This idea is not yet agreed. Nobody named on this page has been asked about it yet. That includes the Transformasie Komitee, the Moravian Church, Theewaterskloof Municipality, the Greyton Conservation Society, the holders of Greyton’s leiwater rights, the Zonderend Water Users Association, the Breede-Olifants Catchment Management Agency, and the Department of Water and Sanitation. Please do not share this page publicly yet. No date has been set for tabling it at a Forum meeting.
What the letters in square brackets mean
Facts on this page are followed by a tag that shows where they come from.
- [IC] Independently Corroborated. Confirmed by at least two sources that do not depend on each other, or by an official record.
- [MS] Mission-Sourced. Comes from the people putting this idea forward, in their own documents or statements. It has not been checked against other sources. On this page that includes the results of the map study.
- [TBV] To Be Verified. Seems likely, but nobody has confirmed it yet.
Statements without a tag are proposals. They describe what the idea could become.
The goal
The valley holds more of its own rain in its mountains and soils, with small dams that residents build and look after themselves.
Why the valley needs it
Two rivers from the mountains. The Baviaans comes down the kloof above Genadendal, and the Gobos comes out of the mountains northeast of Greyton [MS]. Both run into the Riviersonderend below Theewaterskloof Dam [IC].
Water the valley already depends on. In 1899 the Moravian Church bought the mountain farm Langgezocht, about 1,881 hectares, to protect Genadendal’s water sources [MS]. Since 1854 Greyton’s leiwater furrows have carried water from the Gobos to the plots that hold a water right [MS]. See Greyton’s Leiwater.
The dam Genadendal already has. An earth dam of about 2.5 hectares lies at the foot of the mountain about 1.4 km east of the Genadendal church, above the road to Boschmanskloof [MS]. Its water stands at about 320 metres above sea level [MS]. It is fed by a poorly maintained pipe from the Baviaans, and by a diesel pump that runs 24 hours a day, lifting water from the river below the dam [MS]. Who owns and runs it, and what its water is used for, has not been confirmed [TBV]. A dam higher up the Baviaans kloof, such as B2 at about 506 metres, could send water down to it by gravity and cut the need to pump.
Water that must stay in the rivers. In August 2022 the Minister set the Reserve for the Breede and its tributaries, including the Riviersonderend, the Gobos, and the Baviaans [IC]. The Reserve is the water a river must keep for people’s basic needs and for its own health, and it comes before other uses [IC]. See National Water Act.
Children are already looking for sites. In the Class 6 Project, each child uses Google Earth to find a gully in the valley where they would build a leaky dam [MS].
The idea
The idea is to find out which dams the valley could build itself, and where. A map study (see How the sites were found) points to three sizes.
1. Leaky dams in side gullies
A leaky dam is a low wall of stones, logs, or packed branches across a gully. It slows rainwater so that it soaks into the soil and lets the rest pass. It holds no lake. Volunteers and clearing teams could build leaky dams with hand tools, starting in small side gullies away from the main rivers.
2. Low walls of 5 metres or less in the kloofs
The map study found seven places in the mountain kloofs where a short wall closes off a narrow valley. A wall of 5 metres or less at these sites would hold roughly 10,000 to 200,000 cubic metres [MS]. An Olympic swimming pool holds about 2,500 cubic metres, so this is between 4 and 80 pools.
A wall of this height stays below the size the law treats as a dam with a safety risk (see What the law asks). A community group could build it with the help of an engineer.
3. Higher walls are a different kind of project
The same sites could hold far more water behind higher walls: up to about 9 million cubic metres behind a 40 metre wall above Greyton [MS]. Every wall above 5 metres that the study tested would also hold more than 50,000 cubic metres [MS]. Such a dam must be registered as a dam with a safety risk [IC]. That puts it outside what a community could build on its own. The figures are listed below so the Forum can see what the valley’s terrain allows.
Where the sites are
The positions are the centre of each wall, in decimal degrees. “Riverbed” is the height of the river at the wall. To view the walls on a map, see: https://earth.google.com/earth/d/1PejJJkRHA_WrwYwdKrSeea92u3q3vp9y?usp=sharing
| Site | River | Where | Position | Riverbed |
|---|---|---|---|---|
| B1 | Baviaans | Upper kloof, high in the mountains northwest of Genadendal | -33.9958, 19.5303 | 583 m |
| B2 | Baviaans | Middle of the kloof | -34.0025, 19.5431 | 506 m |
| B3 | Baviaans | Lower kloof, about 2 km north of Genadendal | -34.0150, 19.5567 | 318 m |
| B4 | Baviaans | Kloof mouth, about 800 m north of the Genadendal church | -34.0275, 19.5561 | 266 m |
| G1 | Gobos | Upper kloof, east of Greyton | -34.0278, 19.6433 | 300 m |
| G2 | Gobos | Middle of the kloof | -34.0306, 19.6297 | 256 m |
| G3 | Gobos | Kloof mouth, about 2 km northeast of Greyton | -34.0367, 19.6236 | 242 m |
All figures below come from the map study [MS]. Volumes are in cubic metres.
| Site | 5 m wall | 20 m wall | 40 m wall |
|---|---|---|---|
| B1 | 30 m long, 70,000 | 80 m long, 670,000 | 135 m long, 3.2 million |
| B2 | 45 m long, 200,000 | 115 m long, 1.1 million | 185 m long, 3.8 million |
| B3 | 35 m long, 130,000 | 100 m long, 530,000 | 150 m long, 1.9 million |
| B4 | 55 m long, 60,000 | 130 m long, 930,000 | 205 m long, 4.4 million |
| G1 | 45 m long, 10,000 | 90 m long, 680,000 | 130 m long, 2.8 million |
| G2 | 55 m long, 70,000 | 115 m long, 830,000 | 175 m long, 3.6 million |
| G3 | 125 m long, 160,000 | 250 m long, 2.2 million | 405 m long, 9.2 million |
Sites on the same river share the same water. A lake at B4 would reach back towards B3, and a lake at G3 towards G2. The valley would choose one site per kloof, or a chain of small walls.
How the sites were found
The study used the free elevation map from NASA’s Shuttle Radar Topography Mission, which gives one height for about every 30 metres of ground [MS]. A computer traced each river down its valley and tested walls of 5 to 60 metres at points along it [MS]. At each point it measured the length of the wall and the water that would lie behind it [MS]. The sites listed are the ones where a short wall holds the most water [MS].
The study has limits:
- Heights are rough. A 30 metre map smooths out narrow kloofs. Real walls may be shorter and riverbeds deeper, so the figures could be out by a third either way [MS]. For 5 metre walls the map is at the edge of what it can show.
- The valley floor is too flat. Below the kloofs the map cannot show small rises and falls, so the study gives no sites there [MS].
- It shows the shape of the land only. It says nothing about rock, soil, plants, animals, who owns the land, or whether a dam would fill.
Before any site is chosen, someone would need to walk it and check the ground and rock where the wall would stand.
What the law asks
- Dam safety. A dam that can hold more than 50,000 cubic metres and has a wall more than 5 metres high is a dam with a safety risk under the National Water Act [IC]. Its owner must register it [IC].
- Storing water. The national general authorisation for storing water covers only storage off the river, in a dam beside it [IC]. A dam built in the river itself falls outside it [IC], so it would most likely need a water use licence [TBV].
- Work in a river. Whether a leaky dam in a side gully needs any permission has not been checked [TBV].
- The Reserve. Any dam on the Baviaans or the Gobos would have to leave the Reserve flowing in the river [IC].
The Breede-Olifants Catchment Management Agency issues water use licences in the Breede catchment [IC].
Who would benefit
- Growers and food gardens near Genadendal and Greyton, if stored water could be used for them.
- The rivers in the dry months, if water held in the soil reaches them later in the year.
- Firefighters, who would have water close to the mountain slopes.
- Homes and businesses that need electricity. Water running down from a kloof dam could turn a small turbine and make electricity. Two lakes on the same river, one high and one low, could also work as a battery. Water would run down through the turbine when power is needed, and be pumped back up at night, when electricity is cheaper on time-of-use tariffs [TBV]. On the Baviaans, B2 sits about 240 metres above B4 [MS]. A rough calculation for 5 metre walls at both sites gives about 30,000 kilowatt-hours, after losses, each time the lower lake fills and the water is sent back down [MS]. If a home uses about 10 kilowatt-hours a day, that is enough for about 100 homes for a month. On the Gobos, G1 sits only about 60 metres above G3, so the same amount of water would give about a quarter as much electricity [MS]. Whether any of this would pay, and how it would connect to the grid, has not been looked at.
- Volunteers and clearing teams, who could learn to build and look after small water works.
- Learners, who could study real sites in their own valley.
Who would pay
Nothing has been costed [MS]. Leaky dams cost little more than labour and local stone or wood. A 5 metre wall would need an engineer’s design and materials, and perhaps a licence.
Who would decide
- On the Baviaans: the kloof above Genadendal lies on Farm 39 land or on Langgezocht, the mountain farm the Moravian Church bought to protect Genadendal’s water [TBV]. Any work there goes to the Transformasie Komitee first. See Farm 39.
- On the Gobos: the kloof northeast of Greyton may lie inside the Greyton Nature Reserve, which Theewaterskloof Municipality manages with support from the Greyton Conservation Society [TBV]. Holders of Greyton’s leiwater rights draw on the same river [MS].
- Water use: the Breede-Olifants Catchment Management Agency and the Department of Water and Sanitation, under the National Water Act.
How it fits the Forum’s goal
The Forum’s long-term goal plans for the valley to keep more of what it has, including water in the ground. Small dams are one way to hold the valley’s rain.
It serves two of the Forum’s priorities: Conservation and Environment, and Agriculture and Food Sovereignty.
What is still open
- The land. Who holds the land at each site. The Transformasie Komitee and the Moravian Church have not been asked about the Baviaans sites. The municipality and the Greyton Conservation Society have not been asked about the Gobos sites.
- The existing dam. Who owns and runs the dam east of Genadendal, what its water is used for, what the diesel pumping costs each month, and how a new dam upstream would tie in with it.
- Leiwater. How a dam on the Gobos would affect the flow that feeds Greyton’s furrows. The holders of leiwater rights have not been asked.
- Whether the dams would fill. How much water each kloof gives in a year. The study did not look at rainfall or river flow.
- The law. Which permissions each size of dam would need. The catchment agency has not been asked.
- The rivers’ life. What a wall would do to the plants and animals in the river and below it.
- Mud and sand. How fast each lake would fill with silt.
- The ground. Whether the rock and soil at each site can hold a wall.
What happens next
- The Transformasie Komitee, the Moravian Church, the municipality, the Greyton Conservation Society, and the holders of leiwater rights are asked for their views.
- The idea is set down for a Forum meeting.
- If the Forum wants to go further, volunteers walk the sites with someone who knows small dams, and check the figures on the ground.
- The catchment agency is asked which permissions each size of dam would need.
- A first leaky dam could be built in a side gully where the landholder agrees.
Have your say
Contact the moderators via How to Submit, or raise the idea at the next Forum meeting.
Related
- From Water Access to Water Agency
- Restoring the River: Water Skills at the Learning Campus
- Ridge to River to Table: Investing in the Whole Valley
- National Water Act
- Greyton’s Leiwater
- Farm 39
- Class 6 Project
- Zonderend Water Users Association
- Greyton Conservation Society
- Ideas for the Valley
References
- Parliament of South Africa. National Water Act 36 of 1998. LawLibrary. Section 117, the meaning of a dam with a safety risk, and section 120, registration.
- Department of Water and Sanitation. National Water Act, Chapter 12: Safety of Dams. The 50,000 cubic metre and 5 metre limits, and the duty to register.
- SAnews. Dam owners called to register their dams within 60 days (29 November 2024). The same limits, as the Department explained them to dam owners.
- Department of Water and Sanitation. Revision of general authorisation for the taking and storing of water. Government Gazette 40243, Notice 538, 2016. Storage under the authorisation is off-channel only.
- Department of Water and Sanitation. Reserve determination for water resources of the Breede-Gouritz Water Management Area. Government Gazette 46798, Notice 2428, 26 August 2022. The Reserve for the valley’s rivers.
- Registry of Open Data on AWS. Terrain Tiles. The source of the Shuttle Radar Topography Mission elevation map used for the study.