Optimising Water Management with Pump Testing

By Frans Meyer

As we observe World Water Week, the spotlight shifts to the vital work being done to manage our most precious resource—water. Shangoni Management Services plays a crucial role in this effort, particularly through our expertise in hydrogeological field investigations. One of the key methods we utilise is the pumping test, a critical process for assessing groundwater resources. This technique not only helps in understanding the dynamics of aquifers but also ensures the sustainable management of water supplies.

In the following article, we dive deeper into the intricacies of pumping tests, explaining their importance and the meticulous approach required to carry them out effectively. Whether you’re involved in water use licensing, environmental assessments, or need precise data for your operations, our team is equipped to provide the expertise and support you need.

What is a Pumping Test?

A pumping test is a practical method of estimating well performance, well capacity, the zone of influence of the well and aquifer characteristics (e.g., the aquifer’s ability to store and transmit water, and presence of boundaries.

A pumping test consists of pumping groundwater from a well, usually at a constant rate (yield), and measuring the change in water level (drawdown) in the pumping well and any nearby wells (observation wells) or surface water bodies during and after pumping.

When conducted with precision, a pumping test can yield valuable data on borehole capacity, aquifer properties, and groundwater flow. Therefore, pumping tests play an important role in hydrogeological field investigations.

Unawareness and disregard of these limits can lead, at best, to the uneconomical operation of the borehole and, at worst, to over-misuse of the resource.

Pumping tests are time-consuming and are often costly. It is important, therefore, to plan and carry them out with care to obtain the best quality information for the costs and effort involved. Interpreting data from pumping tests can be challenging due to the complexity of geological conditions and groundwater flow systems.

A Constant Drawdown Test can be divided into three categories, namely.

1. Step tests – Normally these tests involve pumping at different rates (yields) for three or four equal periods. The relationship between pumping rate and drawdown is used to define the hydraulic characteristics of the well, allowing the most efficient pump rate to be selected. The test normally includes monitoring the recovery of water levels after the pump has been turned off.

2. Constant Drawdown Test – The borehole is pumped at a constant discharge rate determined by the step test done. Pumping tests can last from hours to days or even weeks, depending on the purpose of the pumping test, but traditional pumping tests typically last for 24 to 72 hours.

3. Recovery Test – This will follow the constant drawdown test where the pump is switched off, and the recovery of the water level is measured constantly over time.

 

Pump testing is normally associated with applications such as water use licences, environmental impact assessments, and contaminant plume delineation.

Contact Shangoni Management Services for a free quote and guidance on your testing requirements, whether it be for personal use, bank certificates or water use licence applications.

Shangoni has highly trained and experienced in-house field geotechnicians and hydrogeologists who will conduct and interpret the tests in accordance with scientific best practice and SANS Guidelines.