Sudan had a modern irrigated agriculture sector totaling about 800,000 hectares in 2010, out of about 84 million hectares that were potentially arable. This was a slight decline from the prior year and well below the more than 2 million hectares of the early 1990s. The Nile and its tributaries were the source of water for 93 percent of irrigated agriculture, and of this, the Blue Nile accounted for about 67 percent. Gravity flow was the main form of irrigation, although pumps served part of the irrigated area.