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Sosiale wetenskappe: aardrykskunde

Graad 7

Oorstromings/vloede

Module 1

1. Oorstromings/vloede

1.1 Die voorkoms en ontstaan van oorstromings

1.1.1 Wat is ‘n oorstroming?

Dit ontstaan wanneer daar ‘n oormaat water is. Grond wat nie normaalweg deur water bedek is nie, word tydens ‘n oorstroming deur water bedek.

Dit gebeur soms dat ‘n jarelange droogte skielik deur swaar, aanhoudende reën beëindig word. Sulke rampe lok dan vrae uit soos: Is die klimaat besig om te verander?

Aktiwiteit 1:

Om ‘n sekere opinie oor ‘n geografiese verskynsel te huldig

[lu 2.1]

  • Wat is jou opinie omtrent die stelling dat die klimaat van die aarde besig is om te verander? Skryf ‘n paragraaf daaroor.

1.1.2 Waar kom oorstromings voor?

Bestudeer figuur 3 (’n wêreldkaart van waar die meeste ernstige oorstromings al voorgekom het) op bl. 10.

Jy sal opmerk dat die meeste oorstromings in Indië, China, Noord- en Suid-Amerika voorkom. Tog kan oorstromings in feitlik enige omgewing voorkom waar water is. Selfs in woestyne kan ernstige oorstromings voorkom. Onthou dat daar verskillende oorsake vir vloede is en hierdie oorsake bepaal WAAR die oorstromings gaan voorkom.

1.1.3 Wat veroorsaak oorstromings?

Water wat dele van die aarde oorstroom, kan verskillende oorsake hê, soos die volgende:

  • Sneeu wat smelt, bring meer water in riviere mee.
  • Uitsonderlike hoe reënval in ‘n area laat riviere hulle walle oorstroom. Hierdie soort reënval kom gewoonlik voor in die vorm van storms, siklone en moesonreën (Indië). Voorbeelde hiervan in Suid-Afrika was die Laingsburg-oorstroming, asook sikloon Demoina, wat Natal getref het.
  • Damme en/of oewerwalle wat meegee of oorloop.
  • Grondverskuiwings, aardbewings en vulkane kan riviere en ander watermassas ontwrig en tot oorstromings lei.
  • Oorstromings langs kuste word veroorsaak deur reusagtige seegolwe (tsunami’s) wat deur aardbewings op die seebodem veroorsaak word. Meer hieroor as ons aardbewings bestudeer.

1.2 Die uitwerking (gevolge) van oorstromings op die lewens van mense en hulle sosio-ekonomiese aktiwiteite

Menslike bedrywighede kan nie oorstromings veroorsaak nie, maar mense kan op indirekte wyse die omvang en skade daarvan vererger, soos hieronder verduidelik word.

  1. Onnadenkende gebruik van die grond as gevolg van
  • ontbossing
  • oorbeweiding
  • gronderosie.

Natuurlike plantegroei en hulle wortels word dus vernietig en dit kan nie meer die bogrond vashou as daar swaar reën val nie. Die reënwater word ook nie maksimaal deur die grond absorbeer nie. Reënwater loop dus vinniger af en neem die bogrond saam. Riviere en damme slik as gevolg hiervan toe.

  1. Die bou van paaie, geboue en kanale veroorsaak ook die vernietiging van die natuurlike plantegroei.
  2. Huise word soms op minder geskikte en selfs gevaarlike terreine gebou, waar oorstromings kan voorkom.

‘n Voorbeeld van so ‘n oorstroming in Suid-Afrika.

Op 30 September 1987 het ‘n geweldige tropiese storm oor Natal gewoed. Minstens 180 mense is dood. Plakkershuise het in hulle duisende in die reën verkrummel. Ander se dakke is afgeruk en huise is ernstig beskadig. Seweduisend gesinne is in een dag koud, honger en dakloos gelaat. Die meeste brûe en paaie is weggespoel en reddingswerkers kon nie per vragmotor hulp aanbied nie. Daar was geen elektrisiteit beskikbaar nie, asook geen riool- en kraanwater nie. Alle pypstelsels is deur die vloedwater vernietig. Besighede het tot stilstand gekom en geweldige finansiële verliese is op ekonomiese gebied gely. Boere het ook hul oeste en diere verloor. Alle ryk bogrond het weggespoel en dit sal jare neem om weer te herstel. Plaasdamwalle het gebreek en alle heinings is meegevoer. Herstelwerk het natuurlik geweldige finansiële implikasies gehad.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
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da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Aardrykskunde graad 7. OpenStax CNX. Sep 09, 2009 Download for free at http://cnx.org/content/col11020/1.1
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