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1.
《干旱区科学》2016,(2)
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. 相似文献
2.
降水是径流的基本来源,分析极端旱涝条件下降水与径流之间演变规律的异步性,可有效表征径流丰枯变化对人类活动的响应。基于渭河流域降水、径流资料,采用泰森多边形法计算渭河流域面降水量及12个月标准化降水指数(SPI12),对比典型频率下SPI12的空间分布特征及其对径流系数的影响;采用经验正交函数和时间序列分析法挖掘SPI12和年径流量的演变规律,对比演变规律的同步及异步变化特征。结果表明:在25%、50%、75%频率下,流域面降水量分别为582.5 mm、518.6 mm、467.5 mm。SPI12第一主成分减少趋势显著,自1991年7月开始突变,于1962-09(1962年9月,下同)—1969-07—1983-02—1985-08—1991-07—1999-12呈现湿润~正常~湿润~正常~干旱状态。渭河年径流量呈显著减少趋势,自1989年开始突变,且分别于1950—1968和1982—1993年经历湿润和正常阶段,于1970—1974、1976—1980、1994—2007年经历干旱阶段。以流域内大规模水利、水土保持措施及城市化等为代表的人类活动使流域年径流量较SPI12第一主成分突变年份提前,使二者于1970—1996年间旱涝类型不匹配,年径流量相对SPI12第一主成分呈现旱化趋势。 相似文献
3.
Murat KARABULUT 《干旱区科学》2015,7(6):741-754
The most parts of the Earth experience precipitation variability as a part of their normal climates over both short- and long-time periods. These variations of precipitation will have unpredictable and perhaps unexpectedly extreme consequences(such as drought and flood) with respect to frequency and intensity for many regions of the Earth. Because of high precipitation fluctuations, the Mediterranean region is also the areas of the world sensitive to precipitation changes which often involve frequent drought conditions in Turkey. In this study, drought conditions at annual, seasonal and monthly time scales over the period of 1975–2010 were examined for Antakya-Kahramanmara? Graben which is located in the eastern part of the Mediterranean region of Turkey. Application of appropriate measures to analyze and monitor droughts is recognized as a major challenge to scientists involved in atmospheric studies. Standardized Precipitation Index(SPI) and cumulative deviation curve techniques were used to determine drought conditions. Results indicated that the study area presented a cyclic pattern of variations with alternating drier and wetter years. From analyses of annual, seasonal and monthly drought series it can be seen that precipitation characteristic of the area is changing. By the results, apparent wet and dry periods can be distinguished. This study also indicated that precipitation totals of winter, spring and summer seasons were slightly decreased during the study period. Drought frequency was increased especially for the northern part of the area in the last ten years. Drought periods were divided into 1982–1985, 1999–2002 and 2004–2008, respectively. According to our analyses, the time scale of 1999–2002 was the driest period in the most of the graben area. The study area, which covers agriculturally important fertile alluvial plains, will experience increasing pressure on its water resources because of its growing population and industry, ever-larger demands for intensive agricultural activities, and frequent drought events. 相似文献
4.
Climate warming will cause differences in precipitation distribution and changes in hydrological cycle both at regional and global scales. Arid lands of Central Asia(ALCA), one of the largest arid regions at the middle latitudes in the world, is likely to be strongly influenced by climate warming. Understanding the precipitation variations in the past is an important prerequisite for predicting future precipitation trends and thus managing regional water resources in such an arid region. In this study, we used run theory, displacement, extreme deviation theory, precipitation concentration index(PCI), Mann-Kendall rank correlation and climatic trend coefficient methods to analyze the precipitation in wet and dry years, changes in precipitation over multiple-time scales, variability of precipitation and its rate of change based on the monthly precipitation data during 1950–2000 from 344 meteorological stations in the ALCA. The occurrence probability of a single year with abundant precipitation was higher than that of a single year with less precipitation. The average duration of extreme drought in the entire area was 5 years, with an average annual water deficit of 34.6 mm(accounting for 11.2% of the average annual precipitation over the duration). The occurrence probability of a single wet year was slightly higher than that of a single dry year. The occurrence probability of more than 5 consecutive wet years was 5.8%, while the occurrence probability of more than 5 consecutive dry years was 6.2%. In the center of the study area, the distribution of precipitation was stable at an intra-annual timescale, with small changes at an inter-annual timescale. In the western part of the study area, the monthly variation of precipitation was high at an inter-annual timescale. There were clear seasonal changes in precipitation(PCI=12–36) in the ALCA. Precipitation in spring and winter accounted for 37.7% and 24.4% of the annual precipitation, respectively. There was a significant inter-annual change in precipitation in the arid Northwest China(PCI=24–34). Annual precipitation increased significantly(P=0.05) in 17.4% of all the meteorological stations over the study period. The probability of an increase in annual precipitation was 75.6%, with this increase being significant(P=0.05) at 34.0% of all the meteorological stations. The average increasing rate in annual precipitation was 3.9 mm/10a(P=0.01) in the ALCA. There were significant increasing trends(P=0.01) in precipitation in Kazakhstan, Kyrgyzstan and Tajikistan, with rates of 2.6, 3.1 and 3.7 mm/10 a, respectively. 相似文献
5.
Drought was a severe recurring phenomenon in Iraq over the past two decades due to climate change despite the fact that Iraq has been one of the most water-rich countries in the Middle East in the past.The Iraqi Kurdistan Region(IKR)is located in the north of Iraq,which has also suffered from extreme drought.In this study,the drought severity status in Sulaimaniyah Province,one of four provinces of the IKR,was investigated for the years from 1998 to 2017.Thus,Landsat time series dataset,including 40 images,were downloaded and used in this study.The Normalized Difference Vegetation Index(NDVI)and the Normalized Difference Water Index(NDWI)were utilized as spectral-based drought indices and the Standardized Precipitation Index(SPI)was employed as a meteorological-based drought index,to assess the drought severity and analyse the changes of vegetative cover and water bodies.The study area experienced precipitation deficiency and severe drought in 1999,2000,2008,2009,and 2012.Study findings also revealed a drop in the vegetative cover by 33.3%in the year 2000.Furthermore,the most significant shrinkage in water bodies was observed in the Lake Darbandikhan(LDK),which lost 40.5%of its total surface area in 2009.The statistical analyses revealed that precipitation was significantly positively correlated with the SPI and the surface area of the LDK(correlation coefficients of 0.92 and 0.72,respectively).The relationship between SPI and NDVI-based vegetation cover was positive but not significant.Low precipitation did not always correspond to vegetative drought;the delay of the effect of precipitation on NDVI was one year. 相似文献
6.
Türkan BAYER ALTIN 《干旱区科学》2021,13(5):470-486
The hydrographic eastern Mediterranean Basin of Turkey is a drought sensitive area. The basin is an important agricultural area and it is necessary to determine the extent of extreme regional climatic changes as they occur in this basin. Pearson's correlation coefficient was used to show the correlation between standardized precipitation index(SPI) and standardized streamflow index(SSI) values on different time scales. Data from five meteorological stations and seven stream gauging stations in four sub-basins of the eastern Mediterranean Basin were analyzed over the period from 1967 to 2017. The correlation between SSI and SPI indicated that in response to meteorological drought, hydrological drought experiences a one-year delay then occurs in the following year. This is more evident at all stations from the mid-1990 s. The main factor causing hydrological drought is prolonged low precipitation or the presence of a particularly dry year. Results showed that over a long period(12 months), hydrological drought is longer and more severe in the upper part than the lower part of the sub-basins. According to SPI-12 values, an uninterrupted drought period is observed from 2002–2003 to 2008–2009. Results indicated that among the drought events, moderate drought is the most common on all timescales in all sub-basins during the past 51 years. Long-term dry periods with moderate and severe droughts are observed for up to 10 years or more since the late 1990 s, especially in the upper part of the sub-basins. As precipitation increases in late autumn and early winter, the stream flow also increases and thus the highest and most positive correlation values(0.26–0.54) are found in January. Correlation values(ranging between –0.11 and –0.01) are weaker and negative in summer and autumn due to low rainfall. This is more evident at all stations in September. The relation between hydrological and meteorological droughts is more evident, with the correlation values above 0.50 on longer timescales(12-and 24-months). The results presented in this study allow an understanding of the characteristics of drought events and are instructive for overcoming drought. This will facilitate the development of strategies for the appropriate management of water resources in the eastern Mediterranean Basin, which has a high agricultural potential. 相似文献
7.
标准化前期降水蒸散指数(Standardized antecedent precipitation evapotranspiration index,SAPEI)是一种新的日尺度干旱指数,相对标准化降水蒸散指数(SPEI)而言,它不仅考虑当日的降水和蒸散情况,还考虑了早期水分平衡对当天干湿条件的影响,在描述和监测干旱方面更为稳健。本文根据新疆地区42个气象站2000—2019年气象要素数据计算SAPEI,利用线性趋势、M-K检验和反距离插值等方法,研究了21世纪以来新疆地区SAPEI时空变化特征,并基于SAPEI的分区和分代际比较分析了新疆地区干旱强度的时空变化,进而对新疆干旱发生的区域性和广泛程度的四季变化以及不同干旱等级发生频率的空间分布格局进行了探讨。结果表明：新疆气候整体呈湿润化,近年来干湿差异扩大,空间上存在部分相对湿润地区显著变干的现象;新疆春季变干,夏、秋、冬季变湿,夏冬两季在时间和空间上的干湿变化差异截然相反;20年来全疆和分区的干旱强度均显著降低,空间上东北部高、中部和西南部低;新疆干旱范围呈缩减趋势,近年来存在干旱等级提升风险,春季干旱范围扩大;新疆不同干旱等级的发... 相似文献
8.
Shanhu JIANG 《干旱区科学》2017,9(2):256-269
The high resolution satellite precipitation products bear great potential for large-scale drought monitoring, especially for those regions with sparsely or even without gauge coverage. This study focuses on utilizing the latest Version-7 TRMM Multi-satellite Precipitation Analysis(TMPA 3B42V7) data for drought condition monitoring in the Weihe River Basin(0.135×106 km2). The accuracy of the monthly TMPA 3B42V7 satellite precipitation data was firstly evaluated against the ground rain gauge observations. The statistical characteristics between a short period data series(1998–2013) and a long period data series(1961–2013) were then compared. The TMPA 3B42V7-based SPI(Standardized Precipitation Index) sequences were finally validated and analyzed at various temporal scales for assessing the drought conditions. The results indicate that the monthly TMPA 3B42V7 precipitation is in a high agreement with the rain gauge observations and can accurately capture the temporal and spatial characteristics of rainfall within the Weihe River Basin. The short period data can present the characteristics of long period record, and it is thus acceptable to use the short period data series to estimate the cumulative probability function in the SPI calculation. The TMPA 3B42V7-based SPI matches well with that based on the rain gauge observations at multiple time scales(i.e., 1-, 3-, 6-, 9-, and 12-month) and can give an acceptable temporal distribution of drought conditions. It suggests that the TMPA 3B42V7 precipitation data can be used for monitoring the occurrence of drought in the Weihe River Basin. 相似文献
9.
柴达木盆地干旱时空变化特征 总被引：1，自引：1，他引：0
利用柴达木盆地气象站收集的降水和气温数据,计算了SPI和SPEI两种干旱指数,并用于评价研究区不同时间尺度的干旱特征。然而,由于测站分布稀疏,两种指数在区域干旱评价方面存在不足。在此基础上基于全球范围内的scPDSIpm数据集,并用PDSI指数分析了干旱演变特征及时空分布规律,研究发现：①温度在年际尺度对研究区的干旱情况影响较大,而在月尺度和半年尺度上对研究区干旱情况影响不明显;②PDSI指数与SPEI和SPI干旱指数的相关系数较高（0.7以上）,与两者具有较好的一致性,PDSI更适宜于无资料地区的干旱评价;③研究区中部干旱状况最为严重,东部边缘和西北部干旱频次相对较少,但2000年以来这种趋势得到改善。本研究对评价不同干旱指数的适用性及资料缺乏地区的干旱评价具有重要的指导意义。 相似文献
10.
Hushiar HAMARASH 《干旱区科学》2022,14(11):1212-1233
Drought occurs in almost all climate zones and is characterized by prolonged water deficiency due to unbalanced demand and supply of water, persistent insufficient precipitation, lack of moisture, and high evapotranspiration. Drought caused by insufficient precipitation is a temporary and recurring meteorological event. Precipitation in semi-arid regions is different from that in other regions, ranging from 50 to 750 mm. In general, the semi-arid regions in the west and north of Iran received more precipitation than those in the east and south. The Terrestrial Climate (TerraClimate) data, including monthly precipitation, minimum temperature, maximum temperature, potential evapotranspiration, and the Palmer Drought Severity Index (PDSI) developed by the University of Idaho, were used in this study. The PDSI data was directly obtained from the Google Earth Engine platform. The Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) on two different scales were calculated in time series and also both SPI and SPEI were shown in spatial distribution maps. The result showed that normal conditions were a common occurrence in the semi-arid regions of Iran over the majority of years from 2000 to 2020, according to a spatiotemporal study of the SPI at 3-month and 12-month time scales as well as the SPEI at 3-month and 12-month time scales. Moreover, the PDSI detected extreme dry years during 2000-2003 and in 2007, 2014, and 2018. In many semi-arid regions of Iran, the SPI at 3-month time scale is higher than the SPEI at 3-month time scale in 2000, 2008, 2014, 2015, and 2018. In general, this study concluded that the semi-arid regions underwent normal weather conditions from 2000 to 2020. In a way, moderate, severe, and extreme dry occurred with a lesser percentage, gradually decreasing. According to the PDSI, during 2000-2003 and 2007-2014, extreme dry struck practically all hot semi-arid regions of Iran. Several parts of the cold semi-arid regions, on the other hand, only experienced moderate to severe dry from 2000 to 2003, except for the eastern areas and wetter regions. The significance of this study is the determination of the spatiotemporal distribution of meteorological drought in semi-arid regions of Iran using strongly validated data from TerraClimate. 相似文献
11.
基于改进的标准化降水指数的黄河中游干旱情势研究 总被引：1，自引：0，他引：1
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。 相似文献
12.
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。 相似文献
13.
甘肃省河东春小麦全生育期降水异常特征分析 总被引：5，自引：0，他引：5
利用甘肃省河东31个测站1958～2001年历年春小麦全生育期（3～7月）的总降水量资料，通过EOF、REOF及Mahat小波分析等方法，对甘肃河东主要雨养农业区春小麦全生育期降水异常的空间特征、时间变化进行了分析研究。结果表明，甘肃河东春小麦全生育期降水的主要空间异常型表现为一致的多雨或少雨型；降水异常区域大致可分为4个区，既甘肃中部区、陇东区、陇南区和甘肃南部区；降水主要表现为13～14年、3年左右和6～8年的周期振荡。 相似文献
14.
山西南部季节性干旱特征及综合防御技术 总被引：1，自引：0，他引：1
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。 相似文献
15.
近40年青海东部春季降水变化特征及小波分析 总被引：2，自引：0，他引：2
应用线性趋势分析和小波变换分析方法对青海东部地区12个气象台站1961~2004年春季降水的变化特征及时~频特征进行了分析。结果表明:近44 a来,青海东部地区春季降水量波动明显,年代际变化表现出20世纪60年代偏多,70年代、80年代偏少,进入90年代以来偏多的趋势;春季降水总体呈弱的增加趋势,分阶段分析,只在1981~2004年时段趋势呈弱的减少,其余时段均呈增加趋势;在10 a及以上相对较大的时间尺度上,春季降水干、湿交替的特征非常明显,经历了6个干、湿交替的阶段,其突变点为1964年、1975年、1983年、1993年、2001年,其10~12 a和16 a左右的周期较为明显;而对于10 a以下相对较小的时间尺度,春季降水变化比较复杂,增加了更多的相对干、湿交替阶段和突变点,其6~8 a的周期突出;当周期振荡表现为较强的负位相时,均会发生强的干旱;从最近几年青海东部地区的春季降水变化来看,其较大尺度和较小尺度的变化均处于较强的偏多期。 相似文献
16.
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. 相似文献
17.
利用1979—2011年英国东英吉利大学气候研究中心（CRU）整理的地面月降水资料和日本气象厅（JMA）加工的全球高空等压面月平均气象场再分析资料,采用标准化降水指数（SPI）,确定了川渝地区典型干旱年,讨论了川渝地区夏季典型干旱的气候特征及其大气环流特征。结果表明：川渝地区夏季典型干旱年具有气温高、降水少的气候特征;东亚中纬度盛行纬向气流,西风锋区偏北,冷空气多偏北东移,川渝地区及其我国北方大部分地区受大陆带状高压控制。500 hPa带状高压与100 hPa南亚高压中心位置基本一致,且500 hPa高压中心与温度场的暖中心相对应,是持续性川渝夏季干旱具有近似正压结构的典型环流特征;同时川渝地区夏季干旱年对流层低层从云贵高原到四川盆地的西南气流明显偏弱,风场距平合成表明,云贵高原到川渝地区为东北距平风,距平风场上华南地区为明显的气旋式环流;川渝地区夏季典型干旱年整层西南气流水汽输送与常年比较明显偏小。 相似文献
18.
LIU Bingxia 《干旱区科学》2016,8(1):47-59
Implementation of the Grain-for-Green project has led to rapid land cover changes and resulted in a significantly increased vegetation cover on the Loess Plateau of China during the past few decades. The main objective of this study was to examine the responses of soil water dynamics under four typical vegetation types against precipitation years. Soil water contents(SWCs) were measured in 0–4.0 m profiles on a hillslope under the four vegetation types of shrub, pasture, natural fallow and crop in a re-vegetated catchment area from April to October in normal(2010), dry(2011), wet(2014) and extremely wet(2013) years. The results indicated that precipitation and vegetation types jointly controlled the soil water temporal dynamics and profile characteristics in the study region. SWCs in 0–4.0 m profiles of the four vegetation types were ranked from high to low as cropfallowpastureshrub and this pattern displayed a temporal stability over the four years. In the extremely wet year, SWC changes occurred in the 0–2.0 m layer under shrub and pasture while the changes further extended to the depth of 4.0-m deep layers under fallow and crop. In the other three years, SWCs changes mainly occurred in the 0–1.0 m layer and kept relatively stable in the layers deeper than 1.0 m for all the four vegetation types. The interannual variation in soil depth of SWCs was about 0–2.0 m for shrub and pasture, about 0–3.4 m for fallow and about 0–4.0 m for crop, respectively. The dried soil layers formed at the depths of 1.0, 0.6, 1.6 and 0.7 m under shrub, and 1.0, 1.0, 2.0 and 0.9 m under pasture, respectively in 2010, 2011, 2013 and 2014. The infiltrated rainwater mostly stayed in the 0–1.0 m layer and hardly supplied to soil depth 1.0 m in normal, dry and wet years. Even in the extremely wet year of 2013, rainwater recharge depth did not exceed 2.0 m under shrub and pasture. This implied that soil desiccation was difficult to remove in normal, dry and wet years, and soil desiccation could be removed in 1.0–2.0 m soil layers even in the extremely wet year under shrub and pasture. The results indicated that the natural fallow was the best vegetation type for achieving sustainable utilization of soil water and preventing soil desiccation. 相似文献
19.
SALEHNIA Nasrin 《干旱区科学》2017,9(6):797-809
Meteorological drought is a natural hazard that can occur under all climatic regimes. Monitoring the drought is a vital and important part of predicting and analyzing drought impacts. Because no single index can represent all facets of meteorological drought, we took a multi-index approach for drought monitoring in this study. We assessed the ability of eight precipitation-based drought indices(SPI(Standardized Precipitation Index), PNI(Percent of Normal Index), DI(Deciles index), EDI(Effective drought index), CZI(China-Z index), MCZI(Modified CZI), RAI(Rainfall Anomaly Index), and ZSI(Z-score Index)) calculated from the station-observed precipitation data and the Ag MERRA gridded precipitation data to assess historical drought events during the period 1987–2010 for the Kashafrood Basin of Iran. We also presented the Degree of Dryness Index(DDI) for comparing the intensities of different drought categories in each year of the study period(1987–2010). In general, the correlations among drought indices calculated from the Ag MERRA precipitation data were higher than those derived from the station-observed precipitation data. All indices indicated the most severe droughts for the study period occurred in 2001 and 2008. Regardless of data input source, SPI, PNI, and DI were highly inter-correlated(R~2=0.99). Furthermore, the higher correlations(R~2=0.99) were also found between CZI and MCZI, and between ZSI and RAI. All indices were able to track drought intensity, but EDI and RAI showed higher DDI values compared with the other indices. Based on the strong correlation among drought indices derived from the Ag MERRA precipitation data and from the station-observed precipitation data, we suggest that the Ag MERRA precipitation data can be accepted to fill the gaps existed in the station-observed precipitation data in future studies in Iran. In addition, if tested by station-observed precipitation data, the Ag MERRA precipitation data may be used for the data-lacking areas. 相似文献
20.
基于加权马尔可夫模型的标准化降水指数干旱预测研究 总被引：7，自引：2，他引：5
基于不同时间尺度标准化降水指数的干旱监测结果,以规范化的各阶白相关系数为权重,采用加权马尔可夫链方法对未来干旱状态进行预测和分析.以关中平原和渭北旱塬36个气泉站39年逐月降水量为分析数据.系统地分析了该方法在不同时间尺度(从1个月到1年)上的预测能力及存在的问题.结果表明:对所选的5个时间尺度该方法都有一定的预测能力,并且随着时间尺度的增加,预测正确率也相应提高.同时,该方法对无旱的预测比较准确.对干旱的发生也有一定预测能力,可以作为早期干旱预警的参考.但是,该方法对干旱状态突变的预测能力较弱;随着干旱程度的加重其预测能力也逐渐降低. 相似文献