What is Catchment Management?

Catchment management aims to effectively and efficiently manage naturally occurring water within catchment areas by managing or accounting for all aspects of the hydrological cycle. (A catchment is the area or region which 'catches' the rainfall runoff flows with reference to a point on a river or drainage system.) Catchment management also aims to achieve a balance between resource protection and resource utilization.

How do we aim to manage our catchments?

The Catchment Management section of the Coastal, Stormwater and Catchment Management (CSCM) Department follows a sustainable and holistic approach to catchment management which includes:

• Liaison with Catchment Management Agencies
• Assisting with co-ordination of Catchment Management within eThekwini Municipality
• Design of river works

- We work towards promoting engineering “best practice” standards that enhances flood control functions as well as ecosystem functionality. The installation of gabion baskets is one such example.

Gabion baskets not only stabilises the river embankment and prevents damage to property and infrastructure but also protects against erosion and offers an opportunity for ground cover vegetation to re-establish.

• Subdivisional approval for Developers/Consultants in respect of floodlines and increased runoff

-  All flood attenuation facilities shall be designed in accordance with the following criteria:

1. Existing drainage courses shall be preserved. Development within the 1 in 10 year floodline need to comply with requirements set out in the National Water Act (NWA) and the National Environmental Management Act (NEMA).
2. All flood attenuation facilities shall be designed to provide control for the 1:10, 1:50 and 1:100-year flood.
3. Unless otherwise specified, local detention should be provided to control on-site runoff.
4. Off-site runoff from upstream drainage areas shall be diverted around any proposed detention facility or the detention facility shall be designed to control the off-site runoff as if it were on-site runoff.
5. Flood attenuation storage volume shall be provided to reduce the peak discharge rate for developed site conditions to the peak discharge rate for pre-development site conditions. Pre-development site conditions are defined as undisturbed natural conditions.    
6. Drainage facilities shall incorporate design features to minimize, maintain, and enhance the physical aesthetics of the site. Design features may include proposed grading that mimics or improves the existing site profile and use of construction materials that visually integrate with the ambient environmental textures and patterns.
7. Properties served by an existing detention facility may only utilize the existing facility if the following conditions are met:
   • Calculations shall be provided that show that the facility is adequate to mitigate the runoff from the property.
   • Calculations shall be provided that show that the drainage system between the property and the facility is adequate to convey the runoff from the property.

• Floodline preparation

-  Preparation of floodlines serves as a tool for planning and management of flood impacts. It allows for developments along rivers and within the 1:100yr floodline to be managed.

In complying with the National Water Act (Act No 36 of 1998), the eThekwini Municipality requires that all new developments, or extensions to the existing properties, provide information relating to the 50yr and 100yr flood. This includes the requirement that the 100 year floodline be indicated on plans for new township developments.

• Education of the public with regard to catchment management

-  CSCM recognizes the importance of communities in catchment management in particular with regards to stormwater systems and rivers.

As part of our holistic approach to catchment management, the Catchment Management section will:

1. Develop and co-ordinate education and communication strategies to communicate and increase awareness of relevant catchment management issues.
2. Create an awareness of stormwater systems and their purpose.
3. Encourage and promote efficient, effective and productive use of water resources through education and awareness campaigns.
4. Encourage activities that contribute to improved water quality that is more suitable for sustaining aquatic ecosystems and human uses.

• Assisting the public

- Investigating and addressing stormwater complaints such as erosion and flooding.
Complaints can be lodged at:
City Engineers

Coastal, Stormwater & Catchment Management
5th Floor

Room 527
166 K. E. Masinga (Formerly Old Fort Road)
Durban

4001
Tel:  031 311 7338

Manager: Mr. Geoff Tooley
Tel: +27 31 311 7271
Email: tooleyg@durban.gov.za