Impact of climate change on water resources

Mojtaba Karbasi, Mir Hadi Madani, Per-Erik Jansson

Wednesday 1 july 2015

8:30 - 8:45h at North America (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Hydrological extremes: floods and droughts

Parallel session: 8I. Extreme events - Flood Drought

Australia has a highly diverse climate, with large regions having arid and semi-arid climates. This has caused additional pressures on groundwater resources which are already under pressure by population growth and industry development. During last decade, the demand for groundwater use has dramatically increased due to surface water scarcity caused by reduction in rainfall. Climate change is of most concern where aquifers are either heavily allocated or particularly vulnerable to changes in recharge. In these systems the reduction in water availability due to climate change may impact on groundwater use and entitlements. The impacts of climate change are also likely to be more profound for unconfined aquifer systems, which may respond rapidly to changes in the recharge regime. Most national and international studies focus on climate change impacts to surface water resources. Climate change effects on groundwater resources have not been systematically assessed, despite many regions being greatly dependent on groundwater for irrigation, industrial use (including mining) and urban water supply. The COUP Model was used to model the impact of climatic change during a 30 year period on groundwater fluctuations in the Musgrave and Southern Basins Prescribed well area within Eyre Peninsula which is located approximately 20 km west of Port Lincoln and 270 km west of Adelaide. Groundwater resources of the study area are found primarily within the Quaternary Bridgewater Formation Limestone, which are largely dependent on local rainfall falling on the overlying land for recharge. There are no regional-scale inflows of groundwater to the Musgrave or Southern Basins PWA’s groundwater systems.The mean annual recharge is estimated to be less than 1 mm/yr whilst the annual precipitation is around 350 mm/yr. The model results reveal that the area is under stress. The inter-annual and within year recharge to the groundwater was simulated. Simulated ground water levels were compared to the dynamics of measurements. Sensitivity analysis results show that the physical properties of soils including hydraulic parameters, texture, porosity and interaction between saturated and unsaturated zone plays an important roles in the model. The water balance shows that almost all the infiltration will returned back to atmosphere as a soil evaporation.