Experimental Assessment of Hydraulic Flow Characteristics through Rainsmart Modules for Use in BIOECODS

The need for developing cost-effective and sustainable techniques to control runoff flooding and maximise the capacity of existing drainage networks cannot be overemphasized. Subsurface drainage modules are now being used and promoted as means of controlling floods. However, flow in these modules is much more complex than expected as high energy dissipation is involved which have a great effect on their overall performance. This research assessed the hydraulic flow characteristics of the Rainsmart module as a potetial subsurface component of the Bio Ecological Drainage System (BIOECODS) by conducting experiments in the recirculating flume under various experimental conditions such as variation in slopes of 1:1000, 1:750 and 1:500, depths of 10, 15 and 20cm with the hydraulic gate fully opened (GFO). Different parameters were studied including flow rate, Manning’s roughnes coefficient, velocity as well as the energy dissipation rates across the test sections. Accordingly, flows were found to be turbulent and subcritical in nature. The energy dissipation rate shows simultaneous behavior with water depths and the effects of slope variation was minimal to the energy dissipation. Also, under the GFO conditions, variations in slope was seen to have great effect on the hydraulic parameters as the flow rate increases simultaneously with water depth. Manning’s roughness coefficient varied inversely with flow rate and velocity. Overall, the Rainsmart module showed evidence of flow attenuation with the presence of higher Manning’s coefficient and high water level at the upstream compared the downstream coupled with the fact that it lowered the upstream discharge by a value greater 72.7%. Hence, the module can be considered suitable for application in the BIOECODS to enhance flood mitigation.