Do water levels and current velocities vary according to the type of water body?
There are differences between water level fluctuations at sea, on tidal and non-tidal rivers, and in lakes and canals. Tide-generated astronomical forces that cause changes at sea are well documented and routinely predicted. Current velocity in coastal waters is influenced by the tide, wind and waves. In rivers, as well, predictions of water level are more readily available because rainfall estimates are known for longer periods and current velocity results from discharge and tidal forces. Lakes and canals require more analysis and may need closer scrutiny regarding water level, but usually they have rather low current velocities. How are current velocities measured? Current velocities are measured by mechanical meters with horizontal axis rotor and vane; elecronmagnetic flow meters; acoustic Doppler current profilers and float- tracking or moving-boat methods. Generally speaking a reasonable overview of maximum and minimum current velocities will suffice for dredging operations. Shoul
