TY  - JOUR
A1  - Telteu, Camelia-Eliza
A1  - Müller Schmied, Hannes
A1  - Thiery, Wim
A1  - Leng, Guoyong
A1  - Burek, Peter
A1  - Liu, Xingcai
A1  - Boulange, Julien Eric Stanislas
A1  - Andersen, Lauren Seaby
A1  - Grillakis, Manolis
A1  - Gosling, Simon N.
A1  - Satoh, Yusuke
A1  - Rakovec, Oldrich
A1  - Stacke, Tobias
A1  - Chang, Jinfeng
A1  - Wanders, Niko
A1  - Shah, Harsh Lovekumar
A1  - Trautmann, Tim
A1  - Mao, Ganquan
A1  - Hanasaki, Naota
A1  - Koutroulis, Aristeidis
A1  - Pokhrel, Yadu
A1  - Samaniego Eguiguren, Luis Eduardo
A1  - Wada, Yoshihide
A1  - Mishra, Vimal
A1  - Liu, Junguo
A1  - Döll, Petra
A1  - Zhao, Fang
A1  - Gädeke, Anne
A1  - Rabin, Sam S.
A1  - Herz, Florian
T1  - Understanding each other's models: a standard representation of 16 global water models to support intercomparison, improvement, and communication
T2  - Geoscientific model development discussions
N2  - Global 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 modeling 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 state-of-the-art GWMs are designed. We analyze water storage compartments, water flows, and human water use sectors included in 16 GWMs 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 further enhance model improvement, intercomparison, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Seven models used six compartments, while three models (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 MPIHM) simulate only water used by humans for the irrigation sector. We conclude that even though hydrologic processes are often based on similar equations, in the end, these equations have been adjusted or have used different values for specific parameters or specific variables. Our results highlight that the predictive uncertainty of GWMs can be reduced through improvements of the existing hydrologic processes, implementation of new processes in the models, and high-quality input data.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/62913
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-629133
SN  - 1991-962X
N1  - Begutachteter Artikel erschienen in: Geoscientific model development, 14.2021, Nr. 6, S. 3843–3878, doi: 10.5194/gmd-14-3843-2021
N1  - Code availability: Information on the availability of source code for the models featured in this article can be found in the Table 12
N1  - Correspondence to: Camelia-Eliza Telteu (telteu@em.uni-frankfurt.de)
VL  - 14
SP  - 1
EP  - 56
PB  - Copernicus
CY  - Katlenburg-Lindau
ER  -