Both formulas are currently widely taught and used. Since both equations reference a single control volume location along the channel, neither address friction factor nor head loss directly, but the change in pressure head may be calculated by combining them with other formulas such as the Darcy–Weisbach equation. The empirical aspect to the C coefficient indirectly addresses friction factor and Reynold's number and is the reason why the Chézy formula remains most accurate in certain conditions, such as river channels with non-uniform channel dimensions. Additionally, both equations are explicitly used with uniform or "steady-state" flow where the hydraulic depth is constant, due to their derivation from the conservation of momentum. In contrast, if the hydraulic conditions fluctuate in open channel flow, they are then described as gradually or rapidly varied flow, and will require further analyses beyond these two formula methods.