Evolution Law of the Runoff and Sediment Discharge of the Weihe River Based on Wavelet Multi-Scale Transform

Guanzhong Plain is the economic engine of Shaanxi Province, which contributed 70% GDP to Shaanxi Province, and however problems such as lower water resources per capita, uneven distribution, higher river sediment concentration restrict its economic and social development. In order to reveal the evolution law of multi-scale the runoff and sediment discharge of the Weihe River,to offer provide theoretical basis for comprehensive utilization of water resources, water and soil erosion for guanzhong area, the Weihe River Basin,and the Yellow River Basin. In this article, Morlet complex wavelet function was used to transform the sequence of runoff and sediment discharge of Huaxian country station during 1935-2011, and combined with the analysis of measured values of the runoffand sediment discharge, to know well periodic variation and catastrophe point of the runoff and sediment discharge of the Weihe River, the methods of moving t test, accumulative anomaly and Yamamoto was applied to detect catastrophe point. The findings of research indicate that the change of runoff and sediment discharge of the Weihe River have the fluctuating descending tendency from1935 to 2011, there are multi-time scales periodic variation of the runoff and sediment discharge of the Weihe River, the main cycles of runoff are 38 a,14 a and 4 a, apart from the 49 a cycle of sediment discharge, other main cycles are similar apporximately, while the main cycles of sediment discharge are 15 a,49 a,43 a and 4 a;catastrophe points of the runoff and sediment discharge in small-scale are much more than big-scale′ s, the amount and situation of catastrophe points of the runoff and sediment discharge in different scale are different;Because of climate and mankind activity the change of sediment discharge more complex than runoff, in addition to the sources of sediment and water are different, so the periodic variation and catastrophe points of sediment more complex than runoff, and the first main cycles of sediment discharge has unique change trend.