ADJUSTMENTS TOWARD EQUILIBRIUM OF A LARGE FLOOD-TIDAL DELTA AFTER A MAJOR DREDGING PROGRAM, TAURANGA HARBOUR, NEW ZEALAND

Terry Healy, Joseph Mathew, Willem de Lange, Kerry Black

Abstract


The Port of Tauranga is located within a tidal inlet estuarine lagoon system which has been dredged to improve navigation for shipping since 1968. In 1992 a major dredging program deepened the entrance navigation channel through the ebb-tidal delta from 10 to 14 m, and the inner harbor channels to -13 m. As a condition of the consent to dredge a detailed monitoring program was required which included annual hydrographic surveys over the flood and ebb-tidal delta as well as recording current meter records from morphodynamically sensitive locations to compare with records taken before the dredging. Results of the hydrographic surveys showed significant morphodynamic change of the flood-tidal delta had occurred essentially by the time the 6 month dredging program was completed. Comparison of the S4 current meter recordings showed current changes consistent with expectations of the EIA. Changes on the ebb-tidal delta were not expected but have occurred although not as rapidly, and seem to be ongoing.

Keywords


harbor; Tauranga Harbor; New Zealand; tidal delta; flood tide; dredging; delta equilibrium

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