ABSTRACT
Implementation of groundsills in headwater streams serves the purposes of grade checking and scour control. However, stream flow overflown from groundsill often causes local scour. Therefore, the objectives of this study are: (1) to assess the feasibility of permeable groundsills for stream governance and (2) to evaluate how permeable groundsill alters hydraulic characteristics and local scour. A series of hydraulic experiments was conducted using 1:50 scaled models in a mobile-bed setting. Scaled models include conventional slab groundsills and two types of permeable groundsills with distinct permeability. Experiment results from 81 runs show that permeable groundsills are capable of transforming stream flow from plunging flow to throughflow or skimming flow depended upon the permeability of groundsills. A dimensionless equation was obtained to help assess the extent of local scour.
