Multidecadal variability of the Tonle Sap Lake flood pulse regime. Issue 9 (9th September 2021)

• Record Type: Journal Article
• Authors: Chen, Aifang; Liu, Junguo; Kummu, Matti; Varis, Olli; Tang, Qiuhong; Mao, Ganquan; Wang, Jie; Chen, Deliang
• Is Part Of: Hydrological processes. Volume 35:Issue 9(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-09
• Subjects: Cambodia -- climate change -- inundation area -- Mekong -- water level; Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.14327
• Languages: English
• ISSNs: 0885-6087

Abstract

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 Niño‐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. Abstract : Water level and inundation area have substantially declined since the late 1990s Flood start and end dates have been delayed since 2000 and 1986, respectively The flood pulse variations strongly correlated with atmospheric circulations