Advancing Process Representation in Hydrological Models: Integrating New Concepts, Knowledge, and Data

Abstract

Introduction Motivation and BackgroundModel fidelity and accurate process representation at the scale of application have been the crux of [scientific] hydrological modeling. Additionally, the need to include ecological and/or anthropogenic factors pushes for a stronger synergy between the development of hydrological models and the growing volume of observational data. The advancement in process representation provides insights into the complex interactions of hydrological processes and potentially results in more reliable simulations and hence decisions. The special issue "Advancing process representation in hydrological models: Integrating new concepts, knowledge and data" in Water Resources Research is part of wider ongoing activities to reconcile the efforts for better process representation in models and in developing and applying hydrological models across scales and for multidisciplinary purposes. This special issue is a materialization of several years of well-attended sessions at the European Geosciences Union General Assembly (2016-2021) and American Geophysical Union Fall Meeting (2016) organized by the editors of the special issue. The editors were also involved in organizing the second modeling workshop of the initiative "Improving the Theoretical Underpinnings of Hydrological Models" in Sopron, Hungary in 2018, initiated by Clark et al. (2016).The special issue received contributions from September 2018 to June 2021. In this editorial, we discuss 29 contributions to the special issue. The authors' affiliations are spanning across 19 countries (Figure 1), and case studies in the submissions cover 11 countries. From the 29 contributions, 10 are openly accessible.We categorize the contributions to the special issue into four major topical themes presented in the following section. We conclude the editorial with our findings and reflection.