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Abstract: The present study examines the spatial and temporal trends of precipitation, flood/drought, runoff, high and low river flow during flood season (May–October) for the Yangtze River Basin. Analyses are based on daily meteorological data for 137 stations from 1960 to 2004, daily hydrological data for two discharge-measuring stations at the Yangtze River and monthly hydrological data for one station for the same reference period. Flood/drought examination was done for the western, middle, and lower Yangtze River Basin. Significant precipitation changes can be detected for June and July during 1960–2004. The strongest precipitation increase was detected in the lower Yangtze region. A statistically significant negative trend can be found in September over the Yangtze River Basin, especially at the middle region. Changes of the precipitation extremes from May to October are of direct importance to the occurrences of high and low river flow. The main increase of flooding events can be detected for July in the lower Yangtze region, together with significant upward trends both for the monthly runoff and for the high river water stage. Drought frequency increased in the middle Yangtze River Basin in May, September and October, where downward trends for the monthly runoff and low river flow especially in May. During these months, flood and drought hazards in the Yangtze River Basin have been aggravated. [Copyright &y& Elsevier]

Abstract: This study investigated future changes of dryness/wetness in ten large river basins: the Songhuajiang River basin, the Liaohe River basin, the Haihe River basin, the Yellow River basin, the Huaihe River basin, the Yangtze River basin, the Pearl River basin, the Southeast River basins, the Southwest River basins and the Northwest Inland River basins across China during the first 50 years of the 21st century. The study was carried out according to the Standardized Precipitation Index (SPI), which is calculated by monthly precipitation data of ECHAM5/MPI-OM. Three anthropogenic greenhouse gas emission scenarios, SRES-A2, SRES-A1B and SRES-B1 have been considered. The frequency of dry/wet periods in these river basins was calculated and the trend detected by the Mann–Kendall non-parametric test. The results reveal that there is a trend towards drier conditions from northeast to southwest China in scenario A2 and a similar spatial distribution pattern in scenario A1B and B1. Areas with a high frequency of drought are detected under all three scenarios. In the next half century, the Haihe River basin, northeast China, is expected to show a significant trend towards drier conditions, which pass the 95% confidence level in scenario A2. In the Yellow River basin, the Huaihe River basin, the Yangtze River basin and the Pearl River basin, an obvious trend towards wetter conditions has been detected in scenario A1B. The Songhuajiang River basin, the Haihe River basin, the Yellow River basin and the Huaihe River basin show a trend towards wetter conditions, which passed the 90% confidence level in scenario B1. The future dryness/wetness frequency situation is complex in the ten large river basins. [ABSTRACT FROM AUTHOR]