Groundwater irrigation in India developed during the period of green revolution and contributed much in increasing the gross irrigated area of the country. In the last five decades, groundwater irrigation has increased from 5 million hectares to 35 million hectares. The proportional area of groundwater to the net irrigated area has increased by 25% alone during the period 2000-2005. In the past, surface water irrigation played a significant role in increasing the net irrigated area. However, from mid sixties, the proportion of surface water to net irrigated area has decreased and in the last decade alone it has decreased largely by 23%. This is largely due to incompletion of planned irrigation projects and poor maintenance of the existing surface irrigation infrastructure. State wise there is wide variation in the source of net irrigated area.
In the northern and western states, the proportion of groundwater irrigation to net irrigated area is more than 70% in the post period 2000 while the share of groundwater and surface water is equal in the southern zone during the same period. Groundwater expansion growth is higher in the states like Assam and West Bengal. Assam has abundant and untapped ground water potential and the state Government has prioritised massive irrigation facility with the concept of Participatory irrigation Management.
Groundwater expansion growth rate is insignificant in Bihar while in Karnataka a decline in the proportion of groundwater irrigated area is observed NIA has increased by 10% the decline in groundwater proportion causing a declined in groundwater level. Groundwater accounts for 67% of the net irrigated area. Groundwater expansion has been growing at an exceptional rate in the recent decades. More reliable water delivery and declining extraction costs due to advances in technology and, in many instances, government subsidies for power and pump installation have encourages private investment in tube wells.
Groundwater irrigation, due to its lesser variation in its supply and higher the reliability in irrigated water supply, reduces the risk of investment in labour, seed, fertilizers, pesticides and other inputs and induces farmers to increase the irrigation intensity. Some states has experienced fast decline in groundwater level which leads to lower productivity of water and cause a decrease in irrigation intensity. Irrigation intensity is lower among southern states where the groundwater depletion problem is severe.