Effect of Climate Variability and Human Activities on Runoff in the Jinghe River Basin, Northwest China

Much attention has recently been focused on the effects of climate variability and human activities on the runoff. In this study, we analyzed 56-yr(1957–2012) runoff change and patterns in the Jinghe River Basin(JRB) in the arid region of northwest China. The nonparametric Mann–Kendall test and the precipitation-runoff double cumulative curve(PRDCC) were used to identify change trend and abrupt change points in the annual runoff. It was found that the runoff in the JRB has periodically fluctuated in the past 56 yr. Abrupt change point in annual runoff was identified in the JRB, which occurred in the years around 1964 and 1996 dividing the long-term hydrologic series into a natural period(1957 – 1964) and a climate and man-induced period(1965 – 1996 and 1997 – 2012). In the 1965 – 1996 period, human activities were the main factor that decreased runoff with contribution of 88.9%, while climate variability only accounted for 11.1%. However,the impact of climate variability has been increased from 11.1% to 47.5% during 1997 – 2012, showing that runoff in JRB is more sensitive to climate variability during global warming. This study distinguishes theeffect of climate variability from human activities on runoff, which can do duty for a reference for regional water resources assessment and management.

西北干旱区降水中氢氧同位素研究进展

借助近年来的相关研究文献对中国西北干旱区降水中氢氧同位素特征和相关科学问题进行了梳理和总结,主要结果:①西北干旱区降水稳定同位素呈现出显著的季节性变化,夏半年高,冬半年低,充分体现了同位素分布的温度效应;从空间上看,同位素低值区分布在天山等山地,盆地为高值区。②温度是西北干旱区大气降水同位素组成的主要控制因素;事件降水尺度上部分区域夏季存在降水量效应;地理因素及水汽来源等对大气降水同位素的分布有区域性差异。③西北干旱区区域大气降水线斜率和截距均较低,整体显示出干旱的气候特点,但内部地域差异性显著。④降水中过量氘值变化幅度大,体现了西北干旱区水汽来源复杂、降水形成时环境要素差异性大的特点;过量氘具有冬高夏低的特点,但由于夏季存在强烈蒸发,部分站点也呈现出冬低夏高的特点。⑤西北干旱区降水主要水汽来源为西风带,也会受到季风和极地气团的影响。

n overview of climate change impacts on the society in China

Society could sustain the impact of climate change by adapting to the change and mitigating risks from adverse effects of increasing changes,so that it can continue maintaining its prospect and improving wellbeing.Nevertheless,climate change is more or less affecting society'sfunctions at different scales,including both individuals and communities.In this review,we discuss the relationship between society and climatechange in China from the aspects of the needs at different socioeconomic developing stages.The relationship as well as the current spatialpattern and future risks of the climate change impacts on societies are summarized.The complexity of social and climatic systems leads to thespatial heterogeneity of climate impacts and risks in China.To more effectively leverage increasing knowledge about the past,we advocategreater cross-disciplinary collaboration between climate adaption,poverty alleviation and Nature-based Solutions(Nbs).That could providedecision makers with more comprehensive train of thoughts for climate policy making.

Assessments on surface water resources and their vulnerability and adaptability in China

A clear understanding of the changes of water resources under the background of environmental changes is of great significance for scientific management and utilization of water resources in China.This study systematically analyzed the spatialetemporal variations of surface water resources in China since 2000.Water vulnerability in current(2010s)and its trends from 2000 to late-2010s in different regions of China were also summarized.In addition,the correspondingly adaptive measures to counter regional risks to water resources were proposed.We concluded that the runoff of major rivers had been decreasing in eastern China and increasing in western China during 2000-2018.In the arid area of Northwest China,the alpine runoff has shown an overall upward trend since the late-1990s/early-2000s,with a 10%-25% increase caused by the increase of glacial meltwater and precipitation.While the runoff of each hydrological station in the 2000s-2010s was 34.7% lower than that in the 1950se2010s on average.The increases in precipitation and glacial meltwater with global warming caused a rapid expansion of lakes in the Qinghai-Tibet Plateau and Xinjiang,thus leading to an increase in total area and water quantity of lakes in China from 1995 to 2015.The mean contribution rates of climate change and human activity to runoff change in river basins of China were 53.5% and 46.5%,respectively,during the period of 2000-2010s.The driving factor of runoff change in many river basins has gradually changed from climate change(1950s-2000)to human activity(2000-2018).During 2000-2018,the contributions of human activities to runoff change were 50%-80% in major rivers of eastern China.The vulnerability in most areas of Northwest China and North China is generally high,with the vulnerability index greater than 0.6.Comparatively,in Northeast,East,South,and Central China,it is lower or not vulnerable.In Southwest China,the vulnerability varies greatly with Yunnan and Sichuan relatively low while Chongqing and Guizhou relatively high.The precipitation increase,the application of water-saving technology,the establishment of flood control and drought relief engineering facilities,and the introduction of relevant policies and measures have helped to gradually reduce the vulnerability of water resources in most areas of North and Northwest China(except Xinjiang)from 2000 to 2010s.Water vulnerability has been increasing in southern China,caused by climate change and the development of industry and agriculture,which increases water resource exposure since 2000.Based on the typical risk factors and vulnerability characteristics of water resources in different regions,this study proposed some targeted adaptive measures correspondingly so as to scientifically deal with the problems of surface water resources in China.