The river has a total drainage area exceeding . Its estimated annual flow is around , twice that of the Nile and three times that of the Tigris and Euphrates rivers combined, making it one of the largest rivers in the world in terms of average annual flow. Its left-bank tributary in Ladakh is the Zanskar River, and its left-bank tributary in the plains is the Panjnad River which itself has five major tributaries, namely the Chenab, Jhelum, Ravi, Beas, and Sutlej rivers. Its principal right-bank tributaries are the Shyok, Gilgit, Kabul, Kurram and Gomal rivers. Beginning in a mountain spring and fed with glaciers and rivers in the Himalayan, Karakoram and Hindu Kush ranges, the river supports the ecosystems of temperate forests, plains and arid countryside.