A novel methodological approach for land subsidence prediction through data assimilation techniques     

Gazzola  Laura  Ferronato  Massimiliano  Frigo  Matteo  Janna  Carlo  Teatini  Pietro  Zoccarato  Claudia  Antonelli  Massimo  Corradi  Anna  Dacome  Maria Carolina  Mantica  Stefano 《Computational Geosciences》2021,25(5):1731-1750

Computational Geosciences - Anthropogenic land subsidence can be evaluated and predicted by numerical models, which are often built over deterministic analyses. However, uncertainties and...  相似文献   

Age and origin of groundwater resources in the Ararat Valley,Armenia: a baseline study applying hydrogeochemistry and environmental tracers     

Schubert  Michael  Michelsen  Nils  Schmidt  Axel  Eichenauer  Laura  Knoeller  Kay  Arakelyan  Alexander  Harutyunyan  Lilith  Schüth  Christoph 《Hydrogeology Journal》2021,29(7):2517-2527

Within the Ararat Valley (Armenia), a continuously growing water demand (for irrigation and fish farming) and a simultaneous decline in groundwater recharge (due to climate change) result in increasing stress on the local groundwater resources. This detrimental development is reflected by groundwater-level drops and an associated reduction of the area with artesian conditions in the valley centre. This situation calls for increasing efforts aimed at more sustainable water resources management. The aim of this baseline study was the collection of data that allows for study on the origin and age distribution of the Ararat Valley groundwater based on environmental tracers, namely stable (δ²H, δ¹⁸O) and radioactive (³⁵S, ³H) isotopes, as well as physical-chemical indicators. The results show that the Ararat Valley receives modern recharge, despite its (semi-)arid climate. While subannual groundwater residence times could be disproved (³⁵S), the detected ³H pattern suggests groundwater ages of several decades, with the oldest waters being recharged around 60 years ago. The differing groundwater ages are reflected by varying scatter of stable isotope and hydrochemical signatures. The presence of young groundwater (i.e., younger that the 1970s), some containing nitrate, indicates groundwater vulnerability and underscores the importance of increased efforts to achieve sustainable management of this natural resource. Since stable isotope signatures indicate the recharge areas to be located in the mountains surrounding the valley, these efforts must not be limited to the central part of the valley where most of the abstraction wells are located.

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A water retention model accounting for void ratio changes in double porosity clays     

De la Morena  Gema  Navarro  Vicente  Asensio  Laura  Gallipoli  Domenico 《Acta Geotechnica》2021,16(9):2775-2790

This paper presents a constitutive model that predicts the water retention behaviour of compacted clays with evolving bimodal pore size distributions. In line with previous research, the model differentiates between the water present inside the saturated pores of the clay aggregates (the microstructure) and the water present inside the pores between clay aggregates (the macrostructure). A new formulation is then introduced to account for the effect of the macrostructural porosity changes on the retention behaviour of the soil, which results in a consistent evolution of the air-entry value of suction with volumetric deformations. Data from wetting tests on three different active clays (i.e. MX-80 bentonite, FEBEX bentonite, and Boom clay), subjected to distinct mechanical restraints, were used to formulate, calibrate, and validate the proposed model. Results from free swelling tests were also modelled by using both the proposed double porosity model and a published single porosity model, which confirmed the improvement in the predictions of degree of saturation by the present approach. The proposed retention model might be applied, for example, to the simulation of the hydromechanical behaviour of engineered bentonite barriers in underground nuclear waste repositories, where compacted active clays are subjected to changes of both suction and porosity structure under restrained volume conditions.

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Single-particle crushing strength under different relative humidity conditions     

Manso  João  Marcelino  João  Caldeira  Laura 《Acta Geotechnica》2021,16(3):749-761

This paper presents a fundamental study on the effect of the relative humidity on the rockfill crushing strength. This aspect plays an important role in the mechanical behaviour of rockfill, and it is known that certain characteristics of the granular materials, such as compressibility and shear strength, depend on the confining stress, which is a function of the particles crushing. An increased interest has been observed regarding the effect of the relative humidity in the mechanical behaviour of rockfill. Unfortunately, limited research has been conducted until now regarding the study of individual particle crushing. Therefore, this paper thoroughly investigated particle crushing, by performing single-particle crushing tests on rockfill particles divided into four size ranges, under different relative humidity conditions. The experimental results reveal a considerable influence of the relative humidity in the studied rockfill particles, whose strength of the particles with the greatest dimensions in saturated conditions was reduced by half. Consistent macro-mechanical evidence demonstrates that particle’s size and relative humidity conditions depict the most important factors that influence particle crushing strength.

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A comparison of fibre‐optic distributed temperature sensing to traditional methods of evaluating groundwater inflow to streams     

Martin A. Briggs  Laura K. Lautz  Jeffrey M. McKenzie 《水文研究》2012,26(9):1277-1290

There are several methods for determining the spatial distribution and magnitude of groundwater inputs to streams. We compared the results of conventional methods [dye dilution gauging, acoustic Doppler velocimeter (ADV) differential gauging, and geochemical end‐member mixing] to distributed temperature sensing (DTS) using a fibre‐optic cable installed along 900 m of Ninemile Creek in Syracuse, New York, USA, during low‐flow conditions (discharge of 1·4 m³ s^?1). With the exception of differential gauging, all methods identified a focused, contaminated groundwater inflow and produced similar groundwater discharge estimates for that point, with a mean of 66·8 l s^?1 between all methods although the precision of these estimates varied. ADV discharge measurement accuracy was reduced by non‐ideal conditions and failed to identify, much less quantify, the modest groundwater input, which was only 5% of total stream flow. These results indicate ambient tracers, such as heat and geochemical mixing, can yield spatially and quantitatively refined estimates of relatively modest groundwater inflow even in large rivers. DTS heat tracing, in particular, provided the finest spatial characterization of groundwater inflow, and may be more universally applicable than geochemical methods, for which a distinct and consistent groundwater end member may be more difficult to identify. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Evidence for Dedolomitization and Mixing in Paleozoic Carbonates Near Oak Ridge, Tennessee   总被引：1，自引：0，他引：1  

James A. Saunders  Laura E. Toran 《Ground water》1994,32(2):207-214

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Large-scale floodplain modelling     

D. Michael Gee  Malcolm G. Anderson  Laura Baird 《地球表面变化过程与地形》1990,15(6):513-523

A two-dimensional horizontal finite element numerical model (RMA-2) was applied to a 24 km river channel-floodplain reach in West Germany. Initial results indicate that finite element schemes may successfully estimate inundation in large-scale floodplain applications. Potentially, the resulting detailed velocity vector distributions and identification of inundation zones throughout storm events could provide an insight into the present day sedimentary environment on the floodplain.  相似文献   

Ground-Water Problems in the Mesozoic Pax Mountain Fault Zone     

David S. Snipes  Peter R. Manoogian  Michael W. Davis  Laura L. Burnett  Jerry A. Wylie  Steven B. Heaton 《Ground water》1986,24(3):375-381

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ISOTOPES IN GROUND-WATER INVESTIGATIONS     

Laura Toran 《Ground water》1982,20(6):740-745

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Palaeomagnetism of the Guaniguanico Cordillera, western Cuba: a pilot study     

L. M. Alva-Valdivia  A. Goguitchaichvili  J. Cobiella-Reguera  J. Urrutia-Fucugauchi  M. Fundora-Granda  J. M. Grajales-Nishimura  C. Rosales 《Cretaceous Research》2001,22(6):705

A palaeo- and rock-magnetic study was carried out on the Jurassic–Cretaceous Guaniguanico Cordillera (15 sites, 112 oriented cores) in order to define a preliminary magnetostratigraphy and to obtain some constraints on the tectonic evolution of western Cuba. Rock-magnetic experiments indicate Ti-poor titanomagnetites as principal remanence carriers. Two magnetic phases seem to be present in a few samples: some spinels, which saturate at moderate magnetic fields and goethite, with higher coercivity. The presence of hematite (or mixture of spinels and hematite) is apparent in two units. In most cases the characteristic palaeodirections could be determined above 300°C. Eleven sites yield normal magnetic polarity and four reverse. The polarity zones can be tentatively correlated to chrons CM29–C24 in the reference geomagnetic polarity time scale. The mean palaeodirection calculated from all sites is Dm=335.7°, Im=43.1°, K=11, α₉₅=12.3 and N=15. The corresponding palaeopole is Plat=66.4°, Plong=205.8°, K=13, and A₉₅=11.1. This pole is not significantly different from North American Jurassic–Cretaceous poles. This suggests that no major latitudinal displacements and deformation have occurred since the Jurassic, in contrast to some previously proposed tectonic models.  相似文献