PART OF THE Sahel region of Africa is suffering drought and famine again. That is the band of eight sub-Saharan nations, from the Cape Verde Islands to Chad, which suffered a devastating six-year drought in the early 1970s. As many as 100,000 people and more than half the livestock of those basically agricultural countries perished from the resulting famine. This year's drought, though severe, has not had a catastrophic effect. That is because both the Sahelian nations and the international community have learned the costly lessons of the previous drought: Early warning and an efficient respone to widespread food shortages, plus a concerted regional and international-development effort can reduce the impact of recurring droughts.

The current drought and famine severly affects four Sahelian nations - the Cape Verde Islands, Gambia, Senegal, and Mauritania. Those countries' appeals for emergency food supplies brought a quick international response. Led by the United States, other countries have shipped about 450,000 tons of food to the area. And, unlike the helter-skelter approach of five years ago, the food apparently is being distributed efficiently and equitably. Most important, the relief effort is part of a larger regional-development program sponsored by the Sahelian nations and a score of more advanced countries. Their aim is to reduce the region's vulnerability to droughts.

The goals of this unique international effort are as numerous as the needs of the Sahelian countries. They include: Increasing crop production in that generally arid region; building thousands of miles of roads and a communications system for the region, which is larger than Europe, but which has a population of only about 30 million people; and bringing modern educational and health services to a population that still lives largely as its ancestors did a century ago.

The host of African, Arabic, and Western nations that have pledged more than $1 billion annually to the Sahel developments effort, in addition to various bilateral agreements, have done so for more than the obvious and laudable humanitarian reasons. They want to learn how to check "desertification" - the spread of desert land, which, in developing countries, is often caused by efforts to modernize rapidly. Because of where it is, the Sahel is especially vulnerable to the rapid growth of arid land. The widespread concern of developing and industrialized countries about this spurred the U.N.-sponsored conference on the subject held in Nairobi last year. The Sahel is the first area of the world where the various techniques discussed during that conference are to be put to the test. Thus, the Sahel has become, in effect, a laboratory for solutions to not only desertification, but a host of problems that affect developing nations - and, in one way or another, the developed nations too.