| 51. |
- Chen, Aifang, 1990, et al.
(författare)
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Multidecadal variability of the Tonle Sap Lake flood pulse regime
- 2021
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 35:9
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Tidskriftsartikel (refereegranskat)abstract
- Tonle Sap Lake (TSL) is one of the world's most productive lacustrine ecosystems, driven by the Mekong River's seasonal flood pulse. This flood pulse and its long-term dynamics under the Mekong River basin's (MRB) fast socio-economic development and climate change need to be identified and understood. However, existing studies fall short of sufficient time coverage or concentrate only on changes in water level (WL) that is only one of the critical flood pulse parameters influencing the flood pulse ecosystem productivity. Considering the rapidly changing hydroclimatic conditions in the Mekong basin, it is crucial to systematically analyse the changes in multiple key flood pulse parameters. Here, we aim to do that by using observed WL data for 1960-2019 accompanied with several parameters derived from a Digital Bathymetry Model. Results show significant declines of WL and inundation area from the late 1990s in the dry season and for the whole year, on top of increased subdecadal variability. Decreasing (increasing) probabilities of high (low) inundation area for 2000-2019 have been found, in comparison to the return period of inundation area for 1986-2000 (1960-1986). The mean seasonal cycle of daily WL in dry (wet) season for 2000-2019, compared to that for 1986-2000, has shifted by 10 (5) days. Significant correlations and coherence changes between the WL and large-scale circulations (i.e., El Nino-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Indian Ocean Dipole (IOD)), indicate that the atmospheric circulations could have influenced the flood pulse in different time scales. Also, the changes in discharge at the Mekong mainstream suggest that anthropogenic drivers may have impacted the high water levels in the lake. Overall, our results indicate a declining flood pulse since the late 1990s.
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| 52. |
- Chen, Aifang, 1990, et al.
(författare)
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Rising future tropical cyclone-induced extreme winds in the Mekong River Basin
- 2020
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273 .- 2095-9281. ; 65:5, s. 419-424
-
Tidskriftsartikel (refereegranskat)abstract
- © 2019 Science China Press The societal impact of extreme winds induced by tropical cyclones (TCs) is a major concern in the Mekong River Basin (MRB). Though no clear trend of landfalling TC intensity along the Vietnam coastline has been observed since the 1970s, climate models project an increasing TC intensity in the 21st century over the Western North Pacific, which is the primary TC source region influencing the MRB. Yet, how future TC activities will affect extreme winds quantitatively in the MRB remains unclear. By employing a novel dynamical downscaling technique using a specialized, coupled ocean-atmospheric model, shorter return periods of maximum wind speed in the MRB for 2081–2100 compared with 1981–2000 are projected based on five global climate models under the RCP8.5 scenario, suggesting increases in the future tropical cyclone intensity. The results point to consistently elevated future TC-related risks that may jeopardize sustainable development, disrupt food supply, and exacerbate conflicts in the region and beyond.
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| 53. |
- Chen, Aifang, 1990, et al.
(författare)
-
Tropical cyclone rainfall in the Mekong River Basin for 1983–2016
- 2019
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Ingår i: Atmospheric Research. - : Elsevier BV. - 0169-8095. ; 226, s. 66-75
-
Tidskriftsartikel (refereegranskat)abstract
- As home to about 70 million people, the Mekong River Basin (MRB), located in Mainland Southeast Asia, is often influenced by tropical cyclones (TCs) landfalling. The TCs not only cause flood and storm hazards, but also play important roles in providing freshwater resource and welcomed sediment transports. Our study focuses on the climatology of TCs and associated rainfall (TCR) in the MRB for 1983–2016. Results show that: (i) the mean landfall occurrence of TCs is 6.2 yr −1 , leading to 36.7 mm yr −1 of annual mean TCR (2.5% of the annual total precipitation), which mainly occur in monsoon-TC season (i.e., June–November); (ii) TCs highly concentrate on the lower eastern MRB, generating the largest TCR contribution of 12.4% to the annual total precipitation; (iii) the annual mean contribution of TCs induced extreme precipitation - R20mm and R50mm (days of heavy precipitation rate ≥20 mm day −1 and ≥50 mm day −1 , respectively) - to that from annual total precipitation is large in the lower eastern MRB; (iv) over 60% of the basin area is influenced by TCR on average; and (v) a significant weakening trend of the TC frequency has been observed. The present findings lay a foundation for further in-depth research of the potential influence of the dynamic TCs and the associated rainfall in the MRB. © 2019
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