中国西北内陆盆地水分垂直循环及其生态学意义

Vertical water cycle and its ecological effect in inland basins, Northwest China

中国西北内陆盆地中的地下水系统,对维系其浅表水分、热量、盐分均衡以及地表的生态平衡、土壤的资源属性和局部地域气候相对稳定性具有不可或缺的调节作用,这种调节作用是通过饱和带水、包气带水(土壤水)、近地表大汽水和植物体内水("四水")之间的垂直循环来实现的。目前的相关研究主要侧重于地下水与地表植被类型间对应关系的统计分析,较少涉及水分运移的机制;而以水分垂直循环的动力学机制为研究对象的SPAC系统(土壤 植物 大气连续体),则对地下水的重视程度不够,且存在着尺度转换的困难,更为完整的应该是GSPAC系统(地下水 土壤 植物 大气连续体)。干旱区内陆盆地地下水生态效应的研究需要开展以下的工作:"四水"垂直循环的动力学过程与机制研究,尤其是饱水带-包气带界面水、汽、热转化过程的研究;人类活动影响下地下水系统演化特征的研究,它不仅是实现水分垂直循环研究的最终目的———水资源合理开发利用的中间环节,更是将"四水"垂直循环这一微观水文循环过程与区域水文循环过程相结合,实现尺度转化的关键所在。

The inland basins in northwest China are of the four great regions short of hydrological cycles in China. By the vertical circle in the water saturation, the water in aeration zone, the water in aerosphere near surface, and the water in plant body ('Four Waters'), the groundwater systems have indispensable adjective effects on maintaining the balance among water, heat and salt in shallow surface, the surface ecological balance, the long-term availability of soil resources and the relative stability of the local climate. At present, the related study pays more attention to the statistical analysis of corresponding relationship between groundwater and vegetation types, but less to the mechanism of water fluxion. Although more and more research on soil-plant-atmosphere continuum (SPAC) system has been carried out, little improvement has been achieved in the ecological effect of groundwater because of the hard scale-transform and the ignorance of the effect of groundwater in simulation. In contrast to SPAC system, the groundwater-soil-plant-atmosphere continuum (GSPAC) system is more integrated. To make clear the ecological effect of groundwater on arid inland basin and guide the exploitation of water resources, such studies should be carried out: (1) the dynamic course and the mechanism of the vertical circle between 'Four Waters', especially the dynamic transition model about water, steam and heat through interface between saturated zone and aeration zone; and (2) the evolution characters of groundwater system under human activities, which is the key to the transform from microcosmic SPAC system to macroscopic water resources management.