How did the use of groynes for river bank stabilization in the Western Cape develop?

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In February 1989 I started working as an engineer for the Department of Agriculture. For a year and a half  I planned hydraulic structures for Irrigation Boards. I was then moved to the Soil Conservation Directorate where I was appointed as the Soil Conservation Engineer for what was to become the Western Cape Province. My duties included the planning of all sorts of soil conservation structures such as erosion control weirs, sub-surface drainage, and surface drainage management structures like stormwater furrows, contour banks and waterways.

After every flood cycle in the Western Cape, I quickly came to understand that of the greatest needs of farmers was to stabilize rivers. With economic pressure forcing farmers to develop the more fertile land adjacent to rivers, erosion of river banks during floods meant that farmers lost access roads, irrigation infrastructure, and costly orchard and vineyard developments. Many farmers were coming to the conclusion that simply bulldozing sediment out of rivers after floods was not a sustainable approach because it had to be repeated after every flood, and was very costly.

The development of a design process for the use of groyne structures

In the early 90’s there was no government funding for erosion control works in rivers but some farmers were so desperate that they funded it themselves, and I attempted to help by planning the works. There is no standard manual or passed down knowledge for the design of river bank erosion works, and this complicated the planning of the work. Luckily the initial projects were small and although failures were common, the consequence of the failures were small. More importantly valuable  lessons were learned from these attempts, and this started the development of a sustainable design process. Effectively these early projects were full scale laboratory trials.

Very early groyne structures in the Berg River (1995)

More recently I have been fortunate enough to be sent overseas several times by the Province to learn from people doing similar work and to share my experiences. As a result I have produced many papers on the use of groynes for river bank stabilization. I have also co-authored a book on river rehabilitation.

The Calitzdorp Project

In the year 2000 the Gamka River at Calitzdorp experienced a large flood. The damage included the washing away of a kilometer of Gamka Irrigation board’s water supply canal that was on the top of a high  river bank. This canal supplied water to more than 600 hectares of table grape vineyards. The economic impact of this damage was huge for many farmers, and for the even more people dependant on the farmers for employment. The canal was quickly reinstated, but because it was on top of a steep 6 m high river bank, the canal was understood to be very vulnerable to collapse if the river bank was eroded again and a solution was urgently needed.

Although this project was very much larger than all the projects I had developed up to that time, I was requested to design the stabilization works. The concept that I had developed up to this stage was the use of groyne structures (as opposed to simply lining the whole river bank with a hard layer such as concrete or dumped rock), and that is what I used. I believed then (as I do now) that the use of groynes structures has economic as well as environmental advantage over other techniques. Post the Calitzdorp project, the standard for the design of groynes has improved in terms of stability as well as lower cost and environmental acceptability. Certainly the Calitzdorp project was a defining moment where the value of such work was realized and funding became more available.

Some of the groyne structures constructed at Calitzdorp (2002)

Environmental aspects and a wholistic approach to river stabilization

After developing initial projects in the Buffeljags, Duiwenhoks, Hex and Pietersfontein Rivers, I realized that addressing random erosion hot-spots in rivers lacked value when the source of river instability was not being identified and addressed.  This started an approach where a whole river would be assessed for factors contributing towards instability, so that the river could be stabilized in a more wholistic way, even if it meant increasing the scope of the project.

Similarly the impact of invasive alien vegetation, and the stripping of natural vegetation from rivers by farmers, on river stability could not be ignored.  It was found that by promoting indigenous wetland vegetation in rivers, structural interventions could be reduced, and this had a profound impact of the environmental acceptability of the projects proposed. As a result  I am passionate about trying to quantify the use of indigenous wetland vegetation as a means to reduce the need for structural intervention to stabilize rivers, and still hope to develop further in this regard.

Job creation

At the time when the Calitzdorp project was being developed, nationally the spotlight was on job-creation and empowerment, as these were being recognized as serious needs in the South African society and economy. I was able to make sure that the project used as much labour as possible (by planning the structures as rock filled gabions), and although funding was not available via the usual flood relief channels, the Provincial Poverty Relief Fund (Department of Welfare) had surplus funds and was convinced to provide 75% of that needed for  the project, because of it’s focus on job-creation and poverty alleviation. The Department of Water Affairs provided the rest.

Stone packing by Calitzdorp community members 2001
One of the local community teams working at the Calitzdorp project (2002)

Since the Calitzdorp project I have continued to be on the lookout for ways to expand the job-creation opportunities with the projects I plan. For some time while I was employed by the Department of Agriculture, I was part of a team that recruited and trained jobless people to pack gabion baskets in various areas. Since I have been focusing on producing solutions using a combination of engineered structures and the use of indigenous wetland vegetation, I have also been instrumental with the expansion or establishment of nurseries run as job-creation projects.

The Gendadendal nursery was expanded to provide 35 000 plants for river stabilization projects
Some of the team drawn from Genadendal establishing indigenous wetland plants (2020)

Awards

In 2003 the Department of Agriculture won an Impumelelo Innovation Award for the Calitzdorp  project, because of the new design technique, the innovative funding model, and the combination of job-creation with resource conservation. This award then gave rise to recognition from the Harvard Kennedy School  (Calitzdorp River Erosion Protection Works | Government Innovators Network (harvard.edu) ).

In 2015 the Department of Agriculture: Western Cape recognized my work with river rehabilitation by awarding me the “Top performer: Program 2” trophy. 

In 2016 I was a co-recipient of the MONDI National Wetland Award for “Wetland Science and Research”.

Funding of projects

Post the Calitzdorp project, I was responsible for many more similar projects. As appreciation for the economic, environmental and job-creation benefits grew, the level of government funding also grew. As recognition the work done by the Department with river stabilization grew, other state entities requested assistance with the design of similar projects, and this included the Provincial Transport Department, Transnet, varies municipalities and Working for Water.

A recent river stabilization project using groynes outside Mossel Bay showing the sloping tip, low overall profile, and well established indigenous wetland vegetation (2020)