Water side is a technical term in hydraulic engineering . It refers to a side of a barrier structure facing the dammed water, i.e. the reservoir , in particular a dam , dike or dam . The opposite side is the air side .
Upper water and lower water are the corresponding terms when there is water on both sides of the structure, for example at a drop step such as a weir , trap stick , hydroelectric power station or a sluice . The difference between the upper and lower water is called the height of fall . These terms are also used more generally for the parts of the body of water above and below a level or a confluence (confluence) or diffluence (fork).