河床沉积物理化学性质对渗透系数的影响研究——以渭河为例

渗透系数在河流与地下水相互作用中起着至关重要的作用。沉积物中有机物、无机物的成分和含量多少，均对渗透系数有影响。以渭河陕西段为研究区域，采用竖管水头下降测试法对渭河中下游位于咸阳市、西安市草滩镇、西安市临潼区和华县4个研究区2011年的63个点位和2012年的52个点位沉积物垂向渗透系数(Kv)进行了测定。研究结果表明，研究区Kv值在0.23~18.74m/d之间，其平均值为5.13m/d。Kv值在空间分布上呈现出在西安市草滩镇最大，临潼区次之；华县和咸阳市相差不大。通过皮尔森系数法进行Kv与沉积物理化性质的相关性分析，得出在沉积物的理化指标中，影响沉积物渗透系数的主要因子为锰、总磷、铁，且有渗透系数随着其含量增大而增大的趋势。

Hydraulic Conductivitys as Affected by Physical and Chemical Properties of Streambed Sediment in Weihe River

Hydraulic conductivity is of importance to the hydraulic connection between surface water and groundwater and the water quantity exchange in hydraulic zone.The composition and content of organic and inorganic compounds in sediment may affect the hydraulic connection.The vertical hydraulic conductivity(K)for a streambed was measured by falling-head standpipe permeameter tests conducted in the four sites of Xianyang City,Caotan and Lintong area of Xi'an City,and Huaxian County in the lower reaches of the Weihe River in Shaanxi Province.The K.,values were between 0.02 and 61.32 m/d,with an average value of 5.13 m/d. Spatial distribution of sediment hydraulic conductivity indicates that the Kr, value was the highest in Caotan area and then in Lintong area.The Kr,values in Huaxian County and Xianyang City were relatively low and in Huaxian County,the lowest.Analysis of the correlations between the Kr,value and sediment physiochemical properties was made using Pearson coefficient method. Among the sediment physiochemical indexes,manganese,total phosphorus and ferrous ion were found to be the main factors affecting streambed hydraulic conductivity and the effect increased with the increased hydraulic conductivity.