采用三维渗流理论对砂卵石层进行反演计算 ,根据覆盖层地质条件 ,建立三维渗流数学模型 ,然后给出一个渗透系数值 ,计算未建库前的地下水位 ,并与勘察所知的实际水位相比较 ,若两者不一致 ,则调整渗透系数 ,直至计算水位基本符合实测水位 以确定河床砂卵石层的渗透系数 ,为防渗处理提供可靠的设计依据 According to the geological conditions of overburden, a three-dimensional seepage mathematical model is established by using three-dimensional seepage theory. Then, a permeability coefficient value is given to calculate the groundwater level before the construction of the reservoir and the actual water level In contrast, if the two are not the same, then adjust the permeability coefficient until the calculated water level is basically in line with the measured water level to determine the permeability coefficient of sand and gravel layer of riverbed, providing a reliable design basis for seepage control