FLOODPLAINS

FLOODPLAINS

1. A FLOODPLAIN IS THE WIDE, FLAT AREA OF LAND EITHER SIDE OF THE RIVER IN ITS LOWER COURSE FORMED BY FLOODS WHEN THE AMOUNT OF WATER IN A RIVER EXCEEDS ITS CHANNEL CAPACITY

2. STAGE 1

   • THE FLOODPLAIN IS FORMED BY BOTH EROSION AND DEPOSITION

3. STAGE 2

   • LATERAL EROSION IS CAUSED BY MEANDERS AND THE SLOW MIGRATION DOWNSTREAM TO WIDEN THE FLOODPLAIN

4. STAGE 3

   • THE RIVER CARRIES LARGE QUANTITIES OF SUSPENDED LOAD

5. STAGE 4

   • THE DEPOSITION ON THE SLIP OFF SLOPES PROVIDES SEDIMENT TO BUILD UUP THE VALLEY FLOOR

6. STAGE 5

   • AS THE WATER FLOODS ONTO THE FLOODPLAIN IT LOSES ENERGY THEREFORE HAS GREATER FRICTION. THE WATER IS THEN THEN SHALLOWER AND THE RIVER VELOCITY FALLS SO DEPOSITION OCCURS. THE REGULAR FLOODING RESULTS IN A BUILD UP OF LAYERS OF ALUVIUM WHICH FORMS A FLAT FERTILE FLOODPLAIN

7. STAGE 6

   • OVER YEARS THE DEPOSITS BUILD UP AND THERE ARE THICK LAYERS OF ALUVIUM WHICH IS WHY FLOODPLAINS HAVE FERTILE SOIL FOR FARMING