干旱区生态环境知识资源中心

Water resources supply and demand conflicts in arid and semi-arid regions are seriously increasing in recent decades. Based on the time series of daily precipitation from 1958 to 2008 at Beijing, Tianjin and Tangshan meteorological stations, the Mann-Kendall test and wavelets analysis were selected to analyse the annual and seasonal precipitation. The results revealed that the annual and wet seasonal (June September) precipitation showed a decreasing trend, while the precipitation in the dry season (October May) showed an increasing trend in the past 51 years; The monthly distributions of decadal precipitation became more even with time. A significant yearly cycle was found at Beijing, Tianjin and Tangshan with periods of 26, 13 and 16 years, respectively. The results of the paper could provide references for the mid long hydrological forecasting and water resources planning in these three regions.