computation of water surface profile through the gravel dams in series

This paper presents an in-depth study of water surface calculation of rockfill detention structures in series. different flow characteristics in porous media were investigated, explaining the influence of velocity, hydraulic gradient and geometric media characteristics. two mathematical models were presented based on the fundamental relationships in gradually varied flow theory in open channels and combining it with the pore velocity equations of wilkins and forchheimer. the analytical solutions were evaluated using laboratory data sets of three angular rockfill materials and four employed discharges. it was observed that presented analytical solutions can accurately predict the water surface profile. however, the forchheimer equation needs the calibration of two coefficients in comparison to the wilkins equation with one coefficient. also, the results show a good association between the froude number and manning’s coefficient in the power form trend. it was seen that power variation provides a suitable interpretation of the flow coefficient for all flow and rockfill geometric conditions.