Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain （3H Plain）, which is a major ...Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain （3H Plain）, which is a major grain production area in China. In this paper, we investigated the variations in drought characteristics （drought event frequency, duration, severity, and intensity） for the past 50 years （1961-2010） and under future scenarios （2010-2099）, based on the observed meteorological data and the Representative Concentration Pathway （RCP） 8.5 scenario, respectively. First, we compared the applicability of three climatic drought indices： the standardized precipitation index （SPI）, the standardized precipitation evapotranspiration index based on the Penman-Monteith equation （SPEI-PM） and the same index based on the Thornthwaite equation （SPEI-TH） to correlate the recorded agricultural drought areas. Then, we analyzed the drought characteristics using ＇run theory＇ for both historical and the future RCP 8.5 scenario based on the best performing index. Correlation analyses between drought indices and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain. Based on the results of SPEI-PM, drought risks including duration, severity and intensity during 1961-2010 showed an decreasing trend. However, under the RCP 8.5 scenario, drought is expected to rise in frequency, duration, severity, and intensity from 2010-2099, although drought components during the 2010-2039 are predicted to be milder compared with historical conditions. This study highlights that the estimations for atmospheric evaporative demand would create differences in the prediction of long-term drought trends by different drought indices. The results of this study can help inform researchers and local policy makers to establish drought management strategies.展开更多
The Yili River Basin in Northwest China is a crucial ecological security barrier,yet it faces frequent droughts amid global climate change,posing significant threats to food security and ecological stability.However,t...The Yili River Basin in Northwest China is a crucial ecological security barrier,yet it faces frequent droughts amid global climate change,posing significant threats to food security and ecological stability.However,the spatiotemporal variations and driving mechanisms of drought in the basin remain unclear.Based on the monthly Standardized Precipitation Evapotranspiration Index(SPEI),this study employed the Run-Length theory to identify drought events in the basin during 1980-2020,applied statistical and time-series analyses to investigate the spatiotemporal variations,trends,periodicity,and persistence of drought,and explored the underlying drivers associated with meteorological factors and large-scale atmospheric circulation patterns.The results showed that droughts in the Yili River Basin are more severe in spring and summer.Droughts in the central and southwestern regions exhibit greater severity,with shorter durations and stronger intensity.Drought conditions have generally worsened(Sen’s slope=−0.146/10 yr),with notable intensification since 2005,especially in the northwestern region.Spring droughts(Sen’s slope=−0.213/10 yr)and summer droughts(Sen’s slope=−0.169/10 yr)have intensified at most stations,while autumn and winter droughts have eased.In the future,droughts are expected to alleviate overall,but summer droughts may continue to intensify.The Yili River Basin exhibits two primary drought periods of 9 yr and 21 yr,with primary periods in autumn(20 yr)and winter(20 yr)being longer than those in spring(10 yr)and summer(17 yr).Finally,droughts are impacted by both meteorological factors and large-scale atmospheric circulation patterns.Rising temperatures and uneven precipitation have intensified droughts.The SPEI exhibits a co-phase relationship with the North Atlantic Oscillation and an antiphase relationship with the East Central Tropical Pacific Sea Surface Temperature.Therefore,close monitoring and mitigation are necessary for spring and summer droughts,with a focus on the central and southwestern areas in autumn and winter.展开更多
Understanding the evolution and lag effects of droughts is critical to effective drought warning and water resources management.However,due to limited hydrological data,few studies have examined hydrological droughts ...Understanding the evolution and lag effects of droughts is critical to effective drought warning and water resources management.However,due to limited hydrological data,few studies have examined hydrological droughts and their lag time from meteorological droughts at a daily scale.In this study,precipitation data were collected to calculate the standardized precipitation index(SPI),and runoff data simulated by the variable infiltration capacity(VIC)model were utilized to compute the standardized runoff index(SRI).The three-threshold run theory was used to identify drought characteristics in China.These drought characteristics were utilized to investigate spatiotemporal variations,seasonal trends,and temporal changes in areas affected by meteorological and hydrological droughts.Additionally,the interconnections and lag effects between meteorological and hydrological droughts were explored.The results indicated that(1)drought occurred during approximately 28%of the past 34 years in China;(2)drought conditions tended to worsen in autumn and weaken in winter;(3)drought-affected areas shifted from northwest to northeast and finally to southern China;and(4)the correlation between meteorological and hydrological droughts was lower in the northwest and higher in the southeast,with all correlation coefficients exceeding 0.7.The lag times between meteorological and hydrological droughts were longest(5 d)in the Yangtze River,Yellow River,and Hai River basins,and shortest(0 d)in the Tarim River Basin.This study provides a scientific basis for effective early warning of droughts.展开更多
Probabilistic assessment of drought plays an important role in providing valuable information for evaluating water resources systems under drought conditions, and bivariate copulas are effective and efficient for the ...Probabilistic assessment of drought plays an important role in providing valuable information for evaluating water resources systems under drought conditions, and bivariate copulas are effective and efficient for the probabilistic assessment of drought based on joint distributions and/or joint return periods of drought characteristics. In this study, hydrological drought events and their characteristics (including duration and severity) in the Tien Yen River Basin of Quang Ninh province are detected using the Standardized Streamflow Index (SSFI). The BB8Copula is selected as the best-fit copula for hydrological drought duration and severity. Joint probabilities and joint return periods of drought duration and severity in the cases “and” and “or” are calculated based on the BB8Copula, which are employed for drought assessment. The results show that the drought events with 1-season or cross-quarter duration were more popular than others;joint probabilities and joint return periods of the detected drought events from 1962 to 2009, ranged from 0.2% to 92.2% and from 0.782 years to 315.414 years, respectively, in the case “and”, and ranged from 3.8% to 99.6% and from 0.724 years to 18.785 years, respectively, in the case “or”.展开更多
The characteristics of drought in Xinjiang Uygur Autonomous Region(Xinjiang),China have changed due to changes in the spatiotemporal patterns of temperature and precipitation,however,the effects of temperature and pre...The characteristics of drought in Xinjiang Uygur Autonomous Region(Xinjiang),China have changed due to changes in the spatiotemporal patterns of temperature and precipitation,however,the effects of temperature and precipitation—the two most important factors influencing drought—have not yet been thoroughly explored in this region.In this study,we first calculated the standard precipitation evapotranspiration index(SPEI)in Xinjiang from 1980 to 2020 based on the monthly precipitation and monthly average temperature.Then the spatiotemporal characteristics of temperature,precipitation,and drought in Xinjiang from 1980 to 2020 were analyzed using the Theil-Sen median trend analysis method and Mann-Kendall test.A series of SPEI-based scenario-setting experiments by combining the observed and detrended climatic factors were utilized to quantify the effects of individual climatic factor(i.e.,temperature and precipitation).The results revealed that both temperature and precipitation had experienced increasing trends at most meteorological stations in Xinjiang from 1980 to 2020,especially the spring temperature and winter precipitation.Due to the influence of temperature,trends of intensifying drought have been observed at spring,summer,autumn,and annual scales.In addition,the drought trends in southern Xinjiang were more notable than those in northern Xinjiang.From 1980 to 2020,temperature trends exacerbated drought trends,but precipitation trends alleviated drought trends in Xinjiang.Most meteorological stations in Xinjiang exhibited temperature-dominated drought trend except in winter;in winter,most stations exhibited precipitation-dominated wetting trend.The findings of this study highlight the importance of the impact of temperature on drought in Xinjiang and deepen the understanding of the factors influencing drought.展开更多
Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to ...Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to reflect drought conditions in the North-Eastern coastal region of Vietnam. The drought events and their characteristics from 1981 to 2019 are detected at 9 meteorological stations and 10 Chirps rainfall stations. The spatio-temporal variation of drought in the study region is analyzed on the basis of the number, duration, severity, intensity, and peak of the detected drought events at the 19 stations. The results show that from 1981 to 2019 the drought events mainly occurred with 1-season duration and moderate intensity and peak. The number, duration, severity, and peak of the drought events were the greatest in the period 2001-2010 and were the smallest in the period 2011-2019. Among the 19 stations, the drought duration tends to decrease at 11 stations, increase at 7 stations, and has a slight variant at 1 station;the drought severity tends to decrease at 14 stations, increase at 4 stations, and has not a significant trend at 1 station;the drought intensity tends to decrease at 17 stations, increase at 1 station, and has a slight variant at 1 station;and the drought peak tends to decrease at 18 stations and increase at 1 station.展开更多
This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated condition...This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated conditions. A two-year greenhouse study was conducted with four hybrids（one conventional hybrid, 33D53AM, two commercial DT hybrids, P1151 AM, N75H, and an experimental hybrid, Exp HB） grown under two water regimes（I（100） and I（50）, referring to 100 and 50% of evapotranspiration requirements）. Under water stress, the hybids P1151 AM, N75, and Exp HB showed more drought tolerance and had either greater shoot dry weight or less dry weight reduction than the conventional hybrid（33 D53 AM）. However, these three hybrids responded to water stress using different mechanisms. Compared with the conventional hybrid, the two commercial DT hybrids（P1151 AM and N75H） had a smaller leaf area, shoot dry weight, and root system per plant. As a result, these hybrids used less water but had a higher WUE compared with the conventional hybrid. In contrast, the experimental hybrid（ExpHB） produced more shoot biomass by silking stage at both irrigation levels than all other hybrids, but it had relatively lower WUE. The hybrids demonstrated different drought response mechanisms that may require different irrigation management strategies. More investigation and validation are needed under field conditions and in different soil types.展开更多
NCEP/NCAR data are utilized to analyze an extreme flood year(1998) and an extreme dry year(2006) in the Sichuan-Chongqing region(SCR) and the results are as follows. The positive divergence of South Asia High(SAH) is ...NCEP/NCAR data are utilized to analyze an extreme flood year(1998) and an extreme dry year(2006) in the Sichuan-Chongqing region(SCR) and the results are as follows. The positive divergence of South Asia High(SAH) is stronger in the flood year; the position of the ridge line of SAH is southward compared with the annual average; Western Pacific Subtropical High(WPSH) extends westward and its ridge line is southward. In the drought year, the positive divergence of SAH is weaker, its ridge line is northward, and the position of WPSH is also northward. As shown in the dynamics, in drought(flood) years, negative(positive) vorticity advection in the upper atmosphere can cause the atmosphere to ascend(descend), and anomalous circulation of SAH displays divergence(convergence), and anomalous circulation of the lower atmosphere shows convergence(divergence). Thermal structure of the atmosphere shows that there is warm(cold) temperature advection in the lower atmosphere, and the vertical distribution of diabetic heating causes SAH's local circulation to display convergence(divergence) and affects vertical motion of the lower atmosphere circulation eventually. To some extent, the two extreme years in the SCR is closely related to the vertical motion of atmosphere circulation and the variation of such vertical motion is caused by differences of interactions between SAH and lower atmosphere circulations.展开更多
In order to study the effective water-saving cultivation of wheat in Sichuan under drought conditions to reduce grain loss,the effects of different irrigation methods（ natural rainfall,artificial irrigation,and infil...In order to study the effective water-saving cultivation of wheat in Sichuan under drought conditions to reduce grain loss,the effects of different irrigation methods（ natural rainfall,artificial irrigation,and infiltrating irrigation） on soil physical characteristics and main agronomic characters and yield of wheat were analyzed. The results showed that different irrigation treatments at different growth stages had different effects on soil physical characteristics and agronomic characters of wheat. At the seedling and jointing stage,there were small differences between the treatments in soil compactness,soil bulk density,and soil water content. At the flowering and maturation stage,different irrigation treatments had great impacts on soil compactness,soil bulk density,soil water content,and agronomic characters of wheat. In the hilly areas of Sichuan Basin,infiltrating irrigation at the jointing stage was the best,and wheat yield increased significantly,2 113. 46 kg/hm^2 higher than that in the control.展开更多
基金supported by the National Basic Research Program of China (973 Program,2012CB955904)the National Key Technologies R&D Program of China during the 12th Five-year Plan period (2012BAD09B01)the National Science Foundation for Young Scientists of China (41401510)
文摘Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain （3H Plain）, which is a major grain production area in China. In this paper, we investigated the variations in drought characteristics （drought event frequency, duration, severity, and intensity） for the past 50 years （1961-2010） and under future scenarios （2010-2099）, based on the observed meteorological data and the Representative Concentration Pathway （RCP） 8.5 scenario, respectively. First, we compared the applicability of three climatic drought indices： the standardized precipitation index （SPI）, the standardized precipitation evapotranspiration index based on the Penman-Monteith equation （SPEI-PM） and the same index based on the Thornthwaite equation （SPEI-TH） to correlate the recorded agricultural drought areas. Then, we analyzed the drought characteristics using ＇run theory＇ for both historical and the future RCP 8.5 scenario based on the best performing index. Correlation analyses between drought indices and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain. Based on the results of SPEI-PM, drought risks including duration, severity and intensity during 1961-2010 showed an decreasing trend. However, under the RCP 8.5 scenario, drought is expected to rise in frequency, duration, severity, and intensity from 2010-2099, although drought components during the 2010-2039 are predicted to be milder compared with historical conditions. This study highlights that the estimations for atmospheric evaporative demand would create differences in the prediction of long-term drought trends by different drought indices. The results of this study can help inform researchers and local policy makers to establish drought management strategies.
基金Under the auspices of the Third Xinjiang Scientific Expedition Program(No.2022xjkk0600)。
文摘The Yili River Basin in Northwest China is a crucial ecological security barrier,yet it faces frequent droughts amid global climate change,posing significant threats to food security and ecological stability.However,the spatiotemporal variations and driving mechanisms of drought in the basin remain unclear.Based on the monthly Standardized Precipitation Evapotranspiration Index(SPEI),this study employed the Run-Length theory to identify drought events in the basin during 1980-2020,applied statistical and time-series analyses to investigate the spatiotemporal variations,trends,periodicity,and persistence of drought,and explored the underlying drivers associated with meteorological factors and large-scale atmospheric circulation patterns.The results showed that droughts in the Yili River Basin are more severe in spring and summer.Droughts in the central and southwestern regions exhibit greater severity,with shorter durations and stronger intensity.Drought conditions have generally worsened(Sen’s slope=−0.146/10 yr),with notable intensification since 2005,especially in the northwestern region.Spring droughts(Sen’s slope=−0.213/10 yr)and summer droughts(Sen’s slope=−0.169/10 yr)have intensified at most stations,while autumn and winter droughts have eased.In the future,droughts are expected to alleviate overall,but summer droughts may continue to intensify.The Yili River Basin exhibits two primary drought periods of 9 yr and 21 yr,with primary periods in autumn(20 yr)and winter(20 yr)being longer than those in spring(10 yr)and summer(17 yr).Finally,droughts are impacted by both meteorological factors and large-scale atmospheric circulation patterns.Rising temperatures and uneven precipitation have intensified droughts.The SPEI exhibits a co-phase relationship with the North Atlantic Oscillation and an antiphase relationship with the East Central Tropical Pacific Sea Surface Temperature.Therefore,close monitoring and mitigation are necessary for spring and summer droughts,with a focus on the central and southwestern areas in autumn and winter.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFC3006505)the Fundamental Research Funds for the Central Universities of China(Grant No.B240203007)the National Key Laboratory of Water Disaster Prevention(Grant No.524015222)。
文摘Understanding the evolution and lag effects of droughts is critical to effective drought warning and water resources management.However,due to limited hydrological data,few studies have examined hydrological droughts and their lag time from meteorological droughts at a daily scale.In this study,precipitation data were collected to calculate the standardized precipitation index(SPI),and runoff data simulated by the variable infiltration capacity(VIC)model were utilized to compute the standardized runoff index(SRI).The three-threshold run theory was used to identify drought characteristics in China.These drought characteristics were utilized to investigate spatiotemporal variations,seasonal trends,and temporal changes in areas affected by meteorological and hydrological droughts.Additionally,the interconnections and lag effects between meteorological and hydrological droughts were explored.The results indicated that(1)drought occurred during approximately 28%of the past 34 years in China;(2)drought conditions tended to worsen in autumn and weaken in winter;(3)drought-affected areas shifted from northwest to northeast and finally to southern China;and(4)the correlation between meteorological and hydrological droughts was lower in the northwest and higher in the southeast,with all correlation coefficients exceeding 0.7.The lag times between meteorological and hydrological droughts were longest(5 d)in the Yangtze River,Yellow River,and Hai River basins,and shortest(0 d)in the Tarim River Basin.This study provides a scientific basis for effective early warning of droughts.
文摘Probabilistic assessment of drought plays an important role in providing valuable information for evaluating water resources systems under drought conditions, and bivariate copulas are effective and efficient for the probabilistic assessment of drought based on joint distributions and/or joint return periods of drought characteristics. In this study, hydrological drought events and their characteristics (including duration and severity) in the Tien Yen River Basin of Quang Ninh province are detected using the Standardized Streamflow Index (SSFI). The BB8Copula is selected as the best-fit copula for hydrological drought duration and severity. Joint probabilities and joint return periods of drought duration and severity in the cases “and” and “or” are calculated based on the BB8Copula, which are employed for drought assessment. The results show that the drought events with 1-season or cross-quarter duration were more popular than others;joint probabilities and joint return periods of the detected drought events from 1962 to 2009, ranged from 0.2% to 92.2% and from 0.782 years to 315.414 years, respectively, in the case “and”, and ranged from 3.8% to 99.6% and from 0.724 years to 18.785 years, respectively, in the case “or”.
文摘The characteristics of drought in Xinjiang Uygur Autonomous Region(Xinjiang),China have changed due to changes in the spatiotemporal patterns of temperature and precipitation,however,the effects of temperature and precipitation—the two most important factors influencing drought—have not yet been thoroughly explored in this region.In this study,we first calculated the standard precipitation evapotranspiration index(SPEI)in Xinjiang from 1980 to 2020 based on the monthly precipitation and monthly average temperature.Then the spatiotemporal characteristics of temperature,precipitation,and drought in Xinjiang from 1980 to 2020 were analyzed using the Theil-Sen median trend analysis method and Mann-Kendall test.A series of SPEI-based scenario-setting experiments by combining the observed and detrended climatic factors were utilized to quantify the effects of individual climatic factor(i.e.,temperature and precipitation).The results revealed that both temperature and precipitation had experienced increasing trends at most meteorological stations in Xinjiang from 1980 to 2020,especially the spring temperature and winter precipitation.Due to the influence of temperature,trends of intensifying drought have been observed at spring,summer,autumn,and annual scales.In addition,the drought trends in southern Xinjiang were more notable than those in northern Xinjiang.From 1980 to 2020,temperature trends exacerbated drought trends,but precipitation trends alleviated drought trends in Xinjiang.Most meteorological stations in Xinjiang exhibited temperature-dominated drought trend except in winter;in winter,most stations exhibited precipitation-dominated wetting trend.The findings of this study highlight the importance of the impact of temperature on drought in Xinjiang and deepen the understanding of the factors influencing drought.
文摘Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to reflect drought conditions in the North-Eastern coastal region of Vietnam. The drought events and their characteristics from 1981 to 2019 are detected at 9 meteorological stations and 10 Chirps rainfall stations. The spatio-temporal variation of drought in the study region is analyzed on the basis of the number, duration, severity, intensity, and peak of the detected drought events at the 19 stations. The results show that from 1981 to 2019 the drought events mainly occurred with 1-season duration and moderate intensity and peak. The number, duration, severity, and peak of the drought events were the greatest in the period 2001-2010 and were the smallest in the period 2011-2019. Among the 19 stations, the drought duration tends to decrease at 11 stations, increase at 7 stations, and has a slight variant at 1 station;the drought severity tends to decrease at 14 stations, increase at 4 stations, and has not a significant trend at 1 station;the drought intensity tends to decrease at 17 stations, increase at 1 station, and has a slight variant at 1 station;and the drought peak tends to decrease at 18 stations and increase at 1 station.
基金supported in part by the UDSA-Ogallala Aquifer ProgramTexas A&M Agri Life Research Cropping System Program, USAthe USDA National Institute of Food and Agriculture Hatch Project, USA (TEX09438)
文摘This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated conditions. A two-year greenhouse study was conducted with four hybrids（one conventional hybrid, 33D53AM, two commercial DT hybrids, P1151 AM, N75H, and an experimental hybrid, Exp HB） grown under two water regimes（I（100） and I（50）, referring to 100 and 50% of evapotranspiration requirements）. Under water stress, the hybids P1151 AM, N75, and Exp HB showed more drought tolerance and had either greater shoot dry weight or less dry weight reduction than the conventional hybrid（33 D53 AM）. However, these three hybrids responded to water stress using different mechanisms. Compared with the conventional hybrid, the two commercial DT hybrids（P1151 AM and N75H） had a smaller leaf area, shoot dry weight, and root system per plant. As a result, these hybrids used less water but had a higher WUE compared with the conventional hybrid. In contrast, the experimental hybrid（ExpHB） produced more shoot biomass by silking stage at both irrigation levels than all other hybrids, but it had relatively lower WUE. The hybrids demonstrated different drought response mechanisms that may require different irrigation management strategies. More investigation and validation are needed under field conditions and in different soil types.
基金National Key Basic Research Development Program Project of China(2012CB417202)Key Project of National Natural Science Foundation(91337215)National Natural Science Foundation of China(41275051)
文摘NCEP/NCAR data are utilized to analyze an extreme flood year(1998) and an extreme dry year(2006) in the Sichuan-Chongqing region(SCR) and the results are as follows. The positive divergence of South Asia High(SAH) is stronger in the flood year; the position of the ridge line of SAH is southward compared with the annual average; Western Pacific Subtropical High(WPSH) extends westward and its ridge line is southward. In the drought year, the positive divergence of SAH is weaker, its ridge line is northward, and the position of WPSH is also northward. As shown in the dynamics, in drought(flood) years, negative(positive) vorticity advection in the upper atmosphere can cause the atmosphere to ascend(descend), and anomalous circulation of SAH displays divergence(convergence), and anomalous circulation of the lower atmosphere shows convergence(divergence). Thermal structure of the atmosphere shows that there is warm(cold) temperature advection in the lower atmosphere, and the vertical distribution of diabetic heating causes SAH's local circulation to display convergence(divergence) and affects vertical motion of the lower atmosphere circulation eventually. To some extent, the two extreme years in the SCR is closely related to the vertical motion of atmosphere circulation and the variation of such vertical motion is caused by differences of interactions between SAH and lower atmosphere circulations.
文摘In order to study the effective water-saving cultivation of wheat in Sichuan under drought conditions to reduce grain loss,the effects of different irrigation methods（ natural rainfall,artificial irrigation,and infiltrating irrigation） on soil physical characteristics and main agronomic characters and yield of wheat were analyzed. The results showed that different irrigation treatments at different growth stages had different effects on soil physical characteristics and agronomic characters of wheat. At the seedling and jointing stage,there were small differences between the treatments in soil compactness,soil bulk density,and soil water content. At the flowering and maturation stage,different irrigation treatments had great impacts on soil compactness,soil bulk density,soil water content,and agronomic characters of wheat. In the hilly areas of Sichuan Basin,infiltrating irrigation at the jointing stage was the best,and wheat yield increased significantly,2 113. 46 kg/hm^2 higher than that in the control.
