Christian Regli

Interpretation of drill-core and georadar data of coarse gravel deposits

Abstract Pollution in the shallow subsurface has led to an increasing need of understanding how to quantitatively characterize both the heterogeneity of gravel aquifers and the influence of heterogeneity on groundwater flow and solute transport. Models play an important role in decision-making processes, especially in the context of better characterizing and in forecasting the behavior of a given geological system. The objective of the present paper is the derivation of a gradual lithofacies-based interpretation of outcrop, drill core, and ground penetrating radar (GPR or georadar) data of different quality. The presented method allows a probability estimation of drill core layer descriptions and radarfacies types representing defined sedimentary structure types. The method includes a determination of ‘initial structure type probabilities’ for grain-size categories and combinations thereof described in drill core layer descriptions as well as a subsequent differentiation of these structure type probabilities in an iterative process considering ‘additional information’ like main constituent, quantity, fraction, and sorting of single grain-size categories, color, chemical precipitation, layer thickness, and adjacent layer. The radarfacies types are calibrated with drill cores located in the vicinity of georadar sections. The calibration process consists of the assignment of the calculated structure type probabilities from the drill core layer descriptions to the corresponding radarfacies types considering the proportion in thickness between drill core layers and georadar structures. The structure type probabilities can be given for points along boreholes and a grid with arbitrary mesh size along georadar sections. The method is applied to field examples from the Rhine/Wiese aquifer near Basel in Switzerland. The resulting structure type probabilities can be used for conditioning stochastic simulations of geological models. However, the conditioned stochastic simulation of the Rhine/Wiese aquifer is the topic of another paper. The results show the importance of a detailed sedimentological analysis of outcrops and drill cores as well as its significance on the distinction of sedimentary structure types.

Analysis of aquifer heterogeneity within a well capture zone, comparison of model data with field experiments: a case study from the river Wiese, Switzerland.

Abstract. This paper describes two groundwater models simulating a well capture zone in a heterogeneous aquifer located near an infiltrating river. A deterministic, large-scaled groundwater model (1.8 × 1.2 km) is used to simulate the average behavior of groundwater flow and advective transport. It is also used to assign the boundary conditions for a small-scaled groundwater model (550 × 400 m) which relies on stochastically generated aquifer properties based on site-specific drill core and georadar data. The small-scaled groundwater model is used to include the large subsurface heterogeneity at the location of interest. The stochastic approach in the small-scaled groundwater model does not lead to a clearly defined well capture zone, but to a plane representation of the probability of a certain surface location belonging to the well capture zone. The models were applied to a study site, which is located in an area of artificial groundwater recharge and production, in Lange Erlen near Basel, Northwestern Switzerland. The groundwater at this site contributes to the city’s drinking water supply, and the site serves as a recreational area to the population of Basel. The river is channelized, but there are initiatives to restore the riverbank to more natural conditions. However, they conflict with the requirements of groundwater protection, especially during flood events. Therefore, a river section of 600 m in the vicinity of an unused and disconnected drinking water well was restored to study changes in the groundwater flow regime depending on hydrologic variations, water supply operation data, progress of river restoration, and subsurface heterogeneity. The results of the groundwater models are compared with data from two tracer experiments using Uranine and the natural Radon isotope Rn-222, and with physical, chemical, and microbiological data sampled in monitoring wells between the river and the drinking water well. The groundwater models document significant variations regarding the dimension of the well capture zone depending on changing boundary conditions and the variability of the hydraulic aquifer properties. The knowledge of the subsurface heterogeneity is important to evaluate transport times and distances of microorganisms from the infiltrating river or the riverbank to the drinking water well. The data from the monitoring wells show that chemical and microbiological processes predominantly occur in the hyporheic interstitial zone and the riverbank within a range of a few meters up to a few 10s of meters from the river. The methods presented here can be used to define and evaluate groundwater protection zones in heterogeneous aquifers associated with infiltration from rivers under changing boundary conditions, and under the uncertainty of subsurface heterogeneity. Furthermore, they allow one to study the site-specific operational alternatives associated with river restoration.

GEOSSAV: a simulation tool for subsurface applications ☆

Geostatistical Environment fOr Subsurface Simulation And Visualization (GEOSSAV) is a tool for the integration of hard and soft data into stochastic simulation and visualization of distributions of geological structures and hydrogeological properties in the subsurface. GEOSSAV, as an interface to selected geostatistical modules (bicalib, gamv, vargplt, and sisim) from the Geostatistical Software LIBrary, GSLIB (GSLIB: Geostatistical Software Library and Users Guide, 2nd Edition, Oxford University Press, Oxford, 1998, 369pp), can be used for data analysis, variogram computation of regularly or irregularly spaced data, and sequential indicator simulation of subsurface heterogeneities. Sequential indicator simulation, based on various kriging techniques (simple, ordinary, and Bayesian), is suitable for the simulation of continuous variables such as hydraulic conductivity of an aquifer or chemical concentrations at a contaminated site, and categorical variables which indicate the presence or absence of a particular lithofacies. The software integration platform and development environment of GEOSSAV is Tool command language (Tcl) with its graphical user interface, Toolkit (Tk), and a number of Tcl/Tk extensions. The standard Open Graphics Library application programming interface is used for rendering three-dimensional (3D) data distributions and for slicing perpendicular to the main coordinate axis. Export options for finite-difference groundwater models allow either files that characterize single model layers (which are saved in ASCII matrix format) or files that characterize the complete 3D flow model setup for MODFLOW-based groundwater simulation systems (which are saved in block-centered flow package files (Users documentation for MODFLOW-96, an update to the US Geological Survey modular finite-difference ground-water flow model, Geological Survey Open-File Report 96-485, Reston, VA, 1996, 56pp)). GEOSSAV can be used whenever stochastic solutions are preferred to solve site-specific heterogeneity problems, e.g., in the field of hydrology, groundwater, groundwater and/or soil contamination, site remediation, air pollution, and ecology. An example from the Rhine/Wiese aquifer near Basel demonstrates the application of GEOSSAV on geostatistical data analysis and subsurface visualization. GEOSSAV has been successfully tested on Microsoft Windows NT 4.0/2000/XP and on SuSE Linux 7.3. The current version is available at http://www.unibas.ch/ earth/pract.

Changes in the Epithelium of the Vaginal Complex during the Estrous Cycle of the Marsupial Monodelphis domestica

The vaginal complex of marsupials differs from that of eutherians. Cervices open separately in a sinus vaginalis or cul-de-sac. Two lateral vaginae adjoin the sinus vaginalis and fuse at the level of the urethra opening and form the sinus urogenitalis. During the estrous cycle the vaginal epithelium undergoes a number of specified morphological changes. This paper is the first to describe these changes on an ultrastructural level in a marsupial. Investigations in Monodelphis vagina reveal that a cyclic switch exists between a keratinized and a stratified nonkeratinized epithelium. Keratinization starts during proestrus and reaches its maximum during estrus. In the postestrus, desquamation of the stratum corneum takes place, mostly in two steps. In metestrus one to two additional layers of the now nonkeratinized surface cells are shed into the vaginal lumen. Typical cell structures, such as keratin filaments, keratohyalin and membrane-coating granules, are involved in the keratinization process. Keratohyalin is found in the cytoplasm as well as in the nucleus of stratum granulosum cells, a phenomenon which is known from other parakeratinized epithelia of rapid turnover. Membrane-coating granules, responsible for the permeability barrier between the epithelial cells, are of the nonlamellated type in the nonkeratinized epithelium and produce an amorphous material in the intercellular spaces after extrusion. At periods, however, when the epithelium is keratinized, membrane-coating granules are of the lamellated type and form a lamellated barrier structure after extrusion in the intercellular space. The loss of the protective keratinized layers asks for an additional defense mechanism for the epithelium. The migration of leukocytes through the epithelium predominantly during post- and metestrus and their presence in the vaginal lumen may play a protective role together with the bacterial content.

Integrated methods for urban groundwater management considering subsurface heterogeneity

Open space in urban areas is very rare and new infrastructure is increasingly constructed in the subsurface. These constructions may temporarily affect urban groundwater systems during construction and permanently after completion. As regards these impacts together with ancient contaminated industrial sites, particular focus was placed on determining the data required to understand changes affecting groundwater flow and transport. The extended knowledge of groundwater flow regimes could lead to reducing and minimizing, as far as possible, the negative impacts throughout the construction phases, and to developing sustainable groundwater use and management tools. The consideration of subsurface heterogeneity is often based on pumping tests, leading to a characteristically large-scale zoning of aquifer parameters. This study compares groundwater modeling results from integrating large-scale zoning of aquifer parameters on the one hand, and a sedimentary structure-based heterogeneous description of the aquifer properties on the other. This approach was applied to an ongoing subsurface highway construction northwest of the city of Basel, Switzerland – an area formerly contaminated by industrial activities. Today, urban groundwater resources are extensively used by industry. An integrated multidisciplinary approach was chosen to predict, mitigate or prevent environmental problems, as well as to ensure groundwater supply throughout construction. It includes integration of geological and hydrological data and results into a groundwater management system comprising: (1) extensive groundwater monitoring; (2) development of a database application facilitating lithofacies-based interpretation of drill-core data; (3) geostatistical analyses of the aquifer’s heterogeneity and simulations of hydraulic parameter distributions as well as; (4) regional and local high-resolution groundwater modeling. The combination of techniques presented exemplifies the fusion of quantitative and qualitative geological and hydrological information of different quality.

Changes in the epithelium of the vaginal complex during the estrous cycle of the marsupial Monodelphis domestica. 1. Transmission electron microscopy study.

The four stages of the estrous cycle in Monodelphis domestica, namely proestrus, estrus, postestrus and the transitional metestrus, were analyzed with the scanning electron microscope and compared with the results of the previously published transmission electron-microscopic paper [Cells Tissues Organs 2002;172:276–296]. During the estrous cycle the vaginal epithelium undergoes dramatic changes from a nonkeratinized to a highly keratinized epithelium. The predominant feature of proestrus with the beginning of keratinization is the presence of polygonal flat cells with pavement-like appearance, bordered by raised ridges and covered with microvilli. The epithelium is fully keratinized in estrus, and the superficial layers overlap like shingles. Many cells are still densely covered by microvilli, whereas others develop a complex pattern of microridges. In postestrus different epithelial structures are revealed depending on the actual stage of desquamation. In early postestrus surface cells resemble those present during estrus. In late postestrus, when only few keratinized cells are left, the nonkeratinized cells become exposed to the lumen through desquamation. These cells border the lumen during metestrus, a cycle stage during which numerous leukocytes migrate into the vaginal canal. A number of these uppermost cells is probably not yet prepared to function as metestrus cells and are therefore sloughed off as well. During metestrus compact cell masses stick in the vaginal furrows. Epithelial surface cells are highly irregular and bulging with their microvilli covered surfaces in the vaginal lumen. This study represents the first comprehensive description of alterations on the surface ultrastructure of a marsupial vagina during the estrous cycle, demonstrating considerable differences in comparison to many eutherians.

Groundwater protection in urban areas incorporating adaptive groundwater monitoring and management — Reconciliation of water engineering measures along rivers

This study investigates groundwater systems and their usage related to interference during flood events and water engineering activities along rivers in urban areas. In the context of river training for flood protection a multitude of river engineering measures are currently planned in Europe. Due to the experience gained from hazardous flood events in the last twenty years, most countries have acquired a more comprehensive view of rivers. This includes the consideration of processes at the catchment scale as well as ecological aspects. Multiple interests concerning groundwater use and protection challenge the intentions of water engineering and groundwater protection schemes that can only be solved by simultaneously considering all of the various interests.

Examples and Case Studies

The presented examples and case studies illustrate specific applications of adaptive management of water resources in the region of Basel, Northwestern Switzerland. Such concepts together with the setup of tools and process-oriented experiments allow testing hypotheses. The applied methods facilitated us to fill several gaps of knowledge of subsurface processes. The examples focus on questions with practical as well as research. Most topics are relevant for urban areas and the sustainable use of subsurface resources in general.