Effect of Climate Change on Water Resource Allocation to Irrigation: A Review

Rapid socioeconomic development coupled with climate changes is likely to result in uncertainty in agricultural water use, making water resource management and regulation even more difficult. Traditional methods used in allocating and regulating water resources are unable to deal with the balance and optimize water supply and demand between different sectors. Achieving this goal requires a fundamental improvement in our current understanding of the hydrological cycle in farmland ecosystems, in particular, to what extent climate change and anthropogenic activities could reshape the hydrological processes such as precipitation, evapotranspiration, surface runoff, seepage and water consumption. Taking China as an example, this paper systematically analyzes the research progress made over the past few decades in the effect of global climate change on demand of agriculture for water, water supply to crop production, supply-demand balance, water recycling in different irrigation districts. We also analyze the areas that were poorly studied, and the perspectives for future research, especially the response of available water for agricultural use to environmental change at irrigation district scale. These include water supply to irrigation districts and their operations, crop water requirement, consolidating the study of the balance between water supply and demand, as well as theory and method for evaluating water resource bearing capacity in irrigation districts due to climate changes. We conclude that future study should address water cycle and transformation in irrigation districts, and mechanisms underlying the impact of water-saving irrigation technologies on the environment at regional scales.