scholarly journals Use of the Standardized Precipitation Evapotranspiration Index (SPEI) to Characterize the Drying Trend in Southwest China from 1982–2012

2015 ◽  
Vol 7 (8) ◽  
pp. 10917-10937 ◽  
Author(s):  
Xing Li ◽  
Binbin He ◽  
Xingwen Quan ◽  
Zhanmang Liao ◽  
Xiaojing Bai
Keyword(s):  
Southwest China ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Drying Trend

scholarly journals Intra-annual differences of 3-month Standardized Precipitation-Evapotranspiration Index dryness/wetness sensitivity over southwest China

2018 ◽  
Vol 19 (8) ◽  
pp. e830 ◽  
Author(s):  
Shanlei Sun ◽  
Yongjian Ren ◽  
Qingqing Li ◽  
Shujia Zhou ◽  
Changyu Zhao ◽  
...  
Keyword(s):  
Southwest China ◽  
Standardized Precipitation Evapotranspiration Index

scholarly journals Spatiotemporal Differences in Dominants of Dryness/Wetness Changes in Southwest China

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Shujia Zhou ◽  
Shanlei Sun ◽  
Wanrong Shi ◽  
Jiazhi Wang ◽  
Jinjian Li ◽  
...  
Keyword(s):  
Climate Change ◽  
Regional Development ◽  
Southwest China ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Full Analysis

A full analysis of 3-month Standardized Precipitation-Evapotranspiration index (SPEI-3) changes and attribution analyses are of significance for deeply understanding dryness/wetness evolutions and thus formulating specific measures to sustain regional development. In this study, we analyze monthly and annual SPEI-3 changes over Southwest China (SWC; including Sichuan (SC), Chongqing (CQ), Guizhou (GZ), Yunnan (YN), and west Guangxi (wGX)) during 1961–2012, using the SPEI model and routine meteorological measurements at 269 weather sites. For SWC and each subregion (excluding wGX), annual SPEI-3 during 1961–2012 tends to decrease, and drying is at most of months in January and September–December, but wetting is in February–August (excluding March for wGX). Additionally, more than 50% of sites show declined and increased SPEI-3 in January, April, June, and August–December and the remaining months, respectively. Except for wGX with dominant of ET0, annual SPEI-3 changes in SWC and other four subregions have dominant of precipitation. Spatially, annual SPEI-3 changes at 59% of sites are because of precipitation, generally located in southeast SC, south YN, CQ, GZ, and south and northeast wGX. Nevertheless, dominants at regional and site scales vary among months, e.g., SWC, SC, CQ, and GZ, having dominant of precipitation (ET0) during September–December (most of months during January–August), YN always with dominant of precipitation, and wGX with dominant of precipitation (ET0) in February–April and July–December (January, May, and June). Importantly, this study provides a reference for quantitatively evaluating spatiotemporal dryness/wetness variations with climate change, especially for regions with significant drying/wetting.

scholarly journals Analysis of Dry/Wet Variations in the Poyang Lake Basin Using Standardized Precipitation Evapotranspiration Index Based on Two Potential Evapotranspiration Algorithms

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1380 ◽  
Author(s):  
Weilin Liu ◽  
Lina Liu
Keyword(s):  
Poyang Lake ◽  
Potential Evapotranspiration ◽  
Social Economy ◽  
Correlation Coefficients ◽  
Lake Basin ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Poyang Lake Basin ◽  
Drying Trend ◽  
Positive Correlations ◽  
Annual Scale

Global warming has resulted in unevenly distributed changes in precipitation and evapotranspiration, which has some influence on dry/wet conditions, thus exerting a tremendous impact on national life and the social economy, especially agricultural production. In order to characterize the dry/wet variations in the Poyang Lake basin during 1958–2013, based on the potential evapotranspiration (PET) estimated by the Thornthwaite (TH) and Penman–Monteith (PM) formulas, two types of Standardized Precipitation Evapotranspiration Index (SPEI), namely SPEI_th and SPEI_pm, were calculated in this study. The characteristic of dry/wet variations in the Poyang Lake basin was analyzed and a comparative analysis of two SPEIs was conducted. The results indicate that both SPEI series showed a wet trend in the Poyang Lake basin on an annual scale as well as seasonal scales during 1958–2013, except for spring and autumn. A drying trend was observed in spring, while in autumn, the dry and wet conditions in two SPEIs had opposite trends. However, all trends from two SPEIs were not significant, except for summer SPEI_pm. Meanwhile, significant positive correlations were detected between precipitation and two SPEIs, with the correlation coefficients above 0.95, whereas negative correlations were detected between PET and two SPEIs, with the correlation coefficients ranging from −0.17 to −0.85. This indicates that precipitation was the main climatic factor to determine change in dry/wet conditions in the Poyang Lake basin. Although there were obvious differences between the accumulated values of the Penman–Monteith-based PET (ET_pm) and Thornthwaite-based PET (ET_th), trends in the SPEI_pm series were generally consistent with those in the SPEI_th series, revealing that the method for PET calculation was not critical to the change in dry/wet conditions. Moreover, the results of the conditional probability of SPEI_pm and SPEI_th show that both SPEI_pm and SPEI_th could detect wet or dry events that were identified by SPEI_pm or SPEI_th.

scholarly journals Spatio-Temporal Variability of Drought in Pakistan Using Standardized Precipitation Evapotranspiration Index

2019 ◽  
Vol 9 (21) ◽  
pp. 4588 ◽  
Author(s):  
Shoaib Jamro ◽  
Ghulam Hussain Dars ◽  
Kamran Ansari ◽  
Nir Y. Krakauer
Keyword(s):  
Climate Change ◽  
Temporal Trends ◽  
Trend Test ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Northern Areas ◽  
Tree Edge ◽  
Edge Removal ◽  
History Of ◽  
Drying Trend ◽  
Spatio Temporal

Pakistan is among the top ten countries adversely affected by climate change. More specifically, there is concern that climate change may cause longer and severer spells of droughts. To quantify the change in the characteristics of droughts in Pakistan over the years, we have evaluated spatio-temporal trends of droughts in Pakistan over the period 1902–2015 using Standardized Precipitation Evapotranspiration Index (SPEI). Additionally, the Spatial “K” luster Analysis using Tree Edge Removal (SKATER) method was employed to regionalize droughts into five contiguous zones. The run theory was then applied to each zone to identify drought events and characterize them in terms of duration, severity, intensity, and peak. Moreover, the Modified Mann–Kendall trend test was applied to identify statistically significant trends in SPEI and drought characteristics in each zone. It was found that the southern areas of Pakistan, encompassing Sindh and most of Baluchistan, have experienced a decrease in SPEI, indicating a drying trend. Central Pakistan has witnessed a wetting trend as demonstrated by an increase in SPEI over time, whereas no statistically significant trend was observed for the northern areas of Pakistan. On a zonal basis, the longest duration drought to occur in Pakistan lasted 22 months in zone 5 (Sindh) from 1968 to 1970. In addition, the drought of 1920 and 2000 can be said to be the worst drought in the history of the region as it affected all the zones and lasted for more than 10-months in three zones.

scholarly journals Monitoring the Reduced Resilience of Forests in Southwest China Using Long-Term Remote Sensing Data

2021 ◽  
Vol 14 (1) ◽  
pp. 32
Author(s):  
Hao Jiang ◽  
Lisheng Song ◽  
Yan Li ◽  
Mingguo Ma ◽  
Lei Fan
Keyword(s):  
Climate Change ◽  
Water Availability ◽  
Southwest China ◽  
Remote Sensing Data ◽  
Root Systems ◽  
Severe Drought ◽  
Spatial Distributions ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Good Agreement

An increase in the frequency and severity of droughts associated with global warming has resulted in deleterious impacts on forest productivity in Southwest China. Despite attempts to explore the response of vegetation to drought, less is known about forest’s resilience in response to drought in Southwest China. Here, the reduced resilience of the forest was found based on remotely sensed optical and microwave vegetation products. The spatial distribution and temporal variation of resilience-reduced forest were assessed using the standardized precipitation evapotranspiration index (SPEI) and vegetation optical depth (VOD). Our findings showed that 40–50% of the forest appeared to have abnormally low resilience approximately 6 months after the severe drought. The spatial distributions of abnormally low resilience had a good agreement with the regions affected by the 2009–2011 drought events. In particular, our results indicated that areas of afforestation were more susceptible to drought than natural forest, maybe due to the different water uptake strategy of the diverse root systems. Our findings highlight the vulnerability of afforestation areas to climate change, and recommend giving more attention to soil water availability.

scholarly journals Effects of Vegetation Restoration on Regional Soil Moisture Content in the Humid Karst Areas—A Case Study of Southwest China

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 321
Author(s):  
Xiaocha Wei ◽  
Qiuwen Zhou ◽  
Mingyong Cai ◽  
Yujuan Wang
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Southwest China ◽  
Vegetation Restoration ◽  
Data Set ◽  
Karst Areas ◽  
Increasing Trend ◽  
Drying Trend

Soil moisture is one of the restricting factors in the humid karst areas, which feature strong spatial heterogeneity. However, current research about the effects of vegetation restoration on soil moisture content have mainly focused on plot scale and slope scale, while these effects still remain unclear at regional scale in this area. Taking Southwest China as a case study and based on the land parameter data record (LPDR) and enhanced vegetation index (EVI) data set during 2002–2018, this study analyzed the spatiotemporal variation characteristics of vegetation and soil moisture content, and evaluated the effects of vegetation restoration on regional soil moisture content dynamics in paired years with similar precipitation conditions. The results showed that the EVI generally increased at a rate of 0.035/10a during 2002–2018, while the soil moisture was dominated by a drying trend at a variation rate of −0.0006 (cm3/cm3)/10a. The increasing trend of EVI accounted for 90.90% across the study area, whereas the decreasing trend of soil moisture accounted for 51.66%, and the increasing trend of soil moisture accounted for 48.34%. In addition, the decreasing trend of soil moisture coupled with an increasing trend of EVI distributed in most of the study area, especially in the homogenous limestone area. Our results demonstrate that there were remarkable vegetation restoration efforts in a series of ecological restoration projects, which resulted in a drying trend of the regional soil moisture content in the humid karst areas. The results suggest that it is necessary to consider reasonable vegetation planting density and suitable revegetation types to balance the relationship between vegetation water consumption and soil moisture supplementation in vegetation restoration practice in the humid karst areas.

Using species distribution modeling to improve conservation of medicinal plants in Southwest China

Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
B Liu ◽  
F Li ◽  
Z Guo ◽  
L Hong ◽  
W Huang ◽  
...  
Keyword(s):  
Medicinal Plants ◽  
Species Distribution ◽  
Southwest China ◽  
Species Distribution Modeling ◽  
Distribution Modeling

Prince Henri d'Orleans (1867–1901): geographical and botanical exploration between inner Asia and southwest China

1978 ◽  
Vol 8 (4) ◽  
pp. 399-399
Author(s):  
WILLIAM GARDENER
Keyword(s):  
Southwest China ◽  
Western China ◽  
Left Bank ◽  
Inner Asia ◽  
Botanical Exploration ◽  
Western Yunnan ◽  
Westerly Direction ◽  
Chinese Province ◽  
The Right ◽  
North Western

Prince Henri d'Orleans, precluded by French law from serving his country in the profession of arms, had his attention turned early towards exploration. In 1889, accompanied by the experienced traveller Gabriel Bonvalet, he set out from Paris to reach Indo-China overland by way of Central Asia, Tibet and western and south western China. The journey made contributions in the problems of the whereabouts of Lap Nor and the configuration of the then unexplored northern plateau of Tibet; and in botany it produced some species new to science. The party reached Indo-China in 1890. In 1895, having organised an expedition better equipped for topographical survey and for investigations in the fields of natural history and ethnography, Prince Henri set out from Hanoi with the intention of exploring the Mekong through the Chinese province of Yunnan. After proceeding up the left bank of the Salween for a brief part of its course and then alternating between the right and left banks of the Mekong as far up as Tzeku, the party found it advisable to enter Tibet in a north westerly direction through the province of Chamdo and instead crossed the south eastern extremity of the country, the Zayul, by a difficult track which led them to the country of the Hkamti Shans in present day Upper Burma, and thence to India completing a journey of 2000 miles, "1500 of which had been previously untrodden" (Prince Henri). West of the Mekong, the journey established that the Salween, which some geographers had claimed took its rise in or near north western Yunnan, in fact rose well north in Tibet, and that, contrary to previous opinions, the principal headwater of the Irrawaddy rose no further north than latitude 28°30'. Botanical collections were confined to Yunnan, where the tracks permitted mule transport, and they produced a number of species new to science and extended the range of distribution of species already known.

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