By Izak SmitWater is life – above and below ground! Now researchers are taking a special interest in the water we cannot see, the groundwater. To access groundwater, boreholes have been sunk throughout the Kruger National Park (KNP) to supply water to the animals. Due to droughts, tourism requirements and fence-lines obstructing ancient migration routes of animals, artificial water provision has steadily increased in the Kruger over the past 80 years.
Disused Boreholes in Kruger to Contribute to Groundwater Monitoring
The first artificial waterhole was created on request of Col James Stevenson-Hamilton, first park warden, in the early 1930s. Since then, many more boreholes have been drilled in the park to provide additional permanent water sources for game. However, in recent years it was realised that a high density of these artificial waterholes might have negative impacts on the biodiversity of Kruger. Areas that used to be grazed only seasonally were being grazed year-round due to water being available throughout the year. Researchers believe that this persistent grazing pressure might have changed the vegetation patterns in the park. Herbivore distribution patterns were changed by the addition of permanent water in the landscape and as a consequence, predation patterns also changed.
Water provision has had a ripple effect on vegetation and the animals using these resources, which could be detrimental for biodiversity conservation. Since Kruger management believes in a constant process of learning and adapting to new challenges and knowledge, the water provision policy was revised in 1997.
As a result many of these artificial waterholes were closed down and the land left to recover. Recently it was recognised that these boreholes that were closed under the revised water provision policy should not be seen as redundant water resources, but rather as valuable research resources. The Department of Water Affairs and Forestry (Dwaf), in collaboration with KNP Scientific Services, are planning to use some of these disused boreholes as groundwater monitoring sites.This project, which was in a planning phase for at least a year, became a reality on June 4, 2007, when Dwaf installed the first data logger close to the Nhlangulene picnic spot, north of Skukuza.
It is hoped that by the end of this year approximately 35 boreholes across the park will be equipped with these data loggers. This will mean that every hour, on the hour, the water level will be measured at 35 boreholes spread across two million hectares, 24 hours a day, seven days a week.
These data loggers are being installed a few metres under the resting level of the groundwater, which can vary from less than three metres below surface up to 30m or deeper. The loggers record the water depth with one mm accuracy at one-hour intervals. These new generation loggers are designed to operate for 20 years. Every six months the data accumulated will be downloaded to a palmtop computer.The boreholes that were selected to be fitted with data loggers provide a good spread across all the catchments and geological formations of the park. It is hoped that the data gained through this project will translate into a better understanding of how groundwater levels vary over time.
For example, how does the water level change over the course of a day, across seasons (dry season and rainy season) and during drought and flood episodes? It will provide valuable information on groundwater patterns across the landscape, for example close to or far away from rivers, in different geological formations and in different climatic regions. This project will provide an excellent dataset to learn about the natural groundwater processes and patterns. The research will also contribute towards groundwater management and protection beyond the park’s boundaries.
This is important to better manage groundwater in areas where boreholes are actively pumped and also to predict how groundwater may be affected under different climate change scenarios. This will guide the sustained utilisation of groundwater without depleting this valuable resource in years to come.