Risk assessment of well contamination using a regional stochastic modelling approach

This paper presents a stochastic risk analysis approach for contamination of water supply wells in agriculturally dominated catchment areas, using a stochastic approach, where a numerical one-dimensional pesticide transport model has been coupled with a numerical three-dimensional groundwater flow- and transport model. The risk analysis is based on Monte-Carlo simulations with multiple realizations of the entire parameter set at a scale of individual agricultural fields. For the generation of the parameter set in the saturated zone the turning band method was used according to the lognormal pdf. Based on a set of soil and aquifer data from literature, the importance of different soil parameter distributions and different agricultural area sizes, were analysed with respect to the variability of the concentration breakthrough curves as observed at an assumed groundwater supply well. Using the coupled stochastic modelling approach the risk of exceeding a given concentration limit was investigated as a result of spatially variable soil and aquifer transport properties

Earth Virtualization Engines (EVE)

To manage Earth in the Anthropocene, new tools, new institutions, and new forms of international cooperation will be required. Earth Virtualization Engines is proposed as an international federation of centers of excellence to empower all people to respond to the immense and urgent challenges posed by climate change

The environmental research field site "Horkheimer Insel" : research program, instrumentation and first results

In order to carry out soil and groundwater related field experiment under controlled natural condition, an environmental research test site has been set up in July 1987 on the "Horkheimer Insel", 70 km north of Stuttgart. At present, the interdisciplinary research program comprises one groundwater project, two projects dealing with the unsaturated zone and the soil, and one environmental database project. The 2 ha field site is extensively instrumented, comprising 24 multilevel groundwater observation- and pumping-wells, a large monolithic lysimeter, a meterological station, as well as numerous tensiometer and suction cups. In order to facilitate the communication and data exchange between the cooperating university institutes, a distributed database sytem is being developed. During the initial phase of the investigations, the field site has been extensively described in terms of underground structure, as well as the soil und aquifer parameters. The investigation program is presented together with first results of the ongoing field experiments.Afin d'effectuer des expériences combinées sol-eaux souterraines dans des conditions naturelle controlées, un site-test de recherche sur l'environnement a été équipé en juillet 1987 sur l'île "Horkheimer Insel", située à 70 km au nord de Stuttgart. A l'heure actuelle, le programme de recherche interdisciplinaire comprend un projet sur les eaux souterraines, deux projets portant sur la zone nonsaturée et le sol ainsi qu'un projet sur la constitution d'un base de donnée sur l'environnement. Le site expérimental de 2 ha est instrumenté de façon extensive et comprend 24 puit de captage et d'observation à différents niveaux, un lysimétre à grand diamétre, une station météorologique, ainsi que de nombreux tensiométre et bougies-poreuses. Dans le but de faciliter la communication et l'échange de données entre les instituts de luniversité impliquées, un système de base de données a été developpé. Pendant la phase initiale d'investigations, le site a été decrit de façon extensive en terme de structure du sol et du sous-sol et de paramétres de l'aquifére. Le programme d'investigations et les premiers résultats de expériences se déroulant sur le terrain sont presentés ici

Evaluation of groundwater sampling techniques for the investigation and monitoring of contaminated sites

The collection of representative groundwater samples is an essential prerequisite in hydrogeological site evaluation and groundwater monitoring. Erroneous or insufficent sampling may lead to wrong conclusions, possibly causing considerable health and/or financial risks, especially in respect to the assessment of contaminated sites. The collection of representative water samples therefore requires the use of appropriate sampling techniques, taking into account the prevailing aquifer conditions, the borehole hydraulics and the chemical parameters to be investigated. Consequently, the definition of the most suitable sampling equipment should be based on multiple criteria. In general these are the changing temperature and pressure conditions and the contact of the water with non-inert materials, which may affect the chemical integrity of the sample during the drilling of the well, the withdrawal and pumping of the water to the ground surface as well as the storage and transport to the laboratory. The major factors have to be investigated and quantified in order to minimize all undesired effects. In this paper the major influencing factors are discussed. Furthermore, an evaluation of various sampling techniques and sampling systems is presented. Special consideration is given to the ability of various systems to adequately sample groundwater with high organic loads. In the last section, some new sample system developments are briefly presented together with the expert system CASES, which was developed at the Stuttgart Institut für Wasserbau

Großpumpversuch Horkheimer Insel : analytische Auswertung

Ein maßgebliches Forschungsziel des genannten PWAB-Projektes ist die Identifikation des hydraulischen Durchlässigkeitsfeldes mit Hilfe von verschiedenen Erkundungsmethoden sowie eine Bewertung der eingesetzten Methoden. Daneben kommt der Problematik des Übergangs von klein- zu großskaligen Erkundungen besondere Bedeutung zu. Während der ersten Projektphase wurden vor allem im Bereich des nordwestlichen Teilfeldes an vielen Beobachtungsmeßstellen sogenannte Kleinpumpversuche durchgeführt. Dabei wurde das Grundwasser über einen Zeitraum von jeweils 2 Stunden abgesenkt. Das Absenkungsverhalten des Aquifers wurde an mehreren umliegenden Meßstellen aufgezeichnet. Als Vergleich zu diesen kleinskaligen Erkundungen wurde die Durchführung eines Großpumpversuchs projektiert. Damit sollten zum einen effektive Aquiferparameter ermittelt und zum anderen eine Untersuchung der Abhängigkeit der ermittelten hydraulischen Parameter vom Abstand zwischen Pump- und Beobachtungsbrunnen ermöglicht werden