Based on the data of runoff and sediment discharge measured from 1951 to 2014 in Dongting Lake

evolution characteristics of water and sediment were analyzed by Mann-Kendall test

sliding t-test and ordinal clustering analysis. The relationship between precipitation

runoff

and sediment was analyzed by regression curve fitting and normalization curve

so that the driving factors influencing the variation of water and sediment in Dongting Lake could be figured out. The main results were as follows: (1) There were differences in the mutation year of runoff and sediment into and out the lake. The mutation year was 1971 for runoff into and out of the lake

1985 for sediment into the lake

and 1970 for sediment out of the lake

respectively. (2) The runoff in Dongting Lake was attenuated by the stage

with the change being the most obvious during 1972 to 1977. (3)The sediment into the lake was characterized by the stage attenuation

and the average annual sediment decreased by 75.34% from 2004 to 2014. (4) The runoff into and out the lake was mainly affected by precipitation change during 1951 to 1971 and 1978 to 1985

and by human activities such as beach natural bending cutting

Gezhouba hydro-power stations

Wuqiangxi reservoir and the Three Gorges Project during 1972 to 1977 and 1986to 2014. (5) The amount of runoff had a certain impact on the amount of sediment into the lake during 1951 to 1971. The main factor affecting the reduction of sediment was the water conservancy project during 1972 to 2014. In summary

the dominant driving factors were different at different stages of the processes of water and sediment in Dongting Lake Basin. The runoff into the lake were mainly driven by water conservancy projects during 1972 to 1977 and 2004 to 2014. The runoff out of the lake were mainly driven by water conservancy projects during 1976 to 1985 and 2004 to 2014.The runoff into and out of the lake were mainly driven by precipitation change in the other two other stages.