A University of Nottingham study has tested the quality of global water models in collaboration with other international partners.
The University of Nottingham has worked with an international team to test the extent to which global water models agree with each other.
The study, ‘Functional relationships reveal differences in the water cycle representation of global water models,’ will also test to see if the models align with data taken from water sources around the world.
The researchers aim to show which climate regions of the world the models agree with and where they differ.
The importance of global water models
Global water models are important for understanding the water cycle, such as to help people learn about the impacts of climate change.
Many of these impacts are being felt through changes in water extremes. For example, increasing droughts and floods which pose growing threats to people and ecosystems.
There are also changes in the availability of water, for example, soil moisture. This is relevant for agriculture and groundwater recharge – important for sustainability.
Model-based conclusions are uncertain
Inconsistencies between the results of global water models make conclusions uncertain. These differences have not been fully quantified.
Previous approaches have provided limited information on how the models could be improved.
Analysing relations between models
The study is the first to use large-scale relationships between climatic and hydrological variables. These relationships will be analysed to reveal the differences between models and observational data.
Functional relations like the ones between climatic and hydrological variables provide an overview of how the global water cycle functions.
Looking at these relationships in the models and comparing them to observations in the environment, the team could understand how much groundwater depends on precipitation. Answers like this are often missing for large areas of the world despite their importance.
Professor Simon Gosling, co-author of the study, concluded: “Global water models are incredibly useful tools for helping understand inequities in patterns of global water supply, and the effects of extremes like river flooding on society.
“It is important, therefore, that we know how well the models do their job, because the quality of the models mirrors the scientific community’s understanding of how global hydrology works.
“In this study, we take a more holistic view than done in past studies, by looking at different parts of the hydrological cycle that interact with each other, and then seeing whether these interactions in the models are the same as what we see in the real world.”
