Development of a Meteorological and Hydrological Coupling Index for Droughts and Floods along the Yangtze River Valley of China

To comprehensively investigate characteristics of summer droughts and floods in the Yangtze River valley, a meteorological and hydrological coupling index （MHCI） was developed using meteorological and hydro- logical data. The results indicate that： （1） in representing drought/flood information for the Yangtze River valley, the MHCI can reflect composite features of precipitation and hydrological observations; （2） compre- hensive analysis of the interannual phase difference of the precipitation and hydrological indices is important to recognize and predict annual drought/flood events along the valley; the hydrological index contributes more strongly to nonlinear and continuity features that indicate transition from long-term drought to flood conditions; （3） time series of the MHCI from 1960-2009 are very effective and sensitive in reflecting annual drought/flood characteristics, i.e. there is more rainfall or typical flooding in the valley when the MHCI is positive, and vice versa; and （4） verification of the MHCI indicates that there is significant correlation between precipitation and hydrologic responses in the valley during summer; the correlation coefficient was found to reach 0.82, exceeding the 0.001 significance level.

Major Scientific Achievements of the First China–Japan Cooperative GAME/HUBEX Experiment: A Historical Review

In the summers of 1998 and 1999, Chinese and Japanese scientists cooperatively conducted the first large-scale energy and water cycle experiment(WCRP/GEWEX/GAME/HUBEX: World Climate Research Program/Global Energy and Water Cycle Experiment/Asian Monsoon Experiment/Huaihe River Basin Energy and Water Cycle Experiment) in the Huaihe River basin, Anhui Province of China. The main objective of this field experiment(HUBEX)was to investigate the multiple-scale structure characteristics, life cycles, and genesis and development mechanisms of the Meiyu system in East Asia as well as the cause of related flooding disasters. It was a joint China-Japan cooperative meteorological and hydrological observation experiment. On the basis of intensive observations, scientists from the two countries conducted follow-up investigations through collating and compiling data and performing scientific analysis during the following five years. It can be concluded that the HUBEX project has yielded comprehensive and remarkable achievements. This paper introduces the major scientific results derived from this field experiment and the ensuing investigations, and reassesses their merits and shortages for the purpose of providing useful experience and proposing new research targets as well as prospects for the initiation of a new joint scientific Meiyu experiment in the middle and lower Yangtze River basin.