Application of Modified Nonstationary Tidal Harmonic Analysis Approach to Data Recovery of Missing Water Level Measurements of Yangtze Estuary
- Min Gan (Hydraulic Engineering Nanjing / College of Harbour / Hohai University Nanjing) | Yongping Chen (Hydraulic Engineering Nanjing / College of Harbour / Hohai University Nanjing) | Shunqi Pan (School of Engineering / Cardiff University Cardiff) | Ying Liu (Hydraulic Engineering Nanjing / College of Harbour / Hohai University Nanjing) | Shicheng Liu (Hydraulic Engineering Nanjing / Hohai University Nanjing / College of Harbour)
- Document ID
- International Society of Offshore and Polar Engineers
- The 29th International Ocean and Polar Engineering Conference, 16-21 June, Honolulu, Hawaii, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. International Society of Offshore and Polar Engineers
- data recovery, MNS_TIDE, Yangtze Estuary, estuarine water level
- 0 in the last 30 days
- 10 since 2007
- Show more detail
High quality and continuous water level measurements in estuaries can be highly important for engineering designs and flood assessment. However, multiple factors such as instrument failure can cause the interruption of the data acquisition. Due to the complex interaction between marine force and riverine force in estuary zone, traditional methods may could not get enough accuracy to recover the discontinued data sets of estuarine water levels. A modified nonstationary tidal harmonic analysis approach (MNS_TIDE) was introduced to preform accurate data recovery for the discontinued field water levels of the Yangtze Estuary.
High-quality and continuous estuarine water level records are important for many areas. On the one hand, it can be used to assess the flood risk. On the other hand, it is an important index for engineering design. Furthermore, estuarine water level can not only be used to validate the hydrodynamic models but also it can provide the open boundary conditions to hydrodynamic models. With the development of the research of estuarine tides, upstream river discharge data can even be estimated from the estuarine water levels records (Moftakhari et al., 2013; Matte et al., 2018).
However, due to some factors such as instrument adjustment or extreme weather condition, the observed water levels may be discontinuous or exist some abnormal points (Hsieh and Pratt, 2001). Therefore, before the application of water level measurements, the abnormal points need to be corrected, while the missing points require to be recovered. For the abnormal points, after they were detected, they can also be regarded as the missing water level points to be recovered.
Classical harmonic analysis (CHA) is one of the main methods to recovery the water levels of offshore zone. By using the observed water levels to regress the harmonic constants, the missing water level points then can be predicted from the harmonic constants. This depends on the accuracy of CHA. In the offshore zone where water level fluctuation is mainly caused by astronomical tides, the missing water levels can be well recovered by CHA. In the estuary zone, especially in the upper tidal reach, there is a strong and complex interaction between river discharge and tides. Because CHA cannot consider this nonlinear interaction, it may could not achieve enough data recovery accuracy of estuarine water levels.
|File Size||881 KB||Number of Pages||6|