By Andrew Cawthorne
GURI, Venezuela, April 13 (Reuters) - Drought has turned parts of the area behind Venezuela's Guri dam, one of the world's biggest, into a desert, but the government is optimistic of rain within weeks to drive the vast installation that provides the bulk of the OPEC nation's power.
On a tour of the hydroelectric complex on the Caroni river, Electricity Minister Luis Motta told Reuters that forecasts showed a 70 to 80 percent chance of rain toward the end of April or in May to stop the waters behind the dam falling to a critical depth of 240 meters (790 feet).
Driving, hiking and rafting round the 4,600 square km (1,780 square miles) area, Motta, 57, pointed to unprecedented scenes revealed by the receding waters: long-sunken boats now visible; sand-dunes in previously submerged areas; cattle wandering across parched earth.
The reservoir in southern Bolivar state, which provides about 60 percent of the nation's 16,000 megawatt power demand, hit a historic low of 243 meters (797 feet) this week.
"We have to hang on," said the general, whom President Nicolas Maduro tasked with managing the electricity sector from late 2015 just as the drought-inducing El Nino phenomenon struck.
"We will do everything humanly possible, and also with God's help some good rains will come so Guri can recover and we can avoid extreme measures other nations are taking."
"LIKE THE SAHARA"
Many Venezuelans say power and water cuts are already affecting them daily, adding to suffering from a recession, though Maduro has said he wants to avoid "painful" rationing.
Motta, who also heads state power utility Corpoelec, has spent three weeks at Guri, supervising its 15,000 workers.
Among crisis measures, canals are being dredged to join pools now cut off by emerging land.
"It's still going down, but we're slowing the descent in hope rain comes," he said.
Motta, often mocked by opposition supporters on social media, was scathing about criticism that insufficient investment, preparation and diversification of power sources were to blame.
"They've tried to ridicule the situation, saying it's a lie, El Nino doesn't exist, not enough has been invested. But here it is: let him who has eyes see ... There are parts here that look like the Sahara Desert."
With about two-thirds of power consumed in homes, Venezuelans must play their part by cutting consumption, he added. "If it doesn't rain, and if we don't make an effort, many of my brothers and sisters are going to suffer a lot - my family, all of us."
For Wider Image photo essay, click here: (http://reut.rs/23ELeP6)
(Additional reporting by Carlos Garcia Rawlins; Editing by Brian Ellsworth, Corina Pons and James Dalgleish)
Our Standards: The Thomson Reuters Trust Principles.