Modelling non-stationary water ages in a tropical rainforest: A preliminary spatially distributed assessment     

Alicia Correa  Christian Birkel  Jason Gutierrez  Joni Dehaspe  Ana María Durán-Quesada  Chris Soulsby  Ricardo Sánchez-Murillo 《水文研究》2020,34(25):4776-4793

Pristine tropical forests play a critical role in regional and global climate systems. For a better understanding of the eco-hydrology of tropical “evergreen” vegetation, it is essential to know the partitioning of water into transpiration and evaporation, runoff and associated water ages. For this purpose, we evaluated how topography and vegetation influence water flux and age dynamics at high temporal (hourly) and spatial (10 m) resolution using the Spatially Distributed Tracer-Aided Rainfall-Runoff model for the tropics (STARRtropics). The model was applied in a tropical rainforest catchment (3.2 km²) where data were collected biweekly to monthly and during intensive monitoring campaigns from January 2013 to July 2018. The STARRtropics model was further developed, incorporating an isotope mass balance for evapotranspiration partitioning into transpiration and evaporation. Results exhibited a rapid streamflow response to rainfall inputs (water and isotopes) with limited mixing and a largely time-invariant baseflow isotope composition. Simulated soil water storage showed a transient response to rainfall inputs with a seasonal component directly resembling the streamflow dynamics which was independently evaluated using soil water content measurements. High transpiration fluxes (max 7 mm/day) were linked to lower slope gradients, deeper soils and greater leaf area index. Overall water partitioning resulted in 65% of the actual evapotranspiration being driven by vegetation with high transpiration rates over the drier months compared to the wet season. Time scales of water age were highly variable, ranging from hours to a few years. Stream water ages were conceptualized as a mixture of younger soil water and slightly older, deeper soil water and shallow groundwater with a maximum age of roughly 2 years during drought conditions (722 days). The simulated soil water ages ranged from hours to 162 days and for shallow groundwater up to 1,200 days. Despite the model assumptions, experimental challenges and data limitation, this preliminary spatially distributed model study enhances knowledge about the water ages and overall young water dominance in a tropical rainforest with little influence of deeper and older groundwater.  相似文献   

Soil–structure interaction effects on seismic inelastic analysis of 3-D tunnels     

George D. Hatzigeorgiou  Dimitri E. Beskos 《Soil Dynamics and Earthquake Engineering》2010,30(9):851-861

This paper investigates the importance of seismic soil–structure interaction in three-dimensional lined tunnels, assuming inelastic material behaviour for both the concrete liner and the soft rock type of soil. The seismic response of the soil–structure system is determined by the finite element method (FEM) in the time domain. Viscous absorbing boundaries are used in conjunction with the discretization of the rock medium. Both the rock medium and the concrete liner are assumed to behave inelastically on the basis of the continuum damage mechanics theory. The seismic waves are assumed to have any arbitrary time variation and direction of propagation. The system is analysed with and without soil–structure interaction in order to assess its importance on the response of the system. Through parametric studies, the influence of the most critical parameters affecting the structural response is determined and critically discussed.  相似文献   

The active fault system of SW Alps     

Guillaume Sanchez  Yann Rolland  Dimitri Schreiber  Gérard Giannerini  Michel Corsini  Jean-Marc Lardeaux 《Journal of Geodynamics》2010,49(5):296-302

Historical and active seismicity in the south-western Alps (France and Italy) shows the recurrence of relatively high-magnitude earthquakes (M ≥ 5.8), like the one that recently affected the Italian Apennine range (M = 6.3 on the 30th March 2009). However, up-to-date detailed mapping of the active fault network has been poorly established. The evaluation of seismological hazard in particular in the highly populated French and Italian coastal region cannot be done without this. Here, we present a detailed study of the main active fault system, based on geological observations along the south-western flank of the Alpine arc. This N140° right-lateral strike-slip active fault system runs along the edge of the Argentera-Mercantour range and can be followed down to the Mediterranean Sea. It is evidenced by (1) Holocene offsets of glacial geomorphology witnessing ongoing fault activity since 10 ka, (2) widespread recent (10–20 Ma) pseudotachylytes featuring long term activity of the faults, (3) active landslides along the main fault zone, (4) geothermal anomalies (hot springs) emerging in the active faults, (5) ongoing low-magnitude seismic activity and (6) localization of the main historical events. In the light of our investigations, we propose a new tectonic pattern for the active fault system in the south-western Alps.  相似文献   

Nanoindentation approach characterizing strain rate sensitivity of compressive response of asphalt concrete     

Daisuke Katsuki  Marte Gutierrez 《Acta Geotechnica》2014,9(5):887-901

This paper presents the results of a study on the use of nanoindentation test to characterize the strain rate-dependent compressive response of asphalt concrete. Nanoindentation is now widely used for characterization and testing of composite as well as single-phase materials. Using a small piece of sample, nanoindentation tests can evaluate material behavior and structure in terms of the elasticity, time-dependent response, yield strength, damage, crack advance, debonding, and fatigues. In this study, a mixture of asphalt and calcium carbonate filler powder filling the intergranular void space of the asphalt concrete was characterized in terms of strain rate sensitivity at room temperature. The indentation hardness is observed to continuously decrease during constant indentation strain rates, but the hardness response clearly indicates positive strain rate dependency when compared at the same indentation depths. Following the constant strain rate tests, indentation creep response of the asphalt–filler mixture was tested at constant load conditions. The strain rate sensitivity values characterized from double logarithmic relationships between indentation hardness and strain rate during constant strain rate and constant load tests are comparable with that determined from uniaxial compression test of cylindrical asphalt concrete samples. The observed indentation size effect on hardness value was analyzed based on an existing size effect model. The size effect in the asphalt–filler mixture, which is stronger than that defined by the model, could be attributed to a plastically graded surface of asphalt–filler sample.  相似文献   

Formation and evolution of planetary systems: the impact of high-angular resolution optical techniques     

Olivier Absil  Dimitri Mawet 《Astronomy and Astrophysics Review》2010,18(3):317-382

The direct images of giant extrasolar planets recently obtained around several main sequence stars represent a major step in the study of planetary systems. These high-dynamic range images are among the most striking results obtained by the current generation of high-angular resolution instruments which will be superseded by a new generation of instruments in the coming years. It is, therefore, an appropriate time to review the contributions of high-angular resolution visible/infrared techniques to the rapidly growing field of extrasolar planetary science. During the last 20 years, the advent of the Hubble Space Telescope, of adaptive optics on 4- to 10-m class ground-based telescopes, and of long-baseline infrared stellar interferometry, has opened a new viewpoint on the formation and evolution of planetary systems. By spatially resolving the optically thick circumstellar discs of gas and dust where planets are forming, these instruments have considerably improved our models of early circumstellar environments and have thereby provided new constraints on planet formation theories. High-angular resolution techniques are also directly tracing the mechanisms governing the early evolution of planetary embryos and the dispersal of optically thick material around young stars. Finally, mature planetary systems are being studied with an unprecedented accuracy thanks to single-pupil imaging and interferometry, precisely locating dust populations and putting into light a whole new family of long-period giant extrasolar planets.  相似文献   

Telecommunication computer networks in Moscow     

Dimitri Federov 《GeoJournal》1997,42(4):449-456

This research note considers the development structure of world-wide computer communications by city territorial divisions, as well as the extent and special factors affecting the use of computer communication services for both providers and consumers. A survey of over 120 Moscow businesses, engaged in a wide range of activities, provided the basis for an analysis of the spread and importance of computer telecommunications systems.  相似文献   

Foreword     

Marc Van Meirvenne  Patrick Bogaert  Dimitri D��Or 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(8):1029-1029

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Macrobenthic community response to copper in Shelter Island Yacht Basin, San Diego Bay, California     

Neira C  Mendoza G  Levin LA  Zirino A  Delgadillo-Hinojosa F  Porrachia M  Deheyn DD 《Marine pollution bulletin》2011,62(4):701-717

We examined Cu contamination effects on macrobenthic communities and Cu concentration in invertebrates within Shelter Island Yacht Basin, San Diego Bay, California. Results indicate that at some sites, Cu in sediment has exceeded a threshold for “self defense” mechanisms and highlight the potential negative impacts on benthic faunal communities where Cu accumulates and persists in sediments. At sites with elevated Cu levels in sediment, macrobenthic communities were not only less diverse but also their total biomass and body size (individual biomass) were reduced compared to sites with lower Cu. Cu concentration in tissue varied between species and within the same species, reflecting differing abilities to “regulate” their body load. The spatial complexity of Cu effects in a small marina such as SIYB emphasizes that sediment-quality criteria based solely on laboratory experiments should be used with caution, as they do not necessarily reflect the condition at the community and ecosystem levels.  相似文献   

Laboratory Experiments on the Hydraulic Conductivity of Sands with Dispersed Rock Particles     

Juan J. Gutierrez  Luis E. Vallejo 《Geotechnical and Geological Engineering》2013,31(4):1405-1410

Many natural and engineered soil deposits are composite materials made of a soil matrix and dispersed large rock particles. Very little is known about the hydraulic conductivity of sand-rock mixtures. In the present study, the hydraulic conductivity of sand with dispersed large particles of gravel was obtained using hydraulic conductivity tests. The results of the experimental investigations indicated that the percentage by weight and the size of the dispersed rock particles had a large influence on the hydraulic conductivity of the mixtures. It was determined that as the percentage by weight and the size of the rock particles increased in the mixtures, the hydraulic conductivity of the mixtures decreased.  相似文献   

Testing new sources of topographic data for flood propagation modelling under structural,parameter and observation uncertainty     

Micah M. Mukolwe  Kun Yan  Giuliano Di Baldassarre  Dimitri P. Solomatine 《水文科学杂志》2016,61(9):1707-1715

ABSTRACT

This study assessed the utility of EUDEM, a recently released digital elevation model, to support flood inundation modelling. To this end, a comparison with other topographic data sources was performed (i.e. LIDAR, light detection and ranging; SRTM, Shuttle Radar Topographic Mission) on a 98-km reach of the River Po, between Cremona and Borgoforte (Italy). This comparison was implemented using different model structures while explicitly accounting for uncertainty in model parameters and upstream boundary conditions. This approach facilitated a comprehensive assessment of the uncertainty associated with hydraulic modelling of floods. For this test site, our results showed that the flood inundation models built on coarse resolutions data (EUDEM and SRTM) and simple one-dimensional model structure performed well during model evaluation.