Assessing water productivity and energy use for irrigating rice in Pakistan
Ghani Akbar, Shahid Hameed, Zafar Islam
Abstract
Abstract Overirrigation of rice crops from groundwater negatively impacts water productivity, energy use and the environment in Pakistan. Therefore, four decades (1981–2020) of data on rice crop area and production were assessed for water productivity, and alternative options for irrigation application and energy use were explored. The results show a maximum average yield of 2.42 t ha‾¹ and water productivity of 0.16 kg m‾ 3 (6211 L kg‾¹) for the last decade (2011–2020), with an average decadal yield increase of 14%. The last year's rice crop during 2020 consumed 14.43 million acre‐feet (MAF) of groundwater, assuming a minimum irrigation application of 1500 mm per season. The maximum equivalent energy required for pumping is approximately 386 MW for electrical and 4966 MW for diesel‐driven tube wells. Diesel combustion for pumping caused 1.26 million t (467 kg ha‾¹) of CO 2 emissions per season. The capital cost for converting all installed capacities of electrical (2311 MW, PKR 481 billion) and diesel (16 517 MW, PKR 1909 billion) tube wells to solar energy can be recovered in less than 4 years. Improved governance and optimized site‐specific solar system designs can avoid undergoing groundwater. Improving water productivity and using solar energy for irrigation indicates the prospects of improved sustainability of rice crops in Pakistan.