In recent years there has been growing interest in Nature-Based Solutions (NBS) as a way of reducing flood risk. The premise is that large numbers of small-scale features distributed across the landscape can provide the same level of protection as large-scale traditional flood defences. The in-channel Leaky Barrier (LB) is an example NBS feature that has been widely implemented. LBs cause flow to back up and temporarily move onto flood plains during high rainfall. However, there is considerable resistance to their use at the scales required to impact significantly on flood risk due to a lack of quantitative data on their effectiveness. Notably, their hydraulics is poorly understood. This motivated the research reported here. Physical modelling of simple LBs was performed in a flume to improve understanding of fundamental behaviour and provide data for mathematical models. The features consist of one or more horizontal sheets spanning the channel with a gap underneath allowing water to pass unimpeded in low flows. For intermediate depths the feature acts as a sluice gate, while for high depths water passes under, over and, in the case of more than one sheet, through the feature. Experiments were carried out in steady-state and flood-wave conditions. A finite volume model of the flume and features was developed using a 1D Godunov-type scheme. Riemann solvers are used to find mass and momentum fluxes between cells. The LB is treated as an internal boundary condition using a combined weir and sluice gate equation. Good agreement with experimental results was obtained for steady-state configurations. Validation is limited for the flood-wave experiments, but general behaviour was captured by the numerical model for these cases. This approach could fill a key evidence gap by answering questions about the optimal leakiness of LBs, the limits to their usefulness, and how combining them may or may not cause synchronisation problems when the effect of multiple features is aggregated.