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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 |
Brymaroo Location: South-eastern Queensland, 50 km northwest of Toowoomba. Area: 14 km2. Rainfall: 670 mm. Land use Grain cropping, perennial pastures and scattered remnant trees. Reference: Smitt et al. (2001) Salinity Salinity in the catchment is caused by the presence of a near-surface ridge of impermeable basement towards the lower part of the catchment. Groundwater is forced to rise here and shallow water tables ensue. During wet years, or following "extreme" rainfall events, groundwater consequently discharges towards the lowlands. The area of salinity appears to expand and contract according to increases and decreases in annual rainfall. Groundwater flow systems The recharge and discharge processes at Brymaroo are similar to systems found in the Great Dividing Range in NSW. The local groundwater flow system in a basaltic fractured rock aquifer discharges where the horizontal layering of the basalt is truncated by the break of slope or where the bedrock ridge forces the groundwater to pool and rise. The highly transmissive nature of the basalts implicates a groundwater system that is very responsive to changes in recharge. Management Crop water balance modelling was not undertaken in this catchment, however, FLOWTUBE modelling simulations showed that if recharge is reduced by 50%, the amount of visually affected saline area would reduce by approximately 30% in 20 years. If a 90% recharge reduction were achieved, the amount of saline land would be reduced by approximately 70% within 20 years. This indicates that changes in agronomic management can have a timely response. Engineering options such as groundwater extraction only seem viable in the lower half of the catchment. |
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| design & production by Talkin' Technical Communications | last updated: April 2002 |