This work evaluates how rivers are projected to change in the near future compared to the recent past in the context of a warming world. We show that important rivers of the world will notably change their flows, mainly during peaks, exceeding the variations that rivers used to exhibit. Such large changes may produce more frequent floods, alter hydropower generation, and potentially affect the ocean's circulation.

The research evaluated the trends and changes in land cover and river discharge in the Upper Columbia River Wetlands using remote sensing and hydroclimatic data. The river discharge increased during the peak flow season, resulting in a positive trend in the open-water extent in the same period, whereas open-water area declined on an annual basis. Furthermore, since 2003 the peak flow has occurred 11 d earlier than during 1903–1928, which has led to larger discharges in a shorter time.

Global climate change is causing some previously arid regions to become more humid. Economic downturns in these areas are leading to a decrease in water demand. These factors are further leading to a certain level of under-utilization of existing water supply projects in the area. This study finds that actively releasing ecological water increases the sustainability of these water supply projects. The cost of ecological water supply can be recovered by investment in water-related businesses.

Mountain snowpack has been declining and more precipitation falls as rain than snow. Using stable isotopes, we found flows and flow duration in Yosemite Creek are most sensitive to climate warming due to strong evaporation of waterfalls, potentially lengthening the dry-up period of waterfalls in summer and negatively affecting tourism. Groundwater recharge in Yosemite Valley is primarily from the upper snow–rain transition (2000–2500 m) and very vulnerable to a reduction in the snow–rain ratio.

Currently, global hydrological models do not benefit from observations of model output variables to reduce and quantify model output uncertainty. For the Mississippi River basin, we explored three approaches for using both streamflow and total water storage anomaly observations to adjust the parameter sets in a global hydrological model. We developed a method for considering the observation uncertainties to quantify the uncertainty of model output and provide recommendations.

This study investigates the impact of floods on the aquatic ecosystem using freshwater mussels instrumented with sensors to monitor the opening of their valves. Signal analysis techniques were used to gain insight into their responses in terms of changes in the intensity and frequency of valve opening. The approach used in the study enables the development of real-time monitoring systems for ecological purposes and provides a pathway for practical biological early-warning systems.

Vegetation plays a crucial role in regulating the water cycle by transporting water from the subsurface to the atmosphere via roots; this transport depends on the extent of the root system. In this study, we quantified the effect of irrigation on roots at a global scale. Our results emphasize the importance of accounting for irrigation in estimating the vegetation root extent, which is essential to adequately represent the water cycle in hydrological and climate models.

The formation of levee systems is an important factor in determining whether a society fights or adapts to floods. This study presents the levee system transformation process over the past century, from the indigenous levee system to modern continuous levees, and its impacts on human–flood coevolution in the Kiso River basin, Japan, and reveals the interactions between levee systems and human–water systems involving different scales and water phenomena.