http://www.vliz.be/imisdocs/publications/242609.pdf

Seawater intrusion processes, investigation and management: Recent advances and future challenges

A GIS based DRASTIC model for assessing groundwater vulnerability in shallow aquifer in Aligarh, India

Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland. Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of Hydrogeology of the Neuchâtel University to develop a new groundwater protection-zones strategy in karst environment. This approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes. Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover, (3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely. This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred. These applications resulted in recommend new boundaries for the karst water supplies protection-zones.

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Water vulnerability assessment in karst environments : a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method)

Although uncertainty about structures of environmental models (conceptual uncertainty) is often acknowledged to be the main source of uncertainty in model predictions, it is rarely considered in environmental modelling. Rather, formal uncertainty analyses have traditionally focused on model parameters and input data as the principal source of uncertainty in model predictions. The traditional approach to model uncertainty analysis, which considers only a single conceptual model, may fail to adequately sample the relevant space of plausible conceptual models. As such, it is prone to modelling bias and underestimation of predictive uncertainty. In this paper we review a range of strategies for assessing structural uncertainties in models. The existing strategies fall into two categories depending on whether field data are available for the predicted variable of interest. To date, most research has focussed on situations where inferences on the accuracy of a model structure can be made directly on the basis of field data. This corresponds to a situation of ‘interpolation’. However, in many cases environmental models are used for ‘extrapolation’; that is, beyond the situation and the field data available for calibration. In the present paper, a framework is presented for assessing the predictive uncertainties of environmental models used for extrapolation. It involves the use of multiple conceptual models, assessment of their pedigree and reflection on the extent to which the sampled models adequately represent the space of plausible models. � 2005 Elsevier Ltd. All rights reserved.

A Framework for Dealing With Uncertainty due to Model Structure Error

Assessment of flood hazard areas at a regional scale using an index-based approach and Analytical Hierarchy Process: Application in Rhodope–Evros region, Greece

DRASTIC is a methodology which allows the pollution potential of any area to be systematically evaluated. The system optimizes the use of existing data and has two major portions: the designation of mappable units, termed hydrogeologic settings, and the superposition of a relative ranking system called DRASTIC. Hydrogeologic settings incorporate the major hydrogeologic factors which are used to infer the potential for to enter groundwater. These factors form the acronym DRASTIC and include depth to water, net recharge, aquifer media, soil media, topography, impact of the vadose zone and hydraulic conductivity of the aquifer. The relative ranking scheme uses a combination of weights and ratings to produce a numerical value, called the DRASTIC Index which helps prioritize areas with respect to pollution potential.

Jay H. Lehr

Papers

Drastic: A Standardized System to Evaluate Groundwater Pollution Potential using Hydrogeologic Setting

DRASTIC: A System to Evaluate the Pollution Potential of Hydrogeologic Settings by Pesticides

It's Time to Make Risk Assessment a Science

How much ground water have we really polluted

The Misunderstood World of Unsaturated Flow