Huge irrigation projects were initiated as a response to demographic pressure. Irrigation was an attempt to overcome environmental constraints.
Efficient irrigation systems were crucial for the Arab and Ottoman world through the centuries in places where the rainfall was insufficient to support agriculture or where intensive agriculture was practised to meet the increasing demand for food. Traditionally, the Ottoman Empire had controlled and recorded the use of water for irrigation, but during the 19th century the increasing needs of agriculture determined the introduction of new irrigation systems, although some traditional irrigation methods were still in use during the 19th and early 20th centuries. Colonial propaganda also used irrigation works built by the colonial powers to show the “benefits” of colonisation in the occupied countries. Huge irrigation projects were also dictated by the intensification of agricultural crops (cotton in Egypt and grapes in Algeria) and the need to expand cultivatable land. In Egypt, for example, 500,000ha of previously uncultivated land had become usable through irrigation projects under Ismail Pasha.