GEOMORPHOLOGY REPORT - CRC LEME

More documents

Recommendations

Info

Figure 7. Diagrammatic representation of relationships between geomorphic and stratigraphic units. 5.1.3 Floodplain The floodplain is formed on sediments on the Coonambidgal Formation (Butler 1958), and consists of three discrete meander belts with well developed scroll bars (Appendix 3). The oldest floodplain meander belt has a degraded scroll bar morphology. Amplitude of the scroll bars and the meander wavelength is greater for this unit that for the younger meander belts, indicating different hydraulic conditions during deposition. This unit is characterised by olive-khaki silty clay drapes over degraded scroll bars with a relief of about 2 m (Figure 8, Figure, 10). There are thin (>2 m) source bordering dunes of grey sand. There is an intermediate floodplain meander belt that has rounded morphology, with scroll bars are not as distinct as on the modern floodplain in the LIDAR DEM. Olive-khaki silty clay drapes over lower relief (~1 m) scroll bars are found in this unit. Source bordering dunes also occur on this unit. The modern floodplain consists of meander belts and high relief (2-3 m) scroll bars with crisp morphology and little or no clay draped over the surface. Scroll bars are distinct in the LIDAR DEM. Surface sediments consist largely of yellow sand. 9
Dune on terrace Alluvial terrace Youngest floodplain Oldest floodplain Uplands Intermediate floodplain Figure 8. Oblique projection looking west from the Murray River at Merbein showing part of LIDAR DEM showing geomorphic elements. Width of image ~5 km. The floodplain has a number of channels, which consist of several morphological types. The main Murray River channel sustains active flow and consists of a typical migrating meandering channel. Abandoned channels of the Murray River consist of broad oxbow billabongs and sustain semipermanent water. There are also anastomosing channels that are sinuous and have fixed banks. These channels have been superimposed on the intermediate floodplain deposits, sometimes exploiting previous abandoned channels, elsewhere cutting across scroll bar and floodplain deposits. Flow in these is determined by water level, and during the period of observation some were flowing, others were stagnant or dry, and lined with clay. Most soils on the floodplain are slightly to moderately saline (see Section 6.2 and Appendix 7 for details). Loamy sands of relict dunes locally overlie the floodplain clays. Clays within the floodplain are typically smectitic and sodic. They are highly dispersive and make an impermeable seal after modest rain. Minor variations in floodplain elevation can significantly affect soil development. Scroll bars found on the oldest and intermediate floodplain units (Coonambidgal Formation) exhibit more profile development with heavier textures and are highly structured in swales compared to the corresponding crest than are those on the youngest scroll bar sets. Due to the formation of a surface seal, water infiltration is limited to the upper layer of the soil profile, leading to surface ponding after rainfall and then lost through evaporation. While in the field we experienced a 50-150 mm rainfall event and observed only 10-30 cm of moisture penetration below ground surface afterwards. 10
Page 1 and 2: CRCLEME Cooperative Research Centre
Page 3 and 4: This report (CRC LEME Open File Rep
Page 5 and 6: Lindsay and Wallpolla Creeks are si
Page 7 and 8: TABLE OF CONTENTS _Toc224538156 1 I
Page 9 and 10: List of Tables Table 1. Association
Page 11 and 12: The main objective of the studies r
Page 13 and 14: 4. Identification of the high recha
Page 15 and 16: The SRTM was used as to provide the
Page 17: Figure 6. Compartmentalisation of t
Page 21 and 22: Intermediate floodplain Modern floo
Page 23 and 24: Locations of sample sites are given
Page 25 and 26: 6.1 Granulometry 6.1.1 Methodology
Page 27 and 28: Table 2). Mean pH and EC profiles a
Page 29 and 30: when sampling. This is also reflect
Page 31 and 32: Figure 12. SPOT image of Wallpolla
Page 33 and 34: REFERENCES Bowler, J.M. and Harford
Page 35 and 36: APPENDIX 1. ASTER data and interpre
Page 37 and 38: APPENDIX 2. SPOT Data and interpret
Page 39 and 40: APPENDIX 3. DEM data and interpreta
Page 41 and 42: APPENDIX 4. Gamma-ray data 500000 (
Page 43 and 44: APPENDIX 6. Site Descriptions and D
Page 45 and 46: Site 3 South Settlement road, ~20 m
Page 47 and 48: Site 5 Western end of Keera Road, s
Page 49 and 50: Site 7 Eastern end of Old Mail Rd t
Page 51 and 52: Site 12 Further to west along Old M
Page 53 and 54: Site 14 Dedmens drive, across aband
Page 55 and 56: Site 16 Same area as previous sampl
Page 57 and 58: Site 18 Same location as 17, interm
Page 59 and 60: Site 20 Adjacent to previous site C
Page 61 and 62: Site 22 2 km east of Finnegans brid
Page 64 and 65: APPENDIX 7: Analytical Results Appe
Page 66 and 67: Appendix 7.2: Lindsay-Wallpolla Las
Page 68 and 69:
Appendix 7.3: Lindsay-Wallpolla XRF
Page 70 and 71:
16 200709 1929587 20-30 Fm1 7 0.611
Page 72 and 73:
Site Number Depth LEME ID Sample #
show all

GEOMORPHOLOGY REPORT - CRC LEME

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?