BATHYMETRIC AND CORE ANALYSIS OF THE LATROBE-RIVER DELTA TO ASSIST INCATCHMENT MANAGEMENT

In this study, an analysis of bathymetric surveys of the Latrobe River delta conducted in 1879 and 1992 is combined with pollen analysis of cores from the delta sediments to assist in setting management priorit ies for the Latrobe River catchment, a 5000 km(2) catchment in the sou th-east of Australia. Reconstructed delta surfaces from 1879 (not long after European settlement of the area) and 1992 were compared to quan tify areas of net erosion and deposition. These were compared to post- European deposition depths determined by the presence of exotic pollen species in the sediment. The results indicated that: (I) average sedi mentation rates in the receiving lake for the Latrobe River are less t han I mm yr(-1); (2) the deposited material is fine with no material c onsidered as bedload; and (3) the fine nature of the deposited materia l makes it suitable for carrying a large load of nutrients. These resu lts created a shift in management focus from concern over sedimentatio n and erosion in general to a greater emphasis on nutrients. While the integrated management of catchments is implicitly contemporary, it sh ould always be performed within a historical context. Failure to do th is can lead to management priorities that do not concur with the facts of catchment response and can therefore result in inefficient resourc e allocation. The use of studies which provide a historical perspectiv e on the problem are therefore critical. (C) 1998 Academic Press Limit ed.