Drought: Valuable Learnings

Drought is not welcomed with open arms by many, but in the Kruger National Park it is now an accepted and integral part of the natural system. In fact, management can use it in their favour. The current drought is a vital learning curve, already yielding valuable lessons that are essential for the future of the park, and protected areas elsewhere.

The building blocks for this management strategy were already laid in 1991/92, when the most severe drought on record hit the Kruger National Park (KNP) and large parts of South Africa. The park only received 44% of the long-term average rainfall from a 100-year record, and the consequences were significant.

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In March 1992 the Sabie River, generally regarded as our most biodiverse, was near to losing its status as a perennial river for the first time in recorded history. The river was saved through collaboration with upstream users outside the park borders. Farmers voluntarily restricted irrigation up to 60% and forestry companies ring-barked hundreds of stray trees along the banks of the river to prevent it from drying up.

Inside the park, the 30 000-strong buffalo population shrank by about 60% to 14 000. Among others, hippo, warthog, common reedbuck, kudu and giraffe numbers plummeted.

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A fine eye was kept on events, and it stands as the most researched drought in Kruger, allowing management a number of key observations. “Mortalities were generally caused by lack of food and not so much by lack of water,” says KNP conservation manager, Dr Freek Venter. Animals trampled vegetation across the park due to the large amount of waterholes that were constructed throughout Kruger when it was established. Had the waterholes not been built, vegetation in dry areas, far away from water would have been allowed to remain as refuges.

The manmade waterholes had more dire consequences. Waterhole-dependent animals like hippos flourished during wet years. When drought hit, many man-made dams dried up, forcing the resident hippos to seek refuge in small, natural waterholes, polluting the water and putting pressure on those areas, says Venter.

Drought hippos

The consequences of the 91/92 drought still ripple through policies and management plans today. Venter says that the main differences are that most manmade water holes inside the park have been closed, and rivers are now managed as part of the larger socioeconomic landscape outside the park. During the same time, culling has stopped, as a natural mechanism to control animal numbers emerged. National parks are now understood as natural systems that will change over time, and is managed to allow for this.

The ground-breaking National Water Act of 1998 was also promulgated, providing legal protection to waterbodies’ right to a certain amount and quality of water to survive (called the Reserve). Furthermore, the Inyaka Dam was constructed to increase water supply in the Sabie-Sand catchment.

All the while, Kruger management has been holding their breath in anticipation of the next severe drought. Now that it has arrived, it is not disappointing. It might break all previous records.

“We are not sure yet,” says KNP manager for water resources, Dr Eddie Riddel. “All signs are that the present rainfall year is at least as low as the 91/92 year, but late-summer rain-depths will tell us if we are in fact lower than 91/92.”

The consequences are already tangible. “All the rivers are very low for this time of year,” says Riddell. “The Sabie and Luvuvhu are being maintained well according to their Reserve requirements with augmentation from Inyaka and Nandoni dams respectively.” Other rivers have challenges, exacerbated by record breaking temperatures. According to Riddell evaporation losses have been very high, leading to intermittent problems to maintain the full Reserve requirements.

Still, he says it’s too early to tell. “The natural hydrology for the rivers doesn’t account for such a dry Dec/Jan, so we are in new territory here. We must remember that the KNP’s sub-tropical lowland rivers are resilient ecosystems and are adapted to such stresses. The main concern is related to water quality rather than quantity, since drought conditions are expected to exacerbate the problems of upstream non-point source pollution, as the dilution capacity is reduced.”

Yet, as mentioned, the impact of drought is felt far beyond the rivers. “It is heaven out there for large predators such as lions, leopards and hyenas,” says Venter. Prey is plenty and easy to get to, resulting in extraordinary sightings for tourists. “I have heard of many recent visitors that have seen the Big Five several times over in one week,” he says.

More special sightings that visitors must look out for are bat eared foxes, rumoured to only be in Kruger during droughts, when they move in from the drier, western parts of the country. Venter says that animals and birds that prefer short grass and bare soil conditions are also benefiting.

However, Mother Nature still has some tricks up her sleeve. Surprisingly, no mass die-offs have occurred during this drought, regardless of many of the animal populations having rebounded in the wet years following the 91/92 drought (though rare antelope numbers remain low). “It can be safely assumed that our buffaloes represent the “cream of the crop” and have bred to the current level of over 47 500,” says Venter. Similarly, the hippo population was in the region of 3000 after the 1990s drought and have increased to a current number of around 7 000.

Venter says it seems as if they have succeeded in maintaining healthy grass reservoirs in areas away from permanent water, and that this will hopefully benefit scarce species. Still, many questions remain and the answers will, unfortunately, only be clear in retrospect.

The main questions regards drought in Kruger:

  • What will be the effect of a severe drought on the elephant population? Currently numbering over 17 000, drought could be a mechanism to naturally control their numbers.
  • The biomass of the large herbivores in Kruger has more than doubled during the past decade, even in the face of large numbers of manmade waterholes having been closed. Will there be an ecological correction?
  • It is becoming more and more evident that pre-historic (hunter-gatherer) man played a significant role in the ecosystem. This role has been removed in recent years. Will it be necessary to reinstate this role and how should it be done?
  • How can we streamline the sharing of resources with communities to benefit them in these difficult times?
  • Will rare antelope, especially roan, sable, reedbuck and tsessebe, all of whose numbers declined dramatically during the previous droughts, be better off during this drought because of the large grazing reservoirs created by a reduction of man-made water points?
  • Will the strategy to rather lobby for large dams outside the borders of the KNP and the setting of Ecological Reserves bear fruit for the rivers, even in the face of much larger human populations and higher water demands outside the KNP?

Written by Petro Kotzé  – SANParks Times Editor

Pictures: Supplied

Content courtesy of SANParks Times: www.sanparkstimes.co.za

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