In addition to its mountains, the country possesses many rivers, river basins, lakes and desert areas. The four major river systems are the Amu Darya, the Oxus of antiquity, (boundary with Central Asia, 1,100 kilometers in Afghanistan); the Hilmand (1,300 kilometers); the Harirud (650 kilometers in Afghanistan); and the Kabul (460 kilometers). Only the Kabul River, joining the Indus system in Pakistan, leads to the sea. Many rivers and streams simply empty into arid portions of the country, spending themselves through evaporation without replenishing the four major systems; others flow only seasonally.

Three major dams harness these rivers for land reclamation and hydroelectric purposes: the Arghandab Dam above Kandahar, completed in 1952, is 145-feet-high and 1,740-feet-long and has a storage capacity of 388,000 acre-feet of water; the Kajakai Dam on the Hilmand River, completed in 1953, is 300-feet-high and 887-feet-long, with a storage capacity of 1,495,000 acre-feet of water; the Naglu Dam on the Kabul River west of Jalalabad, completed in the 1960s, is 361-feet-high and 919-feet-long, stores 304,000 acre-feet of water. These large dams were not destroyed by war, but because of lack of maintenance, looted cables and major silting in the reservoirs, none are functioning to full capacity.