The climatic and topographic characteristics of Indus Basin provided an excellent condition for the development of irrigation system. Archaeological remains of Harappa and Mohenjo-Daro indicated that several canals were constructed in this region. The Indus River System (IRS) was developed into a complex network of canals, and 74% of its water was utilized for irrigation after Indus Water Treaty. After 1947, Indus irrigation network was extended, and cropland area was increased from 8.5 to 18.2 MH in Pakistan and 2.02 to 8.5 MH in India. Construction of dams, barrages, and canals to divert the maximum river water for irrigation resulted in drying up the natural pathways of the rivers, except during monsoon season. The aquifer in the irrigated areas became high and created problems of waterlogging and salinity, but due to extensive groundwater extraction, water table near urban centers is lowered now. Water quality was degraded due to addition of fertilizers, pesticides, chemicals, municipal sewage, and industrial effluents. Due to climate change, the glaciers in the upper catchment areas are continuously retreating and the frequency of floods and droughts is increasing. The objective of this chapter is to provide a comprehensive review of irrigation system developments in Indus Basin and its implications on environmental resources.
Part of the book: Irrigation