Why did Pakistan depend heavily on the Indus River after independence?

Pakistan’s heavy dependence on the Indus River after its independence in 1947 was rooted in the critical role the river system played in the region's irrigation and agricultural economy. Since the mid-19th century, the British had developed the world's largest canal irrigation system in the Punjab and Sindh regions to support crop production.12

Following the partition of India, this integrated water system was bifurcated. The international boundary placed the essential headworks in India, while the downstream canals ran through Pakistan. This disruption threatened Pakistan's water supply, as India began withholding water from these canals in 1948.12

Consequently, Pakistan became deeply reliant on the Indus and its western tributaries to sustain its food security and rural industry. This dependence necessitated the development of massive infrastructure projects, such as the Tarbela Dam and Mangla Dam, and the signing of the Indus Waters Treaty in 1960 to secure and manage the flow of water necessary for the nation's survival.123