The Relationship between Geomorphic River Adjustment and Management Actions over the last 50 years in the Upper Hunter Catchment, NSW, Australia

The installation of 517 river works in the upper Hunter catchment, New South Wales over the last 50 years is linked to geomorphic river adjustment and flood history at catchment and reach scales. Nineteen types of works are classified into three categories consisting of engineering, heavy machinery and vegetation works. Since 1952, a transition in techniques has been detected from engineering-based approaches, to river training/maintenance, to more ecosystem-based approaches. From the 1950s to the mid-1980s extensive river engineering was undertaken. Projects were concentrated along laterally unconfined rivers and were generally implemented after major phases of geomorphic river adjustment. Neither the type of river nor the type of river adjustment guided the implementation of differing management techniques or their distribution in the catchment. A blanket approach was adopted, applying the same types of works across all types of river. Emphasis was placed upon concerns for bank instability rather than bed instability. Hence in many cases, river works addressed the symptoms (i.e. bank erosion) rather than the underlying causes of river change (i.e. bed incision). Since the mid 1980s, techniques have evolved towards vegetation-based procedures. The development of more effective river rehabilitation programmes requires that greater consideration is given to proactive strategies which build upon an understanding of geomorphic river adjustments at the catchment scale.25 page(s