The 1981 Laingsburg Flood was a catastrophic event that occurred on 25 January 1981 in the town of Laingsburg, Western Cape, South Africa. [1] The flood killed at least 104 residents, and the bodies of 72 people were never found. A total of 184 houses were destroyed.
The town of Laingsburg is located near where the Buffels River converges with two of its tributaries: the Wilgehout and Baviaans (also known as Bobbejaans) rivers. The Buffels River catchment is usually dry, due to its location in the rain shadow of the Langeberg, Swartberg and Witteberg mountains. [2] However, occasionally, a high-pressure system offshore of the Western Cape can push moist air from the coast over the mountains, resulting in increased rainfall in the Buffels River catchment, in turn leading to increased water flow in the three rivers that converge near Laingsburg. [2] On 24 and 25 January 1981, a synoptic-scale weather event developed over the south-western parts of South Africa, causing heavy rainfall in the region. [3]
On January 25, 1981, unprecedented rainfall in the Buffels catchment area caused the Buffels River to overflow its banks. [2] The water level started to rise in town at about 12:00, and by 14:00, the town was almost fully covered. [4] Flood waters and mud swept through Laingsburg, with some areas experiencing water levels reaching 10 metres above the usual flow level. [2]
The river current, at its peak, was estimated to be 8000 cubic metres per second. [5]
The flood destroyed two-thirds of Laingsburg's infrastructure, destroying 184 houses and 23 commercial buildings, including the town's old-age home. The flood killed 104 people, with 72 bodies never recovered. [6]
A report published in January 1982 identified the geographical position of Laingsburg as making it particularly vulnerable to large floods. Laingsburg is situated on a natural flood plain on the inside bend of the Buffels River. [7]
Another geographical factor contributing to the damage was the confluence of the Buffels, Wilgehout, and Baviaans rivers, and the east-west ridge directly downstream (south) of the confluence. The two large tributaries and the Buffels River converge immediately upstream of the poort (passage between mountains) through the ridge, and the ridge directed the flow in the tributaries northward into the southern part of town. The combined effects of all three rivers and the constriction of river by the poort accounted for much of the damage in the southern part of Laingsburg between Swartberg St and the river. [7]
The deposition of sediment is a widespread form of flood damage in the drier regions of South Africa. Rivers in the Cape Midlands and the Karoo carry high sediment loads in high floods. The sediment-carrying capacity of flowing water depends on the velocity of the water. When the river overflows its banks, the velocity decreases as the water flows away from the river bed, particularly where it flows through a built-up area. The slower-moving water can no longer carry the sediment loads associated with the mid-stream velocities, and the sediment is deposited as the water slows down. Heavy sediment deposits result, especially in the vicinity of houses nearest to the enlarged river channel, where the flowing water's velocity is rapidly decreasing. Sediment deposits in Laingsburg were up to 3 m deep in many places and the total sediment volume deposited was about 200 000 cubic meters. [7]
Another factor that caused much damage in Laingsburg was the large amount of floating debris. This consisted mainly of trees washed down the river from upstream, but it also included debris from buildings in the town itself. The debris caused physical damage to the buildings and aggravated sediment deposition. [7]
Many buildings in Laingsburg collapsed due to high water levels alone. Those that collapsed were mainly the older buildings. Newer, more soundly constructed buildings were not seriously damaged except those subjected to high scouring velocities. [7]
The first flood reports emerged after SADF Super Frelon helicopters flew over the town at 09:00 on Monday morning the 26th of January 1981. [8]
South Africa occupies the southern tip of Africa, its coastline stretching more than 2,850 kilometres from the desert border with Namibia on the Atlantic (western) coast southwards around the tip of Africa and then northeast to the border with Mozambique on the Indian (eastern) coast. The low-lying coastal zone is narrow for much of that distance, soon giving way to a mountainous escarpment that separates the coast from the high inland plateau. In some places, notably the province of KwaZulu-Natal in the east, a greater distance separates the coast from the escarpment. Although much of the country is classified as semi-arid, it has considerable variation in climate as well as topography. The total land area is 1,220,813 km2 (471,359 sq mi). It has the 23rd largest Exclusive Economic Zone of 1,535,538 km2 (592,875 sq mi).
An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but are also found in more humid environments subject to intense rainfall and in areas of modern glaciation. They range in area from less than 1 square kilometer (0.4 sq mi) to almost 20,000 square kilometers (7,700 sq mi).
The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley. It includes the Kalahari Gemsbok National Park, part of the Kgalagadi Transfrontier Park and an international park shared with Botswana. It also includes the Augrabies Falls and the diamond mining regions in Kimberley and Alexander Bay.
The Karoo is a semi-desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent is also not precisely defined. The Karoo is partly defined by its topography, geology and climate, and above all, its low rainfall, arid air, cloudless skies, and extremes of heat and cold. The Karoo also hosted a well-preserved ecosystem hundreds of million years ago which is now represented by many fossils.
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Laingsburg is a town located in the Western Cape province in South Africa. It is a relatively large agricultural town in the semi-arid Great Karoo; it's economy is based on farming goats, sheep, fruits, and vegetable. The town is served by two numbered road, namely N1 and R323.
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The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.
The Cape Fold Belt is a fold and thrust belt of late Paleozoic age, which affected the sequence of sedimentary rock layers of the Cape Supergroup in the southwestern corner of South Africa. It was originally continuous with the Ventana Mountains near Bahía Blanca in Argentina, the Pensacola Mountains, the Ellsworth Mountains and the Hunter-Bowen orogeny in eastern Australia. The rocks involved are generally sandstones and shales, with the shales persisting in the valley floors while the erosion resistant sandstones form the parallel ranges, the Cape Fold Mountains, which reach a maximum height of 2325 m at Seweweekspoortpiek.
The Vargas tragedy was a natural disaster that occurred in Vargas State, Venezuela on 15 December 1999, when torrential rains caused flash floods and debris flows that killed tens of thousands of people, destroyed thousands of homes, and led to the complete collapse of the state's infrastructure. According to relief workers, the neighborhood of Los Corales was buried under 3 metres (9.8 ft) of mud and a high percentage of homes were simply swept into the ocean. Entire towns including Cerro Grande and Carmen de Uria completely disappeared. As much as 10% of the population of Vargas died during the event.
The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much older basement rocks. It underlies the Beaufort Group in all known outcrops and exposures. Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian in age.
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Ladismith is a town and agricultural centre in the western Little Karoo region of South Africa's Western Cape province.
Meiringspoort is a South African mountain pass on the N12 national road, where it crosses the Swartberg mountain range.
Thomas Charles John Bain was a South African road engineer. As a prolific road building pioneer, Bain was responsible for the planning and construction of more than 900 km of roads and mountain passes, many of them still in use today, over a career spanning from 1848 until 1888. These passes through the mountain ranges between the thin coastal plain and the interior of the former Cape Colony in South Africa, played a major role in opening up the vast hinterland of South Africa.
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