The Yellow River is the second longest river in China. The headwaters of the Yellow River begin on the Tibetan Plateau and the river flows eastward, passing though the Loess Plateau and the North China Plain before emptying into the Bohai Gulf (Figure 1). The river flows 5464 km in distance in the main course and has a drainage area of 752443 km2. The Yellow River has been facing serious water problems, such as water shortage and eco-environmental degradation (Feng et al., 2005; Xu et al., 2002). In particular, the lower Yellow River has suffered from drying up phenomenon, i.e., zero-flow in sections of the river channel, since the 1970s. The water crisis in the Yellow River has raised a critical question: what contributes to the river drying up? The Yellow River drying up has been a hot topic in hydrology in China, attracting focus from many researches (Xu, 2005; Yang et al., 2004; Fu et al., 2004; Xia et al., 2004; Liu and Zheng, 2004).
On the basis of previous studies, the present study will focus on the climatic change and vegetation condition change in the basin. Forty years of hydro-climatic data and twenty years of vegetation condition data have been collected. The spatial climatic change and vegetation condition change will be examined to describe trends in different parts of the basin.