渭河上游天然径流变化及其自然与人为因素影响贡献量

从20世纪60年代开始,渭河上游入陕西境内的水量不断减少,90年代天然径流量仅为60年代的60%。分析天然径流与降水的相关关系,对降水与非降水因素对径流减少的贡献进行了定量分析。结果表明,降水与非降水因素共同作用使得渭河上游径流量不断减少,且从20世纪70年代开始,非降水因素的贡献率逐渐增强,成为影响渭河上游天然径流量减少的主要因素。分析天然径流量与气温的相关关系,两者的相关系数在0.47以上,采用假设法,将气温从非降水因素中提取出来,进一步分析自然因素与人为因素的影响,结果表明,80年代以前,以自然因素影响为主,80年代以后,以人为因素影响为主,且人为因素的影响程度在逐渐增强,其原因在于人类活动改变下垫面导致径流减少。

Change of Natural Runoff and Contribution of the Natural and Artifical Factors to the Upper Reaches of Wei River

Since the 1960s,the quantity of inflow entering Shanxi Province in the upper reaches of the Weihe River has decreased steadily,and in the 1990s,the quantity of natural runoff was only 60% of that in the 1960s.This article analyzed the relationship between natural runoff and precipitation,as well as quantified the extent to that effect of rainfall and non-rainfall on the decreased natural runoff.The result indicated that both rainfall and non-rainfall contributed to the decreased natural runoff in the upper reaches of the Weihe River,and the contribution rate of non-rainfall factors increased from the 1970s,becoming the major reason resulting in the decreased natural runoff in the upper reaches of the Weihe River.This article also analyzed the relationship between natural runoff and temperature,and the correlation coefficient of both is more than 0.47.It further analyzed the influence made by natural and artificial factors,in the case of abstract the factor of air temperature from non-precipitation factor.The results showed that natural factors contributed most before the 1980s,while it was replaced by artificial factors after the 1980s.The extent of the influence of the latter intensified gradually due to runoff decrease resulting from human activity modified underlying surface.