Flood routing in D-shape tunnels through Multilinear Muskingum method

Many designers are interested in D-shape cross-section due to its ease of design and construction. The Multilinear Muskingum (MM) method is one of the hydrological methods in flood routing that was not used before in D-shaped sections. In this research, we developed Multilinear Muskingum (MM) method for D-shape cross-section. Then routed hydrograph of MM method was compared with the Saint-Venant model and water surface profiles were obtained by optimizing the discharge coefficients. Results revealed a suitable agreement between the routed hydrographs and the water surface profiles as the maximum relative error of discharge, the percentage error in the routed peak discharge, and the percentage error in time to peak discharge. Moreover, the maximum of these errors in depth were computed as 6.82 %, 2.78 %, and 5.45 %, and the minimum errors were calculated as 0.98 %, 0.05 %, and 0.00 %. Satisfactory results taken from MM method show that this method has a great potential for hydrograph routing in the D-shape cross-section. In addition, the water surface profiles which were calculated by the use of computational hydrographs indicated remarkable results.