The Characteristic Of Runoff And Its Response On Climate Change And Human Activities In Inland Basins, Hexi Region

As one of the most active sub-systems on the surface of earth, Climatic system has already attracted many scientists focus their research on it. It is no doubt that research on climate change is one of important and key aspect of this kind of work. Climate change has been recognized one of uncontroversial truths we face. However, there is huge disagreement on its impact on different sub-systems (including water system and hydrological processes) and its heterogeneity between different areas. In spite of human’s influence is so little in the long history, considering the population explosion and its increasingly active, we no longer could effort to ignore it. As essential component of hydrological cycle, Runoff plays pivotal role in both landscape and local residents’life. Its change characteristic result from climate change and also be adjusted by human activities (such as building dam).The article applied Mann-Kendall and wavelet analyses to data on annual runoff aim to work out its change characteristic (such as period and tendency) and also conduct correlation and spatial comparison analysis. Base on this, selecting the Changma irrigation district as typical area to analyze the relationship between human activities and runoff change. Finally, the regression analysis is employed to gain such as temperature, rainfall, local population and cultivation area factors’impact to runoff reduction between the Changma and Shuangta reservoir.According to the result, there are short-period, mid-period and long-period cycle in runoff change in research area. In Shiyang Basin (lie in east part of research region), the runoff shows a trend of decrease, especially before the mid-1970s. As for main Heihe basin,1980s is turning point for runoff-after it, runoff increase instead of decrease with time over. Over most of the time, while runoff drops in the west part of Heihe basin. In Shule basin, runoff gradually become rising tendency from decrease trend and further obvious increase.The characters of spatial distribution on precipitation and temperature are show as follow: rainfall is decrease from the east to west, as well as from mountain area to plain; by contrast, temperature closely related to the altitude of one region---he higher altitude, the lower temper--nd result in south temperature is higher than north within research (and Mazong mountain area is except). Before1990s, the change in temperature shows heterogeneity over region and unobvious change tendency. After that, this situation has changed for ever—emperature in nearly all area increase by different degree. With regard to rainfall, its change trend is on rise during the past50years, especially after1990s. This phenomenon obvious agrees with conclusion of the west China become moist during the past few decades. In addition, rate of change in precipitation has close relation to local precipitation itself---the more rainfall, the lower rate. For instance, in mountain area where has relative ample rainfall, rate of change in precipitation accordingly low.The relationship between runoff and temperature displays spatial heterogeneity. That is to say there is gradual reduction in impact of temperature on runoff cross the whole area. Precipitation has better relationship to depth of runoff than runoff self, maybe due to the former, to some degree, consider the producing process of runoff.The relationship between runoff consumption (between Changma and Shuangta reservoir) and local population is unobvious. With regard to cultivation area, there is somehow positive relationship (correlation coefficient is0.244).Temperature has the best relationship to runoff consumption when considered both climate change and human activities, including factors such as Temperature, precipitation, population and cultivation area. This phenomenon could derive from the character of evaporation in arid and semi-arid region. By contrast, the relative little contribution of precipitation on runoff could put down to lack of rainfall and most of it is ineffective precipitation (fail to produce runoff). Runoff consumption also has closer link to population than cultivation area (attribute to local irrigational water sources mainly from groundwater).