Assessment of Streamflow Change in Middle-Lower Reaches of the Hanjiang River

Abstract

The hydrological processes of the middle-lower reaches of the Hanjiang River have been altered significantly because of water diversion and reservoir construction. The combined wavelet transformed Mann-Kendall (WT-MK) trend test was used to improve detection of the variability of streamflow and aberrance points. The indicators of hydrologic alteration (IHA), the Dundee hydrological regime alteration method (DHRAM), the ecosurplus (ES) and ecodeficit (ED), and the double mass curve (DMC) methods were applied to reveal hydrologic alterations associated with reservoir construction from multiple perspectives. Results indicated that (1) the integrated alteration degrees at Huangjiagang, Huangzhuang, and Shayang stations were 35.94, 32.46, and 36.35, respectively, and there were two, one, and one indicators (high level) at the three respective stations; (2) both an annual and seasonal ED occurred, whereby the magnitude of high flows decreased and the magnitude of low flows increased, which led to the ED in normal periods and the ES in dry periods becoming more apparent; and (3) the hydrologic regime was affected by human activities from 1975 to 29, especially from 2 to 29.