Groundwater overexploitation: why is the red flag waved? Case study on the Kairouan plain aquifer (central Tunisia)     

Sylvain?MassuelEmail author  Jeanne?Riaux 《Hydrogeology Journal》2017,25(6):1607-1620

In many parts of the world, groundwater users regularly face serious resource-depletion threat. At the same time, “groundwater overexploitation” is massively cited when discussing groundwater management problems. A kind of standard definition tends to relegate groundwater overexploitation only as a matter of inputs and outputs. However, a thorough state-of-the-art analysis shows that groundwater overexploitation is not only a matter of hydrogeology but also a qualification of exploitation based on political, social, technical, economic or environmental criteria. Thus, an aquifer with no threat to groundwater storage can rightly be considered as overexploited because of many other prejudicial aspects. So, why is groundwater overexploitation so frequently only associated with resource-depletion threat and so rarely related to other prejudicial aspects? In that case, what really lies behind the use of the overexploitation concept? The case of the Kairouan plain aquifer in central Tunisia was used to analyze the way that the overexploitation message emerges in a given context, how groundwater-use stakeholders (farmers, management agencies and scientists) each qualify the problem in their own way, and how they see themselves with regard to the concept of overexploitation. The analysis shows that focusing messages on overexploitation conceals the problems encountered by the various stakeholders: difficulties accessing water, problems for the authorities in controlling the territory and individual practices, and complications for scientists when qualifying hydrological situations. The solutions put forward to manage overexploitation are at odds with the problems that arise locally, triggering tensions and leading to misunderstandings between the parties involved.  相似文献   

Run-up on a body in waves and current. Fully nonlinear and finite-order calculations     

B. Büchmann  P. Ferrant  J. Skourup   《Applied Ocean Research》2000,22(6)

Run-up on a large fixed body in waves and current have been calculated using both a fully nonlinear time-domain boundary element model and a finite-order time-domain boundary element model, the latter being correct to second order in the wave steepness and to first-order in the current strength. The results from the two models agree well in the low Froude number and low wave steepness regime. This serves as a cross-validation of the two boundary element models. Furthermore, the two sets of data provide an excellent method for examining the domain of validity for the second-order method. Such limits are, for the case studied, given in terms of maximum Froude number and maximum wave steepness.  相似文献   

Two large earthquakes in western Switzerland in the sixteenth century: 1524 in Ardon (VS) and 1584 in Aigle (VD)     

Gabriela Schwarz-Zanetti  Donat Fäh  Sylvain Gache  Philipp Kästli  Jeanluc Loizeau  Virgilio Masciadri  Gregor Zenhäusern 《Journal of Seismology》2018,22(2):439-454

The Valais is the most seismically active region of Switzerland. Strong damaging events occurred in 1755, 1855, and 1946. Based on historical documents, we discuss two known damaging events in the sixteenth century: the 1524 Ardon and the 1584 Aigle earthquakes. For the 1524, a document describes damage in Ardon, Plan-Conthey, and Savièse, and a stone tablet at the new bell tower of the Ardon church confirms the reconstruction of the bell tower after the earthquake. Additionally, a significant construction activity in the Upper Valais churches during the second quarter of the sixteenth century is discussed that however cannot be clearly related to this event. The assessed moment magnitude Mw of the 1524 event is 5.8, with an error of about 0.5 units corresponding to one standard deviation. The epicenter is at 46.27 N, 7.27 E with a high uncertainty of about 50 km corresponding to one standard deviation. The assessed moment magnitude Mw of the 1584 main shock is 5.9, with an error of about 0.25 units corresponding to one standard deviation. The epicenter is at 46.33 N and 6.97 E with an uncertainty of about 25 km corresponding to one standard deviation. Exceptional movements in the Lake Geneva wreaked havoc along the shore of the Rhone delta. The large dimension of the induced damage can be explained by an expanded subaquatic slide with resultant tsunami and seiche in Lake Geneva. The strongest of the aftershocks occurred on March 14 with magnitude 5.4 and triggered a destructive landslide covering the villages Corbeyrier and Yvorne, VD.  相似文献   

Late slowdown of the Atlantic Meridional Overturning Circulation during the Last Glacial Inception: New constraints from sedimentary (231Pa/230Th)     

Abel Guihou  Sylvain Pichat  Sìlvia Nave  Aline Govin  Laurent Labeyrie  Elisabeth Michel  Claire Waelbroeck 《Earth and Planetary Science Letters》2010,289(3-4):520-529

Our study gives new constraints on the response of Atlantic Meridional Overturning Circulation (AMOC) export to various forcings during the Last Glacial Inception. The decay corrected excess sedimentary (²³¹Pa/²³⁰Th) activity ratio (hereafter referred to as (Pa/Th)) has been measured over that period in two deep cores from the Western (SU90-11, 44°04′N, 40°01′W, 3645 m) and Eastern (MD01-2446, 39°03′N, 12°37′W, 3547 m) basins of the North Atlantic. Both records display significant changes despite the relatively short half-life of ²³¹Pa (～ 32 kyr) compared to the period we investigate. The (Pa/Th) variability does not correlate to changes in local opal flux normalized to ²³⁰Th. Moreover, the (Pa/Th) profiles display a high degree of coherency with indirect proxies of AMOC activity such as the benthic foraminifera δ¹³C and the mid-latitude summer Sea Surface Temperature in nearby reference cores. These additional pieces of evidence support our interpretation of the (Pa/Th) as reflecting AMOC export. The (Pa/Th) repeatedly underwent rapid changes during the Last Glacial Inception associated with the extension of ice rafted detritus in the North Atlantic, highlighting the control of ice-sheet dynamics through freshwater forcing on AMOC export. AMOC export remains large during periods of ice-sheet growth and its decreases lag the Northern Hemisphere summer insolation forcing. AMOC modulation appears driven by ice-sheet dynamics, itself driven by the seasonal insolation gradient between low and high Northern Hemisphere latitudes and the associated intensity of the meridional oceanic and atmospheric circulation.  相似文献   

Exploring the spatiotemporal variability of the snow water equivalent in a small boreal forest catchment through observation and modelling     

Achut Parajuli  Daniel F. Nadeau  François Anctil  Annie-Claude Parent  Benjamin Bouchard  Médéric Girard  Sylvain Jutras 《水文研究》2020,34(11):2628-2644

In snow-fed catchments, it is crucial to monitor and model the snow water equivalent (SWE), particularly when simulating the melt water runoff. SWE distribution can, however, be highly heterogeneous, particularly in forested environments. Within these locations, scant studies have explored the spatiotemporal variability in SWE in relation with vegetation characteristics, with only few successful attempts. The aim of this paper is to fill this knowledge gap, through a detailed monitoring at nine locations within a 3.49 km² forested catchment in southern Québec, Canada (47°N, 71°W). The catchment receives an annual average of 633 mm of solid precipitation and is predominantly covered with balsam fir stands. Extracted from intensive field campaign and high-resolution LiDAR data, this study explores the effect of fine scale forest features (tree height, tree diameter, canopy density, leaf area index [LAI], tree density and gap fraction) on the spatiotemporal variability in the SWE distribution. A nested stratified random sampling design was adopted to quantify small-scale variability across the catchment and 1810 manual snow samples were collected throughout the consecutive winters of 2016–17 and 2017–18. This study explored the variability of SWE using coefficients of variation (CV) and relating to the LAI. We also present existing spatiotemporal differences in maximum snow depth across different stands and its relationship with average tree diameter. Furthermore, exploiting key vegetation characteristics, this paper explores different approaches to model SWE, such as multiple linear regression, binary regression tree and neural networks (NN). We were unable to establish any relationship between the CV of SWE and the LAI. However, we observed an increase in maximum snow depth with decreasing tree diameter, suggesting an association between these variables. NN modelling (Nash-Sutcliffe efficiency [NSE] = 0.71) revealed that, snow depth, snowpack age and forest characteristics (tree diameter and tree density) are key controlling variables on SWE. Using only variables that are deemed to be more readily available (snow depth, tree height, snowpack age and elevation), NN performance falls by only 7% (NSE = 0.66).  相似文献   

The Multiscale TROPIcal CatchmentS critical zone observatory M-TROPICS dataset II: Land use,hydrology and sediment production monitoring in Houay Pano,northern Lao PDR     

Laurie Boithias  Yves Auda  Stéphane Audry  Jean-Pierre Bricquet  Alounsavath Chanhphengxay  Vincent Chaplot  Anneke de Rouw  Thierry Henry des Tureaux  Sylvain Huon  Jean-Louis Janeau  Keooudone Latsachack  Yann Le Troquer  Guillaume Lestrelin  Jean-Luc Maeght  Pierre Marchand  Pierre Moreau  Andrew Noble  Anne Pando-Bahuon  Kongkeo Phachomphon  Khambai Phanthavong  Alain Pierret  Olivier Ribolzi  Jean Riotte  Henri Robain  Emma Rochelle-Newall  Saysongkham Sayavong  Oloth Sengtaheuanghoung  Norbert Silvera  Nivong Sipaseuth  Bounsamay Soulileuth  Xaysatith Souliyavongsa  Phapvilay Sounyaphong  Sengkeo Tasaketh  Chanthamousone Thammahacksa  Jean-Pierre Thiebaux  Christian Valentin  Olga Vigiak  Marion Viguier  Khampaseuth Xayyathip 《水文研究》2021,35(5):e14126

Mountain regions of the humid tropics are characterized by steep slopes and heavy rains. These regions are thus prone to both high surface runoff and soil erosion. In Southeast Asia, uplands are also subject to rapid land-use change, predominantly as a result of increased population pressure and market forces. Since 1998, the Houay Pano site, located in northern Lao PDR (19.85°N 102.17°E) within the Mekong basin, aims at assessing the long-term impact of the conversion of traditional slash-and-burn cultivation systems to commercial perennial monocultures such as teak tree plantations, on the catchment hydrological response and sediment yield. The instrumented site monitors hydro-meteorological and soil loss parameters at both microplot (1 m²) and small catchment (0.6 km²) scales. The monitored catchment is part of the network of critical zone observatories named Multiscale TROPIcal CatchmentS (M-TROPICS). The data shared by M-TROPICS in Houay Pano are (1) rainfall, (2) air temperature, air relative humidity, wind speed, and global radiation, (3) catchment land use, (4) stream water level, suspended particulate matter, bed particulate matter and stones, (5) soil surface features, and (6) soil surface runoff and soil detachment. The dataset has already been used to interpret suspended particulate matter and bed particulate matter sources and dynamics, to assess the impact of land-use change on catchment hydrology, soil erosion, and sediment yields, to understand bacteria fate and weed seed transport across the catchment, and to build catchment-scale models focused on hydrology and water quality issues. The dataset may be further used to, for example, assess the role of headwater catchments in large tropical river basin hydrology, support the interpretation of new variables measured in the catchment (e.g., contaminants other than faecal bacteria), and assess the relative impacts of both climate and land-use change on the catchment.  相似文献   

Water balance prediction in stormwater infiltration basins using 2-D modeling: An application to evaluate the clogging process     

Patrice Cannavo  Anaïs Coulon  Sylvain Charpentier  Béatrice Béchet  Laure Vidal-Beaudet 《国际泥沙研究》2018,33(4):371-384

Sustainable urban drainage systems are built along roads and in urban areas to collect urban runoff and avoid flooding, and to filter water pollutants. Sediment collected by runoff is deposited in the stormwater basin and progressively reduces water infiltration efficiency, leading to the clogging of the basin. To help stormwater basin managers and stakeholders better understand and predict clogging rates in order to elaborate maintenance plans and schedules, water transport prediction models are necessary. However,because of the heterogeneous sediment hydrodynamic properties inside the stormwater basin, a twodimensional(2-D) water flow model is required to predict water levels and possible overflow as accurately as possible. Saturated hydraulic conductivity(Ks) and sediment water retention curves were measured in the overall sediment layer of the stormwater basin, in addition to sediment layer thickness and organic matter content(11 sampling points). Sediment depth was used to predict organic matter(OM) content, and the OM was used to predict Ks. Water height in the basin was modeled with the HYDRUS-2 D model by taking into account the sediment hydrodynamic properties distribution. The HYDRUS-2 D model gave a satisfactory representation of the measured data. Scenarios of the hydraulic properties of stormwater basin sediment were tested over time, and hydraulic resistance, R, was calculated to assess the stormwater basin performance. Presently, after 20 years of functioning, the stormwater basin still ensures efficient water infiltration, but the first outflow(Hydraulic resistance,R 24 h)) is expected to appear in the next 5 years, and clogging(R 47 h) in the next 13 years. This 2-D water balance model makes it possible to integrate the hydrodynamic heterogeneity of a stormwater basin. It gives interesting perspectives to better predict 2-D/3-D contaminant transport.  相似文献   

Provenance record of late Maastrichtian–late Palaeocene Andean Mountain building in the Amazonian retroarc foreland basin (Madre de Dios basin,Peru)          下载免费PDF全文

Mélanie Louterbach  Martin Roddaz  Pierre‐Olivier Antoine  Laurent Marivaux  Sylvain Adnet  Julien Bailleul  Elton Dantas  Roberto Ventura Santos  Farid Chemale Jr  Patrice Baby  Caroline Sanchez  Ysabel Calderon 《地学学报》2018,30(1):17-23

Biostratigraphic, sedimentological and provenance analyses suggest that a proto‐Andean Cordillera already existed in southern Peru by late Maastrichtian–late Palaeocene times. A 270‐m‐thick stratigraphic section shows changes in depositional environments from shallow marine (early Maastrichtian) to non‐marine (late Maastrichtian) then back to estuarine (late Palaeocene) conditions. An erosional surface separates lower Maastrichtian from upper Maastrichtian deposits. Above this surface, the late Maastrichtian unit exhibits moderately developed palaeosols and syn‐sedimentary normal faults. The sedimentary evolution is accompanied by a decrease in sedimentation rate and by changes in provenance. Shallow marine lower Maastrichtian deposits have a cratonic provenance as shown by their low εNd(0) values (?15 to ?16) and the presence of Precambrian inherited zircon grains. The upper Maastrichtian deposits have a mixed Andean and cratonic origin with εNd(0) values of ~12.6 and yield the first Cretaceous and Permo‐Triassic zircon grains. Estuarine to shallow marine upper Palaeocene deposits have an Andean dominant source as attested by higher εNd(0) values (?6 to ?10) and by the presence of Palaeozoic and Late Cretaceous zircon grains. The changes in depositional environments and sedimentation rates, as well as the shift in detrital provenance, are consistent with a late Maastrichtian–late Palaeocene period of Andean mountain building. In agreement with recently published studies, our data suggest that an Andean retroarc foreland basin was active by late Maastrichtian–late Palaeocene times.  相似文献   

Nickeliferous pyrite tracks pervasive hydrothermal alteration in Martian regolith breccia: A study in NWA 7533          下载免费PDF全文

Jean‐Pierre Lorand  Roger H. Hewins  Laurent Remusat  Brigitte Zanda  Sylvain Pont  Hugues Leroux  Maya Marinova  Damien Jacob  Munir Humayun  Alexander Nemchin  Marion Grange  Allen Kennedy  Christa Göpel 《Meteoritics & planetary science》2015,50(12):2099-2120

Martian regolith breccia NWA 7533 (and the seven paired samples) is unique among Martian meteorites in showing accessory pyrite (up to 1% by weight). Pyrite is a late mineral, crystallized after the final assembly of the breccia. It is present in all of the lithologies, i.e., the fine‐grained matrix (ICM), clast‐laden impact melt rocks (CLIMR), melt spherules, microbasalts, lithic clasts, and mineral clasts, all lacking magmatic sulfides due to degassing. Pyrite crystals show combinations of cubes, truncated cubes, and octahedra. Polycrystalline clusters can reach 200 μm in maximum dimensions. Regardless of their shape, pyrite crystals display evidence of very weak shock metamorphism such as planar features, fracture networks, and disruption into subgrains. The late fracture systems acted as preferential pathways for partial replacement of pyrite by iron oxyhydroxides interpreted as resulting from hot desert terrestrial alteration. The distribution and shape of pyrite crystals argue for growth at moderate to low growth rate from just‐saturated near neutral (6 < pH<10), H₂S‐HS‐rich fluids at minimum log fO₂ of >FMQ + 2 log units. It is inferred from the maximum Ni contents (4.5 wt%) that pyrite started crystallizing at 400–500 °C, during or shortly after a short‐duration, relatively low temperature, thermal event that lithified and sintered the regolith breccias, 1.4 Ga ago as deduced from disturbance in several isotope systematics.  相似文献   

Predicting the effects of climate change on reproductive fitness of an endangered montane lizard, Eulamprus leuraensis (Scincidae)     

Sylvain Dubey  Richard Shine 《Climatic change》2011,107(3-4):531-547

A shift in climatic conditions may directly modify critical organismal traits (such as reproductive output and offspring phenotypes), and experimental studies to document such direct effects thus may clarify the impacts of climate change on the species involved. The endangered Blue Mountains Water Skink (Eulamprus leuraensis) exhibits several traits predicted to imperil it under climate change: ectothermy, low reproductive output, specialisation to a restricted habitat type, montane endemicity, and a small geographic range. Congeneric species exhibit temperature-dependent sex determination, increasing potential sensitivity to climate change. We maintained wild-caught female lizards throughout pregnancy under thermal conditions simulating a shift in basking-time availability (3 vs 7 h/day) as might occur under climate change. Females with longer basking opportunities per day gave birth 2 weeks earlier, to slightly smaller offspring, that grew much faster in the first few weeks of life. Importantly, offspring sex ratios were not affected by maternal thermal regimes. Hence, some traits (e.g., offspring size, growth rates, dates of birth) are sensitive to ambient thermal conditions whereas other traits (e.g., offspring sex ratio and sprint speed) are not. On balance, the greatest threat to population persistence for E. leuraensis under climate change is likely to involve indirect effects mediated via habitat degradation (especially, drying-out of the hanging swamps) rather than direct thermal effects on lizard reproductive output or offspring phenotypes.  相似文献