Abstract:

Hydrological investigations were carried out in the upper reaches of the Hanjiang River. The Huangping profile in the Hanjiang River Valley was found and observed in detail in the field which contains a layer of palaeoflood slackwater deposits. The geomorphology and the parameters of the Huangping reach of Hanjiang River were measured in the field. The grainsize distribution was analyzed in laboratory. The result shows that the gray palaeoflood slackwater deposits inserted in the paleosoil were different from the loess and the paleosol. The palaeoflood slackwater deposits recorded a catastrophic floods events that might occur during the Eastern Han Dynasty (1 900-1 700 a B.P). According to the theory of Sedimentology and Hydrology, using the palaeoflood SWD pinch out and SWD thicksand content method,the palaeoflood water level elevation was found respectively for 154.95 m and 156.85 m;Its peak flow wasrestored by slope method, and the ancient flood peak flow was calculated respectively for 65 320 m3/s and 74 442 m3/s. These results were checked with various methods, which indicate the reconstructed peak discharge is reliable. These results are of great significance to exploit water resources and mitigate flood disasters of the upper reaches of Hanjiang River, at the same time, these results are of great significance to understand hydrological response to global climatic change