ONE of the most important irrigation schemes in the African Sudan is being carried out in the Upper Senegal district of French West Africa, where the project is to irrigate the Macina district from the flood waters of the Niger. A few details are given in Terre Air Mer for February. At Bamako the Sotuba barrage, 1,340 yards long, irrigates about 15,000 acres on the right bank. The chief barrage, however, is in course of construction below Segu about 200 miles farther downstream at Diamarabougu. This will be about 1,300 yards long and will feed a number of canals on the left of the river. Some of these are already cut and embanked. A navigation canal with locks will be built round this barrage. It is estimated that this irrigation scheme will eventually allow the population of the area affected to be increased fivefold with crops of rice, cotton, forage plants and livestock.