非恒定水域盐水入侵特性试验研究

Experimental Study on the Characteristics of Salt Water Intrusion in Unsteady Water Area

通过10组试验研究了非恒定水域盐水入侵特性与上游淡水来流、水深、潮差、下游盐度等参数之间的关系。结果表明:①表层和底层的盐度几乎不受涨落潮的影响,表层盐度一直较低,底层盐度一直较高;中间层的盐度具有周期性,且一般在涨憩时刻附近取得最大值,落憩时刻附近取得最小值。②下游盐度、水深以及潮差越大,上游来流越小,盐水入侵强度越大。垂向平均盐度值在纵向上从下游向上游递减。总体来讲,下游纵向盐度梯度比上游的大,且纵向盐度梯度在中游附近达到最大。③上、中、下游断面盐度垂向分布明显不同,下游表层盐度梯度较大,且下游盐度、潮差、上游来流、水深越大,下游表层垂向盐度梯度越大。总体来说,表层垂向盐度梯度从下游向上游递减,而底层垂向盐度梯度从下游向上游递增。④从下游至上游,表层盐度值基本没有变化,底层盐度减小但减小速率较慢,中间层盐度值减小速率较快。

Based on 10 group experiments,this study analyzed the variation between the characteristics of salt-water intrusion in unsteady water and upstream freshwater coming flow,water depth,tidal range,salinity of downstream and other parameters. The results show that a）the salinity of surface and bottom hardly be effected by tidal fluctuations,surface salinity has been low and the salinity at bottom has been higher,the salinity of the middle layer has a periodic and generally obtain the maximum value among nearby high water stand moment and get the minimum value among nearby low water stand;b）the lager the value of downstream salinity,water depth and tidal range,the lower the upstream flow and the greater in-tensity of salt-water intrusion will be. Averaged salinity of the vertical decreases from downstream to upstream in the longitudinal direction. General-ly speaking,the vertical salinity gradient of downstream is greater than that of the upstream,and it has the maximum value nearby the middle rea-ches;c）vertical distribution of salinity are obviously different in the upper,middle and lower reaches sections,the salinity gradient of surface layer is lager in downstream,the lager the value of downstream salinity,tidal range,upstream flow and water depth,the lager the vertical salinity gradi-ent of surface downstream. In a word,the vertical salinity gradient of surface layer decreases from downstream to upstream,while the bottom layer increases from downstream to upstream;d）from the downstream to the upstream,the surface salinity values is almost unchanged,underlying salini-ty reduces at a lower rate,opposite the middle layer salinity values decreases in a faster rate.