青海湟水流域降水过程的持续性特征与干旱发生趋势

The Persistence of Precipitation and the Trend of Droughts in Huangshui Basin

以湟水流域6个气象站点1959-2016年逐月降水量资料为基础,采用距平分析法、Mann-Kendall检验对流域内降水变化特征进行分析,结合重标极差法分析流域未来降水的变化趋势,并用游程理论和马尔柯夫链分析了流域内干旱特征和未来干旱趋势。结果表明:研究区降水年际变化较为明显,过去58 a间全年及4个季节降水量呈增加趋势,其中冬季增加趋势最为显著;多年平均降水量在空间分布不均匀,流域中部地区降水量最大,下游地区降水量最小,Cv空间分布特征与多年平均降水量相似。通过Hurst指数可知,在1 a时间尺度上,流域年降水量表现为较强的持续性特征,在5 a和10 a时间尺度上呈现极强的持续性特征,未来不同时间段内年降水量与4季降水量可能有所增加。从统计结果来看,流域发生连枯水的概率大于连丰水,说明更易发生连枯水现象。根据加权马尔柯夫预测结果可知,2017年湟水流域为平水年。

Based on the monthly precipitation data of 6 stations in Huangshui Basin from 1959 to 2016,the anomaly analysis method and Mann-Kendall test are used to analyze the characteristics of precipitation process changes in this basin,and the trend of future precipitation is analyzed combined with the method of R/S. The drought characteristics and future drought trends are analyzed by using the run theory and Markov chain. The results show that the interannual variation of precipitation in this basin is more obvious. The precipitation in the whole year and the four seasons in the past 58 years shows an increasing trend,among which the increasing trend in winter is the most significant. The average annual precipitation is not uniform in the spatial distribution,the precipitation in the central region of the basin is the largest,and the precipitation in the downstream region is the smallest. The spatial distribution of Cv is similar to the average annual precipitation. Through the Hurst index,it can be seen that in the 1-year time scale,the annual precipitation in the river basin shows a strong continuous characteristic,showing strong persistent characteristics on the 5-year and 10-year time scales,and the annual precipitation in different time periods in the future. Precipitation may increase with seasons. According to the statistical results,the probability of continuous water in the river basin is greater than that of Lianfengshui,indicating that it is more prone to dry water. From the statistical results,the probability of continuous dry water is greater than that of continuous water,indicating that the phenomenon of continuous low water is more likely.