A Study of the Land In the Catchment of the Gippsland Lakes TC-17 J. M. Aldrick, R. A. Hook, R. H. M. van de Graaff, B. M. Nicholson, D. A. O’Beirne, N. R. Schoknecht VOLUME 1 Manuscript completed 1984 LAND PROTECTION DIVISION 250 Victoria Parade, East Melbourne Australia, 3002 CONTENTS FOREWORD............................................................................................................................................8 SUMMARY ...........................................................................................................................................10 ACKNOWLEDGEMENTS....................................................................................................................12 1. INTRODUCTION..........................................................................................................................14 The Study Area...................................................................................................................................14 The need for Information....................................................................................................................14 The Survey Approach.........................................................................................................................14 Previous Investigations in the Area ....................................................................................................14 Soil Surveys....................................................................................................................................14 Land type surveys...........................................................................................................................15 General resource inventories ..........................................................................................................15 2. CLIMATE ......................................................................................................................................16 Major Features of the Climate............................................................................................................16 General discussion..........................................................................................................................16 Precipitation....................................................................................................................................16 Mean annual precipitation ..........................................................................................................16 Seasonal distribution ..................................................................................................................18 Hail and snow.............................................................................................................................18 Rainfall duration and intensity....................................................................................................18 Temperature....................................................................................................................................18 Frost................................................................................................................................................20 Wind ...............................................................................................................................................21 Evaporation ....................................................................................................................................21 Climate and Plant Growth ..................................................................................................................28 Climatic indices..............................................................................................................................28 Limiting Temperature.................................................................................................................28 Effective rainfall.........................................................................................................................28 Rainfall – evapotranspiration balance.........................................................................................28 Non-climatic factors affecting growing season ..............................................................................28 Soil water storage .......................................................................................................................28 Vegetation type...........................................................................................................................35 Estimate of growing season length.................................................................................................35 Climatic and Water Supply.................................................................................................................35 Annual water budget.......................................................................................................................35 Streamflow .....................................................................................................................................36 Climate and Erosion ...........................................................................................................................37 3. GEOLOGY AND GEOMORPHOLOGY......................................................................................38 Geology ..............................................................................................................................................38 Geological history ..........................................................................................................................38 Geomorphology of the Uplands .........................................................................................................39 Differential erosion.........................................................................................................................45 Tertiary drainage modifications......................................................................................................45 The Geomorphology of the Lowlands................................................................................................47 The eastern lowlands ......................................................................................................................47 The Tertiary deposits..................................................................................................................47 The earlier Pleistocene terrace....................................................................................................50 The inland sand sheets and dunes...............................................................................................52 The later Pleistocene terrace.......................................................................................................53 The modern flood plains.............................................................................................................55 River Bank Erosion ....................................................................................................................56 The Coastal Zone............................................................................................................................57 The barriers.................................................................................................................................57 Sedimentation in the Lakes.........................................................................................................58 The Baragwanath Anticline............................................................................................................58 The Western Volcanic Plateaux......................................................................................................59 The western lowlands .....................................................................................................................60 The Geomorphic Provinces ................................................................................................................61 4. SOILS.............................................................................................................................................69 Introduction ........................................................................................................................................69 Soil Formation....................................................................................................................................69 Weathering, leaching and new mineral formation..........................................................................69 Weathering .....................................................................................................................................69 Leaching .........................................................................................................................................69 New Mineral Information...............................................................................................................70 Lateral surface movement ..............................................................................................................70 Biospheric reactions ...........................................................................................................................70 Vertical differentiation