基于SPEI和SDI指数的云南红河流域气象水文干旱演变分析

本文基于红河流域43个气象站1961-2012年逐月降水、气温数据以及干支流2个水文站1956-2013年逐月流量数据,采用标准化降水蒸散指数(SPEI)和径流干旱指数(SDI)分析流域气象水文干旱的演变特征,并探讨水文干旱对气象干旱的响应。结果表明：①1961-2012年期间,流域总体上表现出干旱化的趋势,季节变化上春季有变湿的趋势,而夏、秋、冬三季有变干的趋势,但趋势并不显著。干旱频率季节空间分布差异较大,春旱和冬旱发生频率较高。从干旱范围来看,春旱范围呈缩小的趋势,夏旱、秋旱和冬旱范围表现出不同程度的增大趋势;②1956-2013年期间,流域水文干旱表现出加剧的趋势,其中1958-1963、1975-1982、1987-1993、2003-2006和2009-2013年为水文干旱多发期,近10年来频率明显增加;③流域水文干旱滞后于气象干旱1~8个月,气象和水文干旱事件的干旱历时、严重程度和强度之间具有紧密的相关性,流域气象干旱是水文干旱的主要驱动力。     

Livestock responses to droughts and severe winter weather in the Gobi Three Beauty National Park, Mongolia

We investigated how both droughts and dzuds (severe winter weather) control livestock mortality in a non-equilibrium steppe ecosystem of Mongolia, Gobi Three Beauty National Park. These steppe ecosystems have developed under high interannual variability of rainfall and nomadic grazing systems. Interannual precipitation variation was 39%, with 128 mm mean annual precipitation. The effect of climate variability and extreme events on livestock mortality is a critical aspect for the Mongolian economy. Analysis of drought and precipitation variability on livestock mortality rate was not significantly influenced by the index of mean annual precipitation and annual winter temperature. Overall, unlike hot dry regions, pastoral livestock mortality in the cold dry regions was affected more by dzuds and annual growing seasonal rain than by droughts. Dzuds can be frequent events, occurring as often as once every 2 and 3 years within a decade. The average annual livestock mortality for the combined drought and dzuds years (18%) was 4.8% greater than the years with dzuds alone, and 7% greater than in years with only drought. Thus livestock mortality appears to be more sensitive to dzuds than to droughts, and that dzuds contributes more to livestock mortality even years where combined drought and winter storms occur.     

松花江区气象水文干旱演变特征

采用标准化降水蒸散指数和径流干旱指数分析了1961~2010年研究区水文干旱和气象干旱时空演变特征,并探讨了水文干旱与气象干旱的关系。结果表明：① 1961~2010年松花江区呈总体干旱化且又有明显时段性的特征,其中1967~1983年和1996~2010年气象干旱频发、覆盖范围广、持续时间长且强度大;其它时段气象干旱少有发生。其次,气象干旱空间分布差异明显,东部的平均干旱频次和强度都大于西部地区,中部（嫩江流域中下游）平均干旱持续时间最长;但在嫩江流域和黑龙江上游地区干旱略有减弱趋势。② 松花江流域和挠力河流域水文干旱呈加剧的趋势,尤其是近15 a干旱化趋势明显;挠力河流域干旱频发、强度大且持续时间很长。松花江流域水文干旱程度弱于挠力河流域,但极端水文干旱事件频发。 ③ 松花江区气象干旱与水文干旱密切相关,嫩江流域水文干旱滞后于气象干旱2个月,而第二松花江流域和松花江流域水文干旱滞后于气象干旱3个月;挠力河流域水文干旱与气象干旱无明显的时滞相关性。     

基于日SPEI的近55 a西南地区极端干旱事件时空演变特征

利用1960~2014年中国西南地区141个气象台站的逐日气象资料,引入一个新的干旱指数——逐日标准化降水蒸散指数（日SPEI）,对极端干旱事件的年代际、年际、季节内变化及持续性特征进行了分析,结果表明：空间上,近55 a西南春季和年极端干旱程度呈一致的减弱趋势,重庆、四川与贵州的交界处及四川西北部极端干旱程度明显缓解,而夏、秋两季极端干旱表现出增强的趋势并有一定的区域性特征。时间上,春季和全年极端干旱频率、强度和持续天数逐渐减少,春季极端干旱的减弱程度较全年明显;夏、秋两季极端干旱频率、强度和持续天数呈增加趋势,夏季极端干旱的加重趋势比秋季明显。从极端干旱事件的持续性来看,20世纪60年代和21世纪初（2000~2014年）西南遭受的极端干旱最严重,持续期达60 d以上的站点分别占到站点总数的60%和73%。     

鄂尔多斯高原地区清代旱灾与气候特征

通过对鄂尔多斯高原地区文献资料的搜集整理, 研究了该区清代旱灾等级、频次、周期和气候特征。结果表明, 鄂尔多斯高原地区清代旱灾频次较高, 约0.34 次/a, 以轻、中度旱灾为主。该区旱灾的发生具有明显的阶段性, 1701-1780 年、1821-1845 年和1876-1911 年为多发阶段, 1644-1700 年、1781-1820 年和1846-1875 年为低发阶段。约90%的旱灾发生在春、夏季或春夏连旱。该区清代旱灾有7 a 左右的短周期, 23-29 a 左右的中周期和54 a左右的长周期;各等级旱灾有准5 a 短周期, 特大旱灾的第1 主周期是17 a。干冷多风的区域气候环境, 以及农业活动是该区旱灾发生的两个主要原因。推测该区清代发生大旱灾和特大旱灾年份的年降水量约为200~250 mm, 年蒸发量约为2400~2600 mm。该区清代气候可划分为6 个阶段:1644-1700 年→1701-1780 年→1781-1820 年→1821-1845 年→1846-1875 年→1876-1911 年, 对应的年降水量特征为:多→少→多→少→多→少, 而蒸发量和风沙天气特征为:少→多→少→多→少→多。确定1762-1766 年、1875-1878 年、1899-1902 年为3 个干旱气候事件, 推测这3个干旱气候事件期间年平均降水量为230 mm左右, 蒸发量为2500 mm左右, 大风沙尘天气频繁。     

基于标准化流量指数(SDI)的石羊河流域水文干旱特征

利用石羊河流域8个水文站1961－2017年逐月实测流量数据和4个气象站点的气象观测资料，采用标准化流量指数（SDI）、游程理论来获得干旱事件的特征指标，分析了石羊河流域水文干旱演变特征，并采用与降水量、最高气温、最低气温、平均气温、蒸发量的相关性来分析石羊河流域SDI的影响因素。结果表明：1961—2017年石羊河流域干旱历时、干旱烈度和干旱强度的变化不是很一致，流域水文干旱历时20世纪70年代最长，80年代最短；干旱烈度全流域90年代最强，烈度最弱出现在80年代；干旱强度全流域60年代最强，80年代强度最弱；石羊河流域及流域中、西部年SDI变化总体上表现为在波动中呈增加趋势，西部增加幅度最大，中部增加幅度很小，流域东部年SDI在波动中呈减小趋势；石羊河全流域及流域东、中和西部年及四季干旱发生频次总体都是中旱和重旱频次最多，四季水文干旱发生频率最高的是春季，冬季干旱发生频率最低；从流域不同地段看，水文干旱发生的频率流域东部最高；构建的SDI 临界值识别出的主要水文干旱事件和实际干旱事件基本一致,干旱等级也较一致，说明使用SDI能够较好地监测到石羊河流域干旱年份及干旱等级；石羊河流域年SDI值与最高气温、平均气温和蒸发量呈负相关，与降水量和平均气温呈正相关。     

干旱强度及发生时间对华北平原五省冬小麦产量影响

本文利用2001-2016年时间分辨率为8 d的MOD09A1和MOD16A2的数据集,构建了基于NDVI和ET/PET的干旱指数（DSI）,分析华北平原五省不同程度的干旱在时间和空间上的分布情况,探究不同程度的干旱作用于冬小麦不同生长阶段对农作物产量产生的影响。研究表明：① 年际分布上,2001-2002年干旱最为严重,其余年份干旱显著减缓,年内分布上,干旱主要集中发生在春季和秋季,夏季次之,冬季最少;② 空间分布上,河北北部、河南南部、安徽及江苏的中部和北部、山东东部是干旱多发区;③ 干旱对冬小麦产量的影响研究表明,越冬期发生初旱对产量起促进作用,而在乳熟成熟阶段发生初旱则会导致农作物减产;轻旱发生在乳熟期会对冬小麦产量产生显著影响,而中旱发生在开花、乳熟成熟期都会对产量产生显著影响,随干旱程度加重,干旱对作物产量产生显著负作用的生长期越长;此外,在播种时若出现水分短缺也会对冬小麦的产量产生影响,尤其是发生重旱和特旱。研究不同强度干旱发生在不同生长阶段对冬小麦产量的影响,对研究区的灌溉时间规划以及保墒增产具有重要理论与现实意义。     

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.     

淮河流域极端径流的时空变化规律及统计模拟

以淮河流域蚌埠闸以上20 个水文站点1956-2010 年日径流量观测数据资料为基础,采用游程检验、趋势检验和Mann-Kendall 检验法分析年最大日径流量的变化规律。分别采用年最大值法(annual maximum,AM) 和超门限峰值法(peaks over threshold,POT) 抽取径流序列样本, 运用广义极值分布(generalized extreme value distribution,GEV) 和广义帕累托分布(generalized Pareto distribution,GPD) 两种极值统计模型对规范化样本进行拟合,分析淮河流域极端径流的时空变化规律。研究表明:1956-2010 年,淮河流域蚌埠闸以上的研究站点中,10 个站点的年最大日径流量有减少的趋势,另外10 个站点有不显著的增加趋势。极端径流事件大多发生在20 世纪60、70 年代,且以汛期居多。淮河流域的极端径流主要来自淮河干流、淮南山区和伏牛山区。使用Kolmogorov-Smirnov (K-S) 法检验发现,GEV和GPD分布分别能较好的拟合AM和POT序列。采用百分位阈值法、平均超出量函数图法和超定量洪峰法三种方法选取阈值,对于淮河流域的极端径流事件模拟而言,百分位阈值法较好。     

1960—2017年中国北方气候干湿变化及其与ENSO的关系

基于中国北方424个气象站实测数据，应用FAO Penman-Monteith模型计算潜在蒸散（Potential evapotranspiration，ET₀），使用降水和潜在蒸散数据计算得到标准化降水蒸散发指数（SPEI），以此研究了1960—2017年中国北方干湿时空变化特征，分析了ENSO对北方气候干湿变化的影响。结果表明：中国北方干湿变化的线性趋势总体不显著，四季中春季和冬季变湿趋势明显。空间上，西北西部存在明显的变湿趋势，干旱化趋势主要发生在黄土高原、内蒙古东部和东北东部地区。全区各级干旱事件呈减少趋势，各级湿润事件呈增加趋势，其中以中等干旱的减少最为显著。西北西部中等干旱和极端干旱明显减少，东北北部和新疆部分地区极端湿润明显增加。全区四季3类干旱事件均表现为减少的趋势，3类湿润事件均表现为增加的趋势，西北西部四季3类干旱事件均呈减少趋势。ENSO对北方干湿的影响存在一定程度的滞后性。El Ni?o翌年气候湿润，La Nina翌年气候干旱。在年际和春季2个尺度上，SSTA与翌年SPEI存在显著的正相关关系。     

文献记录的河西地区小冰期旱涝变化及其机制探讨

基于文献资料重建了河西地区AD 1436-1949旱涝灾害等级序列,结果表明所研究的500余年内河西地区大体出现三次明显的干旱时段,分别为AD 1460-1539、AD 1616-1665和AD 1907-1949,而AD 1725-1748以及AD 1879-1906则为相对湿润时期。重建的旱涝等级序列与毗邻祁连树轮记录的干湿变化存在高度一致的对应关系;将其与NAO指数对比发现,冷期NAO高指数年对应旱灾多发,NAO低指数年对应涝灾多发。     

基于多变量概率分析的珠江流域干旱特征研究

根据珠江流域42 个站点1960-2005 年的46 年日降水资料,以6 个月尺度的SPI 值表征珠江流域干旱情况。通过Mann-Kendall 趋势分析研究了珠江流域干旱时间演变特征,同时基于多变量Copula 函数,在定义的两种不同干旱情景下,根据两变量联合重现期及其对应的第二重现期,比较性地研究了珠江流域的干旱风险。研究结果表明：(1) 珠江流域西部有变旱的趋势而东部有变湿润的趋势,其中显著的变旱趋势集中在11、12、1 月,显著的变湿趋势集中在6、7 月。同时除个别站点外,干旱历时和干旱严重程度趋势不显著;(2) 珠江流域整体上干旱风险较大,东部要比西部干旱风险高。珠江流域内发生长历时干旱时,干旱严重程度也往往很大,对干旱风险管理很不利。在发生严重程度的干旱时,珠江流域东部的干旱高风险区域增加,威胁珠江三角洲地区水资源安全;(3) 由于第二重现期综合考虑了各种情况,可能第二重现期对干旱风险分析的结果更稳健一些。     

500 Years of rainfall variability and extreme hydrological events in southeastern Spain drylands

The semiarid SE fringe of the Iberian Peninsula is considered one of the most sensitive to extreme floods and droughts in the western Mediterranean area. The controlling climatic mechanisms are nevertheless difficult to predict and model. A combined documentary-sedimentary-instrumental 500 years comprehensive register of climatic data (rainfall and flooding) was collated for analysing the decadal to centennial scale hydrological response. Wet years are closely linked to the presence of autumn (SON) positive anomalies (e.g. early 18th century). However, continuous, decadal wet periods seem to correspond in time to both autumn and spring (MAM) positive rainfall anomaly years (e.g. 1570/90, 1830/40, 1870/1900). High frequencies of large floods were registered during the late Medieval Warm Period (AD 950–1200), and during some decades of the Little Ice Age with an average of 0.22 floods/year (1440–1490, 1520–1570, 1600–1740, 1770–1800, 1820–1840, 1870–1900), but flood frequency decreased in the 20th Century (1945–1973; 0.14 floods/year). During wet phases (e.g. late 19th century), large floods occurred during all seasons, whereas a predominantly autumn extreme flooding (>70%) is linked to a rainfall patterns with higher inter-annual variability (e.g. 1945–1973). The recurrence of dry phases is higher since early 17th century, and the frequency of continuous wetter phases lower than the ones with marked annual variability. This results in a trend with less frequent high magnitude catastrophic floods. This study confirms a shift from autumn rainfall maxima towards winter since the early 1990's. The tendency towards longer dry periods and increased inter-annual variability (with 1–3 years maximum wet spells) and a changing seasonal rainfall distribution are thought to be key in modelling projections for this specific arid Mediterranean region.     

Meteorological and Streamflow Droughts: Characteristics,Trends, and Propagation in the Milwaukee River Basin

This study examined meteorological and streamflow droughts for the period from 1951 to 2006 using the Milwaukee River basin in Wisconsin as the study area in an effort to improve the understanding of drought propagation. Specifically, this study aimed to answer the following research questions: (1) What are the temporal trends of meteorological and streamflow droughts identified by drought indicators? (2) How do the drought indicators manifest drought propagation? Meteorological droughts were identified using the Effective Drought Index (EDI), and streamflow droughts were identified using a threshold-level approach. The intensity and duration of both types of drought were found to have decreased over time, most likely due to increasing precipitation. Therefore, in the study area, and likely in the larger region, drought has become of less concern. The propagation of meteorological drought into streamflow drought was detected generally after moderate and severe sequences of negative EDI that eventually led to extreme meteorological drought events. The study finds that both EDI and the threshold-level approach are effective in diagnosing meteorological and streamflow drought events of all durations.     

气象干旱对中亚棉花产量的影响

极端干旱事件频发对中亚棉花生产具有重要影响。本文利用乌兹别克斯坦赞格阿塔实验站棉花大田试验数据评估了APSIM-Cotton模型的适用性,根据CMIP6气候模式模拟的SSP1-2.6、SSP3-7.0和SSP5-8.5等3种共享社会经济路径下的气候变化数据集,分析了2021—2090年SPEI-3干旱指数的变化特征,进而利用APSIM-Cotton模型模拟了考虑CO₂肥效作用的气象干旱对棉花产量的影响。结果表明：APSIM-Cotton模型能够准确模拟乌兹别克斯坦塔什干地区的生育期和产量变化趋势;未来塔什干地区呈现温度明显升高、干旱发生频率明显增加的特征;气象干旱将导致棉花产量下降,SSP1-2.6、SSP3-7.0和SSP5-8.5等3种排放情景下,严重气象干旱导致2021—2050年棉花产量较1961—1990年分别下降28.0%、29.6%和32.1%,2061—2090年棉花分别减产31.5%、33.1%和35.7%,在SSP3-7.0和SSP5-8.5情景下,极端气象干旱导致2061—2090年棉花产量分别下降41.3%和54.2%;CO₂浓度升高可提高棉花产量,贡献率为14.9%~25.0%,但浓度达到750 µmol/mol以上时,棉花增产幅度将不再持续增加。     

Sediment rating parameters and their implications: Yangtze River, China

This study examines the characteristics of sediment rating parameters recorded at various gauging stations in the Yangtze Basin in relation to their controls. Our findings indicate that the parameters are associated with river channel morphology of the selected reaches. High b-values (> 1.600) and low log(a) values (< − 4.000) occur in the upper course of the steep rock-confined river, characterizing high unit stream power flows. Low b-values (< 0.900) and high log(a) values (> − 1.000) occur in the middle and lower Yangtze River associated with meandering reaches over low gradients, and can be taken to imply aggradation in these reaches with low stream power. Higher b-values (0.900–1.600) and lower log(a)-values (− 4.000 to − 1.000) characterize the reaches between Yichang and Xinchang, immediately below the Three Gorges. These values indicate channel erosion and bed instability that result from changes in channel gradient from the upstream steep valley to downstream low slope flood plain settings. Differences in channel morphology accompany these changes. Confined, V-shaped valleys occur upstream and are replaced downstream by broad U-shaped channels. The middle and lower Yangtze shows an apparent increase in channel instability over the past 40 years. This inference is based on sediment rating parameters from various gauging stations that record increasing b-values against decreasing log(a)-values over that time. Analysis of the sediment load data also reveals a strong correlation between changes in sediment rating curve parameters and reduction of annual sediment budget (4.70 × 10⁸ t to 3.50 × 10⁸ t/year, from the 1950s to 1990s), largely due to the damming of the Yangtze and sediment load depletion through siltation in the Dongting Lake. Short-term deviations from the general trends in the sediment rating parameters are related to hydroclimatic events. Extreme low b-values and high log(a)-values signify the major flood years, while the reverse indicates drought events. When compared with rivers from other climate settings, it is evident that the wide range of values of the Yangtze rating parameters reflects the huge discharge driven by the monsoon precipitation regime of eastern China.     

1961-2015年新疆降水及干旱特征分析

基于1961-2015 年新疆地区51 个气象站过去55 a 逐日降水资料,借助标准化降水指数、降水距平百分率表征干旱,利用线性趋势,K-means 聚类,Mann-Kendall 非参数检验,Morlet 小波分析等方法,分析过去55 a 降水及干旱变化特征。研究表明：（1）过去55 a 新疆降水量、雨日整体呈上升趋势,相关系数为0.83,降水量增加主要表现为雨日增长;降水空间分布和聚类得出,降水呈现显著“北多南少”格局,3 个降水分区的降水量表现为III 区 > II 区 > I 区。（2）干旱指数SPI、降水距平Pa极显著相关,干旱频次、影响范围、严重性总体呈现下降趋势;干旱变化率空间分布整体存在一致性,由南向北干旱缓解趋势增大,但局域上又有异质性,北疆个别站点干旱加剧;（3）干旱变化具有周期性,主周期为8 a,次主周期为4 a、16 a。     

贝叶斯框架的Copula季节水文干旱预报模型构建及应用

根据季节径流量相关特性,利用标准径流指数(SRI),通过优选Copula函数和径流量分布函数,构建贝叶斯框架的Copula季节水文干旱预报模型,并对阿克苏河西大桥水文站进行实证分析。结果表明：① Gamma、Lognormal、Normal、Gumbel、Exponential 5种分布函数中,Gamma、Gumbel能较好拟合夏、秋季径流量;② Gumbel-Hougaard、Clayton、Frank 3种Copula函数中,Clayton能较好联结夏、秋季径流量分布函数;③ 构建模型预报表明,2001~2009年秋季发生干旱概率较低(24%~38%),以轻微、中度干旱为主,而2010年发生干旱的概率极高(95%),发生异常干旱的概率偏高(81%),与实际发生的干旱情况基本一致;④ 贝叶斯框架下构建的Copula模型能准确预报季节水文干旱发生,减少预报的不确定性,为特定区域干旱预报提供了一条新的途径。     

Recent advances on reconstruction of climate and extreme events in China for the past 2000 years

China is distinguished by a prominent monsoonal climate in the east of the country, a continental arid climate in the northwest and a highland cold climate on the Qinghai-Tibet Plateau. Because of the long history of Chinese civilization, there are abundant and well-dated documentary records for climate variation over the whole of the country as well as many natural archives (e.g., tree-rings, ice cores, stalagmites, varved lake sediments and corals) that enable high-resolution paleoclimatic reconstruction. In this paper, we review recent advances in the reconstruction of climate and extreme events over the last 2000 years in China. In the last 10 years, many new reconstructions, based on multi-proxies with wide spatial coverage, have been published in China. These reconstructions enable us to understand the characteristics of climate change across the country as well as the uncertainties of regional reconstructions. Synthesized reconstructed temperature results show that warm intervals over the last 2000 years occurred in AD 1–200, AD 551–760, AD 951–1320, and after AD 1921, and also show that cold intervals were in AD 201–350, AD 441–530, AD 781–950, and AD 1321–1920. Extreme cold winters, seen between 1500 and 1900, were more frequent than those after 1950. The intensity of regional heat waves, in the context of recent global warming, may not in fact exceed natural climate variability seen over the last 2000 years. In the eastern monsoonal region of China, decadal, multi-decadal and centennial oscillations are seen in rainfall variability. While the ensemble mean for drought/flood spatial patterns across all cold periods shows a meridional distribution, there is a tri-pole pattern with respect to droughts south of 25°N, floods between 25° and 30°N, and droughts north of 30°N for all warm periods. Data show that extreme drought events were most frequent in the periods AD 301–400, AD 751–800, AD 1051–1150, AD 1501–1550, and AD 1601–1650, while extreme flood events were frequent in the periods AD 101–150, AD 251–300, AD 951–1000, AD 1701–1750, AD 1801–1850, and AD 1901–1950. Between AD 1551–1600, extreme droughts and flood events occurred frequently. In arid northwest China, climate was characterized by dry conditions in AD 1000–1350, wet conditions in AD 1500–1850, and has tended to be wet over recent decades. On the northeastern Qinghai-Tibet Plateau, centennial-scale oscillations in precipitation have occurred over the last 1000 years, interrupted by several multi-decadal-scale severe drought events. Of these, the most severe were in the 1480s and 1710s. In southwest China, extreme droughts as severe as those seen in Sichuan and Chongqing in 2006 are known to have occurred during historical times.     

基于马尔科夫模型的新疆水文气象干旱研究

在气象干旱SPI和水文干旱SRI的二维变量干旱状态的研究基础上,通过一阶马尔科夫链模型对二维变量干旱状态进行频率、重现期和历时分析,并预测未来非水文干旱到水文干旱的概率,研究结果表明：（1）开都河、和田河在干旱形成中危害大,阿克苏河在干旱演变中危害大,开都河和叶尔羌河在干旱持续中危害大。开都河和叶尔羌河主要以气象水文干旱为主,和田河和阿克苏河以水文干旱为主。（2）开都河连续湿润或者干旱的概率最大,状态2与状态4、状态5的相互转移概率低,和田河和开都河状态4不能一步转移到状态2。（3）在长期干旱预测中,塔河流域从状态2达到状态4或者状态5的概率最低,开都河（或和田河）从非水文干旱状态到状态4的概率最大（或最小）,从非水文干旱状态到状态5的概率最小（或最大）。