Port redesign and planned beach renourishment in a high wave energy sandy-muddy coastal environment, Port Gisborne, New Zealand

Redesign of Port Gisborne for the 21st century has encompassed a broad interdisciplinary approach. This procedure has taken into account the operational requirements of the port, effects of dredging and construction upon the benthic fauna, and wave activity within the port confines after the proposed development. Added amenity value of the development to the local community is an important ancillary redesign consideration. Initially, a major research project into the environmental impacts of the developments has been undertaken. oject, which commenced in 1996 and is still continuing, involves an iterative approach integrating the initial design and development options with the operational feasibility, construction constraints, environmental constraints, social acceptability, and economic practicality of the port; all of these require in-depth assessment to obtain the necessary planning and development approvals. This requires close liaison between the professional environmental research scientists, port management, port operation staff (pilots), construction engineers, planners, and the community interest groups. cal modelling of the hydrodynamics of Poverty Bay, simulating waves and current effects on the various initial designs options, and calibrated against data from a substantial field program, has been a fundamental tool. It was applied experimentally to determine the best option for the port layout, as well as to assess sedimentation impacts. Modelling results indicated a significant increase in maintenance dredging expected as a result of deepening the navigation approach channel. Because this may have an impact on the nearby sandy beach by inducing erosion, the best option for disposal of the sandy dredged material was determined to be disposal in the surf zone for subtidal beach profile renourishment. Textural analysis of the sediments trapped in the navigation channel demonstrated that they were suitable for this purpose.