Discussion of “Discharge through a Permeable Rubble Mound Weir” by Kohji Michioku, Shiro Maeno, Takaaki Furusawa, and Masanori Haneda

The writer congratulates Michioki et al. (2005) for their valuable contribution to flow through permeable weirs, including rubble mound weir, rockfill structures and some timber weirs. Their combined theoretical and physical modelling approach yields convincing results, and prototype tests could be a nice complement. The following comments are aimed to complement the findings. Related applications of rubble mound weir include the in-built spillway dam and the stepped weir. While the authors focused their study on seepage flow, the interactions between seepage and overflow cannot be ignored in many applications, and practicing engineers do need some expert guidance.