首页|Addressing Uncertainties in Surface Velocity Profiles and Discharge Estimation through Noncontact Methods: Case Study of Two Himalayan Rivers
Addressing Uncertainties in Surface Velocity Profiles and Discharge Estimation through Noncontact Methods: Case Study of Two Himalayan Rivers
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NETL
NSTL
Asce-Amer Soc Civil Engineers
The study presents a new approach to analyzing the uncertainties associated with the surface velocity profiles (SVPs) while estimating the discharge in mountainous rivers using noncontact hydrometric techniques. The behavior of SVPs was studied based on the surface velocity measurements taken at different verticals using surface velocity radar (SVR) across sections of two major Himalayan rivers, namely Bhagirathi and Ganga, at Devprayag, India. The findings indicate that a sixth-degree polynomial profile (SDPP) more accurately represents SVP than does traditional parabolic and elliptical profiles, with a mean error less than 25% versus 75%-100% for the other profiles. Additionally, the SDPP required fewer data points (approximately 25-50) to delineate the profile, compared with 100 or more needed for the other profiles. The study also proposes a straightforward approach to accurately determining the location of the maximum velocity across the section (or the y-axis) for discharge estimation using one-point velocity measurements. By introducing a dip correction factor, δ_i, the surface velocity was corrected. With the newly derived y-axis (y_d), a significant improvement in discharge estimates was gained, and accuracy increased as much as 20%. Furthermore, the SDPP was utilized to estimate the discharge for a fixed type of telemetry radar if it was wrongly installed near the assumed y-axis (y_a). The SDPP provided a large range of verticals to establish the fixed radar without compromising the accuracy of estimated discharge. The study offers a twofold solution for mountainous rivers: the SDPP requires fewer data points to accurately determine the SVP, and provides a broad range of verticals for fixed radar placement. Additionally, accurately locating the y-axis with the dip correction factor enhances discharge estimate accuracy using portable radars, especially at poorly gauged river sites in mountainous regions.
NETL
NSTL
Asce-Amer Soc Civil Engineers
