河谷区地下水人工回灌试验研究

Experimental Study on Artificial Groundwater Recharge in Valley

河谷区采用现场坑灌和井灌试验,通过测定回灌量衰减和渗透系数的变化来分析回灌效果。坑灌回灌量中期衰减24%,后期衰减40%,在整个回灌过程中区域水位上升1.1～1.3 m,实际形成水丘规模很小,反映出试验层水平渗透能力强。井灌初期回灌量衰减33%,在后期基本稳定,但总趋势仍在衰减,含水层渗透系数以主孔为中心,由远到近渗透系数逐步减小。试验表明:回灌量和渗透系数在前期迅速减小,之后逐渐减缓直到相对稳定,这一过程具有普遍性。在回灌过程中回灌水中的悬浮物颗粒填充孔隙引起机械堵塞。对坑灌而言,泥皮对其影响更为直接,回灌量随泥皮厚度的增加而减少。在河谷区实施大规模人工回灌工程应以坑灌为主。

In this study,the groundwater recharge experiments by pit irrigation and well irrigation were carried out in a valley by measuring the attenuation of recharge volume and the variation of permeability coefficient so as to analyze the recharge effect.The results show that the attenuation of pit irrigation recharge volume was 24% at the metaphase and 40% at the last stage respectively,the rise of groundwater level varied in a range of 1.1-1.3 m,but the formed water dome was small,which reveals that the horizontal permeation capability of the test layer was high.The attenuation of well irrigation recharge volume was 33%,it was stable at the last stage,and the permeability coefficient of the aquifer was gradually decreased with the increase of distance away from the main hole.Recharge volume and permeability coefficient decreased rapidly at the early stage,then they were decreased gradually till relatively stable,and such process was universal.Mechanical blockage of pores was caused by suspended solids in the pit and well irrigation experiments,for the pit irrigation experiment,slurry was more direct,the groundwater recharge by irrigation was decreased with the increase of mud cake thickness.It is considered that the large-scale groundwater recharge should be dominated by pit irrigation.