Some of Ireland's rivers could lose more than 30pc of their existing water levels during dry weather from the middle of the century, environmental researchers have warned.
Research commissioned by Irish Water found many rivers in the west and south of the country are most prone to the effects of climate change.
The study by the Irish Climate Analysis Research Units at Maynooth University carried out a detailed examination of 206 river catchments identified as sensitive to the impact of current and future climate change.
It assessed their sensitivity to changes in both annual rainfall and changes in the seasonality of rainfall through wetter winters and drier summers.
Predictions were modelled on there being an average temperature increase of 2.3C relative to the period 1976-2005.
The report found most river catchments along the wetter, western seaboard and uplands have a poor natural storage capacity and are most sensitive to changes in the seasonality of rainfall due to climate change.
It claimed they could experience a pronounced decrease in water levels as a result of wetter winters and drier summers, even though overall rainfall could increase by around 20pc.
River catchments in the midlands and east are drier, low- lying and have greater natural storage to withstand reduced summer rainfall than other parts of the country.
While it was still forecast they would experience reductions in flow, they are likely to be less affected by changes in the seasonality of rainfall.
The study excluded heavily modified catchments including the Liffey and Shannon.
It found changes in the annual amount and seasonality of rainfall were most likely to have an impact on rivers with a "shorter memory", which were predominantly upland systems with an impermeable geology and thin peaty soils.
The report said the findings would assist Irish Water in assessing the sustainability of abstracting water from different catchments both now and in the future for public water supplies.
The study's findings will be used to inform Irish Water's National Water Resources Plan which, in turn, will inform decision-making about the company's investment in projects to ensure safe and reliable water supplies to customers.
The research was funded by the Water Services Innovation Fund, established by the Commission for the Regulation of Utilities to encourage Irish Water to implement and invest in research projects that have the potential to improve how water services are delivered.