Modelled tests on a key dam show that

under nappe flow over three different slopes on a stepped over-flow structure

unit energy in the flow cross section before the hy draulic jump increases with increasing slope

and Hdam/yc similarly increases.As Hdam/yc approaches a certain value

the rate of increase in the unit energy in the flow cross section slows.The pressure ypat the bot tom of the cross section before the hydraulic jump in stilling basins demonstrates a posi tive linear correlation with critical water depth yc to the water crest

with the number N of the steps not affecting yp.Comparison of energy dissipation ratios at λ>1 and λ=1 (λ is the correction factor for pressure at the cross section before a hydraulic jump)reveals that the relative error amounts to about 7 %w hen Hdam/yc=10

with this error decreasing to 1 %when Hdam/yc ≥70.Experimental results also show that λ has a very strong linear correlation with yp/y1(r =0.9999).