Significance of conditioning to piezometric head data for predictions of mass transport in groundwater modeling     

Xian-Huan Wen  J. Jaime Gómez-Hernandez  José E. Capilla  Andrés Sahuquillo 《Mathematical Geology》1996,28(7):951-968

Transmissivity and head data are sampled from an exhaustive synthetic reference field and used to predict the arrival positions and arrival times of a number of particles transported across the field, together with an uncertainty estimate. Different combinations of number of transmissivity data and number of head data used are considered in each one of a series of 64 Monte-Carlo analyses. In each analysis, 250 realizations of transmissivity fields conditioned to both transmissivity and head data are generated using a novel geostatistically based inverse method. Pooling the solutions of the flow and transport equations in all 250 realizations allows building conditional frequency distributions for particle arrival positions and arrival times. By comparing these fresquency distributions, we can assess the incremental gain that additional head data provide. The main conclusion is that the first few head data dramatically improve the quality of transport predictions.  相似文献   

Gravimetric Determination of Storage Coefficient and Storage Change of Groundwater in an Uncontrolled and Unconfined Aquifer     

Hernández-Sánchez  Rosa Isabel  Castellanos  Francisco  Herrera-Barrientos  Jaime  Belmonte-Jiménez  Salvador Isidro 《Natural Resources Research》2021,30(6):4207-4218

Natural Resources Research - Adequate management of water resources in aquifer systems implies knowledge of the different parameters of hydrological balance. However, only limited data exist for...  相似文献   

Impact ejecta and carbonate sequence in the eastern sector of the Chicxulub crater     

Jaime Urrutia-Fucugauchi  Jose Maria Chavez-Aguirre  Ligia Prez-Cruz  Jose Luis De la Rosa 《Comptes Rendus Geoscience》2008,340(12):801-810

The Chicxulub 200 km diameter crater located in the Yucatan platform of the Gulf of Mexico formed 65 Myr ago and has since been covered by Tertiary post-impact carbonates. The sediment cover and absence of significant volcanic and tectonic activity in the carbonate platform have protected the crater from erosion and deformation, making Chicxulub the only large multi-ring crater in which ejecta is well preserved. Ejecta deposits have been studied by drilling/coring in the southern crater sector and at outcrops in Belize, Quintana Roo and Campeche; little information is available from other sectors. Here, we report on the drilling/coring of a section of 34 m of carbonate breccias at 250 m depth in the Valladolid area (120 km away from crater center), which are interpreted as Chicxulub proximal ejecta deposits. The Valladolid breccias correlate with the carbonate breccias cored in the Peto and Tekax boreholes to the south and at similar radial distance. This constitutes the first report of breccias in the eastern sector close to the crater rim. Thickness of the Valladolid breccias is less than that at the other sites, which may indicate erosion of the ejecta deposits before reestablishment of carbonate deposition. The region east of the crater rim appears different from regions to the south and west, characterized by high density and scattered distribution of sinkholes.  相似文献   

Motivating mitigation: when health matters more than climate change     

Nada Petrovic  Jaime Madrigano  Lisa Zaval 《Climatic change》2014,126(1-2):245-254

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Complexity   总被引：1，自引：0，他引：1  

Gómez-Hernández JJ 《Ground water》2006,44(6):782-785

It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.  相似文献   

Mesocosm experiments for evaluating the biological efficacy of ozone treatment of marine ballast water     

Perrins JC  Cordell JR  Ferm NC  Grocock JL  Herwig RP 《Marine pollution bulletin》2006,52(12):1756-1767

Ballast water is a major pathway for the transfer of non-indigenous species in aquatic environments. The objectives of this study were to determine the ability of ozone to reduce the numbers of a spectrum of marine organisms collected from Puget Sound, Washington in replicated mesocosm (280 l) experiments, and estimate the minimum ozone concentrations as measured by total residual oxidant (TRO) required to reduce organism densities. Ozone treatment was effective in removing bacteria, phytoplankton, and mesozooplankton with initial TRO concentrations of 2–5 mg l⁻¹ as Br₂. Persistence of TRO resulted in an extended period of toxicity and cumulative mortality. TRO decay allowed bacteria populations to multiply when TRO levels fell below 0.5–1.0 mg l⁻¹ as Br₂. Phytoplankton chlorophyll a concentrations were rapidly reduced by ozone treatment and did not increase in any treatments or controls because of lack of light. Overall mesozooplankton viability was rapidly reduced by 90–99% in treatment TRO levels above 1.85 mg l⁻¹ as Br₂. Our study outlines novel protocols that can be used for testing different potential ballast water treatment systems in replicated and controlled mesocosm experiments.  相似文献