宁波市三江河道水沙变化规律及成因分析

宁波市的姚江、奉化江和甬江俗称“三江”。基于2013—2016年7次水文测验资料,并结合多年潮位资料和1987年水文测验资料,对三江河道水沙变化规律及其成因进行了分析。研究表明:三江河道径流“顶浑”作用较强,含沙量自甬江口向上游逐渐递减;受海平面上升、河势变化和人类活动的综合影响,三江河道各潮位站平均高潮位自20世纪80年代起均呈抬升趋势;2010—2016年镇海站平均高潮位较20世纪80年代抬升了0.33 m;近30 a来,同样潮差下,甬江口断面涨潮平均流速无明显变化,涨潮量呈减小趋势,而含沙量和输沙量呈增大趋势。研究成果为三江河道的河床演变分析提供了一定的科学依据,以及为甬江流域的治理提供了一定的技术支撑。

Characteristics and Causes of Flow and Sediment Change in Three Rivers of Ningbo City

Yaojiang River,Fenghua River and Yongjiang River are known as"Three Rivers of Ningbo". According to hydrological data measured for seven times during 2013-2016,together with measured hydrological data in 1987 and tide data for many years,the characteristics and causes of flow and sediment change in the Three Rivers were analyzed. Results revealed that runoff had large effect on slowing down sediment transport from estuaries to up-stream,and sediment concentration gradually decreased from estuaries to the upstream in Yongjiang River. The av-erage high tide level displayed a rising trend since the 1980s on account of sea level rise,river regime change and human activities. In 2010-2016,the average high tide level at Zhenhai station was 0.33 m higher than that in the 1980s. In the past three decades,under the same tidal range, the mean velocity of rising tide in Yongjiang River estuary experienced no significant change;while influx showed a trend of decrease,yet sediment concentration and sediment discharge showed a trend of increase. The research findings offer scientific basis for riverbed evolution re-search and technical support for the regulation of Yongjiang river drainage basin.