Synchronism of runoff response to climate change in Kaidu River Basin in Xinjiang, Northwest China

The runoff in alpine river basins where the runoff is formed in nearby mountainous areas is mainly affected by temperature and precipitation.Based on observed annual mean temperature,annual precipitation,and runoff time-series datasets during 1958–2012 within the Kaidu River Basin,the synchronism of runoff response to climate change was analyzed and identified by applying several classic methods,including standardization methods,Kendall's W test,the sequential version of the Mann-Kendall test,wavelet power spectrum analysis,and the rescaled range(R/S) approach.The concordance of the nonlinear trend variations of the annual mean temperature,annual precipitation,and runoff was tested significantly at the 0.05 level by Kendall's W method.The sequential version of the Mann-Kendall test revealed that abrupt changes in annual runoff were synchronous with those of annual mean temperature.The periodic characteristics of annual runoff were mainly consistent with annual precipitation,having synchronous 3-year significant periods and the same 6-year,10-year,and 38-year quasi-periodicities.While the periodic characteristics of annual runoff in the Kaidu River Basin tracked well with those of annual precipitation,the abrupt changes in annual runoff were synchronous with the annual mean temperature,which directly drives glacier-and snow-melt processes.R/S analysis indicated that the annual mean temperature,annual precipitation,and runoff will continue to increase and remain synchronously persistent in the future.This work can improve the understanding of runoff response to regional climate change to provide a viable reference in the management of water resources in the Kaidu River Basin,a regional sustainable socio-economic development.     

1956-2010年淮河流域极端径流的时空变化及统计模拟(英文)

Based on the daily runoff data from 20 hydrological stations above the Bengbu Sluice in the Huaihe River Basin during 1956-2010, run test, trend test and Mann-Kendall test are used to analyze the variation trend of annual maximum runoff series. The annual maximum series (AM) and peaks over threshold series (POT) are selected to describe the extreme distributions of generalized extreme value distribution (GEV) and generalized Pareto distribution (GPD). Temporal and spatial variations of extreme runoff in the Huaihe River Basin are analyzed. The results show that during the period 1956-2010 in the Huaihe River Basin, annual maximum runoff at 10 stations have a decreasing trend, while the other 10 stations have an unobvious increasing trend. The maximum runoff events almost occurred in the flood period during the 1960s and 1970s. The extreme runoff events in the Huaihe River Basin mainly occurred in the mainstream of the Huaihe River, Huainan mountainous areas, and Funiu mountainous areas. Through Kolmogorov-Smirnov test, GEV and GPD distributions can be well fitted with AM and POT series respectively. Percentile value method, mean excess plot method and certain numbers of peaks over threshold method are used to select threshold, and it is found that percentile value method is the best of all for extreme runoff in the Huaihe River Basin.     

三江源地区气候变化及其对径流的驱动分析(英文)

Based on the precipitation and temperature data of the 12 meteorological stations in the "Three-River Headwaters" region and the observed runoff data of Zhimenda in the headwater sub-region of the Yangtze River, Tangnaihai in the headwater sub-region of the Yellow River and Changdu in the headwater sub-region of the Lancang River during the period 1965-2004, this paper analyses the trends of precipitation, temperature, runoff depth and carries out significance tests by means of Mann-Kendall-Sneyers sequential trend test. Makkink model is applied to calculate the potential evaporation. The runoff model driven by precipitation and potential evaporation is developed and the influence on runoff by climate change is simulated under different scenarios. Results show that during the period 1965-2004 the temperature of the "Three-River Headwaters" region is increasing, the runoff of the three hydrological stations is decreasing and both of them had abrupt changes in 1994, while no significant trend changes happen to the precipitation. The runoff model suggests that the precipitation has a positive effect on the runoff depth, while the potential evaporation plays a negative role. The influence of the potential evaporation on the runoff depth of the Lancang River is found to be the significant in the three rivers; and that of the Yellow River is the least. The result of the scenarios analysis indicates that although the precipitation and the potential evaporation have positive and negative effects on runoff relatively, fluctuated characteristics of individual effect on the runoff depth in specific situations are represented.     

1956-2003年拉萨河流域径流变化趋势

Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956-2003 were analyzed, based on the hydro-data of the two hydrological stations （Lhasa and Tanggya） and the meteorological data of the three meteorological stations （Damxung, Lhasa and Tanggya）. The trends and the change points of runoff and climate from 1956 to 2003 were detected using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. The correlations between runoff and climate change were analyzed using multiple linear regression. The major results could be summarized as follows： （1） The annual mean runoff during the last 50 years is characterized by a great fluctuation and a positive trend with two change points （around 1970 and the early 1980s）, after which the runoff tended to increase and was increasing intensively in the last 20 years. Besides, the monthly mean runoff with a positive trend is centralized in winter half-year （November to April） and some other months （May, July and September）. （2） The trends of the climate change in the study area are generally consistent with the trend of the runoff, but the leading climate factors which aroused the runoff variation are distinct. Precipitation is the dominant factor influencing the annual and monthly mean runoff in summer half year, while temperature is the primary factor in winter season.     

华北平原降水的长期趋势分析(英文)

The North China Plain (NCP) is the most important food grain producing area in China and has suffered from serious water shortages. To capture variation water availability, it is necessary to have an analysis of changing trends in precipitation. This study, based on daily precipitation data from 47 representative stations in NCP records passed the homogeneity test, analyzed the trend and amplitude of variation in monthly, seasonal and annual precipitation, annual maximum continuous no-rain days, annual rain days, rainfall intensity, and rainfall extremes from 1960 to 2007, using the MannKendall (M-K) test and Sen’s slope estimator. It was found that monthly precipitation in winter had a significant increasing trend in most parts, while monthly precipitation in July to September showed a decreasing trend in some parts of NCP. No significant changing trend was found for the annual, dry and wet season precipitation and rainfall extremes in the majority of NCP.A significant decreasing trend was detected for the maximum no-rain duration and annual rain days in the major part of NCP. It was concluded that the changing trend of precipitation in NCP had an apparent seasonal and regional pattern, i.e., precipitation showed an obvious increasing trend in winter, but a decreasing trend in the rainy season (July to September), and the changing trend was more apparent in the northern part than in the southern and middle parts. This implies that with global warming, seasonal variation of precipitation in NCP tends to decline with an increasing of precipitation in winter season, and a decreasing in rainy season, particularly in the sub-humid northern part.     

Impacts of climate change and LULC change on runoff in the Jinsha River Basin

The climate change and Land Use/Land Cover(LULC) change both have an important impact on the rainfall-runoff processes. How to quantitatively distinguish and predict the impacts of the above two factors has been a hot spot and frontier issue in the field of hydrology and water resources. In this research, the SWAT(Soil and Water Assessment Tool) model was established for the Jinsha River Basin, and the method of scenarios simulation was used to study the runoff response to climate change and LULC change. Furthermore, the climate variables exported from 7 typical General Circulation Models(GCMs) under RCP4.5 and RCP8.5 emission scenarios were bias corrected and input into the SWAT model to predict runoff in 2017–2050. Results showed that:(1) During the past 57 years, the annual average precipitation and temperature in the Jinsha River Basin both increased significantly while the rising trend of runoff was far from obvious.(2) Compared with the significant increase of temperature in the Jinsha River Basin, the LULC change was very small.(3) During the historical period, the LULC change had little effect on the hydrological processes in the basin, and climate change was one of the main factors affecting runoff.(4) In the context of global climate change, the precipitation, temperature and runoff in the Jinsha River Basin will rise in 2017–2050 compared with the historical period. This study provides significant references to the planning and management of large-scale hydroelectric bases at the source of the Yangtze River.     

1960-2009年西南地区极端干旱气候变化(英文)

Based on the daily data of temperature and precipitation of 108 meteorological stations in Southwest China from 1960 to 2009, we calculate the monthly and yearly surface humid indexes, as well as the extreme drought frequency. According to the data, the temporal and spatial characteristics of the extreme drought frequency in inter-annual, inter-decadal, summer monsoon period and winter monsoon period are analyzed. The results are indicated as follows. (1) In general, the southwestern Sichuan Basin, southern Hengduan Mountains, southern coast of Guangxi and northern Guizhou are the areas where the extreme drought frequency has significantly increased in the past 50 years. As for the decadal change, from the 1960s to the 1980s the extreme drought frequency has presented a decreasing trend, while the 1990s is the wettest decade and the whole area is turning wet. In the 2000s, the extreme drought frequency rises quickly, but the regional differences reduce. (2) During summer monsoon period, the extreme drought frequency is growing, which generally occurs in the high mountains around the Sichuan Basin, most parts of Guangxi and "the broom-shaped mountains" in Yunnan. It is distinct that the altitude has impacts on the ex-treme drought frequency; during winter monsoon period, the area is relatively wet and the extreme drought frequency is decreasing. (3) During summer monsoon period, the abrupt change is observed in 2003, whereas the abrupt change during winter monsoon period is in 1989. The annual extreme drought frequency variation is a superposition of abrupt changes during summer monsoon and winter monsoon periods. The departure sequence vibration of annual extreme drought frequency is quasi-5 years and quasi-12 years.     

Precipitation cycles in the middle and lower reaches of the Yellow River （1736-2000）

Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that： the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation （PDO） coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong （weak） solar activity is generally correlated to the dry （wet） periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale.     

三江源区径流演变及其对气候变化的响应(英文)

Runoff at the three time scales(non-flooding season,flooding season and annual period) was simulated and tested from 1958 to 2005 at Tangnaihai(Yellow River Source Region:YeSR),Zhimenda(Yangtze River Source Region:YaSR) and Changdu(Lancang River Source Region:LcSR) by hydrological modeling,trend detection and comparative analysis.Also,future runoff variations from 2010 to 2039 at the three outlets were analyzed in A1B and B1 scenarios of CSIRO and NCAR climate model and the impact of climate change was tested.The results showed that the annual and non-flooding season runoff decreased significantly in YeSR,which decreased the water discharge to the midstream and downstream of the Yellow River,and intensified the water shortage in the Yellow River Basin,but the other two regions were not statistically significant in the last 48 years.Compared with the runoff in baseline(1990s),the runoff in YeSR would decrease in the following 30 years(2010-2039),especially in the non-flooding season.Thus the water shortage in the midstream and downstream of the Yellow River Basin would be serious continuously.The runoff in YaSR would increase,especially in the flooding season,thus the flood control situation would be severe.The runoff in LcSR would also be greater than the current runoff,and the annual and flooding season runoff would not change significantly,while the runoff variation in the non-flooding season is uncertain.It would increase significantly in the B1 scenario of CSIRO model but decrease significantly in B1 scenario of NCAR model.Furthermore,the most sensitive region to climate change is YaSR,followed by YeSR and LcSR.     

Climate transformation to warm-humid and its effect on river runoff in the source region of the Yellow River

The change characteristics and trends of the regional climate in the source region of the Yellow River, and the response of runoff to climate change, are analyzed based on observational data of air temperature, precipitation, and runoff at 10 main hydrological and weather stations in the region. Our results show that a strong signal of climate shift from warm-dry to warm-humid in the western parts of northwestern China （Xinjiang） and the western Hexi Corridor of Gansu Province occurred in the late 1980s, and a same signal of climate change occurred in the mid-2000s in the source region of the Yellow River located in the eastern part of northwestern China. This climate changeover has led to a rapid increase in rainfall and stream runoff in the latter region. In most of the years since 2004 the average annual precipitation in the source region of the Yellow River has been greater than the long-term average annual value, and after 2007 the runoff measured at all of the hydrologic sections on the main channel of the Yellow River in the source region has also consistently exceeded the long-term average annual because of rainfall increase. It is difficult to determine the prospects of future climate change until additional observations and research are conducted on the rate and temporal and spatial extents of climate change in the region. Nevertheless, we predict that the climate shift from warm-dry to warm-humid in the source region of the Yellow River is very likely to be in the decadal time scale, which means a warming and rainy climate in the source region of the Yellow River will continue in the coming decades.     

云南红河流域径流的时空分布变化规律

利用红河流域32个气象站1960-2000年逐月降水、气温、蒸发等实测资料,元江、李仙江和盘龙河1956-2000年径流量资料,使用GIS技术支持以及Kendall检验法、方差分析法、累积距平法,分析云南红河流域径流的时空变化规律,重点探讨径流时空分布变化与红河流域河谷与山脉的"通道-阻隔"作用的关联,得出如下结论:(1)在红河流域河谷与山脉的"通道-阻隔"作用的影响下,降水量和径流深等值线在空间上呈西北-东南向分布,分布模式与河谷/山脉的走向基本一致,并在哀牢山北段和李仙江下游地区形成两个高值区.(2)在多年平均尺度上,红河流域河谷与山脉的"通道-阻隔"作用对径流变化的地域差异影响最大,其次是降雨,对气温则不明显:李仙江的降水量明显大于哀牢山东部的元江和盘龙河区,其降水量变化的相对偏差则小于它们,反映出哀牢山的阻隔效应;三个区的平均气温差别不大,反映出在较大的时间尺度上受该区特殊环境格局的"通道-阻隔"作用不明显;多数降雨、径流和气温特征值及其出现时间的变化,在盘龙河与元江及李仙江都明显不同,反映出红河流域山脉的阻隔作用明显.(3)在区域气候变化及红河流域河谷与山脉"通道-阻隔"作用的叠加影响下,红河流域的径流变化在东西方向上差异明显:沿红河断裂发育的元江流域的径流量表现出上升的趋势,而西部的李仙江和东部的盘龙河径流量呈现出减少的趋势;元江和李仙江的年径流有一个准5年的变化周期,而盘龙河则有一个准8年的变化周期;三个区域的径流量变化表现出不一致的阶段性.     

Spatial and temporal variation of runoff of Red River Basin in Yunnan

This paper studies the variation of runoff of Red River Basin and discusses the influence of “corridor-barrier” functions of valleys and mountains on variation of runoff by using GIS and statistic methods based on the monthly precipitation, temperature and evaporation data from 1960 to 2000 at 32 meteorological stations in Red River Basin, and the annual runoff data of Yuanjiang River, Lixian River and Panlong River from 1956 to 2000. The results show out: (1) Under the effect of “corridor-barrier” functions of valleys and mountains in Red River Basin, the patterns of annual precipitation and runoff depth distribution in spatial change a NW–SE direction, which is similar with the trend of the Red River valley and Ailao mountains. (2) In the long temporal scale averaged over years, the most obvious effects of the “corridor-barrier” functions is on runoff variation, and the second is on the precipitation, but not obvious on the temperature. (3) Under the superposed effect of climate changes and the “corridor-barrier” functions of valleys and mountains in Red River Basin, the difference of runoff variation is obvious in the east–west direction: the runoff variation of Yuanjiang River along the Red River Fault present an ascending trend, but the Lixian River on the west side of the Fault and the Panlong River on the east present a descending trend; the annual runoff in Yuanjiang River and Panlong River had a quasi-5a periods, and Panlong River had a quasi-8a periods; the runoff variation are quite inconsistent in different periods among the three river basins.     

红河流域NDVI时空变化及其与气候因子的关系

纵向岭谷区的＂通道-阻隔＂作用及其生态效应多年来一直是山地生态学研究的热点。位于纵向岭谷区东侧的红河流域,其地表关键生态水文要素的时空格局及变化也受到＂通道-阻隔＂作用的极大影响。利用红河流域1981～2006年GIMMS数据和2006年SPOTVEGETATION数据以及42个气象站点1981～2001年逐日降水、温度数据,使用GIS方法和地统计学方法,探讨河谷和山脉地形的＂通道-阻隔＂作用下红河流域NDVI时空变化及与气候因子的关系。研究表明：（1）红河流域植被指数在不同方向的空间自相关程度分异明显,植被指数分布总体上受地形、水热分布格局等因素的结构性影响,但在各个方向存在差异：在哀牢山的阻隔作用下,西南-东北向和东西向的植被指数分维数较低,随机部分引起的植被指数空间分异较小,而结构性变异较大;在河谷的通道作用下,西北-东南向和南-北向的植被指数分维数较高,均匀性程度较好。（2）红河流域NDVI对温度和降水变化的响应具有＂时滞效应＂,滞后时间属于30～165 d,NDVI对降水变化的响应在时间上先于对温度变化的响应;在河谷和山脉的＂通道-阻隔＂作用下,NDVI对温度和降水变化的滞后时间和敏感程度有明显的空间差异。（3）红河流域NDVI总体上没有明显的增加趋势,但存在区域差异性和空间异质性;占流域面积66.77%地区的NDVI有增加的趋势,33.23%的地区有减少的趋势,年NDVI变化率在-15.23%～23.16%间。     

泾河流域近50年来的径流时空变化与驱动力分析

利用近50 a的实测数据,分析了泾河流域的径流时空变化规律和主要驱动因子。研究表明:年降水量和径流深的空间分布均呈现从南到北的明显减少趋势,并在上游山区出现高值区。流域径流总量自20世纪60年代到21世纪初显著减少,由50.1 mm减到22.3 mm,但各区域的变化很不均匀,其中西部、西南和东南的子流域径流大量减少,可达17.5 mm/10 a;北部和东北则减少不明显,最大减少率仅为1.3 mm/10 a。降水量变化曾是径流减少的重要原因,但20世纪90年代后实施的退耕还林等生态工程在2000年后已经成为引起径流减少的最主要原因。     

1960-2007年红河流域强降水事件频次和强度变化及其影响

利用中国境内红河流域23个气象站点1960-2007年的逐日降水数据,分析流域强降水事件频次和强度的变化特征及其相关影响。结果表明:①强降水频次和强度在空间上表现出由东南向西北逐渐递减的趋势,流域下游的河口-金平-绿春-江城一带为高值区,上游的巍山-南涧-弥渡一带则为低值区。②强降水频次和强度的变化趋势存在空间差异,趋势增加的站点大多分布在李仙江上游、元江中上游和藤条江流域,趋势减少的站点大多分布在李仙江下游、元江下游和盘龙河流域。③从流域整体来看,在α=0.05的显著性水平下,近48年来强降水频次和强度没有明显的上升趋势,频次和强度的趋势变化幅度分别为0.26 days/10a和0.18 mm·day^-1/10a;研究时段内频次和强度在时间变化上没有显著突变点。④基于相关统计数据分析强降水变化的影响,表明近20年间强降水频次和强度的增加,增大了局部地区滑坡泥石流、洪涝灾害的风险,河流泥沙含量也随之增加。     

红河流域气温和蒸发量时空变化分析

使用研究区44个气象站1960-2000年的逐月20cm蒸发皿蒸发量、气温的实测资料,分析了红河流域气温和蒸发量的时空变化特征。结果表明：（1）红河流域年均气温呈上升的趋势,1960-2000年间年均气温上升了约0．52℃;其中20世纪60年代和70年代气温变化不大,80年代和90年代急剧上升;季节上以夏季上升趋势最为显著,气候倾向率为0．14℃／10a。（2）红河流域年均蒸发量呈下降的趋势,40年间下降了约45．52mm;其中60年代和70年代相差不大,80年代急剧下降,到90年代有所上升;季节上以春季和夏季下降趋势显著,气候倾向率分别为-1.63mm／10a和-7．63mm／10a。（3）年均气温和蒸发量变化的趋势具有明显的空间分布差异。全流域气温的气候倾向率在-0．21℃／10a-0．35℃／10a,主要的增温区域分布在李仙江和藤条江地区。蒸发量的气候倾向率在-48mm／10a～11mm／10a,蒸发量明显减少区域主要分布在李仙江下游的江城、元江流域的楚雄、元阳、河口和盘龙河流域的文山地区。     

Sensitivity of mountain runoff to climate change for Urumqi and Kaidu rivers originating from the Tianshan Mountains

The mountain watersheds of Kaidu River and Urumqi River, which separately originate from the south and north-side of the Tianshan Mountains in Xinjiang, are selected as the study area. The characteristics and trends on variation of temperature, precipitation and runoff, and the correlativity between temperature, precipitation, and runoff were analyzed based on the past 40 years of observational data from the correlative hydrological and weather stations in the study areas. Various weather scene combinations are assumed and the response models of runoff to climate change are established in order to evaluate the sensitivity of runoff to climate change in the study areas based on the foregoing analysis. Results show that all variations of temperature, precipitation, and runoff overall present an oscillating and increasing trend since the 1960s and this increase are quite evident after 1990. There is a markedly positive correlation between mountain runoff, temperature, and precipitation while there are obvious regional differences of responding degree to precipitation and temperature between mountain runoff of Urumqi River and Kaidu River Basins. Also, mountain runoff of Urumqi River Basin is more sensitive to precipitation change than that of Kaidu River Basin, and mountain runoff of Kaidu River Basin is more sensitive to temperature change than that of Urumqi River Basin.     

潘家口水库入库水资源变化趋势及影响因素

采用滑动平均和线性回归法对潘家口水库1956~2003年入库径流进行了分析,探讨了影响径流变化的基本因素,给出了降雨量、用水量和下垫面等因素变化对径流量变化贡献程度的定量估算方法。结果表明:入库径流呈不规则的周期波动变化,且整体呈较为明显的减小趋势;降雨量、用水量和下垫面等因素变化是影响径流量变化的主要因素,特别是下垫面的变化,其贡献程度可达70%左右。     

西北干旱区阿克苏河径流对气候波动的多尺度响应

基于阿克苏河流域1960~2010年的气象、水文观测数据,利用集合经验模态分解（EEMD）方法,对研究期内阿克苏河径流时间序列进行多尺度的分析,并探讨其在不同时间尺度上的振荡模态结构特征及其对气候因子的多尺度响应。结果表明：① 近50年来,阿克苏河年径流整体上呈现出显著的非线性增加趋势,且其变化在年际尺度上表现出准3 a和准6~7 a的周期性波动,在年代际尺度上表现出准13 a和准25 a的周期性变化;② 各周期分量的方差贡献率表明,年际振荡在径流长期变化中占据主导地位,年代际尺度在径流变化过程中也起着重要作用。重构的径流年际变化能够较为详细地描述原始径流序列在研究时期内的波动趋势,重构的径流年代际变化则有效揭示了阿克苏河径流在不同年代丰、枯水期交替出现的状态。③ 在年际尺度上径流与气温、降水和潜在蒸发都表现为不显著的正相关关系,而在年代际尺度上,径流量与气温和降水均表现为显著的正相关关系,与潜在蒸发表现为显著的负相关关系,且在年代际尺度上相关性和显著性明显强于年际尺度,表明年代际尺度更适于评价径流对气候波动的响应。结果表明EEMD是一种甄别非线性趋势和尺度循环的有效方法。