desertification source : 九龍工業學校譚國新老師 (hkedcity)...

Desertification

Source : 九龍工業學校譚國新老師 (Hkedcity)香港大學課程學系母語教學教師支援中心

1950 s

What are the changes on the landscape ？

1970 s

此照片摘取自新世紀世界地理百科全書

Desertification is intensification of desert-like condition in true desert areas (annual precipitation < 250 mm), or

the extension of desert-like conditions into previously non-desert areas.This often takes place in semi-arid areas (annual precipitation between 250 - 375 mm), e.g. Sahel region at the southern fringe of the Sahara Desert.

此照片摘取自新世紀世界地理百科全書

35

100

Precipitationmm

Temperature C

302520

50

It is a tropical grassland ( ) with equatorial and climate. Rainfall is (annual rainfall lies between mm and mm and rain mainly concentrates in summer.

Savannawet dry

scanty / low250 375

Based on the map of Africa, where

can we find desertification ?

薩赫勒地區Sahel region

Sahara Desert

Tropical rainforestequato

r

1950 60 70 80 90

500

1000 PopulationPasture 草地

Nomadic herding 牲畜

Precipitation mm

Time (year)

Climatic change

Population explosion

less rainfall

overcultivation

overgrazing

devegetation for firewood

as fuel

Soil erosion

dese

rtifica

ti

on

The End