Local Sydney and Hawkesbury land stone create porous aquifers providing a potential, often extractable source of groundwater (see Figures 1 & 2).
Types of Aquifers, Wells and Groundwater Flow
|Some households have access to groundwater onsite (‘urban wells’ in
Fig. 2) but are only allowed to tap into their ‘bore’ water if it is
used for non-drinking purposes.
The Urban Water Cycle
|There are currently trial bores within the Sydney catchment to assess
those aquifers, which will give us a better understanding about
potential water resources in case the current drought continues.
Some groundwater issues on the Central Coast:
For more information on this topic -
A lack of understanding about groundwater issues
Prof Ian Acworth from the UNSW recently (May 2006) talked on a groundwater forum in Sydney about the importance and lack of knowledge about groundwater issues.
He stressed that groundwater is a larger component of the water cycle than surface water and that the both systems (ground and surface water) are one interconnected system which both depend on rainfall - directly or indirectly. Groundwater provides base-flows for many rivers and visa versa: rivers discharge into groundwater reservoirs.
This cycling rate of water moving from the surface into the ground ('recharge') and groundwater moving out of the ground in a river or creek (discharge) creates a water balance in the environment. If ground water is taken out of the system, water will move in from somewhere else to restore this balance.
Groundwater extraction (i.e. through bores) will thus always have an impact somewhere, whether it happens at the actual extracting location, at the discharge point, the recharge point or somewhere in between. Extraction will also impact on the speed and direction the water is moving.
The difference between surface and groundwater is mainly the speed at which the water moves in it's environment. This is dependant on the environment it travels in (sand, clay etc.) and the water balance (saturation) of the environment.
There is a general lack of knowledge of long term impacts of groundwater extraction and a lack of recharge and discharge data.