Analysis Of The Meteorological And Hydrological Charateristics In The Yarlung Zangbo River Basins

Yarlung Zangbo River is the longest river in the Tibet Plateau with plenty of water resources, which is the major water source for the Tibet Plateau. The rivers have high water heads, and the high potential hydropower isnext to the Yangtze River. Understanding the water resources characteristics and the variability is important for utilization and sustainable developmentof the water resources, the eco-environment protection.This study selects six representative hydrological stations located on the main stream and the main tributaries of the Yarlung Zangbo River and uses the statistics methods such as linear regression method, wavelet analysis, trend analysis and jump analysis for investigating the time series of historical river discharge, precipitation, air temperature and evaporation. It aims to revealthe changing trend, periodical change and abrupt change of the major hydrological and meteorological parameters, and to understand the impacts of climate change on the river discharge during the past 50 years.The results of trend analysis shows that all stationshave common increasing trend for the annual discharge, annual precipitation, and annual mean air temperature.The fluctuations of the positive and negative anomaly exists in different decades, and the time series have the same order. The airtemperature at all stations has a significant increasingtrend, which is significantly higher than the national average and the global average. The pan evaporationdecreases with the increase of precipitation.Periodical change analysis shows that the major meteorological elements at all stationshave the changing cycles of 3 ~ 5 years, round 10 years, 25 ~ 35 years mainly.All parameters have a primary cycle of 10 years and secondary cycles of 3 ~ 5 years and more than 20 years.Precipitation and runoff have the same periodical change.Results of abrupt change shows that major parameters at most stations have abrupt changes, the pan evaporation and air temperature have significantly abrupt changes.;The annual dischargehas an abrupt change in 1998 at the main river and the NianChu River.The abrupt change of annual discharge in Lhasa River occurs in 1996, and occurs in 1995 in Nyang River.Correlation analysis shows that rainfall and runoff have significant correlation at a level of 99%. Air temperature and runoff has no obvious correlation. Evaporation and runoff have a negativecorrelation, which is less significant comparing with thecorrelation between precipitation and runoff.Relative humidity are positivelycorrelated with the runoff, this correlation is weaker than that between the precipitation and runoff,but strongerthan the correlation between the evaporation and runoff.