Characteristics of Runoff-Sediment Variation in Ningxia-Inner Mongolia Reaches of the Upper Yellow River

Based on the data of annual runoff and sediment load in four hydrological stations on the upper Yellow River during the period of 1950-2009,the characteristics of temporal,spatial,as well as abrupt change points of incoming water and sediment conditions were analyzed in detail using the liner trend,Mann-Kendall and Morlet wavelet.The results indicate that the annual runoff and sediment load decrease significantly in recent 60 years,and especially at Toudaoguai Station of runoff and Xiaheyan Station of sediment load.There are significant mutation both in the water and sediment sequences and the abrupt change points of sediment load are earlier than that of runoff.Both the water and sediment sequences have particular multi-scale and multi-resolution attributes,but the scale of each is not completely consistent.