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Khan N, Gaire NP, Rahmonov O, Ullah R. Multi-century (635-year) spring season precipitation reconstruction from northern Pakistan revealed increasing extremes. Sci Rep 2024; 14:92. [PMID: 38168593 PMCID: PMC10761852 DOI: 10.1038/s41598-023-50819-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 12/26/2023] [Indexed: 01/05/2024] Open
Abstract
The Hindu Kush Himalaya region is experiencing rapid climate change with adverse impacts in multiple sectors. To put recent climatic changes into a long-term context, here we reconstructed the region's climate history using tree-ring width chronologies of climate-sensitive Cedrus deodara and Pinus gerardiana. Growth-climate analysis reveals that the species tree-growth is primarily limited by moisture stress during or preceding the growing season, as indicated by a positive relationship between the chronology and precipitation and scPDSI, and a negative one with temperature. We have reconstructed 635 years (1384-2018 CE) of February-June precipitation using a robust climate reconstruction model that explains about 53% variance of the measured precipitation data. Our reconstruction shows several dry and wet episodes over the reconstruction period along with an increase in extreme precipitation events during recent centuries or years. Long, very wet periods were observed during the following years: 1392-1393, 1430-1433, 1456-1461, 1523-1526, 1685-1690, 1715-1719, 1744-1748, 1763-1767, 1803-1806, 1843-1846, 1850-1855, 1874-1876, 1885-1887, 1907-1909, 1921-1925, 1939-1944, and 1990-1992, while long dry periods were observed during the following years: 1398-1399, 1464-1472, 1480-1484, 1645-1649, 1724-1727, 1782-1786, 1810-1814, 1831-1835, 1879-1881, 1912-1918, 1981-1986, 1998-2003, and 2016-2018 CE. We found predominantly short-term periodicity cycles of 2.0, 2.2, 2.3, 2.4, 2.6-2.7, 2.9, 3.3, 4.8, 8.1-8.3, and 9.4-9.6 years in our reconstruction. Spatial correlation analyses reveal that our reconstruction is an effective representation of the precipitation variability in the westerly climate-dominated areas of Pakistan and adjacent regions. In addition to the influence of regional circulation systems like western disturbances, we found possible teleconnections between the precipitation variability in northern Pakistan and broader-scale climate modes or phases like AMO and ENSO. The study also highlights the prospects of tree-ring application to explore linkages between western disturbance, increasing intensity and frequency of extreme climate events, and analysis of long-term atmospheric circulation over the western Himalayan region.
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Affiliation(s)
- Nasrullah Khan
- Department of Botany, University of Malakand, Dir Lower, P.O. Box 18800, Chakdara, Khyber Pakhtunkhwa, Pakistan
| | - Narayan Prasad Gaire
- Department of Environmental Science, Patan Multiple Campus, Tribhuvan University, Lalitpur, Nepal
| | - Oimahmad Rahmonov
- Faculty of Natural Sciences, Institute of Earth Sciences, University of Silesia in Katowice, Katowice, Poland.
| | - Rafi Ullah
- Department of Botany, University of Malakand, Dir Lower, P.O. Box 18800, Chakdara, Khyber Pakhtunkhwa, Pakistan
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2
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Tarasova L, Lun D, Merz R, Blöschl G, Basso S, Bertola M, Miniussi A, Rakovec O, Samaniego L, Thober S, Kumar R. Shifts in flood generation processes exacerbate regional flood anomalies in Europe. COMMUNICATIONS EARTH & ENVIRONMENT 2023; 4:49. [PMID: 38665201 PMCID: PMC11041756 DOI: 10.1038/s43247-023-00714-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 02/10/2023] [Indexed: 04/28/2024]
Abstract
Anomalies in the frequency of river floods, i.e., flood-rich or -poor periods, cause biases in flood risk estimates and thus make climate adaptation measures less efficient. While observations have recently confirmed the presence of flood anomalies in Europe, their exact causes are not clear. Here we analyse streamflow and climate observations during 1960-2010 to show that shifts in flood generation processes contribute more to the occurrence of regional flood anomalies than changes in extreme rainfall. A shift from rain on dry soil to rain on wet soil events by 5% increased the frequency of flood-rich periods in the Atlantic region, and an opposite shift in the Mediterranean region increased the frequency of flood-poor periods, but will likely make singular extreme floods occur more often. Flood anomalies driven by changing flood generation processes in Europe may further intensify in a warming climate and should be considered in flood estimation and management.
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Affiliation(s)
- Larisa Tarasova
- Department Catchment Hydrology, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany
| | - David Lun
- Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology, Vienna, Austria
| | - Ralf Merz
- Department Catchment Hydrology, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany
- Institute of Geosciences and Geography, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Günter Blöschl
- Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology, Vienna, Austria
| | - Stefano Basso
- Department Catchment Hydrology, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany
- Norwegian Institute for Water Research (NIVA), Oslo, Norway
| | - Miriam Bertola
- Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology, Vienna, Austria
| | - Arianna Miniussi
- Department Catchment Hydrology, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany
| | - Oldrich Rakovec
- Department Computational Hydrosystems, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague-Suchdol, Czech Republic
| | - Luis Samaniego
- Department Computational Hydrosystems, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Stephan Thober
- Department Computational Hydrosystems, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
| | - Rohini Kumar
- Department Computational Hydrosystems, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
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3
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Extreme local recycling of moisture via wetlands and forests in North-East Indian subcontinent: a Mini-Amazon. Sci Rep 2023; 13:521. [PMID: 36627383 PMCID: PMC9831987 DOI: 10.1038/s41598-023-27577-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/04/2023] [Indexed: 01/12/2023] Open
Abstract
Moisture recycling in precipitation is an important hydrological process, accounting for ~ 67% globally. North-east India, home to the world's wettest place, boasts vast wetlands and forest-cover. Despite its proximity to the coast, we find locally recycled moisture to be the primary annual source of rainfall (~ 45%). During the pre-monsoon season, the enriched δ18O (~ - 0.7 ‰) and high d-excess (~ 14 ‰) are ascribed to enhanced transpiration, owing to atmospheric instability which causes Nor'westers. During the Monsoon season, oceanic flux provides increased surficial moisture, enabling deep-localised convection via evaporation. Significant localised recycling, even during the Monsoon season is estimated (~ 38%), with predominantly high d-excess in precipitation during latter half of the monsoon with increased moisture contribution from floods in Brahmaputra (high d-excess). The increasing δ18O and d-excess during the post-monsoon season is associated with progressively lesser rainout history and increased localized recycling (~ 67%). In light of the dwindling wetlands and forest-cover, our study highlights their indispensable role in governing regional hydro-meteorology and water availability.
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Wu Y, Long D, Lall U, Scanlon BR, Tian F, Fu X, Zhao J, Zhang J, Wang H, Hu C. Reconstructed eight-century streamflow in the Tibetan Plateau reveals contrasting regional variability and strong nonstationarity. Nat Commun 2022; 13:6416. [PMID: 36302859 PMCID: PMC9613640 DOI: 10.1038/s41467-022-34221-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 10/11/2022] [Indexed: 12/25/2022] Open
Abstract
Short instrumental streamflow records in the South and East Tibetan Plateau (SETP) limit understanding of the full range and long-term variability in streamflow, which could greatly impact freshwater resources for about one billion people downstream. Here we reconstruct eight centuries (1200-2012 C.E.) of annual streamflow from the Monsoon Asia Drought Atlas in five headwater regions across the SETP. We find two regional patterns, including northern (Yellow, Yangtze, and Lancang-Mekong) and southern (Nu-Salween and Yarlung Zangbo-Brahmaputra) SETP regions showing ten contrasting wet and dry periods, with a dividing line of regional moisture regimes at ~32°-33°N identified. We demonstrate strong temporal nonstationarity in streamflow variability, and reveal much greater high/low mean flow periods in terms of duration and magnitude: mostly pre-instrumental wetter conditions in the Yarlung Zangbo-Brahmaputra and drier conditions in other rivers. By contrast, the frequency of extreme flows during the instrumental periods for the Yangtze, Nu-Salween, and Yarlung Zangbo-Brahmaputra has increased by ~18% relative to the pre-instrumental periods.
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Affiliation(s)
- Yenan Wu
- grid.12527.330000 0001 0662 3178State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084 China
| | - Di Long
- grid.12527.330000 0001 0662 3178State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084 China
| | - Upmanu Lall
- grid.21729.3f0000000419368729Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027 USA
| | - Bridget R. Scanlon
- grid.89336.370000 0004 1936 9924Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78758 USA
| | - Fuqiang Tian
- grid.12527.330000 0001 0662 3178State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084 China
| | - Xudong Fu
- grid.12527.330000 0001 0662 3178State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084 China
| | - Jianshi Zhao
- grid.12527.330000 0001 0662 3178State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084 China
| | - Jianyun Zhang
- grid.459786.10000 0000 9248 0590State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, 210098 China
| | - Hao Wang
- grid.453304.50000 0001 0722 2552State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, 100038 China
| | - Chunhong Hu
- grid.453304.50000 0001 0722 2552State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, 100038 China
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5
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Protracted Indian monsoon droughts of the past millennium and their societal impacts. Proc Natl Acad Sci U S A 2022; 119:e2207487119. [PMID: 36122235 PMCID: PMC9522357 DOI: 10.1073/pnas.2207487119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protracted droughts lasting years to decades constitute severe threats to human welfare across the Indian subcontinent. Such events are, however, rare during the instrumental period (ca. since 1871 CE). In contrast, the historic documentary evidence indicates the repeated occurrences of protracted droughts in the region during the preinstrumental period implying that either the instrumental observations underestimate the full spectrum of monsoon variability or the historic accounts overestimate the severity and duration of the past droughts. Here we present a temporally precise speleothem-based oxygen isotope reconstruction of the Indian summer monsoon precipitation variability from Mawmluh cave located in northeast India. Our data reveal that protracted droughts, embedded within multidecadal intervals of reduced monsoon rainfall, frequently occurred over the past millennium. These extreme events are in striking temporal synchrony with the historically documented droughts, famines, mass mortality events, and geopolitical changes in the Indian subcontinent. Our findings necessitate reconsideration of the region's current water resources, sustainability, and mitigation policies that discount the possibility of protracted droughts in the future.
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Kumar A, Mondal S, Lal P. Analysing frequent extreme flood incidences in Brahmaputra basin, South Asia. PLoS One 2022; 17:e0273384. [PMID: 35994487 PMCID: PMC9394833 DOI: 10.1371/journal.pone.0273384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 08/07/2022] [Indexed: 11/19/2022] Open
Abstract
The present study is focused on the flood inundation in Brahmaputra Basin, which is one of the most recurrent and destructive natural disasters of the region. The flood inundation was assessed using C-Band Sentinel 1A synthetic aperture radar (SAR) during 2015–2020 with precipitation patterns, runoff discharge, and their impacts on land cover in the basin. The study exhibited a very high precipitation during monsoon in the upper catchment resulting in severe flood inundation in downslopes of Brahmaputra Basin. A very high (900–2000 mm) to extremely high (>2000 mm) monthly cumulative precipitation in the south and south-eastern parts of basin led to high discharge (16,000 to 18,000 m3s-1) during July-August months. The river discharge increases with cumulative effects of precipitation and melting of snow cover during late summer and monsoon season, and induced flood inundation in lower parts of basin. This flood has largely affected agricultural land (>77% of total basin), forests (~3%), and settlement (426 to 1758 km2) affecting large wildlife and livelihood during 2015–2020. The study highlights the regions affected with recurrent flood and necessitates adopting an integrated, multi-hazard, multi-stakeholder approach with an emphasis on self-reliance of the community for sustenance with local resources and practices.
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Affiliation(s)
- Amit Kumar
- Department of Geoinformatics, Central University of Jharkhand, Ranchi, Jharkhand, India
| | - Subhasree Mondal
- Department of Geoinformatics, Central University of Jharkhand, Ranchi, Jharkhand, India
| | - Preet Lal
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, United States of America
- * E-mail:
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Rahman M, Islam M, Masood M, Gebrekirstos A, Bräuning A. Flood signals in tree-ring δ 18O and wood anatomical parameters of Lagerstroemia speciosa: Implications for developing flood management strategies in Bangladesh. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 809:151125. [PMID: 34688736 DOI: 10.1016/j.scitotenv.2021.151125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/16/2021] [Accepted: 10/17/2021] [Indexed: 06/13/2023]
Abstract
Bangladesh consists of 80% of the flood plain of the Ganges-Brahmaputra-Meghna river system (GBM), making the country one of the highest flood prone countries of the world. Due to the high rate of discharge of the GBM caused by the summer monsoon and the snowmelt of the Eastern Himalaya and Southern Tibetan Plateau due to climate change, Bangladesh witnessed 16 flood events over 1954-2017. We performed a multiproxy tree-ring analysis to investigate the impact of extreme flood events on tree growth, xylem anatomical parameters and oxygen isotope composition of tree-ring cellulose (δ18Otr) in a Bangladeshi moist tropical forest and to establish relationships between water level of the regional rivers and tree-ring parameters. By using pointer year analysis and comparing the pointer years with historical flood records (a cut-off threshold of the country's flooded land area of 33.3%), we identified the three extreme flood events (hereafter called flood years) 1974, 1988, and 1998 in Bangladesh. Superposed epoch analysis revealed significant changes in Tree-ring width (TRW), total vessel area (TVA), vessel density (VD), and δ18Otr during flood years. Flood associated hypoxic soil conditions reduced TRW up to 53% and TVA up to 28%, varying with flood events. In contrast, VD increased by 23% as a safety mechanism against flood induced hydraulic failure. Tree-ring δ18O significantly decreased during the flood years due to the amount effect in regional precipitation. Bootstrapped Pearson correlation analysis showed that wood anatomical variables encoded stronger river level signals than TRW and δ18Otr. Among the wood anatomical parameters, VD showed a strong relationship (r = -0.58, p < 0.01) with the water level of the Manu River, a regional river of the north-eastern part of Bangladesh, indicating that VD can be used as a reliable proxy for river level reconstruction. Our analyses suggest that multiproxy tree-ring analysis is a potential tool to study tropical moist forest responses to extreme flood events and to identify suitable proxies for reconstructing hydrological characteristics of South Asian rivers.
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Affiliation(s)
- Mizanur Rahman
- Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh; Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Wetterkreuz 15, 91058 Erlangen, Germany.
| | - Mahmuda Islam
- Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh; Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Wetterkreuz 15, 91058 Erlangen, Germany
| | - Muhammad Masood
- Design Circle-9, Bangladesh Water Development Board (BWDB), Pani Bhaban, 72, Green Road, Dhaka 1215, Bangladesh
| | - Aster Gebrekirstos
- Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Wetterkreuz 15, 91058 Erlangen, Germany; World Agroforestry Centre (ICRAF), United Nations Avenue, P.O. Box 30677-00100, Nairobi, Kenya
| | - Achim Bräuning
- Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Wetterkreuz 15, 91058 Erlangen, Germany
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Ahmed IA, Dutta DK, Baig MRI, Roy SS, Rahman A. Implications of changes in temperature and precipitation on the discharge of Brahmaputra River in the urban watershed of Guwahati, India. ENVIRONMENTAL MONITORING AND ASSESSMENT 2021; 193:518. [PMID: 34312714 DOI: 10.1007/s10661-021-09284-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
The urban watershed of Guwahati situated on the bank of the Brahmaputra River is one of the fastest growing cities of India. During the last two decades, water security concerns due to climatic variabilities have become a pronounced issue in the urban watershed of Guwahati. Thus, the study aims to calculate the long-term temporal trends of temperature, precipitation, extreme climate indices, and river discharge to assess the variations and patterns of hydro-climatic variations in the urban watershed of Guwahati from 1991 to 2019. Furthermore, the current study also tries to correlate these extreme climatic indices to river discharge to determine the degree of hydro-climatic variations. The Mann-Kendall statistical techniques and Sen's estimator were used to calculate the statistical significance, stability, and averaged magnitude of trends in the hydro-meteorological data. The result shows that the wetness indices, R20 and RX5Day, reported a decline in Guwahati's urban watershed from 1991 to 2019, resulting in a reduction in intensity and duration of heavy rainfalls while the dry spell (CDD) has been more distinct in the study area with a rise in the average temperature by 0.023 °C/year. Similarly, the most significant statistical trend was found in the monsoonal discharge of the Brahmaputra with a negative trend of - 204.16 m3/s/year. The results also show that fluctuations in rainfall patterns have a direct impact on the discharge of the Brahmaputra. These phenomena can affect the quantity of river water resulting in a severe impact on water security in the study area.
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Affiliation(s)
- Ishita Afreen Ahmed
- Department of Geography, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi, 110025, India
| | - Dipanwita K Dutta
- Department of Remote Sensing and GIS, Vidyasagar University, Midnapore, West Bengal, 721102, India
| | - Mirza Razi Imam Baig
- Department of Geography, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi, 110025, India
| | - Shouraseni Sen Roy
- Department of Geography and Regional Studies, University of Miami, Coral Gables, FL33146, USA
| | - Atiqur Rahman
- Department of Geography, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi, 110025, India.
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