渭河流域干旱指标空间分布研究

基于月降水数据,运用干旱指标研究渭河流域的干旱特征。以西安站为例,详细对比了Z指数与SPI计算结果的一致性和差异;分别采用1、3、6、9、12个月和24个月时间尺度SPI分析了该站历史旱涝状况及持续时间,并探讨了其季节旱涝特征。计算了渭河流域1995年11月不同时间尺度的SPI值,并绘制了相应的空间分布图。结果表明：多时间尺度SPI[WTBZ]能够反映出降水的分散情况,并给出降水量区间与干旱指标的对应关系,是进行旱涝监测和预报的一种有效手段;发生于1995年的渭河全流域干旱具有季节性和多年特征,干旱程度总体上由东南部向西北部递减。     

近51年西柳沟流域水沙变化特征分析

选取1960-2010年西柳沟流域降水、径流与输沙资料,采用滑动平均法、Mann-Kendall趋势分析及突变检验法、滑动t检验方法及距平法等方法,分析了西柳沟流域近51年水沙的变化趋势和突变。趋势分析表明,降水量年际变化呈缓慢的上升趋势,径流量与输沙量年际变化呈显著下降趋势。突变分析表明,降水量序列没有出现突变,径流量与输沙量序列在下降过程中出现突变,但突变年份不一致,径流量发生在2004年,输沙量发生在2000年。     

典型干旱指数在滦河流域的适用性评价

利用1957-2010年滦河流域9个代表气象站逐月降水量资料及滦河三道河子、韩家营、承德、下板城和滦县站的1956-2000年逐月天然径流量资料,分别应用降水距平百分率、标准化降水指数（SPI）、降水Z指数及径流距平百分率,评价滦河流域干旱情况,并比较4种干旱指数的评价效果。结果表明：降水距平百分率反映干旱程度较轻;与降水Z指数相比,SPI指数能较客观地反映滦河流域干旱程度,3种气象干旱指数在滦河流域的适用性评价结果SPI]指数优于降水Z指数和降水距平百分率;而径流距平百分率的水文干旱指数评价结果与实际旱情更为吻合。但是,这4种干旱指标缺乏综合性和机理性,尚需加强降水、气温、蒸发、径流量等因素的综合考虑,提出反映干旱内在机理的指标。     

黄河上游天然径流变化特性分析

利用黄河上游唐乃亥水文站1956~2012年57年的径流时间序列资料,采用统计分析法、趋势分析法、Mann-Kendall非参数检验法和小波分析法分析了黄河上游径流年内分布特征、径流年际变化趋势、突变特征及其周期性。结果表明:黄河上游多年平均径流量为627.9m~3/s,径流在年际间表现出较大的差异性,极值比K达到3.1;径流在年内分布不均匀,其中7~9月三个月的径流占全年径流量的46.75%;年径流量总体呈下降趋势,下降率为2.65m~3/s/年;黄河上游年径流量在1992年发生突变,突变前后年平均径流量分别为666.05m~3/s和545.75m~3/s,相差120.3m~3/s;黄河上游径流变化存在着多层次的时间尺度结构,径流演变的第一和第二主周期分别为12年和22年,它们控制了流域径流的演变过程。     

祁连山区气候变化与流域径流特征研究

用气候学、水文学及统计学方法,分析了国家级祁连山森林生态站长期定位监测数据,气温、降水对流域径流的影响关系,据此研究了该流域水热条件下流域径流,分析得出试验流域多年平均降水量为354.3mm,年平均气温为1.6℃,年平均出山径流为118.2mm,径流系数为0.33;随着季节温度的升高,径流量呈增加之势,反之亦然;随季节降水量的增加,径流量同时也呈增加的趋势。研究表明了温度、降水与流域出山径流量密切相关,为不同季节气候变化对流域径流的影响提供科学依据。     

基于CRU格点数据集的近百年渭河流域降水变化

基于英国东安格利亚大学Climatic Research Unit(简称CRU)气象格点数据集CRU_TS3.24,分析得出1916~2015年渭河流域100年间年季降水的趋势、突变、周期等变化特征,也从侧面检验了CRU格点数据的应用效果。结果表明近百年来:(1)渭河流域夏季和全年降水呈现不显著减少趋势(-1.73mm/10a和-0.82mm/10a),时间上降水的减少主要发生在夏季,空间上降水的减少主要发生在流域西部;(2)春季降水2个突变点分别为1991年、2009年,夏季降水2个突变点分别为1933年、1961年,全年降水的两个突变点分别为1933年、1968年,秋冬两季各存在5个突变点;(3)夏季与全年降水序列突变点识别结果表明采用CRU格点数据对渭河流域降水变化进行分析更为全面;(4)秋季与冬季降水序列的周期性比其他时段更加明显,四季与全年降水序列的第1主周期分别为19年、3年、13年、5年和18年,第2主周期分别为6年、7年、42年、12年和24年。     

开都河流域降水与径流年内分配特征及其变化的同步性分析

基于开都河流域巴音布鲁克气象站和大山口水文站1960-2007年的逐月降水和径流数据,文中通过采用集中度与集中期为量化指标,对开都河流域降水和径流的年内分配变化以及两者变化的同步性进行了研究。结果表明:(1)不同年代降水与径流年内分配各自具有明显的差异,80年代夏季降水量与夏季径流量显著偏小,而2000-2007年却显著偏大,同时这时期年径流量显著增多、最大径流量出现时间较其他年代有所推迟;(2)近48年来,降水量和径流量的集中度都有缓慢的下降趋势,两者的年际变化有很好的同步性。降水量和径流量的集中期有微弱的上升趋势,但它们的同步性较差;(3)不同年代冬季降水量与同期径流量变化是不同步的,而年内其他季节,径流量分配过程主要依赖于降水量变化,降水和径流峰值表现出了很强的同步性。     

渭河流域极端降水时空演变规律及其对大气环流因子的响应

基于渭河流域内及其周边28个气象站点1961—2017年逐日降水量数据,选取PRCPTOT、SDII、Rx1day、Rx5day、R95P和R99P共6种极端降水指数,采用Mann-Kendall趋势检验和小波变换方法综合分析了渭河流域极端降水时空演变规律,并进一步探究流域极端降水指数与6种大气环流异常因子之间的相关关系。研究表明:(1)在1961—2017年间,渭河流域极端降水指数整体呈减少的趋势。渭河流域极端降水指数由西北向东南地区逐渐增加,流域东南地区较西北地区湿润;(2)1990年以后,极端降水指数在年际间的波动性明显增大,流域发生极端降水事件的概率有上升趋势;(3)在所选择的大气环流异常因子中,渭河流域极端降水受南方涛动指数SOI影响最大。SOI越大,流域发生少雨现象的概率越大,反之,则发生多雨、洪涝现象的概率越大。本文结果对于理解气候变化对于极端降雨的影响机理和加强预防气候灾害的能力有重要意义。     

近60 a渭河流域降水特征

基于1952-2011年渭河流域天水、宝鸡、武功、西安4个气象站的逐日、逐月、逐年降水量资料,利用线性回归、5 a滑动平均法、Mann-Kendall法以及小波分析,对渭河流域近60 a降水量变化进行趋势、突变以及周期分析。结果显示：渭河流域降水季节分配不均,主要集中在夏、秋两季,春、秋两季降水量呈现明显减小趋势,夏、冬两季降水量变化趋势不明显;各季节降水量年际变化显著;流域内除夏季以外,其他季节均存在突变点;4个站点均存在年总降水量突变点;渭河流域降水量的震荡周期为28~30 a;降水天数呈现减少趋势;小雨降水强度有增加趋势;除西安站外,其余3个站点1976-1990年的暴雨天数最多,暴雨天数年际变化较大。     

珠江流域旱涝变化及其与大气环流关系研究

基于珠江流域57个气象站1960-2014年逐日降水量资料,选用标准降水指数(SPI)为旱涝指标,讨论旱涝时空变化特征,研究与极端旱涝相关的大气环流成因。结果表明:(1)珠江流域旱涝严重程度主要受降水量影响,SPI能有效反映流域的旱涝特征;(2)自1980s起,流域有干旱趋势,西北部干旱化趋势显著;(3)流域春旱减缓,秋旱加重,夏季洪涝频发;(4)极端的旱涝变化与大气环流关系密切,西太平洋副热带高压与东亚大槽是两个主要影响珠江流域旱涝变化的环流系统。     

Spatio-temporal variation of hydrological drought under climate change during the period 1960–2013 in the Hexi Corridor,China

In recent years, climate change has been aggravated in many regions of the world. The Hexi Corridor is located in the semiarid climate zone of Northwest China, which is particularly affected by climate change. Climate change has led to the spatial and temporal variations of temperature and precipitation, which may result in hydrological drought and water shortage. Thus, it is necessary to explore and assess the drought characteristics of river systems in this area. The patterns of hydrological drought in the Hexi Corridor were identified using the streamflow drought index(SDI) and standardized precipitation index at 12-month timescale(SPI12) from 1960 to 2013. The evolution of drought was obtained by the Mann–Kendall test and wavelet transform method. The results showed that both the mean annual SDI and SPI12 series in the Hexi Corridor exhibited an increasing trend during the study period. According to the results of wavelet analysis, we divided the study period into two segments, i.e. before and after 1990. Before 1990, the occurrence of droughts showing decreased SDI and SPI12 was concentrated in the northern part of the corridor and shifted to the eastern part of the corridor after 1990. The probability of drought after 1990 in Shule River basin decreased while increased in Shiyang River basin. The wavelet analysis results showed that Shiyang River basin will be the first area to go through the next drought period. Additionally, the relationships between drought pattern and climate indices were analyzed. The enhanced westerly winds and increased precipitation and glacier runoff were the main reasons of wet trend in the Hexi Corridor. However, the uneven spatial variations of precipitation, temperature and glacier runoff led to the difference of hydrological drought variations between the Shule, Heihe and Shiyang River basins.     

基于干旱指数与主成分分析的干旱评价——以锡林河流域为例

利用锡林河流域逐月气象数据,分析了历年降水与气温的最值变化;计算了标准化降水指数(SPI)与综合气象干旱指数(CI)并用其对研究区干旱状况进行表征;利用主成分分析法对锡林河流域的干旱情况进行评价。结果表明:1981-2016年的最高气温变化呈微弱的升高趋势,最低气温的变化趋势基本持平。最大降水量的变化趋势是减小的,各月的最小降水量基本趋于0。CI指数表明,36 a中只出现过轻旱事件,且春季最多,其次为秋季,夏季发生的最少。SPI指数表明,36 a中出现了重涝、中涝、轻涝、重旱、中旱、轻旱事件,且事件的危害程度越高发生的概率相对越小,冬季发生的旱涝事件大多危害程度相对较高。主成分分析结果表明,研究区气象因素的第一主成分主要反映水分胁迫对干旱的影响,第二主成分主要反映日照对干旱的影响,第三主成分主要反映气温对干旱的影响;综合得分结果表明,各地的干旱情况排名为:扎鲁特>巴林左旗>翁牛特旗>多伦县>化德>西乌珠穆沁>锡林浩特>林西县>东乌珠穆沁>朱日和>阿巴嘎旗>二连浩特>苏尼特左旗。     

Spatial and temporal patterns of drought in Zambia

Drought acutely affects economic sectors, natural habitats and communities. Understanding the past spatial and temporal patterns of drought is crucial because it facilitates the forecasting of future drought occurrences and informs decision-making processes for possible adaptive measures. This is especially important in view of a changing climate. This study employed the World Meteorological Organization(WMO)-recommended standardized precipitation index(SPI) to investigate the spatial and temporal patterns of drought in Zambia from 1960 to 2016. The relationship between the occurrence of consecutive dry days(CDD; consecutive days with less than 1 mm of precipitation) and SPI was also investigated. Horizontal wind vectors at 850 hPa during the core of the rainy season(December–February)were examined to ascertain the patterns of flow during years of extreme and severe drought; and these were contrasted with the patterns of flow in 2007, which was a generally wet year. Pressure vertical velocity was also investigated. Based on the gamma distribution, SPI successfully categorized extremely dry(with a SPI value less than or equal to –2.0) years over Zambia as 1992 and 2015, a severely dry(–1.9 to –1.5) year as 1995, moderately dry(–1.4 to –1.0) years as 1972, 1980, 1987, 1999 and 2005, and 26 near normal years(–0.9 to 0.9). The occurrence of CDD was found to be strongly negatively correlated with SPI with a coefficient of –0.6. Further results suggest that, during wet years, Zambia is influenced by a clockwise circulating low-pressure zone over the south-eastern Angola, a second such zone over the northern and eastern parts, and a third over the Indian Ocean. In stark contrast, years of drought were characterized by an anti-clockwise circulating high-pressure zone over the south-western parts of Zambia,constraining precipitation activities over the country. Further, wet years were characterized by negative pressure vertical velocity anomalies, signifying ascending motion; while drought years were dominated by positive anomalies, signifying descending motion, which suppresses precipitation. These patterns can be used to forecast drought over Zambia and aid in strategic planning to limit the potential damage of drought.     

华东地区干旱灾害时空演化特征研究

针对国内外现有干旱应用研究往往忽略所采用模型与方法对研究结果存在的影响这一研究缺陷。利用我国中东部地区42个气象监测站点1961-2011年的降水资料,选用SPI指数对比分析了1月、3月、6月、12月四个时间尺度下中东部地区代表站点和月份的时空演化特征。结果表明:(1)不同时间尺度下研究区轻、中、重度干旱出现的时间和概率差异较大,无明显变化规律,但在中度干旱代表站点呈现出总体趋势一致的情况;(2)不同时间尺度下研究区各等级干旱空间分异明显,在中度干旱代表月份呈现出随时间尺度扩大的突变特征,在轻度和重度干旱代表月份,均表现为1月时间尺度下各等级干旱范围变化较大,3月、6月和12月时间尺度下几乎零面积干旱的特征。文中研究在证实区域干旱时空演化特征会随着所选SPI指数时间尺度变化而改变的同时,也肯定了在今后干旱应用研究中开展评估方法本身稳定性和适用性分析的必要性与意义。     

山西南部季节性干旱特征及综合防御技术

采用标准化降水指数(SPI)为干旱指标,计算了山西省运城市49年(1958—2007年)各月干旱指数,并在此基础上分析了山西南部地区季节性干旱特征。研究表明,干旱强度与干旱频率在不同年代际表现特征不同。与运城地区49年同期均值相比,进入20世纪90年代后,春旱发生频率、干旱强度分别提高了29.0%、5.1%;夏旱发生频率提高41.9%,干旱强度下降了7.4%;秋旱发生频率下降了23.8%,干旱强度提高了7.7%;冬旱发生频率下降了26.6%,干旱强度下降了37.5%。干旱的季节性特征为春旱和夏旱有加重趋势,秋旱和冬旱有减弱趋势。春旱(3—5月)和伏旱(7—8月)作为可预见性干旱,可采用土壤墒情监测、干旱预警、制定系统性抗旱措施等综合防御技术。对于不可预见类型干旱,可采用建立抗旱水源、储备抗旱机械等策略。     

基于改进的标准化降水指数的黄河中游干旱情势研究

提出了一种基于旬累积尺度的月标准化降水指数(SPI)计算方法,该方法不仅考虑了前期降雨量对区域当前旱情的影响,因而对旱情的评估更为客观,同时在实际应用中更具有时间上的灵活性,更能体现气象干旱的累积效应和预报的时效性。计算了黄河中游山西省境内近40a(1971-2009年)各旬干旱指数,分析结果表明改进的标准化降水指数能够很好地表征黄河中游山西省境内的历史旱情状况。引入国际上常用的多种未来气候情景,研究分析了未来气候变化下2021-2050年黄河中游山西省境内地区旱情发展的可能情势,结果表明其存在对农业不利影响加重的可能,需要引起水资源管理部门的重视。     

Impact of climate factors on runoff in the Kaidu River watershed:path analysis of 50-year data

Runoff formation is a complex meteorological-hydrological process impacted by many factors,especially in the inland river basin.Based on the data of daily mean air temperature,precipitation and runoff during the period of 1958-2007 in the Kaidu River watershed,this paper analyzed the changes in air temperature,precipitation and runoff and revealed the direct and indirect impacts of daily air temperature and precipitation on daily runoff by path analysis.The results showed that mean temperature time series of the annual,summer and autumn had a significant fluctuant increase during the last 50 years(P < 0.05).Only winter precipitation increased significantly(P < 0.05) with a rate of 1.337 mm/10a.The annual and winter runoff depthes in the last 50 years significantly increased with the rates of 7.11 mm/10a and 1.85 mm/10a,respectively.The driving function of both daily temperature and precipitation on daily runoff in annual and seasonal levels is significant in the Kaidu River watershed by correlation analysis.The result of path analysis showed that the positive effect of daily air temperature on daily runoff depth is much higher than that of daily precipitation in annual,spring,autumn and winter,however,the trend is opposite in summer.     

Performance of different drought indices for agriculture drought in the North China Plain

The Palmer drought severity index(PDSI), standardized precipitation index(SPI), and standardized precipitation evapotranspiration index(SPEI) are used worldwide for drought assessment and monitoring. However, substantial differences exist in the performance for agricultural drought among these indices and among regions. Here, we performed statistical assessments to compare the strengths of different drought indices for agricultural drought in the North China Plain. Small differences were detected in the comparative performances of SPI and SPEI that were smaller at the long-term scale than those at the short-term scale. The correlation between SPI/SPEI and PDSI considerably increased from 1-to 12-month lags, and a slight decreasing trend was exhibited during 12-and 24-month lags, indicating a 12-month scale in the PDSI, whereas the SPI was strongly correlated with the SPEI at 1-to 24-month lags. Interestingly, the correlation between the trend of temperature and the mean absolute error and its correlation coefficient both suggested stronger relationships between SPI and the SPEI in areas of rapid climate warming. In addition, the yield–drought correlations tended to be higher for the SPI and SPEI than that for the PDSI at the station scale, whereas small differences were detected between the SPI and SPEI in the performance on agricultural systems. However, large differences in the influence of drought conditions on the yields of winter wheat and summer maize were evident among various indices during the crop-growing season. Our findings suggested that multi-indices in drought monitoring are needed in order to acquire robust conclusions.