A framework for an optimised groundwater monitoring network and aggregated indicators

in Environmental Geology (2006), 50(2), 194-201

The implementation of the Water Framework Directive (EU 2000) requires a groundwater quality monitoring. It is used for characterisation of the 'good' chemical status of each groundwater body and for the ... [more ▼]

The implementation of the Water Framework Directive (EU 2000) requires a groundwater quality monitoring. It is used for characterisation of the 'good' chemical status of each groundwater body and for the restoration or protection purposes of those bodies already at 'good' status. Interpretative aspects are lying in the design of monitoring network and in the way of building global indicators. Attention is given here to the global chemical status of the groundwater bodies and to the role of diffuse pollution, much of which is brought via groundwater to surface water. Monitoring 'local' pollution associated with individual sites is not addressed. Groundwater bodies with different contrasted hydrogeology conditions, land use and topography have been considered to establish an approach for choosing an optimised monitoring network. Then, a quality assessment system has been developed and applied for qualifying the general status of each groundwater body. The use of non-dimensional indexes allows us to process with all kinds of chemical parameters in a normalised way and, by means of adequate aggregation rules, to qualify the general quality status of a groundwater body. The obtained diagnostic, even if not fully validated, is closely linked to the pragmatic objectives contained in the EU Water Directive. [less ▲]

Simultaneous use of hydrogeological and geophysical data for groundwater protection zone delineation by co-conditional stochastic simulations

in Stauffer, Fritz; Dassargues, Alain (Eds.) Quantitative Geology from Multiple Sources: S10 Use of multiple sources in conditioning/calibrating groundwater flow and transport models (2006)

Delineation of protection zones is performed by the use of stochastic simulations integrating all available data. In practice, due to the few available measurements of the main parameters, it can be very ... [more ▼]

Delineation of protection zones is performed by the use of stochastic simulations integrating all available data. In practice, due to the few available measurements of the main parameters, it can be very useful to integrate other data to reduce the uncertainty of the results. Most of the solute spreading is governed by the hydraulic conductivity (K) spatial variability at different scales. A stochastic approach adding measured piezometric heads and electrical resistivity data is presented. Results are discussed on a synthetic and on a practical case. Delineating the ‘Capture zone Probability Distribution’ (CaPD) for a given time, it is shown how the uncertainty can be reduced. The methodology can be used in real applications when little or no information is available about the hydraulic properties, through the conditioning on other data sets. [less ▲]

Aggregated indicators from an optimized groundwater monitoring network: example in Walloon region of Belgium for implementation of the European Water Directive

in Proc. of Integrated methods for assessing water quality, COST629 Workshop (2004)

Following prescriptions of the recent European Water Framework Directive, a groundwater quality evaluation system must be adopted for checking the groundwater status with respect to different contaminants ... [more ▼]

Following prescriptions of the recent European Water Framework Directive, a groundwater quality evaluation system must be adopted for checking the groundwater status with respect to different contaminants. A screening evaluation system (based on a system developed by the French Water Agencies) has been adapted to the specific conditions in the Walloon Region of Belgium. Groundwater quality data are aggregated into indicators with respect to different water uses such as drinking water standards, thresholds values for preserving dependent surface ecosystems, or the groundwater ‘natural or patrimonial state’. A global groundwater quality indicator can also be calculated. Different aggregation techniques are discussed with their respective influence on the final indicator. In relation to this evaluation, the monitoring network must be adapted for being (as far as possible) representative of the global quality of water in each groundwater body. Existing knowledge and understanding of the actual hydrogeological conditions were used in priority for choosing an adequate network of monitoring points. At the same time, the spatial density of points was checked in order to obtain a statistically representative network. Applications were performed in five different GWBodies belonging to the hydrographic district of the Meuse River in the Walloon Region and with different contrasted geological conditions: Cretaceous chalks, Carboniferous limestones and Pleistocene gravels of the alluvial plain of the River Meuse. These examples provide a good opportunity for further discussion and work about the main related issues: optimzation procedures, aggregation methods and estimation of the reliability of indicators. [less ▲]

Combining stochastic simulations and inverse modelling for delineation of groundwater well capture zones

in Iu (Ed.) Computational Methods in Engineering and Science (2003)

In hydrogeology, protection zones of a spring or a pumping well are often delimited by isochrones that are computed using calibrated groundwater flow and transport models. In heterogeneous formations, all ... [more ▼]

In hydrogeology, protection zones of a spring or a pumping well are often delimited by isochrones that are computed using calibrated groundwater flow and transport models. In heterogeneous formations, all direct and indirect data, respectively called hard and soft data, must be used in an optimal way. Approaches involving in situ pumping and tracer tests, combined with geophysical and/or other geological observations, are developed. In a deterministic framework, the calibrated model is considered as the best representation of the reality at the current investigation stage, but result uncertainty remains unquantified. Using stochastic methods, a range of equally likely isochrones can be produced allowing to quantify the influence of our knowledge of the aquifer parameters on protection zone uncertainty. Furthermore, integration of soft data in a conditioned stochastic generation process, possibly associated with an inverse modeling procedure, can reduce the resulting uncertainty. A stochastic methodology for protection zone delineation integrating hydraulic conductivity measurements (hard data), head observations and electrical resistivity data (soft data) is proposed. [less ▲]

Integrating geophysical and tracer test data for accurate solute transport modelling in heterogeneous porous media

in Groundwater Quality: Natural and Enhanced Restoration of Groundwater Pollution (GQ’2001) (2002)

Calibration and reliability of an alluvial aquifer model using inverse modelling and sensitivity analysis

in Stauffer, F.; Kinzelbach, W.; Kovar, K. (Eds.) et al Calibration and Reliability in Groundwater Modelling Pre-published Proc. of ModelCARE99 (1999)