Centennial fluctuations of flood-season discharge of Upper and Middle Yangtze River Basin, China (1865–1988): cause and impact.

This paper reveals the nature of flood-season discharge and the associated impact on the upper and middle Yangtze river basin, on the basis of a historical database of daily discharges recorded at the Yichang (1865–1985) and Hankou (1878–1988) hydrological stations. Results show the period of discharge fluctuations of 2–6a, which is significant during 1878–1900 and 1915–1975 at Yichang station and the period of 2–7a during 1865–1905 and 1925–1975 at Hankou station. Within these periods, a major period of 2.9–3.5a and two secondary periods of 7–8a and 13.9–16.5a can be further identified from both stations. Our observation verifies that the fluctuations of streamflows of the upper and middle Yangtze River are fairly consistent with the periodicities of the Asia monsoon precipitation and ENSO event, reflecting coupling effect on the fluctuations of discharges in the Yangtze basin. In the 1920s–1960s, intensified variability of streamflows of the upper and middle Yangtze River was closely associated with warming temperature in the basin and in China as well. In 1975–1988, insignificant discharge fluctuations recorded at both stations can be chiefly attributed to human activities, i.e., the large number of reservoirs constructed and associated increasing capacity of water storage, which has largely weakened the discharge fluctuations throughout the basin. [ABSTRACT FROM AUTHOR]