Snowfall deficiency to reduce water levels in rivers

As the earth warms up and snowfall goes down, rivers in snow-affected regions would be left with less water to discharge, a study that linked rate of snowfall with the amount of water in rivers has indicated.

In a warming climate, if less of the precipitation falls as snow, rivers will discharge less water than they currently do, it noted.

With data from 420 catchments located throughout the US, the researchers showed that snowiness is an important factor for the average river discharge.

"With more than one-sixth of the earth's population depending on meltwater for their water supply, and ecosystems that can be sensitive to streamflow alterations, the socio-economic consequences of a reduction in streamflow can be substantial," warned Ross Woods, senior lecturer at University of Bristol in Britain.

How river flow is generated in snowy areas is poorly understood due to the difficulty in getting appropriate measurements.

Previous studies had mostly focused on the role of snowfall for the within-year distribution of streamflow - how much water is there in the river during a particular period of the year - and assumed that there was no important effect of snow on the average streamflow.

This study is the first to focus on the role of snow for how much water is on average available in rivers.

Global warming is very likely to reduce the amount of snow significantly in snow-affected catchments, even if temperatures rise only two degrees Celsius.

"Our finding is particularly relevant to regions where societally important functions, such ecosystem stability, hydropower, irrigation, and industrial or domestic water supply are derived from snowmelt," the researchers noted.

The study appeared in the journal Nature Climate Change.