I was being spoken to by the Ethiopian Foreign Minister but I had my back to him. I was facing a wall. It was like a bad dream. I quickly swung my chair round and apologised – out loud. A moment ago I had been floating downstream about 20 feet above the river Nile. Suddenly I sailed out over a waterfall. The drop made my stomach churn and I tried to grab a rope to hold onto. Virtual Reality, the BBC’s new toy, will soon be turning your life round – and round and round.

It is quite simple. Every visual experience we have at the moment is on a screen, captured by a lens like an eye, maximum vision 180 degrees. VR is filmed by a ball lens – 360 degrees. This can then be shown as either a complete 360 degrees screen around a room or by sitting on a swivel chair with a box attached to your head so as you turn your chair round the picture completes the 360 degrees view.

So what was the film about? It was about the Next Big Danger spot in Africa: the Nile.

Put simply Egypt is habitable because of the Nile. Its fertile delta and the banks for hundreds of miles enabled the first great Mediterranean civilisations and has been one of the great civilisations ever since. As the Nile reaches the sea, it floods into thousands of channels to water the fields and gardens that feed Egypt. If the Nile dies so does Egypt. Flying over it at 36,000 feet as it winds and wanders through Sudan and lower Egypt it looks like a sleeping blue green snake. At Khartoum the slow moving White Nile is joined by the muddier Blue Nile. It is an extraordinary site seeing the different waters swirl and churn as they meet. The White Nile has come from Lake Victoria in Uganda and moves slowly, spreading out into a vast marsh known as the Sudd. On its own the White Nile would evaporate. It is the annual surge of the Blue Nile that enables the river to reach the sea.

In 1990 I made a film for Channel 4 about the Isreali proposal to build a dam on the Blue Nile. I finished the film with an interview with an Egyptian Minister and asked him about the dam. “If the Israelis build a dam on the Blue Nile we will bomb it,” was his reply.

That dam, now known as the Grand Ethiopian Renaissance Dam (GERD), is near completion so the test will come in May and June next year, the dry season in the Ethiopian Highlands. The worst case is that the lake created by the dam will take more than a year to fill or that evaporation will diminish the amount of water. Either way the Egyptians will get less – or no – water.

Meanwhile in Ethiopia the country is riven with strife and the government is rudderless. This could be the end of regime which took over in May 1991 when the combined guerrilla armies of Tigrayans and Eritreans approached Addis Ababa after 16 years of civil war. When the war started the Eritreans wanted independence from Ethiopia but the Tigrayans were fighting the Russian backed dictatorship of Haile Mariam Mengistu to create a federal system. They made a pact to fight the Mengistu regime. Unlike every other country in Africa, Ethiopia sees itself as a  country containing many nationalities. Ethnicity is important in all of Africa but rarely do constitutions enshrine ethnic group rights and demarcated areas. The Tigrayan Peoples Liberation Front (all the political language is based on Marxist Leninist concepts and language) only wanted self-rule for Tigray. But to establish that they had to overthrow the military ruler, Mengistu Haile Mariam. Throughout the 1980s they fought in the mountains and gradually crushed the national army, even though it was backed by the Soviet Union. At dawn on May 28th 1991 the Eritrean and Tigrayan tanks rolled into Addis Ababa and by lunchtime the capital was in their hands. As soon as the battle for Addis Ababa was over, the Eritreans left and went back to establish the independent Eritrean state. Meles Zenawi and his Tigrayan commanders had not only “liberated” their homeland but found themselves in control of the whole country. They had fought for a slice of the cake but now had the whole cake in their hands.

Meles Zenawi, the Prime Minister, began to construct a new Ethiopia in which each “nation” would have – in theory – autonomy and self government. The nations could – in theory – write their own constitutions and vote to leave Ethiopia. It was a little like the end of the Soviet Union which had been an ally of Ethiopia since 1974. Meles died of cancer in 2012 and his successor was appointed by the generals. None of them wanted the job so they gave it to a technocrat, a southerner from the lowlands, Desalagne Haile Mariam. He has been more like a senior civil servant than a prime minister. In all African countries a picture of the president is hung on the walls of public or official buildings. In Ethiopia the pictures of Meles are still there. Only a few include Desalagne. Deselagne has been more like a civil servant than a president. He has taken his orders from the Tigrayan generals but in the history of Ethiopia that is not unusual. Often the Emperor would be above politics and would rely on a politically weak manager to do the daily work. In Addis today it is still the generals who pull the strings behind the scenes and maintain control over the economy, the army and the constitution.

Deselagne’s resignation has come at a difficult time. Addis Ababa has expanded hugely and now encroaches on the Oromia region. But many of the jobs in Addis Ababa still go to Tigrayans. The Oromia who are Ethiopia’s largest ethnic group have become increasingly militant, feeling they have been marginalised by successive regimes. Even more important, they are losing land and employment. They have always felt marginalised. In history often enslaved by other groups although they are the largest ethnic group in the country.

Meanwhile the Egyptians are looking on with anxiety. How much will evaporate from the vast lake caused by the GERD? if there is severe drought in the Ethiopian highlands – not uncommon – the annual surge will fail to carry the Nile to Cairo. What will the Egyptians do then?