Somalia's bread basket has become a dust bowl as the life-giving waters of the mighty Shabelle river run dry amid intense drought in the war-torn country.

River-fed farmlands have become parched playgrounds for children who kick footballs beneath a cloudless sky, as one sign among many of the failed rains that the United Nations warns has put more than a million people at risk.

Elders in the Lower and Middle Shabelle regions, where most people rely on farming for survival, said it is the first time in decades they have seen such water shortages in the river.

"I have never dreamt of finding myself walking inside the river," said Adow Amin, a resident in Afgoye town, just outside the capital Mogadishu, an area famous for its banana production.

"Can you imagine there is no water? The whole area looks like another place, I used to cross this river with a boat," he said.

Land here should be producing maize, bananas, sesame and other fruits and vegetables, with the once broad waters of the river a lifeline for thousands of Somali families.

- 'This is a nightmare' -

"All the villages in the regions rely on water from the river to survive, there are very few wells here and I don't think life is possible without the flow of water of the Shabelle River," said Mohamed Idle, an elder in Jowhar district, of the more than a 1,000 kilometre (800 mile) long river that begins in Ethiopia's highlands.

"This is a nightmare. I never thought of this river running dry, I can see the riverbed and children playing,"said Abdulahi Mursal, another resident. "People will soon start leaving here."

Floods and failed rains caused by the El Nino weather phenomenon have sparked a dramatic rise in the number of people going hungry in large parts of Africa, including in arid regions of the Horn of Africa.

Northern Somali areas, including self-declared independent Somaliland along the Gulf of Aden and semi-autonomous Puntland, are especially hard hit, with some 385,000 people in dire need of food aid, according to the UN, with that figure feared to quadruple without help.

"Severe drought exacerbated by El Nino conditions has hit parts of Puntland and Somaliland, affecting hundreds of thousands of people," the UN Office for the Coordination of Humanitarian Affairs (OCHA) warned in latest report.

"A further 1.3 million people risk slipping into acute food insecurity if they do not receive assistance... or nearly 40 percent of the 4.6 million people living in Puntland and Somaliland."

- 'We are desperate' -

The warning also comes as neighbouring Ethiopia -- the source of the Shabelle river -- struggles to combat its worst drought for 30 years, with at least 10.2 million people needing food aid.

Getting aid to the people in Somalia is an enormous challenge, especially in southern districts where the Al-Qaeda-linked Shebab remain powerful, fighting government troops and a 22,000-strong African Union force.

Last month the UN warned over 58,000 children will starve to death in Somalia without urgent support.

Severe drought and conflict in Somalia caused a famine in 2010-2012 that eventually killed a quarter of a million people. A similar number died during the previous 1992 famine.

El Nino is triggered by a warming in sea surface temperatures in the Pacific Ocean. It can cause unusually heavy rains in some parts of the world and drought elsewhere.

"The impact of the drought in the north is already being felt in southern and central regions," the UN said recently.

"There are concerns on the rapid deterioration of the water situation in Belet Weyne in Middle Shabelle region due to the rapid reduction of water levels."

While the river is seasonal -- flooding during intense rains, then nearly drying up in the dry season -- residents say the levels are the lowest they have seen in recent memory.

"We are worried as there is serious water scarcity around villages, and many people are now trekking long distances every day to fetch water from wells," said Ibrahim Adam, a resident in Jowhar, saying people were desperate for expected rains due in April to arrive.

"We don't know what is happening, we are desperate," said Mohamed Nur, a farmer.