20世纪80年代以来,由于干旱少雨,北方井灌地区农田地下水位普遍下降,由此使得农田土壤的蓄水能力发生变化。论文根据北京市水利科学研究所在北京市东南郊水资源试验区取得的试验资料,以0～3m土层作为土壤水库的界定深度,分析其对降雨的调蓄能力;经计算,1991～1995年间,春末夏初雨季前,土壤水库的有效调节能力,多年平均值为137.4mm(0～2m)和188.8mm(0～3m)。分析表明,0～3m层土壤有很好的蓄雨调节能力,雨季平均有近85%的降水量滞蓄在3m土层内,其余蒸腾、蒸发散失或补给地下水。研究认为,在田间采取一定的拦蓄水措施,即使遇到10年一遇24小时p=200mm这样的大暴雨,是可以做到农田地表不产流或少产流,从而最大限度地拦蓄汛期降水,增加土壤水资源量的。

Since the1980s,because of scarcy precipitation in northern China,the level of farm-land groundwater has been decreasing and the storage capacity of soil risen accordingly.Ac cord-ing to the information observed from the experimental site of water resources to the south-east plain of Beijing,the0～3m layer soil was determined as the defined depth of soil reservoir and its pondage capacity was analyzed.Through computation it was found out that,before the rainy season during1991～1995,the normal annual available pondage capacity of soil reservoir was137.4mm(0～2m depth)and188.8mm(0～3m depth)respectively.The results showed that soil reservoir had very good regulation capacity and85%of the normal annual precipitation was stored in the3m deep soil(the defined depth of soil reservoir).So if some available measures are taken before an extraordinary rainstorm happens,then there will be no or less surface runoff ap-pearing and most of the precipitation will be stored in soils.