Cape Town's Day Zero - Lessons for New Zealand
Annual Conference
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As Cape Town struggles to survive through the 3rd year of this 3 year drought, the Day Zero concept has captured the imagination of the world; but what has really happened in the lead up to a situation where taps could be switched off for the first time in a major City? As a water resources engineer that has been directly involved with Cape Town water supply issues, I would like to share some pertinent behind-the-scene technical interventions that have probably prevented a Day Zero from having already occurred. We will also discuss key lessons learned which are quite relevant to New Zealand’s water supply systems.
From 1990 to 2000 Cape Town showed a rapidly growing water requirement on the back of population growth and strong economic development, prompting the initiation of a focused approach to identifying and prioritizing future supplementary water resources. In addition to detailed future water requirements and alternative water resources studies, Cape Town has (since the late 1990s) also been planning and implementing resilience measures into the management of its water resources.
Currently the City is almost entirely dependent on surface water resources that are usually replenished during the winter months by frontal rainfall systems. The use of water yield and planning tools in modelling Cape Town’s complex water system for determining long-term system yield and reliability of yield has proved to be invaluable in managing the current situation and for evaluating possible future scenarios. This paper will highlight the use of these tools in assimilating system information to provide an efficient Decision Support System (DSS) for managing water resources and how this knowledge contributed to managing a serious drought period.
Pro-active water demand management (WDM) has also played an important role in curtailing the growing water demand of Cape Town. These WDM tools ranged from hard engineering options to public education drives specifically aimed at changing public perception regarding the value of water.
The effect of having planning tools as well as the implementation of WDM on managing water resources during this drought will be illustrated in this paper, along with relevant lessons learned to help prevent the occurrence of a Day Zero in New Zealand.