African economies are especially vulnerable to water shortages, delegates to the Implementing Environmental Water Allocations (IEWA) conference heard on Monday.

"Many African economies are held hostage to hydrology," World Bank senior water resources specialist Rafik Hirji said at the start of the four-day event in Port Elizabeth.

It has attracted more than 300 experts, academics and officials from 30 countries.

The international conference aims to promote the sustainable use of rivers, wetlands, estuaries and groundwater.

Hirji said Africa's vulnerability stemmed from the extreme variability of its climate, a condition exacerbated by increasing climate change.

He cited Ethiopia, Kenya and Mozambique as examples of countries on the continent where there was a strong correlation between rainfall and GDP.

"Climate events in these countries have huge economic impacts."

Speaking later to Sapa, he said some countries in the SADC region were "quite vulnerable" in this regard, one of which was Zimbabwe.

"A number of countries are really facing serious problems as a result of their inability to deal with existing climate variabilities. And now climate change is only going to make it worse," he said.