Validation of vulnerability mapping methods by field investigations and numerical modelling

Neukum, Christoph; Hötzl, H.; Himmelsbach, Thomas

doi:10.1007/s10040-007-0249-y

Cited by 63 publications

(38 citation statements)

References 26 publications

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“…Various validation techniques exist: hydrographs, chemographs, bacteriological analyses, tracer techniques, water balances, numerical simulations and analogue studies (Daly et al 2002;Gogu et al 2003;Neukum et al 2008). Artificial tracers can be considered as surrogates for contaminants and are consequently the most straightforward and most commonly used validation technique.…”

Section: Conceptual Basis and Proposed Methodsmentioning

confidence: 99%

Comparative application of four methods of groundwater vulnerability mapping in a Slovene karst catchment

2008

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Four methods of groundwater vulnerability mapping have been applied in a Slovene karst catchment and validated by tracer tests. The test site is characterised by high water table fluctuations, manifested in intermittent lakes and variable drainage divides. A first multi-tracer test (two injections) allowed subdivision of the catchment into zones of different degrees of contribution ('inner zone' and 'outer zone'). For vulnerability mapping, only methods that consider the specific nature of karst aquifers such as heterogeneity and duality of infiltration processes, were selected: EPIK, PI, the 'Simplified Method' and the 'Slovene Approach'. For validation, a second multi-tracer test (four injections) was carried out. The time of first detection and the normalised recovery were used as validation criteria. The results suggest that EPIK and the Simplified Method sometimes overestimate vulnerability, while PI and the Slovene Approach tend to deliver more realistic results, at least during low-flow conditions. The Slovene Approach gives the clearest guidance on how to deal with hydrologic variability, for example by assigning lower vulnerability to occasionally active sinking surface waters than to permanent ones. As a conclusion, commonly accepted validation techniques are needed and should be applied by default to evaluate different vulnerability mapping methods and the resulting maps.

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Section: Conceptual Basis and Proposed Methodsmentioning

confidence: 99%

Comparative application of four methods of groundwater vulnerability mapping in a Slovene karst catchment

2008

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“…Index methods are often attractive because they are conceptually simple, usually require few datasets, and are easily implemented in GIS. Their performance, however, is often reported as mixed (Tesoriero and Voss 1997;Neukum et al 2007). Major drawbacks of index methods include (1) the subjectivity inherent in determination of the rating scales and weighting coefficients and (2) the interpretation of the results which are expressed as dimensionless pollution potential index values (Merchant 1994;Antonakos and Lambrakis 2007).…”

Section: Introductionmentioning

confidence: 93%

A Geospatial Approach for Assessing Groundwater Vulnerability to Nitrate Contamination in Agricultural Settings

Merchant

Chen

2014

Water Air Soil Pollut

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Groundwater is the principal source of drinking water for at least one third of Earth's human inhabitants. Thus, protection of groundwater is a critical issue in many locales. Nitrates and other contaminants that impact human health are of particular concern. Mapping of aquifer vulnerability to pollution is a critical first step in implementing groundwater management protection programs; however, mapping is often constrained by generalizations inherent in model formulation and availability of data. In this study, a groundwater vulnerability model, which employs data extracted from widely available national and statewide geospatial datasets, is used to evaluate regional groundwater pollution risk in the Elkhorn River Basin, Nebraska, USA. The model, implemented in a geographic information system (GIS), is specifically structured to address risks of nitrate contamination in agricultural landscapes; thus, land use is a key factor. Modeled groundwater vulnerability was found to be positively correlated with nitrate concentrations obtained from sampled wells. The results suggest that the approach documented here could be used effectively to model regional groundwater pollution risk in other areas.

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“…Although there are different conceptual models to interpret the depositional history of the Quaternary valley fill (Nasmith 1962;Fulton and Smith 1978;Eyles et al 1991;Vanderburgh and Roberts 1996), the stratigraphy of the valley bottom consists of a lower, thick silt package, topped by sands and gravels (Vanderburgh and Roberts 1996). Fingers of diamicton (fan deposits) within the sand and gravel extend from the valley sides and pinch out towards the valley centre (Toews 2007).…”

Section: Study Areamentioning

confidence: 99%

Evaluating the sensitivity of DRASTIC using different data sources, interpretations and mapping approaches

Liggett

Allen

2010

Environ Earth Sci

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When used in a comprehensive risk assessment framework, aquifer vulnerability maps are a tool to identify the relative susceptibility of the groundwater from sources of contamination at the land surface. The DRASTIC method was designed for use over large areas with a wide variety of geological and hydrogeologic settings as a screening tool in groundwater protection and management. In this study, a series of vulnerability maps were made for the Greater Oliver area, in south central Okanagan, British Columbia, Canada, to test the sensitivity of the methodology to changes in input data type, interpretation, and mapping approaches. The study also illustrates how DRASTIC can be modified for use in areas of limited geological variability, where it may be important for smaller-scale changes in vulnerability to be recognized. Maps were produced using the original DRASTIC rating tables, a set of expanded tables using the original properties but modified ranges to accommodate the variability of data in the valley bottom region, and alternate tables, with modified properties and ranges. Differences in vulnerability rating for the maps using selected combinations and data interpretations are compared to the map using original DRASTIC rating tables using visual and statistical methods. One map was generated using expert hydrological knowledge. The modified tables allowed a greater amount of variability to be expressed in the valley bottom area compared to using the original tables and methods, and could provide a reasonable approach for assessing local scale variability for source water protection planning.

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Validation of vulnerability mapping methods by field investigations and numerical modelling

Cited by 63 publications

References 26 publications

Comparative application of four methods of groundwater vulnerability mapping in a Slovene karst catchment

Comparative application of four methods of groundwater vulnerability mapping in a Slovene karst catchment

A Geospatial Approach for Assessing Groundwater Vulnerability to Nitrate Contamination in Agricultural Settings

Evaluating the sensitivity of DRASTIC using different data sources, interpretations and mapping approaches

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