Bài viết Mô hình hóa quan hệ mực nước - lưu lượng tại các trạm thủy văn trên lưu vực sông Đà sử dụng phương pháp xấp xỉ đa thức Chebyshev dạng 1 trình bày kết quả việc áp dụng phương pháp xấp xỉ đa thức Chebyshev dạng 1 trong việc xây dựng các mô hình thực nghiệm cho 3 trạm thủy văn trên lưu vực sông Đà, mỗi trạm có các đặc trưng lưu vực khống chế và các yếu tố ảnh hưởng rất khác nhau. | VNU Journal of Science Earth and Environmental Sciences Vol. 39 No. 2 2023 16-30 Original Article Modelling Stage-discharge Relationships for Hydrological Stations in the Da River Basin using First-kind Chebyshev Polynomial Approximation Nguyen Duc Hanh1 Nguyen Tien Giang1 Dang Tran Duc Minh1 Dao Ba Huy1 Le Huu Minh Quan1 Nguyen Thi Tinh2 1 VNU University of Science 334 Nguyen Trai Thanh Xuan Hanoi Vietnam 2 Center for Hydro-meteorological Observation Vietnam Meteorological and Hydrological Administration 8 Phao Dai Lang Lang Thuong Dong Da Hanoi Vietnam Received 01 June 2023 Revised 05 June 2023 Accepted 10 June 2023 Abstract Observed discharge time series is essential data for hydrological analysis streamflow forecasting as well as water resources planning and management. Estimation of continuous discharge time series is generally based on the curves or empirical models that can properly simulate the relationships between water levels stages and concurrent water discharges observed at a particular hydrological station. For stations with complex hydraulic conditions in addition to gauged stages at the discharge gauging section another variable such as stage measured at an auxiliary station to calculate the slope or rate of change in stage is added to the estimation process. This paper presents the results of applying the first-kind Chebyshev polynomial approximation method in constructing rating curves for three hydrological stations in the Da river basin each having different basin characteristics and various influencing factors. The analysis results using five evaluation indices MAE σ Pbias KGE and MAPE show that the Chebyshev polynomials are highly effective in modelling both simple and complex stage-discharge relationships. The Chebyshev polynomial approximation method is suggested to be used for establishing stage- discharge relationships in hydrometry. Keywords Rating curve Chebyshev Da river backwater degradation amp aggradation. _ Corresponding author. .
