Persistent droughts change how rivers respond to rainfall. Our study of over 5000 catchments worldwide found that hydrological and soil moisture droughts decrease river-flow response to rain, especially in arid regions, while vegetation decline slightly increases it. Snow-covered areas are more resilient due to stored water buffering changes. Droughts can also cause long-lasting changes, with short and intense droughts reducing river response to rainfall and prolonged droughts increasing it.

We measured nitrate-nitrogen concentrations using a UV nitrate sensor over 4 years in a shallow gravel aquifer. We observed pulses of nitrate nitrogen in response to forestry harvesting during subsequent rainfall recharge. Our novel hysteresis analysis helped elucidate event-scale nitrate-nitrogen dynamics, while integrating continuous data improved nitrate-nitrogen load estimates. This research provides new insights into the variability of nitrate nitrogen in permeable aquifers.

In this paper, we use models to demonstrate that even small flood reservoirs – which capture water to avoid floods downstream – can be repurposed to release water in drier conditions without affecting their ability to protect against floods. By capturing water and releasing it once levels are low, we show that reservoirs can greatly increase the water available in drought. Having more water available to the reservoir, however, is not necessarily better for drought protection.