Land use an groundwater quality : How technical instrumentation and scientific knowledge can support groundwater planning

Abstract

Applied science aims at developing knowledge to solve societal problems. However, scientific knowledge is often not used in management and policy processes in an adequate way. This PhD study treats the question how to improve the use of scientific knowledge in the current societal issue of sustainable groundwater management. The study focuses on the relationship between land use and groundwater quality and how knowledge of this relationship can be used for groundwater planning to increase sustainability and improve land use functions depending on groundwater. Land use in the Netherlands is very intense and different types of land use occur within relatively short distances of each other. Land use effects on groundwater quality may result in problems for other land use functions. The challenge of groundwater planning is to take the best course of action in a context of various stakeholders, land use and groundwater functions, policy fields and institutions. For this study, groundwater models have been developed and modified to analyze and quantify the impacts of the various land uses on groundwater quality. This was done in such a way that the results are really used in the groundwater planning process. Firstly, a model was constructed that combines a groundwater flow model, a nitrate-leaching model and a Geographical Information System (GIS). The aim of the model was to understand the impact of the fertilizer use on the nitrate concentrations in abstracted groundwater in Halᳺtelek, Hungary. The model output provided quantitative insight in the relation between agricultural land use and groundwater quality. The model did not result in an adaptation of groundwater management by policy makers. Next, a comparable model was constructed together with stakeholders with the aim to improve the applicability of the model. This modeling was part of a groundwater planning process in Holten, Overijssel, the Netherlands. The interests and role of each stakeholder was addressed to enable the use of the model as Negotiation Support System (NSS). The NSS was used to identify alternative land use scenarios together with the stakeholders. This resulted in an ‘adapted land use scenario’ which was generally accepted and embedded in a regional development plan. This led to a transformation toward sustainable groundwater management, in that the land use safeguards long term drinking water supply. A sensitivity analysis showed that the NSS could sufficiently distinguish between various land uses to get the contrasts between scenarios and that science-based decisions could be made with the NSS together with the available information. This PhD study shows that technical, or scientific, knowledge can help to solve a societal problem like land use conflicts in groundwater planning. For this, it is required that the technical information is acceptable to stakeholders. This acceptability can be greatly improved by interaction and cooperation with the stakeholders in the set-up of the model, the choice of scenarios and the analysis of the results towards spatial planning alternatives.