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Case Studies 1. Kyeamba Creek 2. Liverpool Plains 3. Billabong Creek 4. Wanilla 5. Axe Creek 6. South Loddon Plains 7. Kamarooka 8. Lake Warden 9. Brymaroo Printing help |
Liverpool Plains Location: Northern New South Wales, east of Gunnedah. Area: 11 000 km2. Rainfall: 1200 mm in the ranges steeply grading to 550 mm on the plains, with summer dominant storm events. Land use Cropping and pastures on the Plains, pastures on the hillslopes, remnant trees on the ranges. Reference: Stauffacher et al. (2001) Salinity The catchment can be subdivided into five sub-catchments, two of which are affected by shallow saline water tables. There is no extensive surface expression of salinity, but some creeks draining the shallow water table area are saline. The catchment is unlikely to suffer from extensive dryland salinity due to the stable groundwater dynamics but stream salinisation is an ongoing concern. Groundwater systems The groundwater systems underlying the Liverpool Plains consist of regional-scale alluvial (sand, gravel and clay) aquifers. Runoff and sub-surface flow from the higher rainfall hills recharge the aquifers near the interface between the hard rock and the alluvial aquifers (i.e. into the alluvial/colluvial fans on the lower hill slopes), and onto the alluvial flats during flood events. Diffuse recharge under agronomic farming systems between flood events may leave less storage in the aquifers for flood events and prevent the main aquifer from draining. Groundwater flow is impeded at the outlet of these catchments, causing upward discharge of groundwater and shallow saline water tables. Management Modelling results have demonstrated that there is only very limited scope for changing the quantity of localised recharge into the alluvial/colluvial fans. Recharge control on the Liverpool Plains could possibly be achieved by flooding control but this would require revegetation of the hill slopes with trees and deeply-rooted perennials. Revegetation near the colluvial fans may intercept sub-surface flow. Rotations involving deeply-rooted perennials on the plains may minimise recharge between floods, improving drainage from the aquifers and creating more storage in the aquifers between flood events. Engineering solutions such as groundwater pumping and drainage can also bring some relief, but require careful implementation. |
Hill-slopes and alluvial flats of the Liverpool Plains |
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