Abstract: The experiments with various combinations of water discharge and spacing of artificial roughness elements are conducted to study the resistance characteristics of shallow open channel flows. The results show that(1)flow resistance is affected by the presence of artificial roughness elements with an significantly large increase at low discharges and relatively small at high discharges;(2)the spacing of the artificial roughness elements plays an appreciable role in enhancing flow resistance; (3)as the relative roughness size increases,the resistance coefficient increases following a relationship independent of flow discharge;and(4)uniform flow velocity distribution prevails at the water surface.