According to the analysis of elements

compounds

and grain size of 128 samples

we study the flood variation indicated by sediment in floodplain in the Jingyang reach of Jinghe River during deposit of floodplain. Results show that the contents of Mn

Ni

Cu

Zn

Ga

Pb

Ba

Rb

V

Al2O3

Fe2O3

and K2O change obviously in the profile. Each component changes obviously in the entire profile

which can clearly reflect the variations of flood and precipitation with high resolving power. The profile may be divided into 18 sediment layers

indicating 18 flood events at different scales and 18 years with much precipitation. The finer grain size is

the higher contents of Mn

Ni

Cu

Zn

Ga

Pb

Rb

V

Al2O3

Fe2O3

and K2O are and the lower content of Ba is

which indicates small flood intensity

low flood level

and less precipitation in deposition. In contrast

the coarser grain size is

the lower contents of Mn

Ni

Cu

Zn

Ga

Pb

Rb

V

Al2O3

Fe2O3

and K2O are and the higher content of Ba is

which indicates high flood intensity

high flood level

and more precipitation at deposition. The small changes of two or more elements

compounds

and grain size in the thin layer formed in the same sediment layer in the 18 floods indicate two or more flood peaks frequently appeared in the period of most floods. Sediment in the 14th

12th

13th

8th

5th

and 1st layers in floodplain in the Jingyang reach of Jinghe River reflects that annual precipitation increases in the whole basin and annual rainfall is greater than 800 mm.