Figure 1
Overview of study site. (a) The Murray-Darling Basin (grey) drains the twin Murray and Darling catchments, whose major watercourses are shown in dark grey. The confluence of the Murray and Darling Rivers marks the upstream extent of the lower Murray River (blue) which flows to the Southern Ocean in South Australia. The extent of the Riverine Plain is given in red (see Discussion for context). (b) The lower Murray River enters the Murray Gorge at Overland Corner (rkm 439) and remains confined until debouching into Lake Alexandrina at Wellington (rkm 78). The modern-day estuary comprises the Lower Lakes, Alexandrina and Albert, together with the Coorong lagoon. The lower Murray River flows through the Murray Mouth into the Southern Ocean between Younghusband and Sir Richard Peninsulas. A series of five barrages (black) regulate saline incursion into the estuary. (c) Fieldwork was conducted at Monteith (rkm 104) on grazing land comprising a reclaimed backswamp (white hatch) situated behind an artificial levee on the left bank of the river. Ten CPTs were taken at 100 m spacing commencing 100 m from the channel (orange crosses), with core Monteith-A extruded at the same site as CPT08 (red cross). Three CPTs collected as part of an alternate study completes the transect on the right bank of the river (purple crosses). (d) Elevation profile of transect M-M’ showing the position of each CPT relative to the width of the Murray Gorge. CPTs were pushed until refusal with penetration depths reaching beyond 20 m in all but the two at the valley margins. Satellite imagery source: Esri.
