A Hydroclimatological Analysis of Precipitation in the Ganges–Brahmaputra–Meghna River Basin

Water

M.Giashuddin Miah¹  M.Rafiqul Islam²  Munshi Rahman³  Bimal Paul⁴  Scott Curtis⁵  Thomas Crawford⁶  Mohin Patel⁷ 

[1] Department of Agroforestry and Environment, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh;Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh;Department of Geography and Anthropology, UW-Eau Claire, Phillips Science Hall 257, 101 Roosevelt Ave., Eau Claire, WI 54702, USA;Department of Geography, Kansas State University, 1002 Seaton Hall, Manhattan, KS 66506, USA;Department of Geography, Planning and Environment, East Carolina University, A232 Brewster Bldg., Greenville, NC 27858, USA;Department of Geography, Virginia Tech, 220 Stanger Street, Blacksburg, VA 24061, USA;Department of Meteorology and Climate Science, San Jose State University, One Washington Square, San Jose, CA 95192, USA;

关键词: monsoon;    precipitation;    ENSO;    hydroclimate;    Ganges;    Brahmaputra;    Meghna;    river basin;   

DOI  :  10.3390/w10101359

来源: DOAJ

【 摘 要 】

Understanding seasonal precipitation input into river basins is important for linking large-scale climate drivers with societal water resources and the occurrence of hydrologic hazards such as floods and riverbank erosion. Using satellite data at 0.25-degree resolution, spatial patterns of monsoon (June-July-August-September) precipitation variability between 1983 and 2015 within the Ganges–Brahmaputra–Meghna (GBM) river basin are analyzed with Principal Component (PC) analysis and the first three modes (PC1, PC2 and PC3) are related to global atmospheric-oceanic fields. PC1 explains 88.7% of the variance in monsoonal precipitation and resembles climatology with the center of action over Bangladesh. The eigenvector coefficients show a downward trend consistent with studies reporting a recent decline in monsoon rainfall, but little interannual variability. PC2 explains 2.9% of the variance and shows rainfall maxima to the far western and eastern portions of the basin. PC2 has an apparent decadal cycle and surface and upper-air atmospheric height fields suggest the pattern could be forced by tropical South Atlantic heating and a Rossby wave train stemming from the North Atlantic, consistent with previous studies. Finally, PC3 explains 1.5% of the variance and has high spatial variability. The distribution of precipitation is somewhat zonal, with highest values at the southern border and at the Himalayan ridge. There is strong interannual variability associated with PC3, related to the El Nino/Southern Oscillation (ENSO). Next, we perform a hydroclimatological downscaling, as precipitation attributed to the three PCs was averaged over the Pfafstetter level-04 sub-basins obtained from the World Wildlife Fund (Gland, Switzerland). While PC1 was the principal contributor of rainfall for all sub-basins, PC2 contributed the most to rainfall in the western Ganges sub-basin (4524) and PC3 contributed the most to the rainfall in the northern Brahmaputra (4529). Monsoon rainfall within these two sub-basins were the only ones to show a significant relationship (negative) with ENSO, whereas four of the eight sub-basins had a significant relationship (positive) with sea surface temperature (SST) anomalies in the tropical South Atlantic. This work demonstrates a geographic dependence on climate teleconnections in the GBM that deserves further study.

【 授权许可】

Unknown