VIC-Res Mekong: An open-source hydrological-water management model for the Mekong River basin

Decades of research on the Mekong River basin have vastly expanded our knowledge of key hydrological and ecological processes, in part thanks to the development of modelling tools. However, few of these models are openly available to the research community or adhere to FAIR (Findable, Accessible, Interoperable, Reusable) principles, particularly in the domain of hydrology, in turn limiting transparency, reproducibility, and broader scientific engagement. Here, we address this gap and introduce VIC-Res Mekong, an open-source hydrologicalwater management model for the Mekong River basin. The model is implemented over a spatial domain of ∼630,000 km2 and has a resolution of 0.0625 degrees. Water and energy budgets are simulated with the Variable Infiltration Capacity (VIC) model, while streamflow routing is simulated with VIC-Res, which explicitly accounts for the storage and release dynamics of reservoirs. This is of key importance for a basin like the Mekong, where the active storage capacity of dams has increased from 20 km3 to nearly 80 km3 in the past fifteen years. To this purpose, VIC-Res Mekong integrates information from a database containing reservoir storage time series (inferred from satellite images) for 129 dams that accounts for more than 90% of total storage capacity. These data support both hindcast simulations and the derivation of reservoir operating rules, enabling a flexible and realistic representation of dam operations that allows to characterize in detail dam-induced hydrological alterations.