关键词: 沙漠化地区, 地下水, 时空变化, 原因

Abstract: The time space variation of groundwater in central desertified area in Naiman Banner of Mongolia in the past 20 years and its causes were studied in the paper. (1) The groundwater elevation rose gradually from north to south and the superelevation reached 106-116 m. The depth of groundwater was greater in agricultural area than that in pasture area, and larger in the range close to river than that in inland. (2) The law of annual groundwater dynamics was that groundwater was deeper during the period from the end of 1970s to the beginning of 1980s; trended to rise during the period from middle 1980s to the beginning of 1990s; decreased from middle 1990s, but still markedly higher than that in the end of 1970s. (3) The law of seasonal dynamics of groundwater level was that groundwater level was the highest from April to May; then on declined gradually. The highest groundwater level in agricultural area, pasture area, region close to river was in October, December, and January respectively. (4) The law of the changes in groundwater level which occurred in the past 20 years was closely correlated with the law of seasonal and annual changes in amount of rainfall, but not related to the changes in area used for irrigation and annual dynamics of crop yield. (5) The difference of groundwater distribution in the space was very closely correlated with topography and earth surface feature and way of land use, but not related to the annual rainfall.

Key words: Desertified area, Groundwater, Time space variation, Cause