China's longest river - Chang Jiang.
Catchment - 1/5 of China.
Hydroelectric power - vital for china;s economimc development.
40% of China's output.
Human causes of flooding - soil erosion in upper catchment, land lost to grow more food because of population pressure, rapid urban growth meaning less infiltration.
Physical causes of flooding - huge catchment area, localised rain, timing and amount of rain varies in each sub basin.
Benefits of dam:
The hydropower provides 10% of China's current needs.
It creates jobs causing economic growth.