Sensitivity Analysis of Parameters in HEC-RAS Software

Abstract

As for the level of tail-water often rose when the situation of tailrace river changing during the process of construction of hydroelectric power station, one-dimensional mathematical model is used through two procedures to solve this problem. In the first, the sensitivity of three key parameters including roughness, cross-section spacing Δs, starting regulation level and section in the mathematical model were discussed. The results indicate that: (1) Positive relationship between ΔY/Y and n, shows the greater flow rate, the more sensitive of water depth changes to roughness coefficient; (2) The cross-section spacing Δs affect the large flow more obvious than the smaller; (3) The effect of the middle and lower reaches of river are bigger than the upstream. Research results provided guidance of model parameters selection.

Monitoring the Spring Flood in Lena Delta with Hydrodynamic Modeling Based on SAR Satellite Products

“…The huge range of model accuracies and the overestimated flow velocities are attributable to the lack of riverbed complexity in the estimated bathymetry and estimated Manning's n values. HEC-RAS flow computation is highly sensitive to topography and channel roughness [51][52][53]. The estimated bathymetry might have lost the riverbed relief in details that prevented the model from filling in the small channels with water.…”