A modeller’s compass: how modellers navigate dozens of decisions

The usage of hydrological models is diverse and omnipresent. For practical purposes, these models are applied to, for example, flood forecasting, water allocation, and climate change impacts. Numerous methods exist to execute any modelling study. Choosing a method creates a narrative behind each model result, which implies that models are not neutral. So, how do modellers make these decisions? What motivates them to choose a certain method? We conducted fourteen semi-structured interviews between September and December 2021 with nine modellers from six different water authorities and five modellers from four different consultancy companies in the Netherlands. The interviewees are hydrodynamic modellers executing decision-support modelling. The interviews were all recorded and transcribed. We executed an inductive content analysis on the transcriptions. We will discuss how the interviewees motivate the decisions they have made in the modelling process, exploring the non-neutrality of the modelling process. With these insights, we aim to contribute to a discussion on how models, despite their unavoidable non-neutrality, can be robust and dependable to support decision making. Understanding the social aspects behind the modelling process is necessary to create a more complete picture of all the uncertainties involved in modelling, which should include sharing and reflecting on the narrative behind the modelling results.