The purpose of the present study is multi-folds. Mainly tospecify design criteria for designing the optimum length of theroughened floor for silled heading up hydraulic structures asregulators. To achieve the purposes of the current work,experimental investigations are conducted. Also, a theoreticalstudy is carried out for the purpose of determining thecontrolling relationships and the governing equations of thephenomena under considerations. The dimensional analysis is usedto correlate the different variables affecting the investigatedphenomena to the basic characteristic parameters. Also, the basichydraulic principles are applied to obtain universal theoreticalequations for the relative depth, the relative energy loss andthe relative length of jump.In the experimental work, the followingconducted for different flow conditions inunder a sluice gate:(1) the effect of the different crest shapes of under gate si 11.(2) the effect of different positions of a vertical sluice gateover a flat top sill.(3) the effect of different roughness shapes and types usingvarious roughness intensities (for each shape and type)(4) the combined ef f ect of us ing the under gate sill wi th thebest derived characteristics and the best concludeddownstream roughness (type, shape and intensity) .investigationscase of freeA statistical analysis for all the experimental results fromboth the hydraulic jump and the discharge coefficientcharacteristics points of view are carried out. The comparisonbe~een different tests and the discussion of the obtainedresults from the hydraulic jump point of view yielded thefollowing important cone 1 us ions: (a) The best crest shape is theflat top one; (b) The best position of the gate is to fix thegate at the begi nni ng of the crest from the upstream side; (c)The best roughness type is the staggered one of rectangular shapeith intens i ty e qu a 1 s 10%; (e) The percent increase in the lengthThe purpose of the present study is multi-folds. Mainly tospecify design criteria for designing the optimum length of theroughened floor for silled heading up hydraulic structures asregulators. To achieve the purposes of the current work,experimental investigations are conducted. Also, a theoreticalstudy is carried out for the purpose of determining thecontrolling relationships and the governing equations of thephenomena under considerations. The dimensional analysis is usedto correlate the different variables affecting the investigatedphenomena to the basic characteristic parameters. Also, the basichydraulic principles are applied to obtain universal theoreticalequations for the relative depth, the relative energy loss andthe relative length of jump.In the experimental work, the followingconducted for different flow conditions inunder a sluice gate:(1) the effect of the different crest shapes of under gate si 11.(2) the effect of different positions of a vertical sluice gateover a flat top sill.(3) the effect of different roughness shapes and types usingvarious roughness intensities (for each shape and type)(4) the combined ef f ect of us ing the under gate sill wi th thebest derived characteristics and the best concludeddownstream roughness (type, shape and intensity) .investigationscase of freeA statistical analysis for all the experimental results fromboth the hydraulic jump and the discharge coefficientcharacteristics points of view are carried out. The comparisonbe~een different tests and the discussion of the obtainedresults from the hydraulic jump point of view yielded thefollowing important cone 1 us ions: (a) The best crest shape is theflat top one; (b) The best position of the gate is to fix thegate at the begi nni ng of the crest from the upstream side; (c)The best roughness type is the staggered one of rectangular shapeith intens i ty e qu a 1 s 10%; (e) The percent increase in the length