This is a response from Jonathan Britton the Section Ranger of Wilderness, Garden Route National Park, to a query from a member of the public.
Thank you for the opportunity to share some information on the management of the Touw River Estuary and as well as the matters around the management of the mechanical breaching of the Estuary river. This is a very complex topic but I hope that with some of the information I will share with you will give you some insight into the management as well the challenging environment in which this needs to be done. I have attached information and links which you can refer to. There are several key things that are important to highlight
1. The Touw River Estuary is classified as a temporary open/closed estuary
This refers to the ecological system and functioning of this type of Estuary where there are open and closed phases referring to the state of the river mouth. The Knysna Estuary is different as it is permanently open and functions differently ecologically. I have attached a very nice document by one the best experts in this field that has summarised and reviewed many years of research on the ecology and management of temporarily open closed estuaries. This should give some good insight and understanding of this interesting ecological system as well the management challenges in an urban environment and is based on peer reviewed science.
A review of the ecology and management of temporarily open/closed estuaries in South Africa, with particular emphasis on river flow and mouth state as primary drivers of these systems. AK Whitfield1 et al
2. Approved Management Plan
The Garden Route National Park Management Plan gives the framework and guidelines on the management of the River Mouth. The management plan is based on the peer reviewed research and science that is noted above. This link will take you to the Management Plan - www.sanparks.org/parks/garden_route/about/planning_products.php, the management plan and the annexures are too big to email. Appendix L deals specifically with the Artificial Manipulation of Estuary Mouths.
Contrary to what you believe, the river mouth was not closed artificially and we let this process happen naturally. It will only be closed artificially if there is a threat of pollution from the sea into the estuary. The sand bar is actively managed to reduce the build-up of sand in the river mouth and to reduce the time required to mechanically breach the river mouth should there be a possibility of flooding. Without any management and preparation it could take about 6 - 8 hours to mechanically breach the river. The aim is to reduce this to not more than an hour to ensure that the risk of flooding is lowered as well as trying to ensure that there is enough scouring of the sandbank to prevent a net build-up of sediment in the river mouth. The berm that is currently in place slows down windblown sand building up into the river mouth as well shortening the length of a that channel that needs to be dug to open the river into the sea.
A concern you also noted was around the condition of the water quality. SANParks, George Municipality and Eden District Municipality Health Department all have a water quality testing programme in place to ensure that recreational standards are met. If any there are concerns detected appropriate management actions will be activated (noted in the Management Plan). Currently there are no concerns, I take my kids to swim and canoe on the Touw River.
3. Stakeholders and communication
I have include the Ryan and Chris from the Wilderness Residents and Ratepayers Association(WRRA). They are a great group who work with SANParks around matters that are important to residents in Wilderness and we meet regularly and have open channels of communication between each other on relevant topics.
I trust this will offer some insight into the management of the Touw River Estuary
Wilderness, Garden Route National Park
044 343 1302