Hydrodynamics of a small trained tidal inlet (Currumbin Creek, Australia)

摘要

Small tidal inlets are important features of coastalareas, in terms of provision of access from a back barrier water-body to theocean as well as periodic circulation of fresh nutrients for the localecology. Usually, dimensional and geometrical characteristics contributesignificantly to morphological stability or instability of a particularinlet and necessitate an individual investigation of any desired location.In other words, generalized usage of previous empirical and experimentalresearch of a different position can hardly be used for other places. Inthis regard, one of the powerful tools to understand the physical processesof a particular region is to collect as much field data as possible. Such adataset is used to further analyse and explore the governing processes andcan also be used for building a numerical computer model for supplementarystudies.In this research, the results of a comprehensive field measurement atCurrumbin Creek, Queensland, Australia are presented. This study is part ofbroader research to investigate the long term evolution of the Currumbinentrance and its adjacent beaches. Currently, an annual dredging campaign isneeded to reduce the risk of flooding due to excess rainfall inundations andto maintain water quality.The majority of data were collected over a three month period consistentwith the time of the 2012 dredging operation. However, due to the loss ofsome instrumentation, data collection for some of the parameters wasrepeated till the middle of May 2013. All collected data included: (1)nearshore waves and tide; (2) creek tidal variation; (3) creek flow dischargeand velocity; (4) bathymetric survey of the creek; (5) beach profile evolutionsurvey; and (6) sediment sampling. The measurement showed that the creekentrance is tidally dominated, with flood events having a major role insediment transport into the creek. The nearshore stations' wave dataillustrated the marginal effect of the beach curvature between updrift anddowndrift stations. Thus, the historical dataset available from the updriftwave rider buoy will be selected to be used for future numerical modelling.Although changes of some beach profiles were comparatively insignificant,the dramatic changes of the profile lines nearby the inlet channel and alsorapid bathymetric change of the flood shoal following the dredgingcompletion are valuable information to better calibrate and interpret alocal sediment modelling study for the next phase. Essentially, thisevaluation needs to be considered for proposing any alternative maintenanceactivities.