A Case Study Of Climate Change In The Loess Plateau During The Republic Of China

The Loess Plateau Located in the arid and semi-arid region, the distribution of water resources is uneven, there is floods and droughts frequently,it is very important to observate the water environment, it has a long history, in the process, the tools and techniques of observation and other aspects keep develop. But due to the limitations of technic, it is frequently that the hydrological observation is qualitative before the Republic of China, there is no essential hydrological data based on measurement, the effect it have is limited. The scientific hydrological observation is begin carried out in loess plateau region until the Republic of China, a large number of hydrological records which is actually observed is preserved, the study of the hydrological data can not only lay a foundation for the research on climate change of the Loess Plateau, and also provide theoretical basis for disaster prevention and mitigation in the region.This study take the hydrological observation of the Loess Plateau in the Republic of China as the breakthrough-point, and try to sort out some information about hydrological observation on the Loess Plateau in the Republic of China. we sort out the day-to-day average water level records of 65 hydrological stations on loess plateau and discuss the distribution of hydrological station and the characteristic of hydrologic observation data by teasing hydrological datas which are actually observed on the Loess Plateau and North China in the Republic of China. We can have a general understanding of the establishment and development of hydrologic station of the Loess Plateau in the Republic of China by the study of the development situation of hydrologic station in shaanxi and shanxi. The analysis shows that although the Loess Plateau during the Republic of China is political unrest, in general hydrological observation of this period is in forward gradually, and a large amount of hydrological observation datas is retained.Investigation on climate change of the Loess Plateau is the focus of this article. According to hydrologic observation data of these hydrological stations which are sorted out, combine with the river hydrological data of the Loess Plateau which is reconstruct using tree rings, ice cores and so on by experts in recent years, this study try to research the climate change on the Loess Plateau area using the method of wavelet analysis and so on. The effects of climate change factors in Loess Plateau region is very complex.In this process,to have a in-depth understanding of climate change we choose the summer monsoon and Pacific Decade Oscillation(PDO for short) as the object to research, and show the move process of rain belt in the eastern part of China and the influence on drought and waterlogging of the Loess Plateau, in the end we try to reinterpret the typical drought and flood. The research shows that the strength of summer monsoon are inversely correlation with the beginning time of rainy season in the Loess Plateau area, it means that when the summer monsoon is strong, the beginning time of flood season is late; and the intinal time become early when the summer monsoon is weak.; and there is a significant negative correlation is in exist between PDO and the runoff in the Loess Plateau in years of scale, namely when the PDO grows, the runoffs cut; otherwise, the runoffs increase. Further analysis found that the summer monsoon and the PDO have an important affect on the drought and flood in our county.The hydrological observation was conducted under the limited conditions in the Republic of China, we should take full advantage of these precious first- hand information to research the climate change. In this paper, we can see that there is a inseparable relationship between the rainfall change of the Loess Plateau and subtropical high which affect the rainfall change in the eastern of China. The summer monsoon and PDO influence the speed and time of rain belt movement by influencing the strength and location of subtropical high, and then affect the rainfall and the drought and flood situation of the Loess Plateau,even the eastern part of our country.