Runoff renewability is an important topic in the study of water cycle,and the knowledge of it is important for sustainable utilization of water resources in arid and semi-arid climate areas.Based on hydrological and meteorological data and the information related with human activity including soil and water conservation and water diversion,and using statistical method,we have studied the temporal variation in runoff renewability (Irr) and its formative cause in the middle Yellow River basin.We found that at the time scale of 59 year,Irr shows a decreasing trend superposed by some secondary fluctuations,which divides the variation into four stages.Although the correlations of Irr with three climate variables in the same year such as annual precipitation (Pm),air temperature (Tm) and summer monsoon intensity (SMI) are relatively low,we found significant time-lag effect of the variation in Pm,Tm and SMI on Irr,based on which the characteristic length of time-scale (Lt) can be determined.The correlation coefficients of Irr with N-year moving averages of a climate variable were calculated and then plotted with N.The N associating with the turning point is determined as Lt.We found that the Lt for the influence of Pm,Tm and SMI on Irr are 11,9 and 4 years respectively.There is close negative correlation between Irr and the area of each type of soil and water conservation measures,and the total area.The large-scale implementation of ecological restoration centering on "conversion of degraded farm land into forest and grass land " since 1998 has resulted in a further reduction in Irr.A regression equation between Irr and the index (Iwd,5m) of warming and dryness and the total area (Asw) of soil and water conservation measures was established which indicates that Irr decreases with Iwd and Asw.
drainage basin water cyclerunoff renewabilityclimate changesoil and water conservationmiddle Yellow River
NETL
NSTL
万方数据
维普
