Section 144 of the National Water Act: The 1:100-Year Floodline on Township Plans

Section 144 of the National Water Act is the reason most floodlines in South Africa are drawn. It says that no one may establish a township unless the layout plan shows the level floodwaters are likely to reach on average once in every 100 years, in a form the local authority accepts. That is all it requires. It does not ban building below the line, and it does not say who must determine it; those rules come from municipalities.

Establishing a township or rezoning land next to a river? We determine the 1:100-year floodline in the form your municipality accepts, signed by a registered professional engineer.

Floodline determination

The text

Section 144, headed “Floodlines on plans for establishment of townships”, reads in full:

“For the purposes of ensuring that all persons who might be affected have access to information regarding potential flood hazards, no person may establish a township unless the layout plan shows, in a form acceptable to the local authority concerned, lines indicating the maximum level likely to be reached by floodwaters on average once in every 100 years.”

Four things follow from the wording:

• Its purpose is information. The section exists so that “all persons who might be affected” can see the flood hazard. It is a disclosure rule.
• It applies to establishing a township. The Act does not define “township”; township establishment is governed by provincial planning law and municipal planning by-laws.
• The local authority decides the form. “In a form acceptable to the local authority concerned” leaves the method, the deliverable and the sign-off to the municipality.
• It is a 1% annual chance flood. The Act does not use the term “1:100-year floodline”. It says “on average once in every 100 years”, which is the flood with a 1% chance of being equalled or exceeded in any year. Our post on 1:50 vs 1:100-year floodlines explains what that means in practice.

What section 144 does not do

It does not ban building below the line. Nothing in the Act prohibits or restricts development below the 1:100-year level. The section only requires the line on the layout plan. Restrictions come from municipal land use schemes, by-laws and policies, which differ widely; see building between the 1:50 and 1:100-year floodlines.

It does not say who determines or signs the line. Where a municipality sets a rule, it names a registered engineering professional, usually a professional engineer; Johannesburg also accepts a professional engineering technologist, provided the Johannesburg Roads Agency has approved them. See floodline certificates.

It does not require the 1:50-year line. Some municipalities ask for both lines, and GN 704 uses both for mines, but section 144 asks for the 100-year line only.

It does not cover other applications. Rezoning, subdivision, consolidation and building plans are outside section 144. Municipalities bring them in through their land use schemes and planning forms: Tshwane can require both lines on any application it specifies, and Mbombela’s user guide extends the requirement to subdivision, consolidation and farm rezoning. Our post on SPLUMA and land development applications shows where the floodline enters the process.

It does not mention climate change or future development. The section refers to the level “likely to be reached”. Some municipalities go further: Cape Town’s floodplain policy bases floodlines on the foreseeable ultimate development of the catchment and on the energy level rather than the water surface.

Section 145: public flood information

Section 145, “Duty to make information available to public”, requires a water management institution to make information at its disposal public, at its own expense, on matters including:

• “a flood which has occurred or which is likely to occur”;
• “a waterwork which might fail or has failed, if the failure might endanger life or property”;
• “any risk posed by any dam”;
• “levels likely to be reached by floodwaters from time to time”.

A water management institution is defined as a catchment management agency, a water user association, a body responsible for international water management, or a person who fulfils their functions. Municipalities are not named. Section 145(2) lets the Minister establish an early warning system for these events “where reasonably practicable”.

This is why the public cannot rely on section 145 to find a floodline for a particular property. Our post on how to check if a property is in a floodline lists where each municipality publishes what it has.

A note on copies of the Act

The Department of Water and Sanitation’s PDF of the Act includes plain-language summaries at the start of each chapter and part. They are helpful, but they are not the Act. Quote the section text, not the summary.

What a section 144 floodline should contain

A floodline a municipality can accept for township establishment usually comes with:

• the 1:100-year line, and the 1:50-year line where the municipality asks for it, on the layout plan in the surveyor’s coordinate system;
• a report on the hydrology and the hydraulic model, with the survey and assumptions stated;
• the signature of a registered professional engineer.

Our posts on what reviewers check in a floodline study and rezoning and subdivision cover the rest.

See our floodline determination service, or send us the site and the application.

This post explains the documents listed below. It is not legal advice; requirements change and are applied case by case, so confirm them with the relevant authority before relying on them.