When the desert consumes 250,000 square miles

Human existence in the entire semiarid belt that sweeps across Africa just south of the Sahara is balanced on a precarious knife-edge of survival -- even at the best of times.

The countries of the region are among those with the lowest income per head, the lowest literacy rate, and the lowest life expectancy in the world.

Their rainfall is minimal. Over the past half century, the desert has edged forward and deprived them of an estimated 251,000 square miles of their meager cultivable areas -- more than four times the total area of the six New England states. The desert continues to eat into them at an average of three to five miles a year.

This year, the shadow of anxiety has darkened even more than usual:

* To the west, in the Sahel ("coast" or "edge" in Arabic), there are fears that the lateness of the usual summer rains may mean a recurrence of the six-year drought (1968-74) which cost thousands of human lives in the early 1970 s.

* From the inland limit of the Sahel (Chad) eastward to the Horn of Africa, drought that might have been manageable has been turned into horror by violence of one kind or another. The centers of this grim combination of drought and violence are: Chad, Uganda, and Ethiopia and Somalia.

In Chad, a civil war rages. In Uganda, a people that suffered the excesses of Idi Amin for eight years has been unable so far to restore either the economic infrastructure or political administration left in ruins by the ousted dictator.

In Ethiopia and Somalia, an unofficial but savage war between the two has produced hundreds of thousands of refugees. To their number must be added the refugees from Ethiopia's effort in its northeast to quash the breakaway effort of the Eritreans.

Of all the countries in these stricken areas, Chad is the hardest to get reliable information on because of its geographic remoteness and the chaotic situation in its capital, Ndjamena. But the office of the United Nations High Commissioner for Refugees estimates there are 100,000-200,000 refugees from Chad in neighboring countries. Nearly all these are in Cameroon.

The most immediately desperate situation in the entire belt is in Uganda's Karamoja Province, in the northeast corner of the country adjoining southern Sudan and the Turkana area of Kenya. Drought and raiders have killed off the cattle herds, usually the sole source of livelihood. As many as 400,000 people are believed face-to-face with starvation.

Supplies of relief food are within 200 miles of those needing it to survive, but little of it can get through in truck convoys because of hijacking and thuggery en route.

Some 2,000 Ugandans have crossed into the Turkana area on the Kenya side of the border. But there is drought there, too. Indeed, Kenya has a drought problem of its own: Food production has been reduced by 40 percent by lack of rain.

For sheer numbers of refugees in distress anywhere in the world, no country or region -- not even Indochina -- has anything to compare with the problem Somalia has on its hands. It has up to 1.5 million homeless and hungry people to deal with, virtually all of them ethnic Somalis displaced from Ethiopia's Ogaden Desert area.

Ethiopia disputes the 1.5 million figure. But whatever the correct total, these refugees are victims of the violence resulting from Somalia's challenge to Ethiopia's sovereignty over the Ogaden.

Ethiopia has a problem of displaced persons within its own borders, too, compounded by the drought that has afflicted 9 of its 14 provinces. The Ethiopian government asserts that it is burdened by 700,000 people who have taken refuge in the interior from the violence in the Ogaden -- a figure thought by international relief agencies to be inflated. To these must be added the victims remaining within Ethiopia of the country's other area of major violence: Eritrea.

Outside Ethiopia, in the Sudan (which also has some refugees from Uganda) are 400,000 people who have fled from Eritrea. Djibouti has a total of 40,000 refugees from both Eritrea and the Ogaden.

The relief arms of the United Nations, the Agency for International Development program of the United States government, and various voluntary Western relief agencies are bringing piecemeal help to many of these areas. But as the Economist weekly of London wrote in mid-June:

"It took a coordinated international effort to save the Cambodian survivors; nothing less will avert a potentially bigger tragedy in northeast Africa."

For people living in northwest Africa in the drought-prone Sahel at the other end of the sub-Saharan belt, the outlook is minimally better than it was before their tragedy of a decade ago. This is because a fledgling "coordinated international effort" is in place to help them halt the advancing desert and better prepare themselves to meet a repetition of the 1968-74 drought years.

(Travelers just back from the area say that current fears of another such tragedy beginning this summer because the rains are late are premature. But there is understanding at the international level of sensitivities in the Sahel, because the last time the outside world took so long to perceive the proportions of the suffering there.)

Since the devastation of that great drought, the UN has established at its New York headquarters a Sudano-Sahelian office. But perhaps even more important is the Club du Sahel (Sahel Club), which works out of the Paris headquarters of the Organization for Economic Cooperation and Development. It has a "lean" secretariat of three: Anne de Lattre, a young French widow and mother of three, assisted by an American and a French-speaking Canadian from their respective countries' foreign service.

The French emphasis in the club can be explained by the fact that six of the eight African members of it -- Senegal, Mauritania, Mali, Upper Volta, Niger, and Chad -- are French-speaking and were once part of France's African empire. France remains their single biggest source of outside aid. The other two African club members are the Portuguese-speaking Cape Verde Islands and English-speaking Gambia.

The eight have an organization of their own, the Permanent Interstate Committee for Drought Control in the Sahel, known as CILSS from its initials in French. The non-African members of the club are the aid donors at any given time.

The decision to set up the club was made early in 1976 -- with the express aim of attracting aid to the Sahel to help it deal with its awesome problems. Since then, the amount of yearly outside official help coming into the Sahel has almost doubled -- from $755 million in 1975 to the current flow of about $1.4 billion. In 1978, the single biggest national contributors after France were the US, Canada, West Germany, and the Netherlands, in that order.

In 1976 and 1977, Saudi Arabia was the second biggest national contributor after France. Arab money accounts for about 15 percent of the total now coming in, and the next meeting of the Club du Sahel will be in Kuwait, in November of this year. Arab interest is partly explained by the fact that most of the Sahel's population is Muslim.

For all the promise that this international effort offers, everybody involved in it to whom this writer has spoken asserts that it is only a modest beginning. They all say more money is needed. They all speak of the relentless advance of the desert while bureaucracies argue about programs.

Some talk wryly of how donors are tempted to add conditions to aid and are (perhaps understandably) reluctant to foot the bill for the sustaining costs of projects whose inception they have financed. Some talk of the need for fundamental changes in basic local government procedures, in economic systems, in ways of schooling, and in basic farming methods.

Indeed, Harry Haines, a veteran of relief work for Church World Service in many parts of the world (including the Sahel), says the challenge to the Sahel is a simple one: Change -- or perish.

Per Life capita expectancy GNP in years Population (US ] at birth * Cape Verde Islands 327,000 130 50 * Senegal 5,200,000 430 42 * Gambia 570,000 200 35 * Mauritania 1,50,000 270 42 * Mali 6,100,000 110 42 * Upper Volta 5,500,00 130 42 * Niger 4,900,000 160 43 * Chad 4,200,000 130 43 Sudan 16,900,000 290 46 Uganda 12,000,000 270 53 Kenya 14,600,000 270 53 Ethiopia 30,200,000 110 39 Djibouti 320,000 450 45 Somalia 3,700,000 110 43 US (for comparison) 220,000,000 8,520 73

* Member of Club du Sahel. (Source: Based mainly on World Bank 1977 figures)