改变入渗强度的地下水流模式实验

自Tóth提出地下水流系统理论以来,大多学者基于定水头上边界的解析解或数值模拟研究地下水流系统发育特征,尤其是多级水流系统模式。认为复杂的盆地地形势就会发育多级地下水流系统,简单地形发育单一地下水流系统。利用自主研发的地下水流系统砂槽模型进行系列实验发现,实验条件下(模型尺寸、介质和多个河谷不变)水流系统的发育受控于降水入渗强度。得出随着降水入渗强度的增大,水流系统模式由单一的区域水流系统,到复杂的多级次水流系统,再到局部的水流系统的结论;盆地多个势汇中,只有实际成为地下水排泄点的汇势才能影响地下水流系统模式,而其他的势汇只是可能的潜在势汇。实验表明,用定流量上边界(降水入渗强度)能够更好地揭示盆地地下水流系统模式发育与变化机理。

Experiments of groundwater flow patterns under changes of infiltration intensity

Since Tóth put forward the theory of groundwater flow systems,most of researchers have investigated the development of flow system using analytic solutions or numerical simulations based on given head upper boundary,and believed that multi-order groundwater flow systems developed in the basin of complex topographic potential and simple groundwater flow systems developed under simple topography.However,based on the experiments using the updated groundwater flow system sand-box model,we found that the development of flow systems was controlled by infiltration intensity under the experimental conditions of unchanged model size,medium and valleys.With increasing of infiltration intensity,flow patterns varied from simple regional systems to complex multi-order flow systems,then to local systems.While multiple sinks exist in a basin,sinks that affected the development of flow patterns were ones that worked as actual discharge points of groundwater,and others were possible potential sinks.The experiments show that constant flux upper boundary,namely constant infiltration intensity,can better reveal the mechanism of development and change of basin groundwater flow patterns.