花海湖泊特征时期的水量平衡

应用水热平衡模型,在野外考察及分析的基础上恢复了花海湖泊特征时期的古降水量.结果表明:4300aBP左右花海湖泊面积达到最大时,模型恢复的古降水量约为138mm,比现在降水量高112%;由灵敏度分析,在该区运用水热平衡模型计算古降水量时,对降水反应最为敏感的是云量变化,同时对地表反射率、水汽压和表面温度也具有较高的灵敏度.恢复的古降水量为研究本区土地退化、荒漠化等问题提供了自然背景.

Water Balance of Huahai Lake Basin during a Special Phase

Hydrological and energy-balance model, as a relatively mature method of paleo-precipitation restoration, has been widely applied. The development of this mode and the paleo-lake area and paleo-precipitation of a special phase in Huahai Lake basin restored by this model on the basis of field investigation and analysis are introduced in this paper briefly. It is found that the Huahai Lake reached its maximum area at about 4 300 a BP, when its area reached about 445 km². Ignoring the effect of meltwater in its basin, annual precipitation is primarily estimated to be 151mm at about 4 000 a BP, 132% higher than that at present. However in this basin, meltwater accounts for about 30% at present. Subtracting the effect of meltwater, the lake area was 419 km² at about 4 000 a BP. In this model, the effect of glacier does not be considered owing to the difficult in directly determining the volume of glaciers, but the influence of meltwater on lake coefficient, a decreasing from 0.0309 to 0.0291, is considered. Based on this, annual precipitation is estimated to be 146 mm, 100.6% higher than that at present. Meanwhile sensitivity analysis shows that cloudage is most sensitive to precipitation, followed by surface reflectivity, pressure of vapor and surface temperature. This provides the knowledge for researching the land degradation and desertification in this region, having an important significance for protecting and conducting ecological environments, which is one of the strategic emphases of developing Chinas west.