What Will Stop The Olifants River Drying Up Again

Hundreds of fish gasped their last, hippos battled it out in tiny pools and vegetation wilted and died last year in the Kruger National Park when the Olifants River slowed to a trickle and then dried up for almost three months. Environmentalists were outraged and waved the new national water act at authorities, asking why the 1998 law that gives the environment and basic human needs the first shot at any water in a river was not put into practice.

The simple answer is that in the past, the department of water affairs and forestry has issued so many licences to farmers, miners, industrialists, and other sectors in the Olifants River catchment that in legal terms, more water can be taken out of the river each year than consistently flows along its length.

If the environment is factored in, it is estimated that each year almost 200 million more cubic metres of water are needed to keep the Olifants River flowing until it reaches the Kruger - not counting any economic growth in the catchment that will use more water.

South Africa's 1998 water act is internationally considered to be revolutionary, giving high priority to the needs of the environment, but history has to be overcome before the act can be implemented. In the distant past, the department of water affairs was known as the department of irrigation, and farming and other industries were given priority.

This was also supported by the previous water act of 1956. To now give the environment priority requires a major shift. To keep the Olifants River flowing and implement South Africa's new laws guaranteeing water for the environment, the department of water affairs can use the legal tool of compulsory licensing.

Compulsory licensing is intended for areas that are under water stress, where water quality problems are imminent or already exist, or where the existing water uses are not considered to be equitable. This process will check out every existing legal water user in the catchment, and issue them with a license that should strictly regiment how much water they can take out the system and under what conditions.

Before water affairs and forestry can decide how much water can be taken out of the system and given to people, the department needs to know how much water there is at all times. To find this out, specialists are currently conducting an assessment of water availability in the catchment.

Obviously, the amount of water in a river at any point in time is largely dependent on how much rain fell and found its way into the river system. Collecting rainfall data is relatively simple. From there the matter grows complex, so at the start of the assessment the project team flew over the Olifants River and drove the highways and byways of the 55,000km2 catchment.

They recorded all the major things that affect rainfall runoff and river flows, such as different landuses, dams, weirs, alien vegetation, farming and irrigation, forestry plantations, mines, and others. In order for water to flow over the Mamba weir in the Olifants River at the border of Kruger Park, the inter-relationship amongst all the factors upstream must be taken into account.

High rainfalls in one area of the catchment may not increase flows at Phalaborwa at all, while moderate rainfall elsewhere could boost river flows if it meant that the farmers in the area reduced their irrigation demands. Unravelling how a change at one point affects the situation at another point can be enormously complicated, and the water resource engineers tasked with finding out how much water is available are making use of a complex computer model.

With the model, they hope to work out how to keep enough water in the system to keep the Olifants flowing year-round without destroying a farmer's livelihood by curtailing his water allocation or stopping economic growth in impoverished areas. The computer model uses rainfall as its primary input, and was first developed in the 1970s by Dr Bill Pitman.

It has been refined over the years to take into account more factors, such as the relationship between groundwater and river flows. Although officially retired, Dr Pitman is currently working with a team from Stewart Scott Incorporated, who, with the help of other consultants and specialists are leading the water assessment for the department of water affairs.

Together they are enhancing the model so that it can improve the way it deals with irrigation, alien vegetation, forestry plantations, mines and wetlands. The team has used rainfall and other historical landuse data from as long ago as 1920 to try and work out how the river flows today.

From the computer model, they can figure out with a degree of certainty what would happen at specific points in the catchment under different conditions. When the study is complete, the tricky task of taking the information from the water availability assessment and working out various scenarios in order to supply water to the environment and keep the river flowing until it reaches the Kruger Park will lie ahead.

With the existing allocations taking up more water than is available, and it being highly unlikely that the heavens will open year after year and increase the average rainfall in the catchment, someone's water budget will have to be squeezed when compulsory licensing comes into effect.

In the Olifants catchment, about 60 percent of water taken from the river system is used by farmers for irrigation. About 20 percent is used to generate power, while towns, industries and mines utilise the last 20 percent. Of these sectors in the catchment, mining contributes the most to the water management area's economy and farming the least.

Cutting water allocations would ideally consider not only the needs of the environment, but also economic and social issues. Compulsory licensing of water use aside, there is still a major stumbling block in keeping the Olifants flowing downstream into Kruger and Mozambique dams.

The Olifants catchment has eight major dams, with the ninth being on the way in the form of the De Hoop dam. There are about 20-30 more dams that are large enough to be considered when looking at the river's management, plus about 2,000 other small farm dams and weirs that trap water.

A dam is intended to store the rushing waters of floods so that the stored water can be used in times of shortage, thus evening out the river's flow to meet man's needs. However, the historical perspective on dams means that dams were more concerned with collecting water than letting it go.

The outlet works of the major dams can only release a limited amount of water at a time, unless the dam is spilling, and so few dams currently in existence in the catchment would be able to physically release enough water at a time to always meet the ecological needs of the Olifants River.

In the planning for the De Hoop dam this has been considered, and the engineers have designed the dam in such a way that it should be able to release bigger volumes of water. To stop the river drying up again and to obey the laws of the land, a complex bundle of historical, social, economic, physical and other inputs has to be considered. These will all take time to be weighed up in the balance.

In the meanwhile, a survey has shown that 78 days of zero flow into Kruger has meant that some sections of the Olifants River are now impoverished of fish species. Experts worry that the diversity may never recover to its former level, especially if the river suffers any more setbacks.

By Melissa Wray
In Kruger National Park

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