Caractérisation et suivi des écoulements hydriques dans les milieux poreux par la méthode du Potentiel Spontané

In hydrogeology, the information related to the piezometric surface and hydraulic properties is usually obtained from in situ measurements in a set of piezometers. However, this approach is intrusive and depends on the number of available piezometers. This explains why, in the last decade, research scientists looked for a new geophysical method able to determine the piezometric head variations and the groundwater flow parameters in a non-intrusive way. The self-potential method offers such possibility. Indeed, the flow of groundwater is responsible for a measurable electrical field owing to the electrokinetic coupling between the water flux and the electrical current density. This electrokinetic coupling is one of the sources for the so-called self-potential signals measured passively at the ground surface with non-polarisable electrodes. Field and laboratory experiments were undertaken in order to measure the electric signals of a groundwater flow during pumping and infiltration tests. The field and laboratory results prove the capacity of the self-potential method to follow the groundwater flow in real time. They indicate that the self-potential variations are linearly related, at the first order, to the piezometric head variations. These experiences show the usefulness of the self-potential method to monitor the groundwater flow and to estimate the groundwater flow parameters.Identifier la géométrie des écoulements souterrains est un objectif majeur de l'hydrologie. L'objectif de ce travail de thèse est de montrer que la méthode du Potentiel Spontané (PS) peut fournir des informations spatialisées sur la géométrie des circulations hydriques et sur les propriétés hydrauliques du sous-sol. La méthode PS est basée sur la mesure du champ électrique naturellement présent dans le sous-sol. Des expériences de terrain ont été menées pour mesurer la signature électrique d'un écoulement hydrique lors d'expériences de pompage et d'infiltration. Pour une meilleure compréhension du problème physique sous-jacent, des simulations de pompage et d'infiltration ont été réalisées dans une cuve en Plexiglas. Les résultats obtenus sur le terrain et en laboratoire démontrent la capacité de la méthode PS pour suivre la progression d'un écoulement et confirment l'intérêt de celle-ci comme outil adapté à la détermination du niveau piézométrique et des propriétés hydrauliques du sous-sol

Deep electrical resistivity tomography along the tectonically active Middle Aterno Valley (2009 L'Aquila earthquake area, central Italy)

Pucci et. al.Three 2-D Deep Electrical Resistivity Tomography (ERT) transects, up to 6.36 km long, were obtained across the Paganica-San Demetrio Basin, bounded by the 2009 L'Aquila M-w 6.1 normal-faulting earthquake causative fault (central Italy). The investigations allowed defining for the first time the shallow subsurface basin structure. The resistivity images, and their geological interpretation, show a dissected Mesozoic-Tertiary substratum buried under continental infill of mainly Quaternary age due to the long-term activity of the Paganica-San Demetrio normal faults system (PSDFS), ruling the most recent deformational phase. Our results indicate that the basin bottom deepens up to 600 m moving to the south, with the continental infill largely exceeding the known thickness of the Quaternary sequence. The causes of this increasing thickness can be: (1) the onset of the continental deposition in the southern sector took place before the Quaternary, (2) there was an early stage of the basin development driven by different fault systems that produced a depocentre in the southern sector not related to the present-day basin shape, or (3) the fault system slip rate in the southern sector was faster than in the northern sector. We were able to gain sights into the long-term PSDFS behaviour and evolution, by comparing throw rates at different timescales and discriminating the splays that lead deformation. Some fault splays exhibit large cumulative throws (> 300 m) in coincidence with large displacement of the continental deposits sequence (> 100 m), thus testifying a general persistence in time of their activity as leading splays of the fault system. We evaluate the long-term (3-2.5 Myr) cumulative and Quaternary throw rates of most of the leading splays to be 0.08-0.17 mm yr(-1), indicating a substantial stability of the faults activity. Among them, an individual leading fault splay extends from Paganica to San Demetrio ne' Vestini as a result of a post-Early Pleistocene linkage of two smaller splays. This 15 km long fault splay can explain the Holocene surface ruptures observed to be larger than those occurred during the 2009 L'Aquila earthquake, such as revealed by palaeoseismological investigations. Finally, the architecture of the basin at depth suggests that the PSDFS can also rupture a longer structure at the surface, allowing earthquakes larger than M 6.5, besides rupturing only small sections, as it occurred in 2009.This work was financially supported by Project ‘Fondo per gli Investimenti della Ricerca di Base (FIRB) Abruzzo: High-resolution analyses for assessing the seismic hazard and risk of the areas affected by the 2009 April 6 earthquake’, No. RBAP10ZC8K_005.Peer reviewe

Mixed infections with distinct cytomegalovirus glycoprotein B genotypes in Polish pregnant women, fetuses, and newborns

The purpose of this investigation was to describe a distribution of cytomegalovirus (CMV) single and multiple genotypes among infected pregnant women, their fetuses, and newborns coming from Central Poland, as well as congenital cytomegaly outcome. The study involved 278 CMV-seropositive pregnant women, of whom 192 were tested for viral DNAemia. Human cytomegalovirus (HCMV) genotyping was performed for 18 of 34 pregnant women carrying the viral DNA and for 12 of their 15 offspring with confirmed HCMV infections. Anti-HCMV antibodies levels were assessed by chemiluminescence immunoassay (CLIA) and enzyme-linked fluorescence assay (ELFA) tests. Viral DNA loads and genotypes were determined by real-time polymerase chain reaction (PCR) assays for the UL55 gene. In the pregnant women, we identified HCMV gB1, gB2, gB3, and gB4 genotypes. Single gB2, gB3, or gB4 genotypes were observed in 14 (77.8 %) women, while multiple gB1–gB2 or gB2–gB3 genotypes were observed in four (22.2 %). Maternal HCMV genotypes determined the genotypes identified in their fetuses and newborns (p ≤ 0.050). Half of them were infected with single HCMV gB1, gB2, or gB3 genotypes and the other half with multiple gB1–gB2 or gB2–gB3 genotypes. Single and multiple genotypes were observed in both asymptomatic and symptomatic congenital cytomegaly, although no gB3 genotype was identified among asymptomatic cases. In Central Poland, infections with single and multiple HCMV strains occur in pregnant women, as well as in their fetuses and neonates, with both asymptomatic and symptomatic infections. HCMV infections identified in mothers seem to be associated with the viral genotypes in their children

Caractérisation et suivi des écoulements hydriques dans les milieux poreux par la méthode du Potentiel Spontané

In hydrogeology, the information related to the piezometric surface and hydraulic properties is usually obtained from in situ measurements in a set of piezometers. However, this approach is intrusive and depends on the number of available piezometers. This explains why, in the last decade, research scientists looked for a new geophysical method able to determine the piezometric head variations and the groundwater flow parameters in a non-intrusive way. The self-potential method offers such possibility. Indeed, the flow of groundwater is responsible for a measurable electrical field owing to the electrokinetic coupling between the water flux and the electrical current density. This electrokinetic coupling is one of the sources for the so-called self-potential signals measured passively at the ground surface with non-polarisable electrodes. Field and laboratory experiments were undertaken in order to measure the electric signals of a groundwater flow during pumping and infiltration tests. The field and laboratory results prove the capacity of the self-potential method to follow the groundwater flow in real time. They indicate that the self-potential variations are linearly related, at the first order, to the piezometric head variations. These experiences show the usefulness of the self-potential method to monitor the groundwater flow and to estimate the groundwater flow parameters.Identifier la géométrie des écoulements souterrains est un objectif majeur de l'hydrologie. L'objectif de ce travail de thèse est de montrer que la méthode du Potentiel Spontané (PS) peut fournir des informations spatialisées sur la géométrie des circulations hydriques et sur les propriétés hydrauliques du sous-sol. La méthode PS est basée sur la mesure du champ électrique naturellement présent dans le sous-sol. Des expériences de terrain ont été menées pour mesurer la signature électrique d'un écoulement hydrique lors d'expériences de pompage et d'infiltration. Pour une meilleure compréhension du problème physique sous-jacent, des simulations de pompage et d'infiltration ont été réalisées dans une cuve en Plexiglas. Les résultats obtenus sur le terrain et en laboratoire démontrent la capacité de la méthode PS pour suivre la progression d'un écoulement et confirment l'intérêt de celle-ci comme outil adapté à la détermination du niveau piézométrique et des propriétés hydrauliques du sous-sol

Caractérisation et suivi des écoulements hydriques dans les milieux poreux par la méthode du Potentiel Spontané

Identifier la géométrie des écoulements souterrains est un objectif majeur de l'hydrologie. L'objectif de ce travail de thèse est de montrer que la méthode du Potentiel Spontané (PS) peut fournir des informations spatialisées sur la géométrie des circulations hydriques et sur les propriétés hydrauliques du sous-sol. Celle-ci est basée sur la mesure du champ électrique naturellement présent dans le sous-sol. Des expériences de terrain ont été menées pour mesurer la signature électrique d'un écoulement hydrique lors d'expériences de pompage et d'infiltration. Pour une meilleure compréhension du problème physique sous-jacent, des simulations de pompage et d'infiltration ont été réalisées dans une cuve en Plexiglas. Les résultats obtenus sur le terrain et en laboratoire démontrent la capacité de la méthode PS pour suivre la progression d'un écoulement et confirment l'intérêt de celle ci comme outil adapté à la détermination du niveau piézométrique et des propriétés hydrauliques du sous-sol.AIX-MARSEILLE3-BU Sc.St Jérô (130552102) / SudocSudocFranceF

Realizacja programu rolnośrodowiskowego na terenie województwa lubelskiego

In this paper an analysis of the use of agri-environmental program implemented under the RDP 2007- 2013 the Lublin region, being an obligatory instrument for all Member States of the European Union promotes agricultural production based on environmentally friendly methods. In the Lublin region of agrienvironmental payment grant applied for 54 793 beneficiaries, of whom 98.4% received positive decisions. The amount paid out of funds in the period 2008-2013 amounted to 428.4 million PLN. In the last year, area 204.0 thousand ha has been acquired subsidies. Participating districts in the implementation of particular packages varied. The greatest interest was a package of soil and water protection

Communities of aquatic insects of old-growth and clearcut coastal headwater streams of varying flow persistence

Abstract: Headwater streams, varying in flow persistence from ephemeral to intermittent to perennial, provide the tightest coupling between water and land, yet they often receive the least protection during forest management. We described communities of aquatic insects in perennial, intermittent, and ephemeral channels surrounded by old-growth forest and 4-to 8-year-old clearcuts in Clayoquot Sound, British Columbia, to determine whether temporary streams have unique aquatic communities and to examine the short-term impacts of harvesting. We measured flow persistence, stream size, canopy cover, organic detritus, and algal biomass in 19 streams. We sampled aquatic invertebrates with a combination of emergence cages and kicknet samples. Temporary and old-growth streams had more organic detritus and a higher abundance of shredders. Perennial and clearcut streams had a higher abundance of some algal grazers, but not higher algal biomass. Insect richness was similar in intermittent and perennial streams of each seral stage but lower in ephemeral streams. Intermittent streams contained four taxa not found in the other stream classes; perennial and ephemeral streams had none. Communities of aquatic insects differed between streams surrounded by clearcuts and old growth, and varied with continuity of flow. Résumé : Les ruisseaux de tête de bassins hydrographiques, avec une persistance de débit qui varie d'éphémère à intermittent, puis à pérenne, constituent l'interface le plus direct entre l'eau et la terre, mais ils sont les moins biens protégés dans le cadre de l'aménagement forestier. Nous avons décrit les communautés d'insectes aquatiques dans des ruisseaux pérennes, intermittents et éphémères bordés par des forêts anciennes et des coupes à blanc de 4 à 8 ans à Clayoquot Sound, en Colombie-Britannique, pour déterminer si les ruisseaux temporaires ont des communautés aquatiques uniques et pour examiner les impacts à court terme de la coupe forestière. Nous avons mesuré la persistance du débit, la taille du ruisseau, le recouvrement de la canopée et la biomasse de débris organiques et d'algues dans 19 ruisseaux. Nous avons échantillonné les invertébrés aquatiques en combinant des échantillons provenant de cages à émer-gence et de filets faucheurs. Les ruisseaux temporaires en forêt ancienne contenaient plus de débris organiques et avaient une plus grande abondance de déchiqueteurs. Les ruisseaux pérennes dans des coupes à blanc avaient une plus grande abondance de certains brouteurs d'algues, mais pas une plus grande biomasse d'algues. La richesse en insectes était semblable dans les ruisseaux intermittents et pérennes de chaque stade successoral, mais plus faible dans les ruisseaux éphémères. Les ruisseaux intermittents contenaient quatre taxons exclusifs qui n'ont pas été trouvés dans les autres classes de ruisseaux; les ruisseaux pérennes et éphémères en avaient aucun. Les communautés d'insectes aquatiques diffèrent selon que les ruisseaux sont bordés par des coupes à blanc ou des forêts anciennes et elles varient selon la persistance du débit. [Traduit par la Rédaction] 1432 Price et al

Estimation of the water table throughout a catchment using self-potential and piezometric data in a Bayesian framework

International audienceInformation about spatial variations of the water table that occur throughout catchments is useful to infer large scale flow patterns, but conventional mapping using piezometric data is invasive, slow, and expensive. Water flow in the subsurface generates an electrical current called the streaming current. The resulting self-potential (SP) (electrostatic) signals can be measured non-intrusively, quickly, and inexpensively at the ground surface. We considered two conceptual models to relate SP signals to the water table. The “infiltration model” relates SP signals to the thickness of the vadose zone, while the “water table model” relates SP signals to the distribution of the water table in unconfined aquifers. These models are first calibrated against field data before a Bayesian method is applied to update a kriged map of the water table obtained from piezometric observations using a kriged SP map. The estimated water tables based on the two conceptual models were combined into one final model using concepts from Bayesian Model Averaging. The method was applied to a small agricultural catchment (not, vert, similar1 km2) in southern France. The posterior water table estimates were improved mainly on the slopes surrounding the basin. Understanding the variations in the water table on these slopes is important because infiltration in these areas feed the basin with groundwater flow. The Bayesian framework is useful to avoid overconfident predictions when using SP data in hydrogeological estimation because it provides realistic uncertainty estimates

Subsurface fluid distribution and possible seismic precursory signal at the Salse di Nirano mud volcanic field, Italy

Mud volcanoes are geological systems often characterized by elevated fluid pressures at depth deviating from hydrostatic conditions. This near-critical state makes mud volcanoes particularly sensitive to external forcing induced by natural or man-made perturbations. We used the Nirano mud volcanic field as a natural laboratory to test pre- and post-seismic effects generated by distant earthquakes. We first characterized the subsurface structure of the Nirano mud volcanic field with a geoelectrical study. Next, we deployed a broad-band seismic station in the area to understand the typical seismic signal generated by the mud volcano. Seismic records show a background noise below 2 s, sometimes interrupted by pulses of drumbeat-like high-frequency signals lasting from several minutes to hours. To date this is the first observation of drumbeat signal observed in mud volcanoes. In 2013 June we recorded a M4.7 earthquake, that occurred approximately 60 km far from our seismic station. According to empirical estimations the Nirano mud volcanic field should not have been affected by the M4.7 earthquake. Yet, before the seismic event we recorded an increasing amplitude of the signal in the 10–20 Hz frequency band. The signal emerged approximately two hours before the earthquake and lasted for about three hours. Our statistical analysis suggests the presence of a possible precursory signal about 10 min before the earthquake