Assessing the Potential Resistance of Floating Vegetations Against Different Flow Rates

Abstract

Constructed floating wetlands (CFWs) have been rising an innovative and environment-friendly water treatment technology for both stormwater and wastewater over the decades. For the sustainability of these systems, hydraulic components of wetland should be very well monitored and managed. This study examined the root resistance of Baumea rubiginosa (PA) and Phragmites australis (PB) grown in normal drinking water and a synthetic water mix representing stormwater and domestic wastewater with low and high nutrient content against different flow rates. With the nutrient uptakes from intermediate bulk container (IBC) water tanks, two plant species had reached at harvest stage over the period of 35 weeks, and then they were subjected to flume test experiment. Two plant species from five different water types showed different growth levels in roots and shoots, and thanks to their stronger and denser root structures, plant species of PA and PB in domestic wastewater with low nutrient were found more resistant to the flow by pushing water deeper and cause a higher hydraulic head loss between upstream and downstream in comparison to the rest of plant types. The relationship between three different components root volume, flow rate and head loss was also analysed through correlation test in SPSS and the relationship between root volume and head loss was found positive at the higher flow rate(s). The results demonstrate that these native plant species in CFWs could be used to reduce extreme flow rates in upstream side and provide a safe environment during extreme flood events.