The capacity to discern surface water improved as satellites became more available. Because remote sensing data is discontinuous, integrating models with satellite observations will improve knowledge of water resources. However, given the current limitations (e.g., parameter errors) of water resource modeling, merging satellite data with simulations is problematic. Integrating observations and models with the unique approaches given here can lead to a better estimation of surface water dynamics.

Global hydrological models (GHMs) are usually applied with a spatial resolution of about 50 km, but this time we applied the H08 model, one of the most advanced GHMs, with a high resolution of 2 km to Kyushu island, Japan. Since the model was not accurate as it was, we incorporated local information and improved the model, which revealed detailed water stress in subregions that were not visible with the previous resolution.

Six schemes were added to the H08 global hydrological model (GHM) to represent human water abstraction more accurately and ensure that all water fluxes and storage are traceable in each grid cell at a daily interval. The schemes of local reservoirs, aqueduct water transfer, and seawater desalination were incorporated into GHMs for the first time, to the best of our knowledge. H08 has become one of the most detailed GHMs for attributing water sources available to humanity.

Electricity generation may become a key factor that accelerates water scarcity. In this study, we estimated the future global water use for electricity generation from 2005 to 2100 in 17 global sub-regions. Consequently, We indicated that the socioeconomic changes had a larger impact on water withdrawal and consumption for electricity generation, compared with the climate mitigation changes represented by the climate mitigation scenarios.

Supraglacial debris is widely spread in many high-relief mountain regions and affects glacier melting rate and resulting runoff, however, there is no global dataset of debris information. Here we present a first global map of thermal resistance of debris on glaciers at 90 m by using multi-temporal satellite images and radiation data. We believe our result provides a solid basis for evaluating debris effects in global glacier models, which could refine future predictions of glacier meltwater.