过去50年中国西部气候和径流变化的区域差异

通过对过去50年中国西部降水和主要河流径流变化的对比分析, 研究降水和径流的区域变化差异, 结果表明, 黄河上游径流和降水与新疆北部和青藏高原南部雅鲁藏布江流域径流、降水呈显著的反相关关系. 中国西部降水变化大体上以青藏高原唐古拉山和天山为界, 表现出南北一致, 中部(西部的喀喇昆仑山除外)相反, 即从南到北呈现出干-湿-干或湿-干-湿的区域变化差异; 在河流径流上表现为北部伊犁河流域和南部雅鲁藏布江流域径流变化的一致性, 而与黄河上游径流变化呈反位相变化; 同时, 新疆和黄河径流的反位相变化表现在年代际上, 而黄河和雅鲁藏布江径流变化表现在年际变化上. 黄河上游径流的变化与西北太平洋季风指数的变化比较一致, 这表明黄河上游径流变化受到较强的东亚季风的影响; 新疆总径流分别与西北太平洋季风指数和西风指数存在显著的正负相关关系, 寻找不同地区径流变化异同对于认识和预测径流未来变化具有重要的指导意义.     

青海湖流域近六百年来的气候变化与湖水位下降原因

根据青海湖流域及其邻近地区树木年轮资料重建的历史时期气候资料序列,给出了流域近六百年来的主要冷、暖、干、湿期,并对器测时期的气候变化趋势作了分析。指出,近百年来气候暖干化是造成湖水位下降的主要原因;对于湖水位年际变化与前期降水影响系统、不同气候类型以及地面气象要素的关系作了统计分析。     

长江流域降水径流的年代际变化分析

应用1951-2001年长江流域年、季降水量资料、1885-2001年梅雨量资料以及一百多年以来长江重要控制站宜昌、汉口、大通年径流量资料,对长江流域降水径流的年代际变化、气候转折以及降水径流的变化趋势进行了分析研究.反映出长江流域夏季降水将有更加集中的趋势,即降水时间更集中、强度趋向于更大,对防洪不利.据趋势预测,宜昌、汉口径流量有减少的趋势,大通径流量有增加的趋势.     

20世纪下半叶全球干旱化的事实及其与大尺度背景的联系

利用CRU(Climatic Research Unit)的全球格点月降水及月平均气温资料, 通过计算地表湿润指数分析了1951~2002年全球干湿变化趋势. 重点对比研究了北美大陆、南美大陆、欧亚大陆、非洲大陆及澳洲大陆干湿变化的特征及差异, 并在此基础上对各大陆乃至全球的干湿变化与影响气候变化的大尺度背景的相关关系进行了分析. 结果表明, 在增暖背景下, 20世纪下半叶全球干湿变化趋势具有明显的区域差异, 非洲大陆、欧亚大陆、澳洲大陆和南美大陆近52年主要以干旱化趋势为主, 尤以非洲大陆和欧亚大陆最为剧烈. 北美大陆在1976年以后表现为变湿趋势, 南美大陆存在30年左右的干湿振荡周期, 但最近仍然处于干化的时段, 澳洲大陆的变化与之类似. 研究还表明, 增暖已经改变了全球环境干湿变化的分布格局, 南美大陆和澳洲大陆尽管降水为增加趋势, 但仍然表现为干旱化趋势, 其中温度升高是其表现为干旱化特征不可忽视的原因. 全球环境的干湿变化与大尺度背景密切相关: 非洲大陆、欧亚大陆的干旱化趋势、北美大陆的湿化趋势与北太平洋年代际振荡(PDO)显著相关; 而南美大陆、澳洲大陆干湿的年代际振荡与南方涛动指数(SOI)的年代际变化一致.     

变化环境下近60年西江流域径流时空演变特征

气候变化叠加人类活动的双重影响下,西江流域的河川径流发生了不同程度的改变,重新认识和掌握变化环境下的径流时空演变规律对流域的科学管理具有重要意义。基于西江流域干支流7个控制性水文站近60年的日径流资料,综合极点对称模态分解法(ESMD)、Mann-Kendall检验、R/S分析、小波分析等方法,从年代、年、季和年内多个时间尺度对径流的时空演变特征进行分析,研究结果表明:年代尺度下,西江流域径流丰枯交替、变化悬殊,1970s与1990s径流丰沛,2010s径流偏枯,降雨影响着径流的丰枯变化,流域上、中游更易发生干旱与洪涝灾害;春、夏、秋、冬季径流振荡周期依次为2～7、15～20、28～29 a,3～5、7～10、20 a,2～3、6～8、12～15 a和3～8、12～15、20 a,均呈现年际与年代的双重周期特征,IMF1的年际振荡在径流变化中占主导地位;受降雨与水库调蓄作用的影响,年、夏、秋季径流呈下降趋势,预测下降变化具有持续性,春、冬季径流整体呈上升趋势。空间内上游的变化趋势更显著;年和季尺度径流在1980年后突变增多,尤其集中于2000—2010年间,人类活动与气候变化是造成西江...     

鄱阳湖流域过去1000 a径流模拟以及对气候变化响应研究

为研究过去千年尺度径流变化及其对气候变化的响应,以长江中游鄱阳湖流域为研究区,运用气候模式CCSM4和ECHAM5模拟过去1000 a气候数据,空间降尺度后驱动水文模型模拟了鄱阳湖流域过去近千年流域径流序列.利用快速傅里叶变换、小波分析等手段,分析流域极端径流变化特征、周期和该流域旱涝事件发生频率.结果表明:2种气候模式均能反映出中世纪暖期及小冰期阶段的干湿交替变化,且小冰期内中干旱状态维持时间较长;径流的丰枯变化与降水量变化具有较好的对应关系.CCSM4和ECHAM5模式下发生旱涝灾害与极大极小降水事件发生频率基本相同,径流丰枯变化与降水变化周期相近,均具有30 a左右的主周期,10~15、7 a左右的子周期.小波系数模平方图中30 a左右显著的能量信号揭示了该周期与北太平洋气候的主要环流机制的太平洋年代际振荡周期相近,因此,大气环流涛动是造成气候-水文变化的主要原因.研究结果拓展了基于近代60 a观测记录的流域水文变化的认识,探讨了千年时间长度下流域干湿变化特征和水文对气候响应的动力机制,有助于全面系统认识长江中游在全球气候暖化背景下旱涝极端水文事件的发生机制与变化规律.     

中国气候干湿变率与ENSO的关系及其稳定性

利用1951-01~2000-10中国160站气温和降水月平均资料, 计算了自修正PDSI指数. PDSI指数EOF分析第一模态空间场分布和1951~2000年PDSI指数的变化趋势分布十分相似, 第一模态时间系数反映了空间场随时间的演变情况. 研究发现, EOF分析所揭示的中国气候干湿变率和ENSO有着很好的关系. 这种关系表明, 在典型的ENSO暖状态, 中国大部分地区都偏干, 特别是华北地区更易偏干, 长江以南地区和西北容易偏湿, 而长江中下游地区处于变干和湿的过渡区, 变干或湿不明显. 在典型的ENSO冷状态则情况相反. 而中国气候干湿变率年际和年代际变化都对应着强El Niño事件; 反过来当发生强El Niño事件时, 中国气候干湿变率在年际和年代际尺度上有可能发生剧烈变化. 最近20~30 a中国气候干湿的年代际变化, 特别是华北自20世纪70年代末的变干和西北自80年代中期的变湿, 与ENSO朝更暖的状态变化及全球变暖有着紧密的联系. 1951~2000年中国气候干湿变率和ENSO关系的稳定性分析表明, 中国气候干湿变率和ENSO之间在3~8 a变化周期上存着很好的相关关系, 但这种相关关系不稳定, 存在着年代际变化: 1951~1962和1976~1991年两个时间段两者相关关系很高, 而在1963~1975和1992~2000年两时段内, 两者相关关系较差.     

长江流域近50年降水变化及其对干流洪水的影响

根据我国长江流域气象观测站近42年的资料,分析了整个流域年和季节平均面雨量、暴雨日数和暴雨量的变化特征,以及降水对流域径流和洪水的影响.长江流域年和夏季平均面雨量存在明显的年际和年代变化特征,也表现出比较显著的趋势变化特点.大部分测站年平均面雨量呈增加趋势,夏季和冬季平均面雨量的增加趋势尤其明显;秋季平均面雨量呈显著下降趋势.同时,年和夏季暴雨日数和暴雨量也在较大范围内呈显著增加趋势.长江流域的降水对干流平均流量具有重要影响.1973年、1983年和1998年的洪水主要是由明显高于平均的流域面雨量引起的;长江下游平均流量变化趋势也同流域年平均面雨量、夏季平均面雨量变化趋势基本一致,特别是70年代末以来,下游平均流量和流域面雨量的上升趋势更加明显,并同时在1998年达到最高值.长江流域大的丰水年一般对应El Nino年或El Nino次年,表明E1 Nino对长江较大洪水可能具有一定影响.     

气候变化和人类活动对鄱阳湖流域赣江径流影响的定量分析

气候变化和人类活动对流域径流影响的定量研究是当前研究的热点,赣江作为鄱阳湖流域最大的子流域,径流变化对鄱阳湖湿地水生态系统具有重要的影响.利用Mann-Kendall突变检验分析了赣江流域径流1955—2010年间演变趋势,再分别应用统计方法和IHACRES集总式模型分析气候要素和人类活动对径流的影响.研究表明IHACRES能够较好地模拟赣江流域径流,适用于中亚热带湿润季风气候区.Mann-Kendall突变检验表明赣江流域径流在1979年发生突变,可划分为1955—1979年和1980—2010年两个时段.降水是影响赣江流域径流年际变化的主要因素,而土地利用等人类活动的影响并不明显.水库建设显著影响赣江径流的季节分配,1980—2010年间人类活动影响更加显著,其中45%的年份秋季径流增加50%以上,26%的年份秋季径流增加超过100%,其中1989年的秋季径流增加幅度达到320%.     

1990s以来气候变化和人类活动对洪湖流域径流影响的定量辨识

为针对性地提出洪湖流域水资源适应与应对气候变化和人类活动影响的措施,保护洪湖流域生态资源,促进其可持续发展,采取分布式水文模型SWAT定量辨识了1990s流域城镇快速发展以来气候变化和人类活动对洪湖流域地表径流的影响程度.结果表明:近20年来,人类活动是洪湖流域地表径流减少的主要原因,其影响量占径流减少量的63.72%,气候变化的影响占36.28%.但不同阶段人类活动与气候变化对流域径流影响的程度不同,1990s气候变化对流域径流的影响量高于人类活动,2000s气候变化对流域径流的影响量低于人类活动,近20年来的水土保持措施已经发挥了较好的径流调节和保水效益.     

Regional difference of annual precipitation and discharge variation over west China during the last 50 years

Using annual precipitation and discharge data measured in the past five decades,this paper analyzed the regional differences over west China in terms of climate and discharge variations,and investigated the relationship between the regional characteristics and the activities of South and East Asian sum-mer monsoon. Results revealed that the precipitation and discharge in the upper reaches of the Yellow River (Central West China) have a negative correlation with those in Xinjiang (northwest China) and the Yarlung Zangbo River (the upper reaches of the Brahmaputra Rive,southwest China) regions. The geographical patterns of precipitation and discharge variations are different over west China,i.e. the regional climate displays the alteration of dry-wet-dry or wet-dry-wet from north to south in west China. The negative correlation of annual discharges between Xinjiang and the upper reaches of the Yellow River is found statistically significant in the decadal scale,and that between the Yarlung Zangbo River and the upper reaches of the Yellow River is found active in the interannual scale. The regional char-acteristics indicate that the discharge/precipitation variations in the upper reaches of the Yellow River are dominated by the East Asian summer monsoon while their variations in Xinjiang are affected by both the west wind and East Asian summer monsoon.     

长江与黄河入海活性硅输送规律及变化趋势

根据长江与黄河各一个完整水文年的调查数据,并结合历史资料分析了我国这两条大型河流活性硅((RSi,RSi=溶解硅(DSi)+生物硅(BSi))的入海通量及长时间序列的变化规律与影响因素.结果表明,长江与黄河RSi的组成存在显著的差异,二者水体中BSi/RSi的平均比值分别为0.22和0.49;黄河DSi的年平均浓度为长江的74%,而BSi年平均浓度却是长江的3倍.黄河水体中相对较高的BSi浓度反映了黄河流域水体浑浊度与土壤侵蚀程度较高,源自黄土高原高的泥沙输送量是导致黄河水体中BSi浓度较长江高的主要原因.长江与黄河下游RSi通量在丰水期、平水期与枯水期的比值分别为5.3∶3.1∶1.6与3.8∶3.4∶2.8,长江半数以上的RSi入海通量是在丰水期输出的,而黄河在3个时期的差异不明显.相比于径流的变化,1958-2014年间长江DSi通量变化主要是由DSi浓度的变化引起的,流域气候变化(如温度变化)是其浓度及其通量年代际变化的重要原因;而黄河1985-2001年间DSi通量下降是由于径流量与DSi浓度降低的双重原因引起的.气候变化,特别是温度的变化会对流域硅的风化速率与硅的产出产生重要影响,但其具体的影响有待进一步揭示.     

A spatial analysis of hydro‐climatic and vegetation condition trends in the Yellow River basin

Stream‐gauge data indicate that the flow of the Yellow River has declined during the past several decades. Zero flow in sections of the river channel, i.e. the Yellow River drying‐up phenomenon, has occurred since the 1970s. In this paper we present an analysis of changes in the spatial patterns of climatic and vegetation condition data in the Yellow River basin based on data from meteorological stations and satellites. The climatic data are from 1960 to 2000 and the vegetation condition data are from 1982 to 2000. The angular‐distance‐weighted interpolation method is used to get climatic data coverage from station observations. The spatial distribution of tendency is detected with Student's t‐test. The spatial patterns of climatic and vegetation condition change was analysed together with the statistical data on human activities. The analysis indicates that the precipitation decreases and temperature increases in most parts of the Yellow River basin, the evaporative demand of the atmosphere decreases in the upper reaches and increases in the lower reaches, and human activities have improved the vegetation condition in the irrigation districts. The Loess Plateau, the Tibetan Plateau, and the irrigation districts are respectively suggested as precipitation, temperature, and human activity hot spots of the Yellow River drying‐up phenomenon. Copyright © 2007 John Wiley & Sons, Ltd.     

汉江上游安康东段全新世古洪水沉积学与水文学研究

通过沿汉江上游河谷深入的考察,在安康东段发现了典型的古洪水滞流沉积剖面.通过采集样品、实验分析,确定它们是古洪水在高水位滞流环境当中的悬移质沉积物.根据地层对比、OSL测年和相关文化层年代,确定它们分别记录了发生在BL+AL与YD事件转折阶段(12500 a B.P.)的古洪水事件和发生在1000-900 a B.P.(1000-1100AD),即北宋后期的洪水事件.根据古洪水SWD的高程恢复其洪峰水位,结合相关参数,利用面积比降法计算恢复流量.结果表明在万年尺度,汉江上游古洪水洪峰流量介于35970~47400 m³/s之间.同时,利用2010年大洪水洪痕恢复计算洪峰流量,对古洪水洪峰流量计算结果进行了验证.进而结合历史洪水和观测洪水数据,获得了汉江上游万年尺度洪水洪峰流量与频率关系.这为汉江上游的水利水电和交通工程建设以及沿岸城镇防洪减灾提供了基础性数据.     

Long‐term trend analysis for major climate variables in the Yellow River basin*

Some previous studies have shown that drying‐up of the lower Yellow River resulted from decreasing precipitation and excessive industrial and agricultural consumption of water from the middle and downstream regions of the Yellow River. On the basis of average air temperature, precipitation, and pan evaporation data from nearly 80 gauging stations in the Yellow River basin, the monotonic trends of major climate variables over the past several decades are analysed. The analysis was mainly made for 12 months and the annual means. The isograms for annual and typical months are given in the paper. The result shows that the average temperature in the study area exhibits an increasing trend, mainly because of the increase of temperature in December, January and February. The largest trend is shown in December and the smallest is in August. There are 65 of 77 stations exhibiting a downward trend for annual precipitation. In all seasons except summer, there is a similar trend in the upstream region of the Yellow River, south of latitude 35°N. It is interesting to note that the pan evaporation has decreased in most areas of the Yellow River basin during the past several decades. April and July showed the greatest magnitude of slope, and the area from Sanmenxia to Huayuankou as well as the Yiluo River basin exhibited the strongest declining trend. The conclusion is that the decreasing pan evaporation results from complex changes of air temperature, relative humidity, solar radiation, and wind speed, and both climate change and human activities have affected the flow regime of the Yellow River during the past several decades. Copyright © 2007 John Wiley & Sons, Ltd.     

Responses of runoff to climate change and human activities in the Ebinur Lake Catchment,western China

Based on hydrological and climatic data covering the period from 1961 to 2008, this paper studies the hydrological responses to climate change and to human activities in the Ebinur Lake Catchment. The results show that the annual runoff of three rivers in Ebinur Lake Catchment exhibited different change trends. Specifically, in Jinghe River and Kuytun River exhibited a slightly increasing trend, but an adverse trend in Bortala River, and the variation trend has been the most dramatic since the mid-1990s. The observed variation in the runoff was resulted from the elevated alpine precipitation, rather than rising temperature, and that precipitation is a major factor for runoff generation. The runoff CAR model proposed by this paper can be used to predict the annual runoff in three rivers, and demonstrated annual runoff in Bortala River and Jinghe River will display an increased trend, while a less decreasing trend in Kuytun River under the climate change scenarios of warm-humid variation. In addition, the exploitation of the area of cultivated land led to more water resources consumption, primarily for agriculture irrigation, is the cause of the persistently ecoenvironment degradation, which have reached in a critical state thus, a more pressing concern is the development a scientifically reasonable and administratively practical water resource management scheme.     

Temporal and spatial patterns of low-flow changes in the Yellow River in the last half century

Low-flow is widely regarded as the primary flow conditions for the anthropogenic and aquatic communities in most rivers, particularly in such an arid and semi-arid area as the Yellow River. This study presents a method integrating Mann–Kendall trend test, wavelet transform analysis and spatial mapping techniques to identify the temporal and spatial patterns of low-flow changes in the Yellow River (1955–2005). The results indicate that: (1) no trend can be identified in the major low-flow conditions in the upper Yellow River, but downward trends can be found in the middle and lower Yellow River; (2) similar periodic patterns are detected in the 7-day minima (AM7Q) in the upper and middle Yellow River, while different patterns are found in the lower Yellow River; (3) the increasing coefficients of variance in the primary low-flow conditions suggest that the variability of the low-flow is increasing from the upper to lower stream; (4) climate change and uneven temporal-spatial patterns of precipitation, jointly with highly intensified water resource utilization, are recognized as the major factors that led to the decrease of low-flow in the lower Yellow River in recent decades. The current investigation should be helpful for regional water resources management in the Yellow River basin, which is characterized by serious water shortage.     

极端气候事件综合危险性等级指标构建及近60年来长江流域极端气候综合分析

本文利用经过均一化订正的长江流域共669个气象站近60年(1961—2020年)逐日观测资料,采用相对阈值和绝对阈值相结合的极值分析方法,对长江流域近60年极端高温事件、极端低温事件、极端干旱事件和极端降水事件进行识别,分析了年发生频率和线性变化趋势.在此基础上,考虑到全国极端气候事件发生情况,构建了多个极端气候事件综合危险性等级指标,比较客观地给出了长江流域极端气候事件综合危险性等级.研究结果表明,相对于全国其他地区,长江流域大部分地区极端气候综合危险性等级较高,虽然自1961年以来综合年发生频率呈现弱的线性减少趋势,但自20世纪90年代以来,长江流域极端气候事件发生的危险性相对于全国其他地区明显偏高.通过对不同极端气候事件危险性和变化规律研究,结果表明：长江流域近60年极端干旱事件年发生频率呈现线性减少趋势,与全国他其区域相比较,长江流域大部分地区极端干旱发生的危险性等级都在中级以上,说明长江流域容易发生极端干旱事件;长江流域近60年极端降水事件年发生频率呈现弱的增加趋势,危险性等级指数分析表明,高危险区主要位于长江中下游地区,湖南西部、江西大部、湖北南部等地发生极端降水事件的危险性很高;近60年长江流域大部分地区极端高温事件显著增加,尤其进入21世纪以来发生更加频繁,但相对于全国其他地区,危险性等级较低;近60年长江流域极端低温事件显著减少,但相对于全国其他地区,极端低温事件发生的危险性增加明显.进入21世纪以来,长江流域极端气候事件的综合危险性不断增加,极端高温和极端干旱相伴而生的高温干旱复合型事件频繁发生,极端降水事件和极端低温事件在全国的占比不断升高,造成的社会经济影响越来越严重,说明长江流域加强极端气候事件风险防范的重要性和紧迫性.

     

Run-off affected by climate and anthropogenic changes in a large semi-arid river basin

A rapid reduction in run-off has been observed in the middle reaches of the Yellow River basin in recent decades. Understanding the contributions of climate change and human activities, such as vegetation restoration and water consumption, to surface water resource reduction has become urgent and very important for future regional planning. Here, we use attribution approaches to explore the effects of climate change and human activities on run-off over the past six decades. The results showed that the observed annual run-off at Tongguan station, which is located within the mainstream of the Yellow River, exhibited a significant decreasing trend of −0.69 mm year⁻¹ (p < .01) and varied from −0.28 to −1.46 mm year⁻¹ (p < .01) in the eight selected tributaries from 1960 to 2015. Two relatively abrupt changes in the double mass curves occurred around 1979 and 1999; compared with Period 1 (P1; 1960–1979), the average catchment run-off decreased 32% during Period 2 (P2; 1980–1999) and up to 49% during Period 3 (P3; 2000–2015). We calculated that approximately 29% of the reduction in the run-off during P2 and 18% during P3 were attributed to climate change. Increased surface water consumption resulted in effective run-off reduction, with relative contributions of approximately 27% and 28% during P2 and P3, respectively. With the implementation of the “Grain-for-Green” project, the vegetation coverage rapidly increased from 36% in P1 to 52% in P3 and reduced run-off by 35% during P3. These findings explain the run-off reduction and benefit water resource management in the middle reaches of the Yellow River basin.