MATILDA-Online v1.0.1: A Cloud-based Open-Source Workflow for Modeling Water Resources in Glacierized Catchments

Abstract. The mountain cryosphere is a linchpin of global water security. Changes in high mountain systems due to climate change are putting the freshwater resources of almost a quarter of the world's population at risk. Hydrological modeling is the foundation for developing mitigation and adaptation strategies, supporting policy and water management decisions, and preventing water-related conflicts. However, many vulnerable regions lack access, resources, and training to implement advanced (glacio-)hydrological modeling in decision-making and resource management processes. The open-source Toolkit for Modeling glacier evolution and wATer resources In meso-scale gLacierizeD cAtchments (MATILDA) provides a cloud-based modeling workflow that allows users to generate scenario-based projections and analyze runoff contributions in glacierized catchments. A combination of a temperature-index melt model, an updated Δh routine for glacier evolution, and the HBV hydrological model is forced with open-access datasets provided via cloud services and complemented by a set of processing tools. MATILDA is published as a Jupyter Book on a self-contained website, allowing easy access to the entire processing chain from data acquisition and model calibration to scenario generation and output analysis in a user-friendly Python environment. This paper is the first of a two-part publication outlining the general workflow, describing input data and modeling routines, and assessing parameter sensitivity. The second part demonstrates the application in a case study and discusses the uncertainty in the projections.