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URBANISATIONDefinition of urbanisation.The advantages and disadvantages of urbanisation.Factors influencing storm hydrographs.Case study on urbanisation.when the rural character of a town is gradually replaced by housing and industrial development, resulting in more suburbs. Essentially, it is an increase in the proportion.WHAT IS URBANISATION?THE ADVANTAGES AND DISADVANTAGES OF URBANISATIONAdvantages:

Growth in industrial productions to increase the economic growth of a country.Growth in trade and commerce to help the nations business sector.Development in tourism industries.Improvement in culture. Disadvantages:

In increasing of population will cause housing problems and slum will develop in this areas.The decrease in rural population effects the agricultural productions due to shortage of workers in rural areas.The increase in population in urban places pressurize water and sanitation facilities. It results in environmental pollution and self hygiene.The unemployment increases in urban areas due to limited job vacancies.Factors Influencing Storm Hydrograph: Human Activities (Urbanisation)Before Urbanisation:

Vegetated areas help to reduce flood risk by increasing the time it takes foe water to reach a river by encouraging infiltration (roots opening up the soil), intercepting water by their leaves and taking up water in their roots.

Effects on storm hydrograph:

Low peak discharge.Gentle rising limb and recession limb.Longer lag time.Less surface runoff.After Urbanisation:

Areas cleared by deforestation will respond quickly to rainfall due to the reduced interception.Impermeable surfaces (such as tarmac) have a much lower infiltration rate than naturally vegetated surfaces.

Effects on storm hydrograph:

High peak discharge.Steeper rising limb & recession limb.Shorter lag time.More surface runoff.CAUSES AND EFFECTS OF FLOODING IN MOZAMBIQUE 2000:

The flooding was triggered by exceptionally heavy rain in South Africa, lasting for 5 weeks in early 2000. Botswana was particularly badly hit, receiving 75% of its yearly rainfall in 3 days. On 22nd February , Cyclone Eline hit, bringing more heavy rainfall. The rain from Botswana and other South African countries ran into Limpopo, Zambezi and other rivers which flow through Mozambique to the sea. The river eventually burst causing severe flooding in Mozambique.In addition, the loss of grassland and draining of marshland for farms contributed to more rapid surface run off .The results were disastrous : services were cut off and many people were stranded, homeless or had died. Urbanisation in South Africa contributed to the large quantities of surface water run off swelling the rivers.

CASE STUDY

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