A network of scientists is cooperating within the COST Action "Harmonious" to promote UAS monitoring strategies and establish harmonized practices. The action has 36 partner countries and aims to transfer advances in UAS methods through a global network. It has five working groups focused on data processing, vegetation monitoring, soil moisture, streamflow monitoring, and harmonization. The overall goal is to increase the capacity to describe water resources and assist management through consistent UAS monitoring of key variables.