Generally, drops are common hydraulic structures to dissipate flow excess kinetic energy in irrigation networks and erodible waterways owing to their simplicity in construction and enhanced performance. Considering the upstream approach flow, the flow acceleration is increased within a short distance and subsequently raise the curvature in flow lines by forming a M2 water surface profile. Consequently, the pressure distribution tends to be non-hydrostatic in the vicinity of the drop and thereby the channel bed, channel walls and even the edge of drops are exposed to severe erosion. Notably, downstream of the drop, a supercritical flow with a high kinetic energy is engendered. Considering the mentioned circumstances, the exploitation of energy dissipators is inevitable. Therefore, drops are put to use with the main purpose of pacifying and dissipating the flow extra energy to prevent bed and walls erosion, especially in erodible channels. The present study is subjected to investigate the effects of a grid drop-type dissipator along with a grid free-overfall in different sizes at the edge of drops, on increasing energy dissipation efficiency, the basin size and other related hydraulic characteristics of flow. Accordingly, three different heights of drop, five grid drop-type dissipators and twelve sizes of grid free-overfall have been investigated for five different discharges with the ratio of critical depth to drop height (Yc/h) within 0.15-0.26, with a subcritical upstream approach flow. Furthermore, the hydraulic characteristics of a simple vertical drop are studied as well. Results reveal that compared to the simple vertical drops, grid drop-type dissipators and drops equipped with dissipators and a convergent transition at the upstream end, the grid drop-type dissipators along with a grid freeoverfall, reduce the pool depth and length, the wetted perimeter and the bed reaction force downstream of the drop. On the contrary, the relative length of the rolling waves at the drop base is increased. It should be remarked that energy dissipation in a grid drop-type dissipator along with a grid free-overfall is almost identical to drops equipped with dissipators and a convergent transition. Finally, empirical correlations were derived for the estimation of the hydraulic characteristics of flow at the present structures including; wetted length of the grid drop-type dissipators, depth and length of the pool at the drop base, the length of rolling wave created downstream the drop, energy dissipation and the reaction force of the bed at the downstream, using the experimental data and the statistical software. Key words: Flow hydraulics; Energy dissipation; Vertical drop, Grid drop-type dissipater; Grid free-overfall.