HKDSE Geography/M2a/Hydrographs and Flooding

Flooding is the condition in which the water in a river overflows. Hydrograph TODO: Need actual hydrographs Peak discharge is the maximum river discharge during a certain period of time. A hydrograph's rising limb shows the time during which discharge increases. A hydrograph's falling limb shows when discharge decreases. Factors All the factors above that affect discharge affect flooding. The greater the discharge, the greater the flood risk. In addition: Elongated drainage basin → Time lag ↑ → Floods ↓ Circular drainage basin → Time lag ↓ → Floods ↑ Straight river → Time needed for river to flow away ↑ → Floods ↓ Meandering river → Time needed for river to flow away ↑ → Floods ↓ Lakes ↑ → Act as a buffer during floods → Capacity ↑ → Bankfull discharge ↑ → Floods ↓