Managing morphological changes through urban planning

Abstract

Tallebudgera Creek is a wave-dominated estuary on the Eastern Coast of Australia. Offshore wave condition is a key parameter, which controls morphological changes at the entrance of this creek. Numerical modeling shows that under dominant southeasterly wave condition significant mouth infilling can happen. This can result in full blockage of the creek mouth (over a few years period), partial blockage (over a year period) or sudden blockage during cyclonic events. Full or partial blockage of the creek mouth can have substantial impact on flood risk on heavily populated Tallebudgera Creek floodplain. Another consequent of such blockage is degradation of water quality of the Tallebudgera estuary. Currently an annual costly dredging program is undertaken to mitigate the flood risk by keeping the creek mouth open. This study investigates the feasibility of an alternative approach to dredging for keeping the creek mouth open. This approach focuses on increasing the tidal forces of the estuary. An increase in tidal prism is expected to increase flow velocity at the mouth of the creek and therefore flushing the deposited sand into the ocean. The increase in tidal prism can be achieved through town planning (effective connection of the existing lake system within the study area to the main river, developing new recreational lakes or building new canal estates in the basin of the creek).