The Effect Of Sea Level Variation On The Calculation Of Engineering Water Level

The effect of human activity on earth system has been extensive, global warming and global sea level rise is one of the typical character of global change over the past 20th century. Sea level variation has seasonal period, for example the seasonal range of sea level variation in the Bohai Sea exceeds 60cm. The sea level variation of both the seasonal and long term scale affects directly the calculation of engineering water level, such effect will be discussed in detail in this paper in the following aspect: the stochastic dynamic method is used to analyze the seasonal and long term sea level variation;the sea level analysis from Topex/Poseidon data, firstly the global tide in the Topex/Poseidon data is obtained from harmonic analysis; how the seasonal and long term sea level variation affect the calculation of design water level and check water level; a joint probability method with conditional distribution is used to calculate the design water level and check water level when sea level rises. Two distributions corresponding to the astronomical tide and wind tide are obtained according to whether the astronomical tide and storm tide are correlative or not. So the two check water levels are obtained with the joint probability method. The maximal difference between the two water levels of 100 years' recurrence is more than 30cm.. A comparison between the two check water levels indicates that the effect of SL variation upon design water level and check water level is larger than 80cm at some stations.