Design Water Level Calculation for Tidal River in Ungauged Basins

Abstract

感潮河段的洪水过程由于既受上游河道径流和下游潮汐的双重作用，使感潮河段的水文情势尤为复杂。本文针对无资料感潮河段设计洪水位计算，提出根据短期潮位对比观测，通过准同步比较，将长期潮位观测站逐年实测潮位资料转引至工程海域后，对逐年的极端高潮位采用PIII型频率曲线进行适线计算，得到不同频率设计高潮位，从而解决不同频率潮位计算问题；针对河流洪水计算，由于缺乏实测河流流量资料，采用水库最大下泄流量加区间流量作为上游流量边界，采用一般大潮高潮位作为下游水位边界，同时对河口地形根据不同时期影像资料进行了适当假定，采用水动力模型进行了河流洪水计算，得到满足工程需要的设计洪水位；上述所述方法对无资料感潮河段设计洪水位计算提供了重要参考。 The hydrological regime of the tidal reach is complicated because it’s influenced by both the upstream runoff and the downstream tide. This paper focuses on the design water level calculation for tidal river in ungauged basin based on the short-term tidal level observation, the long term tidal observation and short term tidal level observation relationship. After the quasi-synchronous comparison, the tidal level data of long-term tide observation stations are transferred to the engineering sea area. By using the P-III frequency curve, the extreme tidal level of each year is estimated for different design tide levels. As a result, the problem of different frequency tide calculation is solved. As to the river flood design water level calculation, because the lack of observation river flow data, the maximum reservoir discharge flow and interval flow is used as the upstream flow boundary conditions, the average high tidal level is used as the downstream water level conditions. Besides, based on different time of the remote sense image at the estuary, the rational assumptions of estuarine topography is put forward using the hydrodynamics model, the design water level satisfied the project need is calculated. The above-mentioned methods provide an important reference for the calculation of the design flood level of tidal reach inungauged basins.