History of the hydrogeochemical study of groundwater in the Netherlands and the research motives

An overview is presented of research on the hydrogeochemical aspects of groundwater resources in the Netherlands conducted since the early nineteenth century. The earliest studies investigated groundwater as a resource for drinking water. The first systematic, national study was in 1868 and was motivated by the cholera epidemics at that time. At the beginning of the twentieth century, research for drinking water production was institutionalised at national level. Since the 1960s, the range of organisations involved in hydrogeochemical research has broadened. Societal motives are also identified: shallow, biogenic methane as fossil fuel (already researched since the 1890s); groundwater contamination; freshening/salinisation of aquifers; ecohydrology and nature conservation; aquifer thermal energy storage; national and regional groundwater monitoring for policy evaluation; impact of climate change and weather variability; and occurrence of brackish groundwater and brines in the deeper subsurface. The last-mentioned has been driven by a series of motives ranging from water supply for recreational spas and mineral water production to subsurface disposal of radioactive waste. There have been two major scientific drivers: the introduction of techniques for using isotopes as tracers, and geochemical computer modelling. Another recent development has been the increasing capabilities in analytical chemistry in relation to the contamination of groundwater with emerging pollutants. Many of the motives for research emerged in the 1980s. Overall, the societal and associated technical motives turn out to be more important than the scientific motives for hydrogeochemical research on groundwater in the Netherlands. Once a research motive has emerged, it commonly tends to remain

Combining statistical methods for detecting potential outliers in groundwater quality time series

Quality control of large-scale monitoring networks requires the use of automatic procedures to detect potential outliers in an unambiguous and reproducible manner. This paper describes a methodology that combines existing statistical methods to accommodate for the specific characteristics of measurement data obtained from groundwater quality monitoring networks: the measurement series show a large variety of dynamics and often comprise few

Innovative mapping of groundwater redox status and cation exchange conditions in a GIS environment

Understanding the complexities of regional groundwater quality is crucial for managing groundwater resources. Groundwater quality assessment involves investigating specific dissolved groundwater components, for example, comparing them to established standards. To fully understand all aspects of groundwater quality, one should assess composite properties, one being the redox status and another being the cation exchange condition. The first may, for example, impose a control on the degradation of organic micropollutants. While groundwater numerical indices can be easily interpolated and visualised using various GIS applications, consistently mapping the redox status and cation exchange conditions as non-numerical indices remains challenging. Furthermore, no study has yet conducted a regional-scale mapping of cation exchange classes in a GIS environment using extensive groundwater samples. To deepen our understanding of these groundwater components, we employed ArcGIS in this study to map the redox and cation exchange conditions in two stages. First, we mapped the groundwater components of interest, including Cl, SO4, SO4/Cl, Fe, NO3 and base exchanges of Na and Mg, by the most appropriate interpolation method identified by a geostatistical analysis. Then, variables were combined, and the conditional functions were used in ArcMap's Math toolbox to determine redox status or cation exchange classes. Our innovative GIS method for mapping regional redox status and cation exchange conditions was developed for 3,350 groundwater sampling locations in the coastal lowlands of the Western Netherlands. The method was successful, with generally 75%–95% similarity between predicted and observed situations for most classes. The introduced method is more straightforward than others and can map other non-numerical linguistic indices like Wilcox groundwater and irrigation water classifications, as well

Adapting classical water quality diagrams for ecohydrological and policy applications

Ecological values of water have gained increasing attention over the past decades in both (eco)hydrological research and water resources management. Water quality is an important ecological steering variable, and graphical water quality diagrams may aid in rapid interpretation of the hydrochemical status of a site. Traditionally used water quality diagrams for showing multiple variables (e.g. Stiff, Maucha) were developed primarily for hydrogeological purposes, with limited information on ecologically relevant nutrient parameters. This paper presents adapted classical water quality diagrams that retain the traditional information on ions for hydrogeological characterization, and additionally provide information on nutrients for ecological water quality characterization. A scaling factor is used for the minor ions to visually get them across more equally compared to the macro-ion ions in the water quality diagram. Scaling of minor ions is presented based on average concentrations, as well as on water quality policy norms. Four different water quality diagrams are presented, all with the same ions included, but with different appearances to suit different preferences of individual users. Regional, national and continental scale data are used to illustrate how the different diagrams show spatial and temporal water quality characteristics. The adapted diagrams are innovative with respect to adding comprehensive visual information on the four ecohydrologically relevant nutrient species levels (NO3, NH4, PO4, K), advanced insight in redox status from the combination of four redox sensitive parameters (Fe, NO3, SO4, NH4) and the option to scale minor ions relative to average measured concentrations or to water quality policy norms. Using policy norms for scaling has the advantage of providing an ‘alarm function’ of exceedance of norms when concentrations surpass the ring used in the diagram. We discuss possible standardisation of scaling factors to enable comparability between sites

Coupling ANIMO and MT3DMS for 3D regional-scale modeling of nutrient transport in soil and groundwater

We developed an on-line coupling between the 1D/quasi-2D nutrient transport model ANIMO and the 3D groundwater transport model code MT3DMS. ANIMO is a detailed, process-oriented simulation model code for the simulation of nitrate leaching to groundwater, N- and P-loads on surface waters and emissions of greenhouse gasses. It is the leading nutrient fate and transport code in the Netherlands where it is used primarily for the evaluation of fertilization related legislation. In addition, the code is applied frequently in international research projects. MT3DMS is probably the most commonly used groundwater solute transport package worldwide. The on-line model coupling ANIMO-MT3DMS combines the state-of-the-art descriptions of the biogeochemical cycles in ANIMO with the advantages of using a 3D approach for the transport through the saturated domain. These advantages include accounting for regional lateral transport, considering groundwater-surface water interactions more explicitly, and the possibility of using MODFLOW to obtain the flow fields. An additional merit of the on-line coupling concept is that it preserves feedbacks between the saturated and unsaturated zone

Metro Mapping:development of an innovative methodology to co-design care paths to support shared decision making in oncology

Treatment decision-making can be complex, notably when there are multiple treatments available, with different (probabilities of) benefits and harms, for example, survival and side effects.1 It is precisely in these complex situations that the preferences of the patient are of utmost importance, as the trade-offs of benefits and harms are subjective and concern patients' lives.2 In such trade-offs, shared decision making (SDM) has gained momentum as a strategy to include both the best available evidence and the patient's preferences.3</p