Spatio-temporal patterns and drivers of irrigation water requirement in mainland China

As a major agricultural country, China’s grain production relies heavily on irrigation. Given the impacts of climate change and human activities, accurately quantifying changes in irrigation water requirements for staple grains (rice, wheat, and maize) and identifying the key drivers behind these changes are critical for effective water resource management and food security. This study integrated meteorological, hydrological, and land use data, crop growth profiles, and agricultural statistics to estimate irrigation water requirements in mainland China. The spatio-temporal variations in the total irrigation water requirement (total IWR) for staple grains were analyzed at both national and provincial scales from 1980 to 2020, and the drivers of these changes were identified. At the national scale, we found that both total IWR and planting area have significantly increased by 5.60 million m³ yr−1 and 405.32 thousand hm² yr−1, respectively. The center of gravity of total IWR has shifted towards water-scarce regions in the north, as the planting area expanded northward. At the provincial scale, total IWR and planting area were the highest in the north and lowest in the northwest, and both have been witnessed significantly increase in the north, especially in the northeast. Moreover, the variation in total IWR was primarily driven by the planting area, followed by climate change and crop planting structure. This study clarifies the dynamics of irrigation water requirement for China’s staple grains and provides valuable guidance for sustainable agricultural development.