Groundwater myths
Climate extremes across the globe have shined a spotlight on groundwater and its potential for building resilience to the effects of climate change. However, development and sustainable use of this unseen resource remains clouded in myth and misconception.
In South Africa, all of its residents have a constitutional right to basic water supply and basic sanitation, promulgated in the National Water Services Act (NWSA; No. 108 of 1997). If access to water is then considered a primary right in South Africa, why is the development of groundwater still, in many cases, not informed by scientific hydrogeological principles and approaches?
The reluctance of groundwater users to adopt a scientific approach to groundwater development (supported by relevant legislation), is possibly linked to past misconceptions, such as:
- “I paid to drill this borehole, it’s my water”
- “The diviner said I have strong groundwater on my farm”
- “An airlift yield is equal to the sustainable yield of a borehole”
- “My borehole is a source of endless good quality water”
- “Groundwater resource development and management should be cheap; the cost of specialist groundwater resource development services is too great”.
Legal framework of groundwater use
The first myth is a legal one, which is common amongst groundwater users, particularly in areas where enforcement of the law is lacking. After a new groundwater resource has been developed, the legal requirements in terms of the National Water Act (NWA; No. 36 of 1998) need to be considered. The NWA stipulates that any water use requires authorisation from the Department of Water and Sanitation (DWS) or its delegated authority. Section 21 of the NWA defines what type of registration or licence is required for a specific water use. Domestic or non-commercial water uses (Schedule 1 water uses) are excluded from the licencing process. To lighten the administrative burden of water use registration, the DWS has established the General Authorisation (GA) thresholds, which are specified per quaternary catchment, if a water use falls within these thresholds (usually related to abstraction or storage volume and water quality parameters) a GA can be registered. If the water use exceeds the GA thresholds the water use will need to follow a Water Use Licence Application (WULA) process. A WULA requires specialist input for the application to prove the sustainability of the water use, as well as the benefit of the new commercial water use to ordinary South Africans (such as water supply services, sanitation or job creation). Water service providers, including municipalities, mines, water boards, irrigation boards, farmers, and private landowners are all subject to registering their water uses in terms of the NWA.
Groundwater divining
The second myth mentioned has vexed the professional groundwater industry for many years. The practice of water divining dates back centuries and entails a diviner or “water witch” using a random inanimate object, such as a forked branch (mikstok), metal rods, a pendulum, a coconut, a plastic cold drink bottle, or a shotgun, to perform an arbitrary action whereby a “suitable” drilling site is selected. A diviner will often claim that “this farm has strong water” or “there are many breaks here, you won’t have to drill deep”. These claims are unfortunately not supported by any quantifiable scientific evidence. This is mostly because of a lack of exposure to the additional benefits of having a trained professional assist in the development of a groundwater resource.
Appropriate groundwater resource development considers a multitude of factors before pegging a drilling site. A good hydrogeological assessment should consider the regional and local setting of the planned development, the presence of any known aquifers within the development area, risks related to drilling into the underlying aquifer(s), the groundwater recharge, storage, availability and potential of the underlying aquifer, and other users or ecosystems that also rely on the groundwater resource. Siting a borehole can be simple or complex, depending on the type of aquifer and its properties. If the development, for example, is underlain by a homogenous sandy aquifer with a simple geometry, an appropriate drilling site could easily be selected. However, if a development is underlain by a fractured aquifer with a very sparse fracture network and the success of a drilling is dependent on centimetre accuracy in borehole siting, additional work is required, such as a combination of structural mapping and geophysical surveying.
Umvoto published an article earlier this year describing the process of drilling a borehole. A suitably qualified and experienced professional hydrogeologist can provide insights to the risks related to the planned drilling, whether it be related to the borehole construction, yield or water quality of the area. Under the supervision of a hydrogeologist, a borehole should be constructed in accordance with the South African National Standards (SANS) 10299-2:2003 guidelines, which specify regulatory standards for the design, construction, and drilling of boreholes.
Sustainable groundwater use
If a borehole is drilled successfully, often the owner/developer will stop the groundwater resource development process after the driller reports the airlift yield or the borehole is pumped at an arbitrary rate for a random period without sufficient water level monitoring. Herein lies the third myth. This is often a fatal flaw in any proposed development that is reliant on the use of the newly drilled borehole, which may only become apparent later after some use. Test pumping a borehole according to the SANS 10299-4:2003 guidelines protects the user and opens up the possibility for the user to insure the water use. Supervised and analysed by a professional hydrogeologist, test pumping data can provide valuable information to the user regarding the sustainable yield of the borehole, the aquifer characteristics, or the presence of flow boundaries. Depending on the use of groundwater, there are regulatory standards that also need to be considered in terms of water quality, such as the SANS 241:2015 limits and the South African Water Quality Guidelines (SAWQG).
Resource management
The fourth myth relates directly to management practices. A professional hydrogeologist will consider the risks related to the sustainable and compliant use of a borehole when determining the operational and management recommendations for a specific borehole or wellfield. Risks related to over-abstraction of groundwater, which is often overlooked by groundwater users, often include:
- A decline in water quality due to over abstraction near a source of potential contamination or saline water intrusion from the ocean or adjacent aquifers;
- A decline in groundwater level and yield due to the continuous de-watering of a fracture network that feeds a borehole;
- A decline in the specific capacity of a borehole due to clogging (chemical precipitates, biofouling or mechanical blockage);
- Borehole collapse due to poor construction or aged infrastructure;
- Failure of borehole infrastructure, due to rampant use outside operational parameters, (e.g., pump sets); and
- Legal action due to non-compliance with relevant legislation and water use licence conditions.
To ensure that management recommendations remain applicable, and the proposed use of a borehole is sustainable, groundwater levels, quality, and abstraction should be monitored on a routine basis. The analysis of monitoring data (and in some cases iterative modelling) by a hydrogeologist is imperative to provide valuable insights and recommendations for compliant, sustainable use of groundwater.
The relative cost of groundwater development and management
The fifth myth, and one of the main reasons for the reluctance of groundwater users to seek professional help, is the perceived cost of groundwater resource development. Drilling a borehole is a costly endeavour and can cost upwards of R200 000 at present rates. This cost, however, is generally far lower compared to other water supply options for industrial processes, irrigation or bulk supply. If developed, operated, monitored, and maintained as recommended by a professional hydrogeologist, a borehole can provide groundwater sustainably for several generations.
Do not hesitate to contact us to assist with any of your groundwater development and management needs.
