On Monday 20th February, the South African Weather Services issued a weather warning, for a storm that delivered about 36 mm of rain over a 24 hour period across the Cape Town Metro. That’s not a huge amount of rain. But by 2pm, the streets of lower Observatory were witness to an extraordinary event – flooded streets and the Liesbeek River overflowed its banks about a km upstream. As can be seen in the images above, the streets affected (alongside the Hartleyvale Stadium) are ones which have a stormwater drainage canal running next to the street towards the portion of the Liesbeek River now infilled by the River Club development.

It's clear that the Observatory storm water system was unable to cope with a small amount of intense rainfall. Infilling the western arm of the Liesbeek River alongside the River Club and diverting storm water runoff into underground pipes has led to a situation where the stormwater system was not able to cope with a brief late summer downpour. 

What can we anticipate when heavy winter rains arrive? Every year, Cape Town normally has a few rainfall events of up to 80mm of rain over 24 hours and this episode was a test of how the river responds to slightly higher rainfalls. Clearly, it looks as if it failed dismally on 20 February.

This risk of flooding, which Observatory residents and public officials had long warned about, was minimised by the developers in the Basic Assessment Report (BAR) who claimed in February 2020 there was only a “small increase” in the risk of flooding which would only affect two houses in lower Observatory. The developers further indicated that they would  engage the owners directly “in order to agree on flood mitigation measures required at these properties to be implemented at the cost of the developer.” To date, the affected owner has confirmed he has had no further communication from the developer, some three years later.

Moreover, the evidence in the images above indicated it is much more than two houses affected.

Importantly, in their comments on the BAR, City officials noted that the City’s Catchment, Stormwater and River Management Branch did not support the proposals because of a real concern about possible flooding.

Their comments noted that “the proposed River Club development would block the existing flow route that would have connected the ‘Old’ Liesbeek River. Consequently, this would force all the flow down the Liesbeek Canal Route which would mean increased flow levels in the vicinity of the South African Astronomical Observatory. As such, there is no guarantee that the effect of the increased flows would be localised along the course of the Liesbeek Canal and not extend to neighbouring properties during extreme flood events. However, the BAR report largely minimizes the potential impacts of the development, in changing the flow regime and character of the riverine system, and the risk of flooding events and flood inundation to neighbouring properties, as a result of the proposed raising of ground levels on the site.”

The City’s comments also pointed out that international best practice is to make “Room for the River” which relocates developments away from the flood plain so as to make “room” to allow the river to flood safely. Their comment was that, despite the suggestion of “negligible impact, the City should carefully consider why it would deviate from current international best practice. The high levels of development and their hardening of surfaces is inconsistent with the commitment the City has made to become a water sensitive city,” in terms of which, the City commits to make "optimal use of stormwater pipes and urban waterways for flood control, aquifer recharge and recreation."

What we are now seeing is exactly what the City’s water and environmental officials warned about. But their concerns were ignored by decision-makers both in the City and the Department of Environmental Affairs and Development Planning who blundered ahead to approve the development contrary to existing policies.

These are part of the matters that we will be raising in the High Court review to challenge the authorisations granted to the development.

As always, please help us fund these legal costs by contributing at our fundraising site.  

Visit our website and follow the Liesbeek Action Campaign on twitter: @LiesbeekAction. 

Make the Liesbeek Matter!