Response Characteristics Of Runoff Components To Climate Elements In The Source Region Of The Yellow River

The source region of the Yellow River is a typical cold and arid region.Since 1980 s, lakes has withered in size and river has become dry and many other degeneracy of hydrologic cycle has appeared in the source region. Thus, it is of important scientific significance to study the response of runoff components to climate change.The datum used in this paper are from 2000 to 2012 shown as follow:the precipitation and temperature datum with resolution ratio of 0.5°x 0.5°downloaded from China Meteorological Science Data Network, the MOD16 annual land evapotranspiration datum of MOD16 from the MODIS WED and daily runoff datum in Ji Mai hydrological station. Applying the software of ArcGIS and by means of the combination of primary factor analysis and stepwise multiple linear regression,the datum of precipitation and temperature are downscaled in space. The precipitation in state of solid and liquid are separated with the critical air temperature method, and by doing so, the spatial and temporal distribution of different precipitation state are determined; This paper also studies the connection of evaporation with precipitation and runoff in time scale; Besides, the base flow are computed and the variation of runoff component by using the Kalinin flow segmentation method. Based on all the work mentioned above, I analyzed the sensitivity of runoff component to climate elements, the results are shown as follow:Runoff in the region is mainly affected by precipitation during precipitation concentration period; And the time lag between runoff and precipitation is about 32 days, while certain phases showed the synchronous feature; Base flow index has a positive correlation with precipitation, and there is a trend to increase by year. The state of precipitation in the region is influenced by temperature in the whole year,precipitation in liquid starts from southeast and moves forward to northwest, while precipitation in solid moves in the opposite way. Water yield is in positive equilibrium in summer, while the balance is mainly controlled by discharge in winter;surface runoff and base flow has a positive correlation with precipitation, but they have a negative correlation with evaporation, and they more sensitive to precipitation compared to evaporation. Comparatively speaking, the sensitivity between surface runoff and evaporation is larger than that between base flow and evaporation, while surfacerunoff is less sensitive to precipitation than that between baseflow and precipitation.