A Google Earth Engine tool to assess water budget and its individual components

In the present work a new freely available web-based tool is developed within Google Earth Engine (GEE) that aims to support water agencies, farmers and public services acquire information on the water budget components in the areas of their interest. The tool makes use of the high-resolution land component of the fifth generation of European ReAnalysis (ERA5), i.e. ERA5-Land, post processed by the European Centre for Medium-Range Weather Forecasts (ECMWF). The application accesses the bands associated with the hydrologic variables from ERA5-Land, in order to estimate the water budget at the local, river basin and regional scales. Therefore, the time series of major water budget constituents i.e. precipitation, runoff, evapotranspiration, soil moisture and storage changes are computed at the monthly time step. Considering the use of freely available data sets and the convenient cloud functionalities offered by GEE, the developed application will offer a free supporting tool for farmers and decision makers to plan activities, infrastructures and measures in water resources management, emergency services and agricultural sectors.