Tidal level forecast of Yangtze River at the source of East Route of South-to-North Water Transfer Project
- Article
- Figures
- Metrics
- Preview PDF
- Reference
- Related
- Cited by
- Materials
Abstract:
The East Route of South-to-North Water Transfer Project diverts water from the Yangtze River through Jiangdu Water Conservancy Project.Accurate and timely water-level forecast of the diversion project plays a key role in the scientific operation of water conservancy project and reasonable allocation of water resources.The Sanjiangying tide station near the diversion project was selected as a representative.Due to the Sanjiangying tide station locating in the tidal limit,the water level was affected by a combination of astronomical tide and upstream inflow.The interval precipitation should be taken into consideration in the tidal level forecast since the precipitation was unevenly distributed throughout the year because of the unique subtropical monsoon climate.Due to the numerous influencing factors,the tidal level forecast of Sanjiangying can be more complicated. Tidal harmonic analysis method was used to forecast astronomical tide.The average daily tidal level and the hourly tidal level can be obtained by the tidal harmonic analysis method.Four methods,including secondary correction method,multiple linear regression method,support vector machine method and random forest method were applied to forecast the average daily tidal level of Sanjiangying station.The hourly tidal level forecast was based on the forecast of the average daily tidal level of the above four methods and the tidal harmonic analysis method.The precision index,including qualified rate,absolute error and root mean square error were used to compare the accuracy of four methods for average daily tidal level and hourly tidal level.Moreover,a linearly dependent coefficient was used to compare the degree of fitting between simulated tidal level and measured tidal level.Finally,the optimum forecasting scheme was recognized. The qualified rate of a simulated tidal level using tidal harmonic analysis method was too low to meet the actual engineering requirement and therefore other methods are needed to improve the forecast precision.The results of simulated average daily tidal level and simulated hourly tidal level showed that the accuracy of the simulated average daily tidal level determined the accuracy of simulated hourly tidal level.Better average daily tidal level forecast was followed by a better hourly tidal level forecast.In addition,the accuracy of the model training period was higher than the verification period,which was consistent with the assumption of the general case.The prediction accuracy of the average daily tidal level by four methods can reach class B or above in both the training period and verification period.Moreover,the precision index showed that secondary correction method owed the highest accuracy and stability with prediction accuracy reaching class A,followed by the support vector machine method,and the multiple linear regression method and random forest method had the relatively worst performance.The order was kept when forecasting the hourly tidal level,with secondary correction method also reaching class A.The result was also verified by linearly dependent coefficient;secondary correction method had the highest linearly dependent coefficient in the forecast of average daily tidal level and hourly tidal level,which means the simulated tidal level forecasted by secondary correction method was closer to the measured tidal level.Thus,it can be seen that secondary correction method was the best method to forecast tidal level in the four methods on account of its highest prediction accuracy and stability. Out of comprehensive consideration,secondary correction method is suitable for applying in the fine scheduling of the water conservancy project in contrast to support vector machine,multiple linear regression and random forests,which are more appropriately used for tidal level warning owing to longer prediction period.
Keywords:
Project Supported:
Clc Number:
Mobile website
