Situated within the broader Breede River catchment in the Western Cape Province of South Africa, the Hex River Valley lies in an enclosed area, geographically bound by high mountain ranges on either side of the valley. The high rising Matroosberg Mountain range (1,900-2,200m) to the north-east and a south-eastern mountain range encapsulate the valley centred around the small town of DeDoorns.
For more than two hundred years economic activities in the Hex River Valley have been centred on the commercial cultivation of one product: table grapes. On 5,200 hectares of land, an average of 18 million cartons of table grapes are produced each year, mainly for the European markets of United Kingdom and Germany. Each carton holds 4.5kg and contains nine 500 gr plastic boxes as we know them from the supermarkets.
However, to produce only one kilogram of table grapes in the Hex River Valley, around 300 litres of irrigation water is required, depending on the yearly rainfall. Grapes are 90% water. Thus, the annual water requirements for irrigated agriculture in the Hex Valley accounts for 24 billion litres, which is equivalent to 24 million cubic meters, or 10,000 Olympic swimming pools full of water.
In a year with less rainfall than average the amount of water used for the production of table grapes goes up to 30 or 35 million cbm. But the total dam capacity in the Hex Valley accounts for only 12-13 million cubic meters. The remainder is taken out of the ground.
As a result, the water bearing geological formations under the Hex Valley are heavily overexploited – water is taken out of the ground at four times the recharge rate of the aquifer. The outcome is a dramatic decline of the water table. “40 years ago we drilled 40 metres and got water of good quality,” says a commercial farmer, a third generation descendent of European settlers. “Today our deepest drill is 280 meters and the water is mostly brackish,” he adds.
The reason for the decrease in ground water availability and quality lies in the over-abstraction for irrigated agriculture. The consequence is a reduction of the outward pressure within the underground aquifer that the mass of water stored in the earthen layers exerts towards the northern side of the Valley. But this northern side is bordered by a water-bearing geological formation that contains a much higher degree of salt. Saltwater intrusion into the groundwater of the Hex Valley is the result. “The more of the fresh water that is pumped out, the more of the salty, brackish water comes here. That is a big problem,” another commercial farmer told me during my research interviews in 2015.
This does not only jeopardise the economic activities based on irrigated agriculture in the Hex River Valley, but the subsequent livelihoods depending on the availability of water of sufficient quality. However, the consequences are even more direct – the over-abstractions by commercial farmers in the Hex River Valley endanger the water supply security for human consumption of its inhabitants, as 60% of the total water consumption falls on ground water.
This furthermore has an impact on the overall price of water, as new and costly alternatives, like water recycling or desalination, have to be developed to ensure the supply of the population with drinking water. As another grape farmer explained: “we actually grow table grapes with water which we don’t have or shouldn’t use. We don’t look after our resources properly. We overuse them in such a way that ground water has now become an unreliable resource.”
In scholarly terms of systems-thinking, the situation in the Hex River Valley can be described as: the economic system coined by irrigated agriculture impacts negatively on the ecological system, which, in turn, jeopardises the social system as an integral part of the ecological system. One aspect often underemphasised by theoretical notions of socio-ecological systems approaches, however, is the existential dependency of one system on the other. Neither the social system, nor the economic system can exist without a healthy and thus functioning ecological system.
In a more and more climate-constrained world, it is time to think about this dependency relationship as the ultimate conditio sine qua non for our very existence.
Jan Janosch Fӧrster is a PhD candidate at the Monash South Africa’s Water Research Node. This blog article represents a part of his 2015 research findings of a cross-case analysis of water access in South African water governance in two South African Provinces. Contact him here.