Groundwater Irrigated Agriculture in Central Punjab, Pakistan

Kurzfassung

Irrigation water for agriculture in Pakistan is an issue due to a significant difference between rainfall and crop water needs. Irrigation water is either coming from snowmelt and rainfall in the northern mountains, or being pumped from groundwater. Canal water is limited, and water distribution using the warabandi system, a fixed canal water rotation system among water users on a particular irrigation channel, is not adequate and flexible. The result is overdependence on groundwater, which has impaired crop growth, notably in regions of bad groundwater quality. The history of groundwater use is not very old in Punjab, Pakistan. By the end of 1990s, canal irrigation was dominant, which was then surpassed by groundwater at the start of 1991s. Since then the groundwater development has expanded exponentially, and recently the groundwater share in irrigated agriculture of the country is about 50%. By the end of 2013, more than one million tubewells are operational in the country and most of them are located in the Punjab province. The consequence is a drop of groundwater level in majority canal commands including the lower Chenab canal irrigation system. Evapotranspiration is the major outflow from the water balance in the region. Cultivation of high delta crops during kharif seasons including rice, cotton and sugarcane are responsible, which is triggered by elevated temperatures. During rabi seasons, wheat is the single major crop all over the lower Chenab canal with its coverage on more than 50% area. The overall recharge results showed that rainfall is the major inflow during kharif seasons, while during rabi canal seepage dominates all other recharge sources. During kharif, the other major sources of recharge are field percolations, canal seepage, watercourse losses and distributary losses. Rainfall recharge, field percolation, watercourse losses and distributary losses are considered major recharge sources during rabi seasons.