Johanna Merisalu, Geologi och geoteknik

Groundwater systems support vital services and benefits to human well-being, but underground construction and the associated leakage of groundwater may impair the capacity of these systems to perform their essential functions and provide vital services. Leakage of groundwater into underground constructions must therefore be managed to reduce the risk of negative impact due to lowering groundwater levels in the surrounding hydrogeological environments. The overall aim of this thesis is to develop methods and present examples of how the well-established risk management process according to the International Organization för Standardization (ISO) can be applied to manage hydrogeological risks in a sustainable and transparent manner. Four studies were carried out and specific contributions from the studies include: a risk-management framework for developing decision support for leakage management (Paper I); a method and example for identification of leakage induced risks (Paper III); a method for translating risks and risk-mitigation measures into relevant cost and benefit items to be valued in a risk-based decision analysis (Paper II and III); model chains for risk analysis and risk evaluation using CBA and CEA that allow for updating when new information is available (Paper II and IV); and methods for monetization of costs and benefits (Paper II and IV). Results from the studies in this PhD thesis all constitute key aspects of a successful and transparent risk management process and thus decisions on implementation of risk-mitigation measures. The thesis also provides a discussion on the importance of probabilistic modelling and transparency when developing models, the need to consider relevant boundary conditions that result in limitations regarding possible decisions, the limitations of using CBA or CEA for risk evaluation, as well as the task of taking a decision based on the decision support provided by the framework and methods presented in this thesis. Recommendation on how to apply the framework and the methods is also presented. As a final part of the thesis, the main conclusions from the thesis are presented and the need for further studies and developments of methods are discussed.