     

The influence of 10 years of water conveyances on groundwater and juvenile Populus euphratica of the lower Tarim River

The changes in the depth of groundwater were studied from the period before water conveyance through 2010, and the TDS of groundwater was analyzed in the lower reaches of the Tarim River during the period 2001–2010. Besides, the numbers of juvenile P. euphratica were investigated in the lower reaches of the Tarim River during the period 2001–2010. The findings indicate that: (1) the hydrological environment of the lower reaches has slowly deteriorated again; and (2) few juvenile P. euphratica were observed along the channel. These results show that the positive influence of the ecological water conveyance project on the ecosystem of the lower Tarim River should be beneficial in the long term; however, the long-term stability of the ecosystem cannot be achieved by the current water diversion scheme.     

Quantification of the water balance and hydrogeological processes of groundwater–lake interactions in the Pampa Plain, Argentina

This paper gives an account of the assessment and quantification of the water balance and the hydrogeological processes related to lake–groundwater interaction in the Pampa Plain by using hydrogeochemical, isotopic and flow numerical modeling techniques. La Salada is a permanent shallow lake, with an area of 5.8 km², located on the SE of Buenos Aires Province. A total of 29 lake water samples and 15 groundwater samples were collected for both hydrochemical analysis and environmental stable isotope determination. Water table depths were measured in wells closed to the lake. Groundwater samples appear grouped on the Local Meteoric Water Line, suggesting a well-mixed system and that rainfall is the main recharge source to the aquifer. Water evaporation process within La Salada is also corroborated by its isotopic composition. The model that best adjusts to La Salada Lake hydrochemical processes includes evaporation from groundwater, calcite precipitation with CO₂ release and cationic exchange. The annual water balance terms for the lake basin indicates for each hydrological component the following values: 1.16 E⁰⁸ m³ rainfall, 8.15 E⁰⁷ m³ evapotranspiration, 1.90 E⁰⁶ m³ runoff, 1.55 E⁰⁷ m³ groundwater recharge, 6.01 E⁰⁶ m³ groundwater discharge to the lake, 9.54 E⁰⁶ m³ groundwater discharge to the river, 5.00 E⁰⁵ m³ urban extraction and 4.90 E⁰⁶ m³ lake evaporation. Integrated analysis of hydrochemical and isotopic information helped to calibrate the groundwater flow model, to validate the conceptual model and to quantitatively assess the basin water balance.