Acta Geographica Sinica ›› 2016, Vol. 71 ›› Issue (9): 1494-1508.doi: 10.11821/dlxb201609003

• Orginal Article • Previous Articles     Next Articles

Spatial-temporal characteristics of soil moisture in China

Lei ZHANG1(), Houquan LU1(), Liangyu WANG1, Bingyun YANG2   

  1. 1. National Meteorological Center, Beijing 100081, China
    2. National Satellite Meteorological Center, Beijing 100081, China
  • Received:2016-04-29 Revised:2016-06-16 Online:2016-11-25 Published:2016-11-28
  • Supported by:
    Meteorological Public Welfare Profession of China, No.GYHY201306045

Abstract:

Using actual observed soil moisture data of 155 agro-meteorological stations across China, at dekadal scale from 1981 to 2010, this paper examined the spatial and temporal characteristics of soil moisture at each 10 cm depth from 0 to 50 cm, at regional and national scales. Annual trend and significant change point were detected through tendency analysis and Cramér-von Mises test methods. Since soil texture and crop types were approximately homogeneous in each climatic region, regional average variation of soil moisture could be observed in the analysis. Mean soil moisture was between 15% and 25% in most regions while it was above 25% in the northern part of Northeast China and southern part of Southwest China. At each depth, larger soil moisture was detected in Southwest China, Jianghuai, Northeast China, Jiangnan, Jianghan, Huanghuai and South China, while the smallest value was observed in Inner Mongolia. As soil deepening, except in Tibetan Plateau, increases in soil moisture were apparent, being a maximal magnitude in Southwest China. Obviously, as well as periodical characteristics, annual and seasonal difference of soil moisture emerged at each depth, corresponding well to regional precipitation, temperature, and water demand for planting crops. An obvious freezing-increasing-deceasing-increasing trend existed in Northeast China, Inner Mongolia and Xinjiang, a variation of deceasing-increasing-fluctuating in North China, Huanghuai, and eastern Northwest China, a multiple fluctuation in Jianghuai, Jianghan and Jiangnan, and a deceasing-increasing-deceasing trend in South China and Southwest China, while an increasing-deceasing trend was found in the Tibetan Plateau. Soil moisture at a greater depth was higher than that at superficial layers. Annual soil moisture varied at each depth, but the mean value decreased from 1981 to 2010. Such annual variation could be well explained by corresponding temperature and precipitation. Consequently, soil moisture tended to decrease in response to temperature increase, following climate change. Apart from climatic factors, soil texture and crop type, as well as human activity, can have influence on soil moisture, which is needed to be studied further. Soil moisture decreased in Xinjiang, South China, North China, Tibetan Plateau, Northeast China and Huanghuai among which Xinjiang was most remarkable with a velocity above -2.3%?(10a)-1. Except in Jianghuai, a significant change of soil moisture was detected, mainly during two periods, i.e. from the late 1980s to early 1990s, and late 1990s.

Key words: soil moisture, climatic zoning, linear tendency, Cramé, r-von Mises test, China