近50a东江流域径流变化及影响因素分析

以1956—2005年降雨、径流与气象资料为基础,应用Mann-Kendall趋势检验、小波分析以及R/S分析等多种方法,探讨了东江流域径流年际变化特征及其对气候变化以及植被覆盖变化的响应。结果表明:①50 a来流域年径流序列变化趋势不明显,存在4 a、7~9 a、11~13 a、16~22 a等4类尺度的周期性变化规律;河源、岭下站径流序列具有较强的状态持续性,博罗站持续性很小。②厄尔尼诺现象出现的当年,东江流域年径流量普遍减少;厄尔尼诺现象出现的次年,年径流量普遍增加。太阳黑子数的急剧变化,与东江径流量的丰、枯也有良好的响应关系。③50 a来,在降雨量呈不显著减少趋势的背景下,河源、岭下站径流仍然呈不显著增加趋势的主要原因是蒸发量下降的缘故,是气候因素和流域植被退化共同作用的结果。

Runoff Variation and Its Impacting Factors in the Dongjiang River Basin during 1956-2005

Based on the runoff and precipitation data at Heyuan, Lingxia and Boluo sations during 1956-2005, the Mann-Kendall, Rescaled Range analysis and wavelet transform analysis methods are used to find out the variation law of runoff and its impacting factors in the Dongjiang River Basin. The results show that there are no significant changing trend and abruptly jumping point for runoff series in the Dongjiang River Basin. The results of continuous wavelet transform indicate that there are obvious periodic variations with scales 4 a, 7-9 a, 11-13 a and 16-22 a for the annual runoff series, and scale 7-9 a is the first period. The computed Hurst exponents indicate that a long-term memory characteristic exists in the annual runoff series. Annual runoff amount is related to the occurrence of El nio event. And sunspot number(SSN) is significantly correlated to annual runoff amount. The results of linear correlation indicate that the more SSN is, the less annual runoff amount is. The results of statistical analysis show that trends and abrupt change of runoff are in accordance with that of precipitation, evaporation respectively, especially with the precipitation. Among the climate factors,precipitation and evaporation are the most important factors to the changes of runoff. NDVI(Normalized Difference Vegetation Index) series in the Dongjiang River Basin show a significantly decreasing trend during 1982-2005, but NDVI series presents insignificant effect on runoff directly, which may indirectly affect runoff by impacting evaporation. Runoff variations in the Dongjiang River Basin are affected by synthetic effect of regional climatic elements and vegetation deterioration.