珠江流域降雨结构时空演变特征研究

Spatial-Temporal Changes of Precipitation Structure across the Pearl River Basin, China

摘要: 本文利用珠江流域42个站点1960~2005年46年的日降雨资料，分析了年降雨总量(ATP)、年降雨总天数(ATD)、年降雨强度(ATI)、年平均降雨历时(MWP)以及各降雨历时的发生率和贡献率等降水指标，探讨了各种不同历时降雨的时空演变特征，并运用了改进Mann-Kendall法检验了降雨序列变化的显著性。研究结果表明：1) 珠江流域上游和中部地区降雨量呈现减少趋势，降雨天数在整个流域范围内呈现减少趋势，由此，流域的降雨强度总体上呈现上升趋势，特别是流域的中部和东部地区；2) 流域短历时降雨(2~5 d)的发生率较高，且占总降雨量的比重较大，表明易于出现集中性的降雨，而长历时降雨则出现下降趋势；3) 珠江流域的暴雨多集中在流域东部地区，而且暴雨在短历时降雨事件中的发生率和贡献率都比较高，特别是流域下游的三角洲地区，洪灾风险会显著提高，增加水资源供给的不确定性，加上经济的发展，人口的增加，需水的提高，将为水资源管理与利用带来新的挑战。

Abstract: Daily precipitation data over the Pearl River basin (1960-2005) from 42 rain gauges is used in this article. Precipitation indices such as annual total precipitation amount, annual total rainy days, annual precipitation intensity and annual mean rainy days are defined. These precipitation indices are analyzed using the modified Mann-Kendall method. Results show that: 1) Decreasing trend of precipitation is found mainly in the middle and upper Pearl River basin. Rainy-days are decreasing almost over the entire basin. Thus, the precipitation intensity of Pearl River basin is increasing, particularly in the middle and the eastern parts of the basin; 2) The occurrence and fractional contribution of wet periods with shorter durations (2 - 5 d) are tending to be predominant while longer durations are decreasing in recent decades; 3) Heavy storms are easy to occur in the eastern of the basin during shorter durations. Higher risk of floods and reduction of water yield in the lower basin will increase uncertainty of water supply in the Pearl River Delta and hence pose new challenges for water resources management.