Climate change is predicted to increase both drought frequency and duration. Arid and semiarid regions, which account for 45% of the global land area, support 38% of the global population, but are regions that have very fragile ecological and water resource systems. Over the past 100 years, the global mean temperature increase for arid regions was 0郾 94益 / 100a, which is higher than the average global mean temperature increase of 0.74益 / 100a. Over this period, global arid and semiarid regions have become drier and drier. About 10%-20% of the global arid and semiarid land has become seriously degraded, the area of extremely arid land has doubled and the total area of land classed as arid is nearly 30%. Large scale droughts have recently occurred in North America, Africa, Europe, South America and Australia, resulting in major changes to terrestrial ecosystems, the carbon balance and food security. The continuous aridification over 30 years of the semiarid region of North China has led to serious environmental degradation and a lack of water resources, which has seriously restricted sustainable regional development. The semiarid area in Northwest China is also sensitive to climate change. Over the past 50 years, the air temperature has risen and rainfall has fallen, which have caused the climate to