Flooding in South Africa Narrative Essay
Assignment GEO 234 D Sonnekus 2011042526 Flooding In South-Africa A Deeper Insight to What Happens Around Us [pic] Photo: Ivan Sonnekus 2012 Index Page Number 1. Introduction3 2. The Nature Of Flooding3 3. The Main Causes Of Flooding In South-Africa4 4. The Effect Of Development On Flood Hazards in SA5 5. The Effect Of The Economic Status Of People – Regarding Flood Hazards6 6. Conclusion7 7. Bibliography8 1. Introduction
Floods play a major role in our everyday lives, and how we react to the daily changing climate is of course our way of surviving our planetary conditions. Floods determine our building styles and play a very large role in the economy by means of devastating destruction and environmental engineer specialists in terms of flood prevention. The hydrological definition for a flood states that a flood is a rise in water level in a stream to a peak point where after the water level will recede at a slower rate (UNESCO-WMO 1974). Control Key and Word – Text and Graphics.
A flood event can be described as a flow of water in a stream constituting a distinct progressive rise, culminating into a crest, together with the recession that follows the crest (Linsley, 1942). In this Assignment I will be explaining some key features about flooding regarding a South-African point of view. 2. The Nature of Flooding. Floods can be broken down into different classes or divisions between different types of floods in this section I will explain the main flood types and their nature.
Floods can be divided between major floods, minor floods and flash floods. Major Floods: In the event of a major flood the flooding is caused by the overflowing of rivers and dams by means of breaks in dikes, levees, dam walls and other protective structures; by uncontrollable releases of impounded water in reservoirs and by the accumulation of excessive runoff. In the case of a major flood the floodwaters will cover a wide spread contiguous area and will spread rapidly to adjoining areas of relatively lower elevations.
The flooding will be deep in most parts of the total flooded area and there is a highly perceptible current as the flood spreads to a greater extent. [pic] Minor Floods: In the cause of a minor flood the inundation may or may not be due to overbanking. If there is no bank overflow, flooding happens due to the accumulation of excessive surface run-off in lower lying flat areas. In these cases flooding will mostly be restricted to flood plains along a river channel or low-lying areas or terrain depressions around the direct source of the flood.
The flood water will be shallow and there may not be a perceptible flow apparent or present. Flash Floods: Flash floods is as the name states a flood that happens relatively quick, normally no more than 6 hours to a normal flooding time of 12 to 24 hours or longer. Flash floods is the result of a short concentration time of the drainage catchment or a steep river slope, this means that the precipitation falling on a point in the catchment farthest from the river takes a very short time to reach the river itself and become a part of the stream flow.
Thus the amount of flow will rapidly increase and the water level will rise, when the capasity of the river/stream is exceeded the channel overflows and the result is a flash flood. [pic] 3. The Main Causes of Flooding in SA. South Africa was subject to some intense floods over the last couple of years mainly as the result of cloud breaks and very heavy precipitation in very short time periods which leads to flooding of most small streams and rivers, what then leads to the larger rivers to flood.
South Africa is also a victim of the Southern Oscillation which leads to El-Nino: dry conditions with high surface pressure and; La-Nina: low air surface pressure accompanied by cold and wet weather. See next page for simple diagram illustration [pic] As a result of the Earth surface temperature to keep on rising due to the greenhouse effect the results being a more and more drastically changing macro climate which in turn leads to more rain and eventually will lead Earth into another Ice-Age but that is a topic for another day.
The heavy rains on a constant basis keeps the rivers and dams full up to their limits so in the event of a heavy cloud break the already full rivers and dams cannot enclose all the extra water and all that water needs to go somewhere thus leading to floods, in most cases in South-Africa the floods will be flash floods. But there is also the chance of major floods in the form of a dam overflowing and then breaking the wall or even minor floods like in the December of 2012 the Ncandu River flowing through Newcastle KZN overreaches its banks and fills the Trim park with water at least 1-2 feet deep as the trim park is adjacent to the rivers. . The Effect of Development on Flood Hazards in SA Right around the world the population keeps growing at an alarming rate as the birth to mortality rate is not balanced which leads to a world population always wanting and needing to expand city and/or town borders. In this case the chances are very good that eventually there will be building developments inside flood plains or lower laying terrain in the proximity of a dam or large volume of water.
Thus the engineers of the modern world in developing countries like for instance South-Africa need to come up with new initiatives to improve building techniques to overcome the obstacle of flooding as the floods can be the cause of havoc among the inhabitants of developments within flood plains or beneath the flood level, and also cause a lot of structural and esthetic damage to a city or town. The MooiRivier Mall in Potchefstroom is a classic example of development within a flood hazard. The mall has been constructed on stilt type of tructures that allows the river to flow through underneath the mall but the engineers along with environmental specialists sought to come up with a few ingenious plans to prepare for floods of High hazard (1 in 20 years), medium flood hazards (1in 50 years) and low flood hazard (1 in 100 years) by means of designing a drop away wall where if a certain amount of water flows into a catchment a buoy lifts up and triggers a release on the wall which allows for the brick wall to fall down and allow water to flow into an drainage water way down to the central collection point at the bottom most point of the parking lot back into a stream (the release mechanism works on the same principal as a toilet bowls’ float valve). The parking lot has also been designed on a slope (no flat parking) to act as a funnel leading water away from the mall or danger zone and down into a sub stream or channel. The Mall had a few good tests in the last 5 years of its existence and the engineers and environmental specialists did a good job to overcome the developing in a flood hazard obstacle (Jan-Albert Wessels. IAIA North-West, 2012. ) [pic] Picture: (Viljoen, MF. The Application of flood lines in land use controll. 2009) 5. The Effect of The Economic Status of People Regarding Flood Hazards.
Flooding can and have caused a lot of damage in the past and will continue to do so as the macro climate will keep changing in favor of floods so all we can to do is to prepare ourselves and adapt to the changes of climate, floods cost the head of states and countries a great deal of money to develop in flood plains as well as being prepared to deal with any floods and the cleaning up there after. But it is not just the people on top that lose money, the people who actually live in the house that gets swept away or drive the car that rolls over or submerges, it is them that lead the most damage to their financial stance in life and 80% of the time it will be people from informal settlements or rural areas that lead the damage as they do not follow proper procedure to build their houses and then they build in areas of a high flood risk without them even knowing.
Thus the counties management somehow needs to get it under control as they have tried to do the in the past and actually still trying to do with regard to the housing subsidiary they offer to people of South-Africa. 6. Conclusion My conclusion regarding floods in South-Africa is that our main floods are flash floods that happen as result of heavy rains from the La-Nina time period of the Southern Oscillation, we as the people of our country need to stand together to make a difference in preventing people to build in dangerous high flood risk areas and also need to convince the children of today in developing countries to come up with fresh and new ideas to overcome development issues in flood risk areas. A countries economic development also greatly depends on its readiness for fighting disaster situations and keeping a disaster under control.
A country like South-Africa can suffer great losses financially as result of floods that could have been prevented by means of making use of the right infrastructure on the key areas in developed areas as well as developing areas. Flooding is a natural occurrence and will never be fully under control but the minds of today can shape the ideas of tomorrow with that I leave my mark on the topic of flooding in South-Africa. [pic] 7. Bibliography • Anonymous. 2012. Causes and types of floods. [Web: http://kidlat. pagasa. dost. gov. ph/genmet/floods/cause_types. html]. [Accessed: 14 March 2013] • Department: provincial and local Government. 2009. National Disaster management centre. Flood awareness. PDF 5p. [Accessed: 15 March 2013] • Anonymous. 2011.
La Nina Influenced Flooding in South Africa. AccuWeather. [web: http://www. accuweather. com/en/weather-news/la-nina-influenced-flooding-in/44853]. [Accessed: 13 March 2013] • SAPA. 2013. Floods Cause havoc across South Africa. Mail ; Guardian, Africa’s best read. [web: http://mg. co. za/article/2013-01-20-floods-cause-havoc-across-south-africa]. [Accessed: 15 March 2013] • Anonymous. 2013. Definition and nature of flood. [web: http://kidlat. pagasa. dost. gov. ph/genmet/floods/def_nature. html]. [Accessed: 15 March 2013] • SSC. 2011. The nature of flooding. Sunshine coast council, Queensland. [web: http://www. sunshinecoast. qld. gov. au/sitePage. cfm? code=flooding-nature]. Accessed: 13 March 2013] • Department: Provincial and Local Government, Prof Viljoen. MF, Swiegers. C. 2009. The application of flood lines in land use control. Disaster reduction conference. [web: http://conferences. ufs. ac. za/dl/userfiles/Documents/00000/134_eng. pdf]. [Accessed: 14 March 2013] • Times Live. (2011, February 2). [web: Urgent flood warning along Orange River. ] [Accessed February 14, 2011]. • United Nations Integrated Regional Information Networks. (2011, February 10). Southern Africa: Risk of food insecurity in wake of floods. IRIN News. [Accessed February 14, 2011. ] • Anonymous. 2011. Floods in South Africa. Earth Observatory, NASA. [web: