Impacts of Irrigation and Vegetation Growth on Summer Rainfall in the Taklimakan Desert

In recent decades, a greening tendency due to increased vegetation has been noted around the Taklimakan Desert (TD), but the impact of such a change on the local hydrological cycle remains uncertain. Here, we investigate the response of the local hydrological cycle and atmospheric circulation to a green TD in summer using a pair of global climate model (Community Earth System Model version 1.2.1) simulations. With enough irrigation to support vegetation growth in the TD, the modeling suggests first, that significant increases in local precipitation are attributed to enhanced local recycling of water, and second, that there is a corresponding decrease of local surface temperatures. On the other hand, irrigation and vegetation growth in this low-lying desert have negligible impacts on the large-scale circulation and thus the moisture convergence for enhanced precipitation. It is also found that the green TD can only be sustained by a large amount of irrigation water supply since only about one-third of the deployed water can be “recycled” locally. Considering this, devising a way to encapsulate the irrigated water within the desert to ensure more efficient water recycling is key for maintaining a sustainable, greening TD.