Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>The notion of permeability is critical to compute underground fluid flow. In most cases rock permeability is anisotropic, due to physical processes including gravitational compaction, which often results in the principal permeability directions being approximately horizontal and vertical in undeformed rocks. However, rocks often are tilted and/or deformed over time, therefore permeability orientation varies. Anisotropic permeability with varying orientation is hard to quantify in three-dimensional (3D) models and is therefore sometimes approximated, for convenience, by setting the principal permeability directions to horizontal and vertical, and assuming that corresponding errors in fluid flow might be negligible when the change in orientation is minimal. This study shows how minor misalignment of the permeability tensor can lead to large errors in fluid flow magnitude and corresponding transport times for strongly anisotropic rocks. It also provides a method to set anisotropic permeability orientation appropriately in geometrically complex 3D models using implicit 3D geological modelling. The misalignment is particularly costly when fluid flow is localised in thin channels, where a misalignment of just 5° leads to errors of two orders of magnitude for anisotropy ratios (between the largest and smallest principal values of the permeability tensor) of 10<jats:sup>4</jats:sup>. It is therefore recommended to set anisotropic permeability accurately, using longitudinal and transverse components along with their respective orientations, rather than horizontal and vertical components. This approach will become increasingly important as 3D models gain realism in their representation of complex geometries.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Climate change is projected to threaten groundwater resources in many regions, but projections are highly uncertain. Quantifying the historic impact potentially allows for understanding of hydrologic changes and increases confidence in the predictions. In this study, the responses of karst discharge to historic and future climatic changes are quantified at Blautopf Spring in southern Germany, which is one of the largest karst springs in central Europe and belongs to a regional aquifer system relevant to the freshwater supply of millions of people. Statistical approaches are first adopted to quantify the hydrodynamic characteristics of the karst system and to analyse the historic time series (1952–2021) of climate variables and discharge. A reservoir model is then calibrated and evaluated with the observed discharge and used to simulate changes with three future climate-change scenarios. Results show that changes in the annual mean and annual low discharge were not significant, but the annual peak discharge shifted to a low state (&lt;13.6 m<jats:sup>3</jats:sup> s<jats:sup>−1</jats:sup>) from 1988 onwards due to decreasing precipitation, increasing air temperature, and less intense peak snowmelt. The peak discharge may decrease by 50% in this century according to the projections of all climate-change scenarios. Despite there being no significant historic changes, the base flow is projected to decrease by 35–55% by 2100 due to increasing evapotranspiration. These findings show the prolonged impact of climate change and variability on the floods and droughts at the springs in central Europe, and may imply water scarcity risks at similar climatic and geologic settings worldwide.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Intense use of groundwater in urban areas requires appropriate monitoring, which in turn necessitates proper data management with employment of increasingly sophisticated statistical methods and mapping tools. An example of such an urban area with intensive use of groundwater is the study area of GeoPot Project, namely Munich (Germany) and its surroundings. The aim of the presented study was to provide a description of the hydrogeochemical characteristics of the aquifers occurring in the Quaternary and Upper Freshwater Molasse (German: Obere Süßwassermolasse – OSM) sediments and to further improve the understanding of interactions between the aquifers. The focus was put on the identification of hydrochemical facies, the chemical signatures of different water types, an understanding of occurring processes, and spatial relationships between the aquifers. In order to deal with hydrogeochemical data generated for this study, as well as with data coming from existing external databanks (e.g. BIS-BY), a methodology of quality assurance was developed. The analytical methods focused on multivariate statistics. To enhance the interpretation of the obtained clusters, a recently developed three-dimensional geological model was used for better understanding and presentation. It was found that in the study area, deeper aquifer systems represent the most distinct hydrogeochemical signature of the Na–HCO<jats:sub>3</jats:sub> water type. In the remaining clusters, a transition from deeper (alkaline) to shallow (alkaline-earth) groundwater can be observed. The results of the study can be utilized for improved, sustainable groundwater management.</jats:p>

<jats:title>Abstract</jats:title><jats:p>With an extent of ~1,860,000 km<jats:sup>2</jats:sup>, the Upper Mega Aquifer System on the Arabian Platform forms one of the largest aquifer systems of the world. It is built up by several bedrock aquifers (sandstone and karstified limestone aquifers), which are imperfectly hydraulically connected to each other. The principal aquifers are the Wasia-Biyadh sandstone aquifer, and the karstified Umm Er Radhuma and Dammam limestone aquifers. The stored groundwater is mainly fossil. Groundwater recharge took place in the geologic past under more humid climatic conditions. Due to the good water quality and high yield, the aquifers are intensively exploited, which has caused depletion of the groundwater resources. The presented qualitative and semi-quantitative description of the hydrogeology and the groundwater budget is the basis for integrated groundwater management of the aquifer system.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Land subsidence in the city of New Orleans (USA) and its surroundings increases flood risk, and may cause damage to buildings and infrastructure and loss of protective coastal wetlands. To make New Orleans more resilient to future flooding, a new approach for groundwater and subsidence management is needed. As a first step in developing such an approach, high-quality and high-resolution subsurface and groundwater information was collected and synthesized to better understand and quantify shallow land subsidence in New Orleans. Based on the collected field data, it was found that especially the low-lying areas north and south of the Metairie-Gentilly (MG) Ridge are most vulnerable to further subsidence; north of the MG Ridge, subsidence is mainly caused by peat oxidation and south of the MG Ridge mainly by peat compaction. At present, peat has compacted ~31% on average, with a range of 9–62%, leaving significant potential for further subsidence due to peat compaction. Phreatic groundwater levels drop to ~150 cm below surface levels during dry periods and increase to ~50 cm below surface during wet periods, on average. Present phreatic groundwater levels are mostly controlled by leaking subsurface pipes. Shallow groundwater in the northern part of New Orleans is threatened by salinization resulting from a reversal of groundwater flow following past subsidence, which may increase in the future due to sea-level rise and continued subsidence. The hydrogeologic information provided here is needed to effectively design tailor-made measures to limit urban flooding and continued subsidence in the city of New Orleans.</jats:p>