Understanding each other's models: an introduction and a standard representation of 16 global water models to support intercomparison, improvement, and communicationUnderstanding each other's models: an introduction and a standard representation of 16 global water models to support intercomparison, improvement, and communication Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2023-03-212021enGlobal water models (GWMs) simulate the terrestrial water cycle on the global scale and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modelling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how 16 state-of-the-art GWMs are designed. We analyse water storage compartments, water flows, and human water use sectors included in models that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to enhance model intercomparison, improvement, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Six models used six compartments, while four models (DBH, JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water for the irrigation sector. We conclude that, even though hydrological processes are often based on similar equations for various processes, in the end these equations have been adjusted or models have used different values for specific parameters or specific variables. The similarities and differences found among the models analysed in this study are expected to enable us to reduce the uncertainty in multi-model ensembles, improve existing hydrological processes, and integrate new processes.http://creativecommons.org/licenses/by/4.0/Geoscientific Model Development1463843–3878Telteu_et_al_Geosci. Model Dev._14(6)_2021.pdfChania [Greece]Library of TUC2023-03-21application/pdf1.0 MBfree Telteu Camelia-Eliza Müller Schmied Hannes Thiery Wim Leng Guoyong Burek Peter Liu Xingcai Boulange Julien Andersen Lauren Seaby Gryllakis Emmanouil Γρυλλακης Εμμανουηλ Gosling Simon N. Satoh Yusuke Rakovec Oldrich Stacke Tobias Chang Jinfeng Wanders Niko Shah Harsh Lovekumar Trautmann Tim Mao Ganquan Hanasaki Naota Koutroulis Aristeidis Κουτρουλης Αριστειδης Pokhrel, Yadu Samaniego Luis Wada Yoshihide Mishra Vimal Liu Junguo Döll Petra Zhao Fang Gädeke Anne Rabin Sam Herz Florian Copernicus Publications Global water models (GWMs) Climate Uncertainty Impact