Jean-Denis Taupin

A new Andean deep ice core from Nevado Illimani (6350 m), Bolivia

Abstract A new ice core record from the Nevado Illimani (16°S), Bolivia, covers approximately the last 18 000 years BP. A comparison with two published ice records, from Sajama (18°S), Bolivia [Thompson et al., Science 282 (1998) 1858–1864] and Huascaran (9°S), Peru [Thompson et al., Science 269 (1996) 46–50], documents a regionally coherent transition from glacial to modern climate conditions in South America north of 20°S. The strong resemblance between the Illimani and Huascaran water isotope records and their differences from the Sajama record, in particular during the period from 9000 years BP to 14 000 years BP, suggest that local water recycling or local circulation changes played a major role for Sajama. We interpret the common Illimani/Huascaran water isotope history in terms of a common change from wetter/cooler conditions during glacial times to drier/warmer conditions in the Early Holocene.

Empirical mass balance modelling of South American tropical glaciers: case study of Antisana volcano, Ecuador

Abstract Most Latin American glaciers are located in the tropical Andes. The melting processes of Glacier “15” on Antisana volcano were studied to understand the relationship between glacier retreat and natural climate variability and global climate change. Glaciers on the Antisana volcano are crucial sources of water as they feed the headwater rivers that supply Quito with potable water. The aim of this study was to build empirical models based on multiple correlations to reconstruct the mass loss of glaciers over a period of 10 years at three scales: local (data recorded by meteorological stations located around the volcano), regional (data from stations located around the country) and global (re-analysis data). Data quality was checked using graphical and statistical methods. Several empirical models based on multiple correlations were created to generate longer time series (42 and 115 years) of the mass balance for the glacier ablation zone. The long mass balance series were compared with the temperature variation series of the Earth’s surface in the Southern Hemisphere to estimate the relation between the mass balance and global warming. Our results suggest that the meteorological factors that best correlate with mass balance are temperature and wind. Editor D. Koutsoyiannis Citation Manciati, C., Villacís, M., Taupin, J.-D., Cadier, E., Galárraga-Sánchez, R., and Cáceres, B., 2014. Empirical mass balance modelling of South American tropical glaciers: case study of Antisana volcano, Ecuador. Hydrological Sciences Journal, 59 (8), 1519–1535. http://dx.doi.org/10.1080/02626667.2014.888490

Analysis and interpretation of electrical resistivity tomography data of alluvial aquifer of Tamanrasset Southern Algeria

A groundwater exploration work in the Tamanrasset region in southern Algeria was started in August 2016 to assess the water reserves in the hydrogeological system related to the Oued Tamanrasset underflow water table which overcomes a volcanic basement. Five (05) electrical resistivity tomography (ERT) surveys were conducted in Tamanrasset area by using ABEM Terrameter LS system. the low electrical contrast between wet alluvium and water saturated alterites makes difficult the electrical response interpretation. to overcome the difficulties of interpretation of ERT profiles, field investigations, laboratory tests and software simulations, were carried out in order to clearly identify the structure of the hydrogeological system. The experimental investigation of the electrical characteristics of the alluvium as a function of water saturation was carried by the use of two devices (Wenner α and Schlumberger). Samples true resistivity values varies between 50 Ω.m for a 100% saturated sample and 1250 Ω.m for a 25% saturation sample. The interpretation of the measurements by the RES2DINV software made it possible to give 2D images of the subsoil up to a depth of 50 m. the electrical contrast between the bedrock and the overlying formations made it possible to identify it, however, it was difficult to distinguish alterites from alluvium. A methodology combining piezometric survey, geo-electrical measurements and field observations improves the interpretation of electrical tomography profiles and the application of the ERT method for accurate characterization of water resources in the Tamanrasset region.

Geochemical and Isotopic Study of a Coastal Phreatic Aquifer from the NE of Tunisia: Guenniche Basin

The geochemistry and isotopic composition (18O, 2H) of groundwater from the alluvial phreatic aquifer in the Wady Guenniche basin (NE of Tunisia), were investigated in order to reveal the origin of the water salinity. The major geochemical processes in the aquifer are evaporite mineral dissolution and mineral exchange with clays. The salinization of groundwater would be a limiting factor in their use for irrigation. The stable isotopic composition of water indicates a groundwater recharge in current climate condition and the point closest to the sea indicates the possible beginning of a seawater intrusion as a result of the intensive exploitation of resources. The tritium data confirm a recent recharge younger than 1950.

Naturel Tracer and Isotopic Approach to Describe Groundwater Behaviour: An Example of the Mateur Plain (North-Eastern Tunisia)

Physical and chemical data, have been taken from the whole of Mateur plain (NE Tunisie) (Fig. 1a). In Mateur region, most waters come from phreatic aquifer and deep aquifers. These aquifers show indications of advanced overexploitation, revealed by decreasing piezometric surfaces and degradation in water quality. The total dissolved solids (TDS) were measured in September–October 2015 at 72 water points drilled in the phreatic aquifer and deep aquifers. The upstream zone of Mateur shows good chemical quality water, with a TDS varying from 0.7 to 1 g/l. However, highly mineralized waters (over 1.5 g/l) were found in the middle-Mateur plain and downstream zone.

Caractérisation géochimique et bactériologique des nappes d’une région à climat tropical sec au centre Sud de Madagascar

Résumé Le district de Betroka, soumis à un climat tropical sec, connaît d’importants problèmes de ressource en eau. Cette situation se traduit pour de nombreux habitants par la consommation d’eau de très mauvaise qualité tant sur le plan physico-chimique, que sur le plan bactériologique. Pour tenter d’améliorer cette situation, le gouvernement malgache a entrepris un programme d’alimentation en eau potable et assainissement en milieu rural (projet 350 forages), cadre du présent travail, afin d’assurer à l’eau destinée à l’alimentation humaine une qualité suffisante en termes bactériologique et minéral. L’étude microbiologique de l’eau souterraine du district de Betroka a confirmé l’absence de bactéries d’origine fécale. L’étude hydrochimique a révélé différents processus conduisant à la minéralisation des eaux souterraines en relation avec : (a) la remontée d’eau saline d’origine profonde à partir des fractures transversales du cisaillement majeur de Betroka, et à partir des failles normales à l’origine du graben de Mangoky et du domaine du massif en dôme et bassin du complexe intrusif d’Ianakafy ; (b) la dissolution des aérosols et embruns marins déposés, dissous par la pluie et entraînés jusqu’aux aquifères ; et (c) l’interaction des eaux météoriques et souterraines avec les minéraux des roches encaissantes (scapolite, phlogopite, biotite, hornblende, pyroxène…) qui pourrait également contribuer à la forte minéralisation observée.