洪季长江口径流量与近海海平面的响应关系

Response of Offshore Sea Level to River Discharge in Flood Season in Yangtze Estuary

摘要:

为了分析长江口洪季径流量对其近海海平面上升的影响权重，基于1950~2011年大通站实测洪季月均径流量资料，统计分析出大通站洪季发生频率为25%，50%和75%时对应的径流量以及多年平均径流量，并利用长江口杭州湾潮流数学模型，计算分析长江洪季径流量对长江口口内平均潮位和近海海平面的影响.研究结果表明：随着径流量的增加，整个计算区域的平均潮位也随之增大，且从上游到口外平均潮位增幅沿程减小，近海南部平均潮位增长幅度比近海北部大.口内及近海平均潮位与径流量呈正相关关系，在径流量增加20 000 m3·s-1的情况下，杭州湾大部分区域平均潮位增加0.005~0.010 m.

Abstract:

To clarify the impacts of river discharge on offshore sea level in the Yangtze estuary. Based on the river discharge frequency of 25%, 50% and 75% as well as multi year monthly discharge statistically calculated from measured runoff from 1950 to 2011 at Datong Station in the Yangtze River, the impacts of river discharge on offshore sea level were computed and analyzed using the tidal model of the Yangtze estuary and the Hangzhou Bay. The numerical results indicate that the mean tidal levels of the whole computational region rise as the river discharge increases, and the amplification decreases from upstream to the entrance. The amplification of the southern part is greater than that of the northern part in the offshore area. The mean tidal level has a very good positive correlation with river discharge in the Yangtze estuary. When the river discharge increases by 20 000 m3·s-1, the area where the mean tidal levels increase by 0.005~0.010 m covers most of the Hangzhou Bay.