Impact of Irrigation on Regional Climate Over Eastern China

Abstract

Irrigated area has rapidly expanded over the North China Plain (NCP), over the second half of the twentieth century. Simultaneously, there has been an observed increase in specific humidity and precipitation and a decrease in surface temperature during summer. The impacts of irrigation on regional climate in Eastern China are investigated using the Massachusetts Institute of Technology-Regional Climate Model with irrigation module. The results of our experiments clearly support that surface cooling as well as enhanced precipitation are attributable to irrigation over the NCP. The irrigation-induced soil moisture change simulated over the NCP during summer resulted in cooler surface temperatures by 1~4°C over this region, which led to a reduction of the planetary boundary layer, higher surface pressure, and significant changes in low-level circulation. Our results indicate that moisture convergence is enhanced over Hebei and Henan province along the Taihang-Mountain, which generated a significant increase in precipitation by 20~40% over this region.