气候变化和人类活动对中国地表水文过程影响定量研究

利用中国372个水文站月径流数据（1960-2000年）及41个水文站年径流数据（2001-2014年）,采用基于Budyko假设的水热耦合平衡方程,构建气候变化和人类活动对径流变化影响定量评估模型,在Penman-Monteith潜在蒸发分析基础上,进一步分析气象因子对径流变化的弹性系数,量化气候变化和人类活动对径流变化的影响。结果表明：① 中国北方地区流域径流变化对各气象因子弹性系数明显大于中国南方地区。就全国而言,径流变化对各因子的弹性系数为：降水>土地利用/土地覆盖变化（LUCC）>相对湿度>太阳辐射>最高气温>风速>最低气温;② 1980-2000年,气候变化总体上有利于增加中国年径流量,而降水对年径流量增加的贡献最为显著;③ 1980-2000年,中国南方流域中,气候变化对年径流变化的影响以增加作用为主,而北方流域,以减少年径流作用为主。对中国大多数流域径流变化而言,人类活动的影响主要以减少年径流量为主。2001-2014年,气候变化以减少径流量为主,人类活动对径流变化的影响程度明显增强,气候变化与人类活动对径流变化的贡献率分别为53.5%、46.5%。该研究对气候变化与人类活动影响下,中国水资源规划管理、防灾减灾及保障水资源安全具有重要理论与现实意义。     

1982—2014年中国沿海地区归一化植被指数(NDVI)变化及其对极端气候的响应

基于1982—2014年GIMMS NDVI3g数据集,分析中国沿海地区生长季归一化植被指数（NDVI）的时空变化特征,探讨NDVI对极端气温和极端降水年尺度和月尺度的响应特征。结果表明：中国沿海地区及其子区域NDVI均呈上升趋势,且该趋势具有一定持续性;江南及其以南各子区域的NDVI高于江南以北,但长江三角洲、珠江三角洲等地区NDVI下降较明显,而江南以北沿海地区NDVI多呈上升趋势。NDVI在东北沿海西部、华北和黄淮沿海各子区域与极端气温暖指数（暖昼日数和日最高气温的极高值）多呈负相关,在其他沿海地区多呈正相关。NDVI与极端气温冷指数（冷昼日数和日最低气温的极低值）在整个沿海地区基本呈负相关,且对冷指数的响应具有一定滞后性;江淮（含）以南各子区域的NDVI与气温日较差多呈正相关,以北基本呈负相关。NDVI在黄淮以北与极端降水之间一般呈正相关,在黄淮（含）以南和东北沿海中东部地区多呈负相关,黄淮（含）以北各子区域的NDVI对极端降水的滞后效应较明显。     

雅鲁藏布江流域1961-2005年气候变化趋势

The Yarlung Zangbo River (YR) is the highest great river in the world, and its basin is one of the centers of human economic activity in Tibet. Using 10 meteorological stations over the YR basin in 1961–2005, the spatial and temporal characteristics of temperature and precipitation as well as potential evapotranspiration are analyzed. The results are as follows. (1) The annual and four seasonal mean air temperature shows statistically significant increasing trend, the tendency is more significant in winter and fall. The warming in Lhasa river basin is most significant. (2) The precipitation is decreasing from the 1960s to the 1980s and increasing since the 1980s. From 1961 to 2005, the annual and four seasonal mean precipitation is increasing but not statistically significant, especially in fall and spring. The increasing precipitation rates are more pronounced in Niyangqu and Palong Zangbo river basins, the closer to the upper YR is, the less precipitation increasing rate would be. (3) The annual and four seasonal mean potential evapotranspiration has decreased, especially after the 1980s, and most of it happens in winter and spring. The decreasing trend is most significant in the middle YR and Nianchu river basin. (4) Compared with the Mt. Qomolangma region, Tibetan Plateau, China and global average, the magnitudes of warming trend over the YR basin since the 1970s exceed those areas in the same period, and compared with the Tibetan Plateau, the magnitudes of precipitation increasing and potential evapotranspiration decreasing are larger, suggesting that the YR basin is one of the most sensitive areas to global warming.     

1961-2010年武威市气温日较差变化趋势及影响因子分析

利用1961-2010年武威市5个气象站逐日地面最高气温、最低气温及年平均气温、日照时数、蒸发量、降水量、相对湿度、平均风速等观测资料,运用趋势系数法系统分析了该区域近50年气温日较差的时空分布及强度特征,采用多元线性回归中的标准化回归系数分析了影响气温日较差的气象因子。结果表明：受天气系统、地形地貌以及海拔等影响,武威市气温日较差低海拔地区大于高海拔地区。各地年、年代气温日较差总体呈减小趋势,民勤县、古浪县的减小趋势尤为显著,年平均气温日较差的时间序列存在着6～8年的准周期变化;各季节气温日较差变化趋势不太一致,总体上呈减小趋势;月气温日较差变化也存在差异,除天祝藏族自治县外,3月和9月为两个低谷,4-6月和10月为两个高峰。年气温日较差极大值和极小值均呈减小趋势。年最高、最低气温均呈升高趋势,年气温日较差与年最高、最低气温呈相反的变化趋势,最低气温的快速升高和最高气温的缓慢升高是气温日较差减小的直接原因,最低气温显著升高的季节气温日较差的减小趋势更大。影响武威市气温日较差的主要因子是蒸发量、平均气温、平均风速、日照时数,关联性最强的是蒸发量,其次是平均气温,其中气温日较差与日照时数、蒸发量、相对湿度以及平均风速呈正相关,与平均气温和降水量呈负相关。影响各地气温日较差的主要因子有所不同。     

新疆博州地区近46年来的气候变化特征

根据新疆博尔塔拉蒙古自治州(简称博州,下同)四个气象代表站点的气温及降水资料,利用线性趋势函数及t检验法分析了该地区近46年的气候变化。结果表明,博州年平均气温、平均最高气温、平均最低气温均呈上升趋势,而且平均最低气温上升的幅度远大于平均最高气温的上升幅度。年平均气温及年平均最低气温约在20世纪80年代中期出现了显著的均值突变,而年平均最高气温在80年代末出现突变;除春、夏季平均最高气温无明显变化趋势外,其它各季平均气温、平均最高气温、平均最低气温均呈上升趋势,其中均以冬季增幅最大,秋季次之;80年代冬夜升温最强劲,90年代则明显减弱;夏季的平均气温与平均最低气温均在70年代中期出现突变,比其它任何突变时间都早;暖温年多发生在80年代后,冷温年多发生在20世纪60年代、70年代。年降水量略呈上升趋势,少雨年多在60年代、70年代,多雨年多在近20年,除春季外,其余各季降水略有上升趋势。     

Climate change over the Yarlung Zangbo River Basin during 1961–2005

The Yarlung Zangbo River (YR) is the highest great river in the world, and its basin is one of the centers of human economic activity in Tibet. Using 10 meteorological stations over the YR basin in 1961–2005, the spatial and temporal characteristics of temperature and precipitation as well as potential evapotranspiration are analyzed. The results are as follows. (1) The annual and four seasonal mean air temperature shows statistically significant in-creasing trend, the tendency is more significant in winter and fall. The warming in Lhasa river basin is most significant. (2) The precipitation is decreasing from the 1960s to the 1980s and increasing since the 1980s. From 1961 to 2005, the annual and four seasonal mean precipi-tation is increasing but not statistically significant, especially in fall and spring. The increasing precipitation rates are more pronounced in Niyangqu and Palong Zangbo river basins, the closer to the upper YR is, the less precipitation increasing rate would be. (3) The annual and four seasonal mean potential evapotranspiration has decreased, especially after the 1980s, and most of it happens in winter and spring. The decreasing trend is most significant in the middle YR and Nianchu river basin. (4) Compared with the Mt. Qomolangma region, Tibetan Plateau, China and global average, the magnitudes of warming trend over the YR basin since the 1970s exceed those areas in the same period, and compared with the Tibetan Plateau, the magnitudes of precipitation increasing and potential evapotranspiration decreasing are larger, suggesting that the YR basin is one of the most sensitive areas to global warming.     

Study of thermal properties of supraglacial debris and degree-day factors on Lirung Glacier,Nepal

The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons.Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon(2013), winter(2013), and pre-monsoon(2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors(DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of-20.81 °C/m, 4.05 °C/m, and-7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.     

Surface hydrological processes of rock glaciated basins in the San Juan Mountains,Colorado

Glaciers in the western USA contribute summer meltwater to regional hydrological systems. In the San Juan Mountains of Colorado, where glaciers do not exist, rock glaciers serve that function during the summer runoff period. Most rock glaciers in Colorado are located on northern slopes in mountainous areas; however, some rock glaciers in southwest Colorado have different aspects. In this study, we asked how slope aspect and rising air temperatures influence the hydrological processes of streams sourced from rock glaciers in the San Juan Mountains. We focused on three adjacent basins, Yankee Boy basin, Blue Lakes basin, and Mill Creek basin, which share a common peak, Gilpin Peak. Using HOBO® U20-001–04 water-level loggers, streamflow data were collected in each of these basins, below each rock glacier. Air temperature significantly influenced stream discharge below the rock glacier. Discharge and air temperature patterns indicate a possible air temperature threshold during late summer when rock glacier melt increases at a greater rate. The results also suggest that the aspect of rock glacier basins influences stream discharge, but that temperature and precipitation are likely larger components of melt regimes.     

Spatial and temporal variability of daily precipitation in Haihe River basin, 1958–2007

The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events. The study of spatial distribution and temporal trend of precipitation in river basins has been paid more and more attention. However, in China, the precipitation data are measured by weather stations (WS) of China Meteorological Administration and hydrological rain gauges (RG) of national and local hydrology bureau. The WS data usually have long record with fewer stations, while the RG data usually have short record with more stations. The consistency and correlation of these two data sets have not been well understood. In this paper, the precipitation data from 30 weather stations for 1958–2007 and 248 rain gauges for 1995–2004 in the Haihe River basin are examined and compared using linear regression, 5-year moving average, Mann-Kendall trend analysis, Kolmogorov-Smirnov test, Z test and F test methods. The results show that the annual precipitation from both WS and RG records are normally distributed with minor difference in the mean value and variance. It is statistically feasible to extend the precipitation of RG by WS data sets. Using the extended precipitation data, the detailed spatial distribution of the annual and seasonal precipitation amounts as well as their temporal trends are calculated and mapped. The various distribution maps produced in the study show that for the whole basin the precipitation of 1958–2007 has been decreasing except for spring season. The decline trend is significant in summer, and this trend is stronger after the 1980s. The annual and seasonal precipitation amounts and changing trends are different in different regions and seasons. The precipitation is decreasing from south to north, from coastal zone to inland area.     

全球气候变暖情景下黑河山区流域水资源的变化

利用有关水文气象观测资料,对全球气候变暖情景下祁连山区黑河流域水资源的变化特征、成因及趋势进行了分析,并在此基础上提出了未来各种假定气候情景下黑河山区径流变化的计算模式。分析及计算结果表明:黑河山区水资源对全球气候变暖的响应十分明显,但受其特殊地理位置的影响,水资源的变化又有着显著的地域性特征。总体上,山区的气温和降水随全球增温均呈上升和增加的趋势,且气温上升的幅度大于全球平均水平,山区径流亦随降水量的增加而增加,但增幅随着气温升高而逐渐减小,除非遭遇到比较极端的气候情景,如气温升幅与降水减幅同时出现较大值的"暖-干"气候组合或气温降幅与降水增幅的同时出现较大值的"冷-湿"气候组合等。因此,可以预计,未来几十年里黑河山区水资源量虽随着降水、气温的变化而上下波动,但变化相对稳定,其幅度基本在目前出山径流量的±10%左右范围内。     

石羊河流域1961-2005年蒸发皿蒸发量变化趋势及原因初探

 利用1961—2005年石羊河流域上、中、下游当地气象站的逐月20 cm口径蒸发皿蒸发量、平均气温、平均相对湿度、降水量、平均风速、日照时数、最高气温和最低气温资料,研究了近45 a石羊河流域蒸发皿蒸发量变化趋势及原因。结果表明,45 a来,石羊河流域及上、下游年蒸发皿蒸发量呈上升趋势,中游年蒸发皿蒸发量呈下降趋势,上游上升趋势最明显。四季中,春、秋、冬季蒸发皿蒸发量呈上升趋势,上升最明显的是冬季,其次为秋季,春季变化不明显,夏季蒸发皿蒸发量变化呈下降趋势。石羊河流域在不同时段不同区域年蒸发皿蒸发量都存在明显的6～7 a周期和1～2 a的短周期,并都发生了突变。相关系数法分析表明,影响石羊河流域及中、下游年蒸发皿蒸发量变化的主要影响因子是相对湿度和降水,上游的主要影响因子是相对湿度和气温。四季中,春季的主要影响因子是相对湿度和降水;夏季影响石羊河流域及上、中蒸发皿蒸发量变化的主要因子是相对湿度和气温,下游的主要影响因子是相对湿度和降水;秋季影响石羊河流域及中、下游蒸发皿蒸发量变化的主要影响因子是相对湿度和气温日较差,上游其主要影响因子是相对湿度和降水;冬季的主要影响因子是气温和相对湿度。影响年以及春、夏、秋最显著的因子是相对湿度,冬季最显著的影响因子是气温。     

Estimate of Ablation Rate of Glacier Ice under a Supraglacial Debris Layer

The ablation rate under a debris layer is very difficult to measure directly at debris-covered glaciers, because the surface is highly heterogeneous, and the ablation rate varies tremendously from place to place. Heat budget considerations with a debris layer on top of glacier ice suggested that 'thermal resistance' of the debris layer could be estimated from surface temperature and the heat fluxes at the debris surface, and the ablation rate of the underlying glacier ice from the thermal resistance and meteorological data. The method was tested at the Lirung Glacier in Langtang Valley, Nepal Himalayas, using the thermal band of LANDSAT satellite for estimating surface temperature distribution of the debris top surface. The amount of melt water thus estimated was compatible with the observed discharge data from the glacier basin for periods of the monsoon season in 1985 and the pre-monsoon to the monsoon season in 1996. The investigation also revealed that the amount of discharge was much larger than the amount of precipitation over the basin, and it was suggested that the melt water from the debris-covered glacier contributes significantly to the river flow as a result of the shrinkage of the glacier.     

呼图壁河基流变化及其影响因素

基于石门水文站实测日径流数据和流域气象资料,运用平滑最小值法和递归数字滤波法对呼图壁河流量过程进行了基流分割研究。在不同的时间尺度上探讨了呼图壁河年均基流量和基流指数（BFI）的变化特征,以及不同水平年基流量与BFI的变化特征,并按照不同水平年份的划分从气温和降水两方面剖析影响基流变化的因素。结果表明：研究区内平滑最小值法优于递归数字滤波法。呼图壁河基流量的年内分布表现为单峰型,7月达到最大值,BFI先减小后增加,5月最小,枯水期BFI接近1。呼图壁河年基流量呈现为增加的趋势,多年平均基流量为3.67×10⁸ m³,多年平均BFI为0.78,呈递减趋势。枯水年份的平均BFI为0.78,平水年为0.76,丰水年为0.74。春秋两季气温和降水对呼图壁河基流量的影响最为显著,不同的水平年份相关系数也存在一定差异。各年份气温对春秋两季基流量的影响均大于降水,说明气温是呼图壁河基流变化的关键性因素。     

中亚天山山区冰雪变化及其对区域水资源的影响

冰川和积雪是构成山区固体水库的主体,对区域水资源稳定性具有调节功能,但深受气候变化的影响。以中亚天山为研究区域,基于长时间序列的观测数据,分别从冰川、积雪、水储量、径流等方面进行分析,并选取阿克苏河、开都河及乌鲁木齐河3个典型流域,研究天山山区冰雪变化对流域水资源的影响。结果表明：① 冰川退缩速率与面积的函数关系为f（x） = -0.53×x^-0.15 （R² = 0.42,RMSE = 0.086）,说明小型冰川对气候变化的响应更为敏感。同时,中低海拔区域的冰川退缩速率大于高海拔区域;② 2003-2015年天山山区水储量的递减速率为-0.7±1.53 cm/a,天山中部区域的递减速率最大,这一结果与该区域冰川急剧退缩相吻合;③ 近半个多世纪以来,冰雪融水径流增加是这3个典型流域径流量增加的主要原因,其中阿克苏河增幅最大（达0.4×10⁸ m³/a）。但自20世纪90年代中期以来,3个流域的径流量都呈减少趋势,与流域内冰川面积减少、厚度变薄及平衡线海拔升高的关系密切。研究结果揭示了气候变化驱动下的山区固态水体储量变化对流域水资源的影响机制,以期为流域水资源管理提供有价值的决策参考。     

Changing features of extreme precipitation in the Yangtze River basin during 1961-2002

The total precipitation of the highest 1 day, 3 day, 5 day and 7 day precipitation amount (R1D, R3D, R5D and R7D) in the Yangtze River basin was analyzed with the help of linear trend analysis and continuous wavelet transform method. The research results indi-cated that: 1) Spatial distribution of R1D is similar in comparison with that of R3D, R5D and R7D. The Jialingjiang and Hanjiang river basins are dominated by decreasing trend, which is significant at >95% confidence level in Jialingjiang River basin and insignificant at >95% con-fidence level in Hanjiang River basin. The southern part of the Yangtze River basin and the western part of the upper Yangtze River basin are dominated by significant increasing trend of R1D extreme precipitation at >95% confidence level. 2) As for the R3D, R5D and R7D, the western part of the upper Yangtze River basin is dominated by significant increasing trend at >95% confidence level. The eastern part of the upper Yangtze River basin is dominated by decreasing trend, but is insignificant at >95% confidence level. The middle and lower Yangtze River basin is dominated by increasing trend, but insignificant at >95% confidence level. 3) The frequency and intensity of extreme precipitation events are intensified over time. Pre-cipitation anomalies indicated that the southeastern part, southern part and southwestern part of the Yangtze River basin are dominated by positive extreme precipitation anomalies be-tween 1993–2002 and 1961–1992. The research results of this text indicate that the occurrence probability of flash flood is higher in the western part of the upper Yangtze River basin and the middle and lower Yangtze River     

中国高分辨率温度和降水模拟数据的验证

PRISM模型是一种基于地理特征和回归统计方法生成气候图的模型。基于中国及其周边国家地区2450多个气象台站观测数据,以PRISM模型模拟生成了中国2.5′×2.5′(≈4～5km)逐月温度和降水数据。利用独立于模拟数据的中国生态系统研究网络18个野外观测站的长年气候观测数据,检验了PRISM模型的模拟结果,表明PRISM模型较好地模拟了我国温度和降水的空间分布及季节变化,除了在高山和亚热带地区由于地表覆盖和局部地形的差异影响模拟结果,其模拟值与实测值之间的趋势线同1∶1线基本一致,具有显著相关关系,其中降水效果略差     

1958~2015年疏勒河上游出山径流变化及其气候因素分析

利用1958~2015年疏勒河出山口昌马堡水文站径流资料以及同期流域气象资料,揭示了疏勒河出山径流及其对流域气候变化的响应。结果表明：总体上,疏勒河出山径流量呈现增加趋势,特别是20世纪90年代后期以来,出山径流增加趋势更为明显,但近几年,疏勒河出山径流量缓慢回落,21世纪初暂时成为代际变化的拐点。研究亦显示,疏勒河出山径流对河源处高海拔山区气候变化的响应更为敏感,出山径流年际变化实际受到山区气候因素的共同影响,不同时段各因素影响强度具有一定差异;降水是出山径流变化的主控因素,但气温升高导致冰雪融化加快是近年来出山径流增长较快的重要原因。定量分析表明,20世纪90年代后期以来气温等对径流影响比重超过60%,而降水约为30%左右。     

黄土高原地区极端气候指数时空变化

黄土高原生态环境脆弱,极端气候频发,越来越多的影响到人类的生产生活。通过基于 138 个气象站点观测资料,利用一元线性方程和 Mann-Kendall 法分析了黄土高原地区 27 个极端气 候指数的时空变化,得到以下主要结论：（1）极端气温指数中霜冻日数、冰冻日数、日最低气温的极 高值和冷持续日数在逐渐减少,生长季长度、夏季日数,热夜日数、日最高气温的极高值、暖持续日 数在逐渐增加。（2）极端气温指数中冷昼日数、冷夜日数、日最低气温极低值、日最高气温极高值、 气温日较差在子区域与全区变化趋势存在不同,主要表现在黄土塬区、黄土峁状丘陵区和石质山 地区。（3）极端降水指数变化趋势平缓,与多年均值接近。在空间分布上,除极强降水量、强降水量 和年均雨日降水强度在各子区域上与全区变化趋势一致外,其余指数在各子区域上与全区变化趋 势存在不同,主要表现在黄土塬和黄土梁状丘陵区。（4）多数极端气温指数的突变主要发生在 1980—1985 年和 2010—2015 年;多数极端降水指数的突变主要发生在 1985—1990 年和 2010— 2015 年。     

1981-2010年中国西北地区东部大气可降水量的时空变化特征

利用1981-2010年NCEP/NCAR再分析资料以及同期西北地区东部58个气象站的日降水、蒸发资料,采用一种新的方法统计分析了该地区大气可降水量的时空分布特征,并对大气可降水量与实际降水量的相关性进行了分析。结果表明:西北地区东部大气可降水量空间分布极不均匀,无论年或季,均呈现为西北少东南多的分布特征。逐月大气可降水量分布呈单峰型,7月最大,1月最小; 近30年,西北地区东部年、各季大气可降水总量均呈微弱减少趋势,四季中夏季减少趋势最为显著,冬季不明显; 58个站点30年平均的实际降水量空间分布与大气可降水量分布基本一致,年际变化也呈微弱减少趋势; 大气可降水总量与实际降水量呈显著正相关,年平均相关系数为0.545,各季节中春季相关系数最大,秋季和冬季次之,夏季最小; 不同区域大气可降水总量与实际降水量的相关性因季节不同而不同,总体来说,甘肃东部、南部和陕西中部、南部相关性较高,大气可降水量对降水量的贡献较大; 将大气可降水量和降水日数结合起来,更能准确、客观地反映一段时间内总的大气可降水量分布情况。     

长江流域1961-2002年极端降水特征

The total precipitation of the highest 1 day, 3 day, 5 day and 7 day precipitation amount （R1 D, R3D, R5D and R7D） in the Yangtze River basin was analyzed with the help of linear trend analysis and continuous wavelet transform method. The research results indicated that： 1） Spatial distribution of RID is similar in comparison with that of R3D, R5D and R7D. The Jialingjiang and Hanjiang river basins are dominated by decreasing trend, which is significant at 〉95% confidence level in Jialingjiang River basin and insignificant at 〉95% confidence level in Hanjiang River basin. The southern part of the Yangtze River basin and the western part of the upper Yangtze River basin are dominated by significant increasing trend of RID extreme precipitation at 〉95% confidence level. 2） As for the R3D, R5D and R7D, the western part of the upper Yangtze River basin is dominated by significant increasing trend at 〉95% confidence level. The eastern part of the upper Yangtze River basin is dominated by decreasing trend, but is insignificant at 〉95% confidence level. The middle and lower Yangtze River basin is dominated by increasing trend, but insignificant at 〉95% confidence level. 3） The frequency and intensity of extreme precipitation events are intensified over time. Precipitation anomalies indicated that the southeastern part, southern part and southwestern part of the Yangtze River basin are dominated by positive extreme precipitation anomalies between 1993-2002 and 1961-1992. The research results of this text indicate that the occurrence probability of flash flood is higher in the western part of the upper Yangtze River basin and the middle and lower Yangtze River basin, esp. in the southwestern and southeastern parts of the Yangtze River basin.