HESS Opinions: Participatory Digital eARth Twin Hydrology systems (DARTHs) for everyone – a blueprint for hydrologists

Abstract. The “Digital Earth” (DE) metaphor is very useful for both end users and hydrological modelers (i.e., the coders). In this opinion paper, we analyze different categories of models with view making them part Digital eARth Twin Hydrology systems (DARTHs). We stress idea that DARTHs are not models, rather they an appropriate infrastructure hosts (certain types of) provides some basic services connecting to input data. also argue a modeling-by-component strategy right one accomplishing requirements DE. Five technological steps envisioned move from current state art modeling. step 1, decomposed into interacting modules with, instance, agnostic parts dealing inputs outputs separated model-specific contain algorithms. 2 4, software layers added gain transparent model execution in cloud, independently hardware operating system computer, without human intervention. Finally, 5 allows be selected as if were interchangeable others giving deceptive answers. This includes use hypothesis testing, inclusion error estimates, adoption literate programming guidelines obtain informative clean code. urgency open source supported here light open-science movement its ideas. Therefore, it argued must promote new participatory way performing science, which researchers can contribute cooperatively characterize control outcomes various territories. three enabling technologies discussed context – Earth observations (EOs), high-performance computing (HPC) machine learning (ML) well how these integrated overall boost research activity scientists generate knowledge.