Hydro-environmental Characteristics for Flows Over Inclined Block Carpet

Abstract

A significant oxygenation is associated with flows over most of the hydraulic structures due to the entrainment of air into the flow. Block carpets are low-head hydraulic structures, which aim to control the sediment transport, dissipation of flow energy and contribute to considerable oxygenation. Studies have been conducted to investigate the effects of block carpet on the hydraulic jump, scouring phenomenon and variation in the hydro-environmental parameters. The study also investigates the aeration efficiency created by the hydraulic jump inflows over block carpet. Dissolved oxygen as a principal hydro-environmental parameter was measured and analysed upstream of the block carpet, along the BC (heel, mid and toe) and post hydraulic jump in the channel bed. The results show that in the tested range of slopes (20%, 25% and 30%) and block carpet material, the flow has attained a maximum aeration efficiency of 0.181. The characteristics of the hydraulic jump for different inclinations of block carpet and for two-channel bed sediment sizes were observed. Predominantly, for higher discharges and steep slopes, considerable scouring takes place downstream of the block carpet. Based on the physical features of the downstream scour, a qualitative description of three scour forms has been distinguished.