黄河三角洲沿岸海浪风暴潮耦合作用漫堤风险评估研究

海浪、风暴潮是重要的海洋灾害因子,过去人们主要对这些灾害因子本身进行研究,而对它们作用的承灾体研究甚少。实际上,只有它们作用的承灾体遭到破坏,才产生海洋灾害。本研究的目的就是要针对海浪风暴潮漫堤灾害,提出漫堤灾害的风险评估标准及风险评估方法和程式,为沿海防灾减灾提供科学依据。针对黄河三角洲示范区,根据漫堤程度,提出了漫堤灾害风险等级标准,并基于建立的海浪和风暴潮潮汐数值模式及长期预测结果,提出了风险评估方法和程式步骤。对黄河三角洲近岸海域主要堤段进行了多年一遇和典型台风过程漫堤灾害的风险评估。得到的结果是:该区沿岸海堤在风暴潮水位下一般都不能发生水位漫堤现象,只有加上波浪作用时,才会出现海水漫堤;当发生五十年一遇的风暴潮、浪时,多数的海堤的风暴潮、浪漫堤灾害风险在3—4级,即有效波高的浪已爬上或接近爬到堤顶;9216和9711号台风所产生的风暴潮、浪灾害约为150—200年一遇的情况。从实际情况看,本研究中提出的漫堤风险评估标准、评估方法是可行的,评估结果为有效防减海浪风暴潮漫堤灾害造成的损失提供了参考。

RISK ASSESSMENT OF OVERTOPPING DAM UNDER WAVES AND SURGES IN COASTAL AREAS OF THE HUANGHE(YELLOW)RIVER DELTA

Oceanic waves and storm surges are severe factors for causing coastal disasters. In the past, the regarding studies focused usually on those factors but disaster-suffering objects. In fact, only if the suffering objects are destroyed, can marine disasters happen. The aim of this study is to present the assessment standard and method as well as the procedures for the risk of overtopping dam subject to waves and surges. In the coastal areas of the Huanghe River Delta, Dams were built to protect on-land constructions. Based on the features of the dams, the standard of risk level determination was developed;and the methods and procedures are presented in this paper. Applying the established wave-tide-surge coupled numerical model and long-term prediction, the assessment on the main part of the dam was conducted. A long-term prediction for subject dam was made in different return periods of waves and elevations. In the present, overtopping dam would not occur in general only if the wave action co-works. The current dam construction is able to protect against the storms with 50-year return period during which the overtopping would reach level 3 to 4. In other words, the significant wave height could reach or nearly reach the top of dams. The study shows also that the storms of 9216 and 9711 typhoons that caused disaster in the area have the return period of 150-to-200-year. The established standard and procedures are practicable in both real-case simulation and long-term prediction of hidden risk on the coastal constructions.