Groundwater resource development is often required in a wide range fields including:
- Domestic and rural water supply;
- Agricultural (stock watering to large scale irrigation);
- Mine water supply; and
- Construction usage.
The required use volumes range dramatically depending on the use and scale of the development.
Future Flow GPMS has provided specialist input into water supply schemes for a number of projects. These include studies in climates ranging from tropical to semi-desert where there is little recharge to the groundwater resource and careful management is crucial. Another factor that is investigated in our water supply studies is the effect of the host geology on water supply.
Our staff have been involved in water supply studies to a number large scale mines in a variety of African countries. We have also been involved in water supply schemes from small scale rural domestic use to large scale (4 500 m3/hr) agricultural and construction projects.
Water supply studies rely on a sound understanding of the aquifer characteristics and the factors that control groundwater flow in the area such as:
- Depth and yield of water strikes;
- Preferential groundwater flow paths formed by extensive faulting;
- Recharge zones formed by surface water bodies; or
- Flow barriers formed by low permeability intrusives.
In addition, a sound understanding of recharge from rainfall is required to calculate the sustainable yield from each borehole.
We make use of the appropriate ground geophysical methods matched to the geological conditions on site in conjunction with satellite and aerial geophysical imagery, as well as geological maps to identify the optimal potential water supply points. Following identification of the supply positions we supervise the drilling process, ensuring optimum construction and development of the boreholes to maximise the yield of each borehole. During the drilling programme important hydrogeological information is collected, including:
- Depths and yields of water strikes;
- Lithologies or features associated with water strikes; and
- General features including the contact between weathered and competent rock, fracturing in the competent rock and clay content of the weathered material.
Aquifer (pumping) tests are performed on the boreholes to calculate the sustainable yield of each of the boreholes and a pumping schedule is compiled taking into consideration not only the groundwater level response to the pumping, but also recovery of the groundwater level after pumping is stopped and recharge from rainfall. A pumping schedule is developed taking into consideration the operational water requirements and yield characteristics of the boreholes.