Hydrological droughts can persist up to 3.5 years even if it rains

2023-10-11 14:31:45

MADRID, 11 Oct. (EUROPA PRESS) –

New UC Riverside research shows that even as rainfall returns to normal, the impact of drought may persist in streams and rivers for up to 3.5 years.

There are two measures of drought in streams. One measure is the total water level, which is affected by snowmelt and precipitation. Many researchers examine this measure. Another measure is the base flow, which is the portion of the flow fed by groundwater.

Fewer researchers examine baseflow droughts, and previously there was no accurate way to measure them. Because baseflow is strongly tied to groundwater, and because its lack has significant impacts on water management and ecosystem services, the UCR team decided to examine baseflow more closely.

“People often use rainfall as an indicator of drought because it is easier to measure. But there are other types of drought and each has its own impacts,” he said. it’s a statement Hoori Ajami, corresponding author of the study and associate professor of groundwater hydrology at UCR. “We needed a new way to see how long it takes for one form of drought to turn into another.”

Baseflow belongs to a category of drought that affects streams and rivers, called hydrologic drought. It affects the availability of water for activities such as drinking, irrigation and bathing, and affects wildlife, plants and the overall health of the ecosystem. Furthermore, a severe hydrological drought could affect the stability of the infrastructure.

To develop a more nuanced, location-specific method for defining the beginnings and endings of hydrological droughts, the research team examined 30 years of data from more than 350 locations throughout the United States.

For this study, the team only examined the base flow of streams or rivers that were not affected by human activity and do not have reservoirs or dams.

Your results, published in the Journal of Hydrology, show that the beginning and end of a hydrological drought depends on a variety of factors. These include the typical climate of a place as well as its geography.

There was a wide range of lag times between the end of a precipitation drought and the end of a baseflow drought. In parts of Kansas, streams took 41 months to recover, while in the Arroyo Seco area near Pasadena in California, recovery took almost a year.

These results are consistent with previous studies showing that The water in underground aquifers also suffers a delay in its response to the lack of precipitation. These aquifers supply the base flow of rivers and are a key source of water for agriculture. However, excessive pumping of groundwater during drought could cause sinkholes to form, which would cause the displacement or collapse of buildings and other infrastructure.

“A key message we want to send is that people need to be careful how they manage the water they have,” Lee said. “Due to rising temperatures, baseflow drought is becoming longer and more severe in many parts of the country. And because watershed boundaries often cross state or international borders, Preserving precious water resources will require more cooperation.”