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Calculation of water surface level at downstream

  • Mar 14 2023
  • fuhrman8


After reading through the Nays2DH solver manual, I‘m curious about the method used to estimate the water surface level/height (variable h) from the inlet discharge values.

Thanks in advance,


  1. pritikumaricetpa says:

    Calculating the water surface level at downstream is an important aspect of hydraulic engineering, as it helps to ensure the safety and efficiency of water management systems. The calculation of water surface level at downstream can be done using several methods, depending on the specifics of the system and the available data. Here are some of the common methods:

    Manning’s equation: Manning’s equation is a commonly used equation for calculating water surface levels in open channel flow systems. It relates the flow rate to the hydraulic radius, slope, and Manning’s roughness coefficient. By using the upstream water level and the channel cross-sectional geometry, the downstream water level can be calculated.

    Backwater curve method: The backwater curve method is used to determine the water surface profile along a river or open channel. It involves solving the energy equation along the flow path, which accounts for friction losses, velocity changes, and changes in elevation. The resulting curve represents the water surface profile, which can be used to determine the downstream water level.

    Hydraulic modeling: Hydraulic modeling is a powerful tool for simulating water flow in complex systems. It involves using numerical methods to solve the equations of motion and continuity for fluid flow. By inputting the upstream conditions and modeling the downstream boundary conditions, the water surface level at downstream can be calculated.

    Empirical methods: There are also several empirical methods available for calculating downstream water levels, based on statistical relationships derived from historical data or field observations. These methods may be less accurate than other methods, but can be useful in situations where data is limited or when a quick estimate is needed.

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