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. This implies that models are not neutral. So, how do modellers make these decisions? 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 interviews were all recorded and transcribed. We executed an inductive content analysis on the transcriptions. We will discuss the motivation modellers have to make choices during 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. Standardisation, e.g. automation, can be a way to achieve this. Understanding the social aspects behind the modelling process is necessary to move forward in modelling and modelling workflows, as well as being able to share and reflect on the model results including the narrative behind it.