Sedimentation in reservoirs and its removal is one of the serious and biggest challenges in reservoirs which has serious consequences for water management, flood control and production of energy. Several methods like catchment’s management, flushing, sluicing, density current venting, and dredging have been proposed to control the significant problem of sediment deposit on water storage facilities. Among them, pressure flushing is considered to be one of the methods with a few local effects. During pressure flushing a scour cone will be developed in the vicinity of the bottom outlet. To study the formation and characteristics of funnel-shaped crater laboratory experiments were carried out of different hydraulic parameters such as discharge, depth of sediment, flow depth and bottom outlets. In this study, 16 experiments were carried out for two sediment height of 140 and 120 mm of two different lightweight material and one sand samples at different discharges and different water depth with four different bottom outlets. The result revealed that the volume and dimension of flushing cone were affected by the outlet discharge, sediment depth, flow depth, and bottom outlets. Also, by comparing the outcomes between lightweight material and corresponding sand it notified that there exists a strong correlation between one another. This study unfolded that, with the use of proper scaling relation among prototype, lightweight material could be conveniently used for quantitative studies of the process involving sediment transport. Finally, MatLab and Eureqa program was employed to ease the calculation of flushed volume during experiments and to carry out the regression analysis and proposed an empirical dimensionless relationship for estimating the volume of flushing cone. Keywords: - Pressure Flushing, Flushing Cone, Outlet Discharge, Sediment Depth, Flow Depth, Bottom Outlets.