The morphology of tidal inlet deltas change in response to varying hydrodynamic conditions. Matakana Banks ebb-tidal delta is located at the Tauranga Harbour entrance. A shipping channel was dredged through the delta in 1968 and it was further enlarged in 1992. A biennial maintenance dredging programme deals with infilling of the Entrance Channel. Analysis of 13 years (1998 ??? 2011) bathymetric data of the swash bars on the delta indicate a very dynamic morphology. However, the main body of the ebb-tidal delta is very stable; there is no detectable response to maintenance dredging and the swash bar variability may be in response to El Ni??o-Southern Oscillation effects. Swash bars provide important surf breaks, and under the New Zealand Coastal Policy Statement (2010), there is a requirement to protect surfing breaks of national significance. Therefore, this study is assessing the short term response of the swash bars to dredging, and potential mitigation measure if any adverse effects are identified. This study will track swash bars response to hydrodynamic forcing using repetitive Multibeam Echosounder (MBES) surveys, continuous video monitoring of the swash bars and a major field programme. Suspended sediment data (concentration and flow field vectors) and surficial sediment distributions over the ebb tidal delta are also provided by the MBES surveys. Sediment traps are used to calibrate the MBES water column backscatter data. Three concentric transects of wave and current recorders measure the depth dependent hydrodynamic forcing across the swash platform of Matakana Banks. In order to quantify differences due to accretion or erosion, the swash bars variability is visualized from the measured cross-shore profiles and the sand volume changes determined between successive MBES surveys. The variability of the swash bars, and hence surf breaks, will be linked to suspended sediment data and waves and currents regimes
