Groundwater vulnerability mapping assessment of central West Bank catchments using PI method

A groundwater vulnerability assessment was carried out in order to understand and control the pollution sources affecting vulnerable regions in two adjacent catchments (Sarida and Natuf), located in the western middle part of the West Bank. The catchments were subjected to groundwater vulnerability mapping and assessment using the modified German State Geological Surveys (GLA method) method called Protective Cover and Infiltration Conditions method (PI method) via ArcGis 2014.2 software package in February of 2016. The results showed that the study area has high effectiveness of protective cover (P-factor), which was obtained by overlying top soil, bedrock, subsoil, and recharge layers. On the other hand, the dominant flow types, land usage, slopes, and topographical classification layers were overlaid to get the infiltration conditions (I-factor). The interaction between the two main factors was carried out in order to obtain the final spatially distributed π-factor values (vulnerability map), which was classified into four vulnerability classes. Statistically, about 4% of the overall area was of extreme vulnerability and concentrated along the sinking streams, while 22% was of low vulnerability and existed outside the main watersheds, followed by high vulnerability with 26%. The largest proportion with 48% of the overall area was of moderate vulnerability to groundwater contamination.     

The Campanian-Maastrichtian rudist bivalves succession in the Chiapas Central Depression,Mexico

The restudy of the Late Cretaceous rudist fauna of the Chiapas Central Depression, considered Campanian-Maastrichtian with no more precisions in literature, reveals that, in fact, three successive rudist assemblages occur: (1) a lower one, early and middle Campanian, in the uppermost part of the Sierra Madre Formation (distinguished as Suchiapa Formation); (2) a middle one, early Maastrichtian, in the upper part of the Ocozocoautla Formation; and (3) an upper one, late Maastrichtian, in several horizons within the Angostura Formation. Published data on planktic and benthic foraminifers and inoceramid bivalves, as well as new findings of ammonites, helped bracketing the age of the three rudist assemblages. Their stratigraphic position fits with a depositional model assuming a basal carbonate platform fragmented into blocks each following a different tecto-sedimentary evolution: (1) a drowned block constituting the Tuxtla Gutiérrez Basin, deepening towards the neighbor raised block and receiving terrigenous material from the emerged Sierra Madre de Chiapas, that, after a long hiatus, was filled up and, subsequently, a marginal shallow carbonate platform, surrounded by a detritic belt and prograding towards the basin, installed on top; (2) a raised block constituting a high where, after a long hiatus, an insular shallow carbonate platform installed.     

Groundwater vulnerability and risk mapping of the Hajeb-jelma aquifer (Central Tunisia) using a GIS-based DRASTIC model

The aim of this study is to elaborate a synthetic document for the assessment of groundwater vulnerability to pollution in the Hajeb-Jelma aquifer. The specific object is to incorporate the Geographical Information System (GIS) to generate groundwater vulnerability and risk maps with DRASTIC model. Indeed, GIS could help to make the results of a complicated model more clear through visual representation, providing an applicable tool for decision makers. The vulnerability map of Hajeb-Jelma watershed shows three classes: moderate, high and very high depending on the intrinsic properties. The risk map shows a very high risk dependant on hydrogeological characteristics, land use and human impacts in major part of the Hajeb-Jelma region. These maps could serve as a scientific basis for sustainable land use planning and groundwater management in the Hajeb-Jelma region.     

Groundwater vulnerability assessment in coastal plain of Rio Grande do Sul State,Brazil, using drastic and adsorption capacity of soils

Groundwater vulnerability assessment to delineate areas that are more susceptible to contamination has become an important element for resource management and land use planning. The objective of this work was to integrate hydrogeologic data in a geographic information system (GIS) for phreatic groundwater vulnerability assessment of a pilot area from the Coastal Plain of the Rio Grande do Sul State, Brazil, using the DRASTIC method and adsorption capacity of soils. The studied ions were copper, lead, sulfate and phosphate. Using the original DRASTIC method, the vulnerability presented high values, mainly due to the texture of the sediments and the low depths of waters, which favor the accessibility of the contaminants to the groundwaters. DRASTIC with adsorption capacity of soils showed specifics results for each studied ion. Groundwater vulnerability to metals in relationship to anions was lower. These results show that the original DRASTIC method represents better contaminants with high mobility. An erratum to this article can be found at     

Evaluation of the risk of induced seismicity at the itzantun hydroelectric site, Chiapas, Mexico

Consolidation theory and concepts of rock failure can be used to evaluate the probable risk of induced seismicity as a result of filling of reservoirs. This evaluation indicates the safest way to fill a reservoir, and depends only on the geometry of the load, the rate of filling and the geological structures in the area. The stability function is actually a measure of the risk of having failure, with time, for a particular loading history in respect to a plane of weakness.

The stability function is applied to the area of the Itzantun reservoir, which will be in southern Mexico. Drawdowns can increase the risk of triggering earthquakes in this area, which is prone to thrust faulting. It is possible to estimate the stresses after a period during which the water level is maintained and a decrease in stresses with the depth of the observation point.

The estimates of the probable induced seismicity are limited as the residual stress in the area prior to the impounding is unknown. With a measure of the residual tectonic stress it will be possible to determine an optimal filling rate to reduce the probability of induced seismicity.     

Groundwater vulnerability and risk mapping in a geologically complex area by using stable isotopes, remote sensing and GIS techniques

Groundwater vulnerability and risk mapping is a relatively new scientific approach for facilitating planning and decision making processes in order to protect this valuable resource. Pan European methodology for aquifers vulnerability has recently been developed by assessing all the existing relevant techniques and emphasizing on karstic environments. In the particular study, state-of-the-art methods and tools have been implemented such as remote sensing, isotopic investigations and GIS to map the groundwater vulnerability and pollution risk in a geologically complex area of W. Greece. The updated land use map has been developed from a Landsat 7+TM image elaborated with image analysis software, while the detailed hydrogeologic properties of the area have been recorded with an intensive isotopic study. The local groundwater vulnerability map has been produced following the aforementioned Pan European method, in a GIS environment while the risk map, which was the final product of the study, has been developed after combining the vulnerability and the land use maps. The results indicated that the areas comprised of highly tectonized calcareous formations represented high vulnerability and risk zones while forested areas away from the karstic aquifer illustrated moderate to low vulnerability. Moreover, human activities increase the pollution risk in lowland areas consisting of sedimentary deposits that have been classified as moderate vulnerability. The particular methodology operated efficiently in this study and due to its accuracy and relatively easy implementation can be used as a decision support tool for local authorities.     

Groundwater vulnerability and risk mapping of the Angad transboundary aquifer using DRASTIC index method in GIS environment

The protection and preservation of groundwater resources are compulsory, particularly in the arid and semiarid countries where the waters are scarce. The effects of increasing urbanization, economic development, and agricultural activities, along with the erratic and scarce rainfall, contribute to the quantitative and qualitative deterioration of these resources. This paper attempts to produce groundwater vulnerability and risk maps for the Angad transboundary aquifer using DRASTIC model. The data which correspond to the seven parameters of the model were collected and converted to thematic maps in Geographic Information System environment. The modified DRASTIC map, which is the summation of the DRASTIC index and the network fractures maps, shows two degreed of vulnerability: medium and high. This map is then integrated with a land use map to assess the potential risk of groundwater to pollution in the Angad transboundary aquifer. There are three risk zones that are identified: moderate, high, and very high.     

Groundwater vulnerability assessment of the Cork Harbour area,SW Ireland

In the Cork Harbour area of SW Ireland, high yield karst and intergranular gravel aquifers are extremely vulnerable to pollution from a variety of sources, mainly due to the limited protection afforded by the thin cover of low permeability glacial and alluvial overburden. The main potential sources of pollution are due to rapid urbanisation of the Cork city area and its attendant infrastructure, and increased industrialisation in the area, with numerous new industries, particularly pharmaceutical and chemical industries, located around Cork Harbour. Other potential sources of pollution are a number of landfills in the area and an oil refinery near the mouth of Cork Harbour. Traditional agricultural sources of pollution also exist, due to increased use of chemical fertilisers. Finally, the susceptibility to saline intrusion of the karst and gravel aquifers around Cork Harbour is high due to the long coastline of the harbour and the low-lying nature of the karst synclines with their superimposed buried valleys.     

Groundwater vulnerability assessment of the SW Trans-Danubian Central Range, Hungary

 The most important karst water reservoir of Hungary is found in the SW Trans-Danubian Central Range, selected as test area for the proposed "system approach" and the application of GIS/ARC-INFO to vulnerability mapping. In addition, a case-study exemplifies the particularities of regional karst-aquifer vulnerability, and moreover the interpretation of data and maps from the very same point of view. The work has resulted in plotting an atlas to be a useful tool in the hands of land-users and waste-disposal managers, helping them to prevent groundwater deterioration. Received: 22 July 1996 · Accepted: 12 September 1997     

Groundwater flow model of the Pipiripau watershed, Federal District of Brazil

In order to understand the groundwater dynamics and to improve the management of water resources in the Federal District of Brazil, this research proposes a 3D groundwater flow model to represent the groundwater level and flow system. The selected test site was the Pipiripau catchment. The development of the model was based on available geological, hydrogeological, geomorphological, climatological and pedological data. Geological and hydrogeological data were used to generate the 3D groundwater flow model. The 3D mesh elements of the domain were generated through the Groundwater Modeling System software, based on the logs of the well materials. The numerical simulation of the finite element method was implemented in the framework of the scientific software OpenGeoSys. With the 3D mesh-appropriated boundary conditions, annual average infiltration data and hydrogeological parameters were incorporated. Afterwards, the steady-state model was calibrated by the PEST software using available data of the water level from wells. The results showed the distribution of the steady-state hydraulic heads in the model domain, where the highest values occurred in the east and west recharge areas and the lowest values were found in the southwest of the basin. The results of this study can be a used as initial condition for the transient groundwater flow simulation and to provide a scientific basis for water resource management.     

Groundwater optimization model for sustainable management of the Valley of Puebla aquifer, Mexico

The Valley of Puebla aquifer (VPA), at the central region of Mexico, is subject to intensive exploitation to satisfy the urban and industrial demand in the region. As a result of this increased exploitation, a number of state and federal agencies in charge of water management are concerned about the problems associated with the aquifer (decline of groundwater table, deterioration in water quality, poor well productivity and increased pumping and water treatment costs). This study presents a groundwater management model that combines “MODFLOW” simulation with optimization tools “MODRSP”. This simulation–optimization model for groundwater evaluates a complex range of management options to identify the strategies that best fit the objectives for allocating resources in the VPA. Four hypothetical scenarios were defined to analyze the response of the hydrogeological system for future pumping schemes. Based on the simulation of flow with the MODFLOW program, promising results for the implementation of the optimization of water quantity were found in scenarios 3 and 4. However, upon comparison and analysis of the feasibility of recovery of the piezometric level (considering the policy of gradual reductions of pumping), scenario 4 was selected for optimization purposes. The response functions of scenario 4 were then obtained and optimized, establishing an extraction rate of 204.92 millions of m³/year (Mm³/year). The reduction in groundwater extraction will be possible by substituting the volume removed by 35 wells (that should be discontinued) by the same volume of water from another source.     

Geographical distribution of arsenic in sediments within the Rio Conchos Basin,Mexico

Arsenic (As) content of sediments from the Rio Conchos and Rio San Pedro in northern Mexico were measured to determine if this toxic metalloid had accumulated to unsafe levels to humans and aquatic life. The spatial distribution of As in each of the six clusters of river and arroyo sediments was analyzed to determine variations with respect to background levels and to infer about potential As sources and sinks. In the northern part of the study area, background concentrations varied little throughout the area and concentrations in river sediments were close to background levels. In the southern part, however, the content of As in arroyo sediment contained a wider range of values and anomalous concentrations. The latter could be traced in part to the presence of mine tailings. As concentrations were below the limit in all studied river stretches and thus do not pose an immediate threat to the river environment, but As content in reservoir sediments exceeded the guideline values. Reservoirs seem to act as a sink for As, warranting closer observation and monitoring.     

Palaeomagnetic results from the Chiapanecan Volcanic Arc,Chiapas, Southern Mexico: geomagnetic and geodynamic significance

This article presents the first palaeomagnetic results from 13 independent cooling units in the Chiapanecan Volcanic Arc (ChVA). Six sites were directly dated by Ar–Ar or K–Ar methods: their dates range from 2.14 to 0.23 Ma. We isolated the characteristic palaeodirections for all 13 lavas. Eleven non-transitional directions yield a mean direction with inclination, I?=?30.7°, declination, D?=?4.1°, and precision parameters k?=?63 and α₉₅ = 5.8°. The corresponding mean palaeopole position is Plat = 83.3°, Plong = 203.8°, K?=?227, A ₉₅ = 5.1°. The mean inclination is in good agreement with the expected value for the last 5 million years, as derived from the synthetic North American polar wander path [Besse and Courtillot 2002 Besse, J. and Courtillot, V. 2002. Apparent and true polar wander and the geometry of the magnetic field in the last 200 million years. Journal of Geophysical Research, 107(B11) doi:10.1029/2000JB000050[Crossref], [Web of Science ®] , [Google Scholar], Apparent and true polar wander and the geometry of the magnetic field in the last 200 million years: Journal of Geophysical Research, v. 107, no. B11, p. 2300], but a measured rotation of the palaeodeclination of about 8° with respect to the expected direction suggests the possibility of a clockwise rotation of the studied ChVA units. We have estimated the characteristics of palaeosecular variation through study of the scatter of virtual geomagnetic poles, obtaining a palaeosecular variation parameter S _b = 14.5° with upper limit S _U = 19.6° and lower limit S _L = 11.7°, in reasonable agreement with the fit of model G [McFadden et al., 1988 Quidelleur, X., Carlut, J., Gillot, P.Y. and Soler, V. 2002. Evolution of the geomagnetic field prior to the Matuyama-Brunhes transition: Radiometric dating of a 820 ka excursion at La Palma. Geophysical Journal International, 151: F6–F10. [Crossref], [Web of Science ®] , [Google Scholar], Dipole/quadrupole family modeling of paleosecular variation: Journal of Geophysical Research, v. 93, no. B10, p. 11583–11588; 1991, Reversals of the Earth's magnetic field and temporal variations of the dynamo families: Journal of Geophysical Research, v. 96, no. B3, p. 3923–3933] to the Johnson et al. [2008 Johnson, C.L., Constable, C.G., Tauxe, L., Barendregt, R., Brown, L.L., Coe, R.S., Layer, P., Mejia, V., Opdyke, N.D., Singer, B.S., Staudigel, H. and Stone, D.B. 2008. Recent investigations of the 0–5 Ma geomagnetic field recorded by lava flows. Geochemistry, Geophysics, Geosystems, 9(4) ID Q04032, doi:10.1029/2007GC001696[Crossref], [Web of Science ®] , [Google Scholar], Recent investigations of the 0–5 Ma geomagnetic field recorded by lava flows: Geochemistry, Geophysics, Geosystems, v. 9, no. 4, ID Q04032, doi:10.1029/2007GC001696] databases for the last 5 million years. In those cases in which age determinations are available, the polarity obtained for the studied flows is consistent with their stratigraphic positions, except for the Huitepec site, which probably reflects the transitional geomagnetic regime prior to the Matuyama–Brunhes geomagnetic reversal.     

Diverse mantle and crustal components in lavas of the NW Cerros del Rio volcanic field,Rio Grande Rift,New Mexico

Products of Pliocene (2–4 Ma) mafic to intermediate volcanism in the northwestern Cerros del Rio, a dominantly mafic volcanic field in the Española Basin of the Rio Grande Rift (RGR), range from 49% to 63% SiO₂ and exhibit diversity in silica saturation, trace-element patterns, and isotopic compositions. Tholeiites, which are largely confined to west of the Rio Grande, have trace-element abundances that resemble those of oceanic basalts, but with mild depletions in Nb and Ta, and high ⁸⁷Sr/⁸⁶Sr, low ¹⁴³Nd/¹⁴⁴Nd, and high δ¹⁸O compared to typical OIB. They are regarded as asthenospherically-derived magmas contaminated with continental crust. Alkali basalts and hawaiites erupted from vents east of the Rio Grande are geochemically distinct, having generally higher overall incompatible-element abundances, but with pronounced depletions in K, Rb, Nb and Ta with respect to Th and LREE. Spatially-associated benmoreites, mugearites and latites (collectively termed “evolved” lavas) have similar trace-element characteristics to the mafic mildly-alkaline compositions, but are typically not as depleted in K. Hawaiites and evolved lavas exhibit a good negative correlation of ¹⁴³Nd/¹⁴⁴Nd with SiO₂, due to interaction with lower continental crust. The most silicic “evolved” lavas carry the highest proportions of crustal material, and consequently have higher K/Th than the related hawaiites. Several (mostly mafic) lavas contain abundant crustally-derived resorbed quartz xenocrysts in O-isotope disequilibrium with the host magma. The δ¹⁸O values of xenocrystic quartz range over 4‰, indicating a variety of quartz-bearing crustal contaminants beneath the Española Basin. The hawaiites, with their unusual combination of trace-element enrichments and depletions, cannot be generated by any process of fractionation or crustal contamination superposed on a common mantle source type (oceanic or arc-source). It is a regional mantle source type, inasmuch as it was also present beneath NW Colorado during the mid-late Cenozoic. We argue that the hawaiite source must have originally existed as arc-source mantle enriched in LILE, generated during Mesozoic to early Cenozoic subduction at the western margin of North America. This arc-source mantle lost K, Rb and Ba, but not Th or LREE, prior to magmagenesis. Selective element loss may have occurred during lithospheric thinning and uprise of hydrated phlogopitebearing peridotite-possibly as a thermal boundary layer between lithosphere and asthenosphere — to shallow mantle depths, with consequent conversion of phlogopite to amphibole (an inferior host for K, Rb and Ba). We suggest that this occurred during the early extensional phase of the northern RGR. Further extension was accompanied by partial melting and release of magma from this source and the underlying asthenosphere, which by the Pliocene was of oceanic type. The hawaiite source mantle is the product of a long history of subduction succeeded by lithospheric extension of the formerly overriding plate. Similar chemical signatures may have developed in the mantle beneath other regions with comparable histories.     

Pyroclastic geology of the rhyolitic volcano of La Primavera,Mexico

Explosive eruptions of this large Quaternary rhyolitic volcano have produced voluminous pumice fall deposits and ignimbrites. A stratigraphie study reveals more than 30 fall deposits, totalling more than 90 km³, which have come from many different vents. Some are of plinian type, and one is among the largest known in the world. The main ignimbrite (Rio Caliente) is of intra-plinian type. In all, 140 km³ of rhyolitic material were erupted during the past 10⁵ years, of which 50 km⁵ are dispersed well outside the volcano. The dense rock equivalent volume is 60 km³, of which fall deposits, ignimbrites and lava bodies comprise 45 %, 25 % and 30 % respectively. The average output rate of 0.06 km³ per century is nearly an order of magnitude less than for the most productive rhyolitic volcanoes known. A circular area 10 km across in the centre of La Primavera contains updomed lacustrine ashes and associated sediments, including a remarkable giant pumice bed, which probably accumulated in a caldera lake. La Primavera has no record of historical eruptions, and hot springs are the only signs of present activity, but the updoming is thought to be due to the uprise of a new acid pluton beneath the volcano and future eruptions are probable.

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Zusammenfassung Explosionsartige Eruptionen des gro\en quartÄren Rhyolith-Vulkans La Primavera haben mÄchtige Bimstuffe und Ignimbrite aufgehÄuft. Eine stratigraphische Untersuchung hat über 30 Aschelagen erkennen lassen, die aus verschiedenen Schloten stammen und insgesamt mehr als 90 km³ an Volumen ausmachen. Einige davon gehören zum plimanischen Typ, von denen eine sogar die grö\te bisher bekannte Lage der Erde ist. Der Haupt-Ignimbrit (Rio Caliente) gehört zum intraplimanischen Typ. Insgesamt wurden in den letzten 100 000 Jahren 140 km³ rhyolithisches Material ausgeworfen, von denen 50 km³ deutlich au\erhalb des eigentlichen Vulkans liegen. Das Äquivalentvolumen des dichten Gesteins betrÄgt 60 km³, von dem 45 % auf Tuffe, 25 % auf Ignimbrite und 30 % auf Lavakörper entfallen. Die durchschnittliche Auswurfrate von 0,06 km³ pro Jahrhundert liegt fast eine Grö\enordnung unter den meisten bekannten aktiven Rhyolith-Vulkanen. Ein kreisrundes Gebiet von 10 km Durchmesser im Zentrum des La Primavera zeigt aufgewölbte lakustrine Aschen und damit assoziierte Sedimente, darunter eine bemerkenswerte riesige Bimslage, die wahrscheinlich in einem Caldera-See abgelagert wurde. Der Vulkan La Primavera ist in historischer Zeit nicht ausgebrochen und hei\e Quellen sind die einzigen Anzeichen heutiger AktivitÄt, aber die Aufwölbung wird als Hinweis auf das Hochdringen eines neuen sauren Plutons unter dem Vulkan angesehen, so da\ zukünftige Eruptionen wahrscheinlich sind.

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Résumé Des éruptions explosives de ce grand volcan rhyolitique quaternaire ont produit de volumineux dépÔts de ponces et d'ignimbrites. Une étude stratigraphique fait apparaÎtre plus de 30 dépÔts totalisant plus de 90 km³ provenant de nombreuses bouches volcaniques différentes. Certaines sont du type plinien, dont l'une est parmi les plus grandes connues au monde. L'ignimbrite principale (Rio Caliente) est du type intraplinien. En tout 140 km³ de matériaux rhyolitiques ont été rejetés au cours des 10⁵ dernières années, dont 50 km³ ont été dispersés bien au delà du volcan. Le volume de roche compact équivalent est de 60 km³, parmi lequel les tuffs, les ignimbrites et les laves occupent respectivement 45%, 25% et 30%. L'émission moyenne, de 0,06 km³ par siècle, est d'un ordre de grandeur moindre que pour la plupart des volcans rhyolitiques les plus productifs actuellement connus. Une région circulaire de 10 km de diamètre dans le centre de La Primavera contient des domes de cendres lacustres et autres sédiments associés, et parmi eux une couche géante de ponce remarquable, qui s'est probablement accumulée dans un lac-caldère. On ne connaÎt pas d'éruptions historiques de la Primavera, et seules des sources chaudes témoignent d'une activité actuelle; toutefois on pense que l'allure en dome est due à la poussée d'un nouveau pluton acide sous le volcan, et que des éruptions sont probables dans le futur.

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Reconstructing the ancestral (Plio-Pleistocene) Rio Grande in its active tectonic setting, southern Rio Grande rift, New Mexico, USA

Deposits of the ancestral Rio Grande (aRG) belonging to the Camp Rice Formation are preserved and exposed in the uplifted southern portion of the Robledo Mountains horst of the southern Rio Grande rift. The sediments are dated palaeomagnetically to the Gauss chron (upper Pliocene). The lower part of the succession lies in a newly discovered palaeocanyon cut into underlying Eocene rocks whose margins are progressively onlapped by the upper part. Detailed sedimentological studies reveal the presence of numerous river channel and floodplain lithofacies, indicative of varied deposition in channel bar complexes of low‐sinuosity, pebbly sandbed channels that traversed generally dryland floodplains and shifted in and out of the study area five times over the 1 Myr or so recorded by the succession. Notable discoveries in the deposits are: (1) complexes of initial avulsion breakout channels at the base of major sandstone storeys; (2) common low‐angle bedsets ascribed to deposition over low‐angle dunes in active channels; (3) palaeocanyon floodplain environments with evidence of fluctuating near‐surface water tables. Sand‐body architecture is generally multistorey, with palaeocurrents indicative of funnelling of initial avulsive and main fluvial discharge from the neighbouring Mesilla basin through a narrow topographic gap into the palaeocanyon and out over the study area. An avulsion node was evidently located at the stationary southern tip to the East Robledo fault during Gauss times, with aRG channels to the north flowing close to the fault and preventing fan progradation. Subsequent Matuyama growth of the fault caused (1) deposition to cease as the whole succession was uplifted in its footwall, (2) development of a thick petrocalcic horizon, and (3) fan progradation into the Mesilla basin. Parameters for the whole aRG fluvial system are estimated as: active single channels 2 m deep and 25 m wide; valley slope 0·24–0·065°; maximum mean aggradation rate 0·05 mm year^–1; major channel belt avulsion interval 200 ky; individual channel recurrence interval 100 ky; minimum bankfull mean flow velocity 1·54 m s^–1, minimum single‐channel discharge 77 m³ s^–1, bed shear stress 22·3 N m^–2; and stream power 34·3 W m^–2.