PROGRESS IN GEOGRAPHY ›› 2020, Vol. 39 ›› Issue (3): 433-442.doi: 10.18306/dlkxjz.2020.03.008

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Estimation of monthly evapotranspiration and soil moisture in the Central Asia

JIANG Bo1,2, TIAN Jing1,*(), SU Hongbo1   

  1. 1.Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
    2.University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2019-02-18 Revised:2019-09-29 Online:2020-03-28 Published:2020-05-28
  • Contact: TIAN Jing
  • Supported by:
    Strategic Priority Research Program of Chinese Academy of Sciences(XDA2004030201);National Natural Science Foundation of China(41671354)


There is insufficient study of evapotranspiration (ET) and soil moisture (SM) in arid ecosystems such as the Central Asia. To address this issue, we applied the land surface model (CLM 4.5) to simulate monthly ET and SM in the Central Asia from 1980 to 2009. Other products including GLDAS (Global Land Data Assimilation System), GLEAM (Global Land-surface Evaporation Amsterdam methodology), and AMSR-E (Advanced Microwave Scanning Radiometer for EOS) were used to compare with the simulated results. The comparison indicates that the simulated results agree favorably with other products. Most of the annual evapotranspiration concentrates in spring and summer, reaching its maximum in May. In summer, the high evapotranspiration areas in the Central Asia are concentrated in the northern and northeastern corner of Kazakhstan, and in the southeastern mountainous areas. Vegetation transpiration plays a leading role in the main farmland and forest areas. In spring, the Tianshan Mountains and the Pamir Plateau in the southeast are the high value areas of evapotranspiration, mainly because with the high rainfall and the beginning of snow melting, there is sufficient water for evapotranspiration. The spatial patterns of annual ET and SM in the Central Asia show that the areas with high ET are distributed in the northern and northeastern corner of Kazakhstan and in the southeastern mountainous areas, and the low ET areas are mainly located in Turkmenistan and Uzbekistan, where desert is the main land cover type. The results of simulated surface soil moisture show that in winter, land surface evapotranspiration is low, and precipitation is mostly stored in the surface soil or in snow cover. In spring, air temperature rises, snow melts, and water seeps into the soil. Soil moisture increases continuously, reaching its peak in April. In summer soil moisture continues to decrease, and reaches its lowest value in September. In autumn and winter, evapotranspiration decreases and soil moisture increases. The high value areas of soil moisture in the Central Asia are concentrated in the woodland and farmland areas in the northern and northeastern part, as well as the Amu River and Sir River basins in the Tianshan Mountains and downstream, while the desert areas in the southwest are low value areas. In summer rainfall, evapotranspiration, and soil moisture are low, so the correlation between them is very high; winter precipitaton and soil moisture are highly correlated, especially in barren areas; in the case of high vegetation coverage, spring rainfall and evapotranspiration are highly correlated, and the correlation between soil moisture and rainfall, evapotranspiration is low, and a negative correlation can be observed. Overall, the result of this study will lay foundation for further research on water issues in the Central Asia.

Key words: evapotranspiration, soil moisture, CLM 4.5, the Central Asia