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Signature and hydrologic consequences of climate change within the upper–middle Brahmaputra Basin
Author(s) -
Mukhopadhyay Biswajit
Publication year - 2012
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.9306
Subject(s) - structural basin , meltwater , glacier , climate change , precipitation , snow , monsoon , drainage basin , geology , physical geography , climatology , hydrology (agriculture) , glacial period , digital elevation model , environmental science , geography , geomorphology , cartography , meteorology , remote sensing , oceanography , geotechnical engineering
A prevailing perception is that the glaciers and perennial snow and ice covered areas (SCA P ) or in the Himalayan region are fast contracting. However, systematic studies providing the quantitative estimates of SCA P as a function of time within individual river basins are lacking. The importance of meltwater in river flows varies greatly from one river basin to another, yet the actual estimates of those contributions are largely unknown. This study bridges such knowledge gaps for the upper–middle Brahmaputra Basin by using best available digital cartographic and remotely sensed snow cover data. We find that when the entire basin is considered, SCA P decreased from 7637 ± 764 in 1980 to 4298 ± 1422 km 2 in 1992. However, it has increased to 7160 ± 2248 km 2 in 2000. From 2000 to 2010, the SCA P has remained nearly constant around a mean of 10 052 ± 1468 km 2 . The same trend is observed within individual physiographic zones of the basin. Such increase in SCA P is due to the increase in the precipitation over the middle Brahmaputra Basin and the Nyainquentanglha Mountains, as observed in station records. The incursion of moist air through the Brahmaputra valley to the higher elevations within the Nyainquentanglha Mountains causes snowfall during pre‐monsoonal and post‐monsoonal seasons and an expansion of the SCA P . Glacial expansions in the Nyainquentanglha Mountains have also been observed in other recent studies. In addition to the increase in precipitation and SCA P , another manifestation of climate change observed in this basin is the increasing temperature with a mean annual trend of +0.28 °C/decade. The hydrologic consequences of the observed effects of climate change are expected to be an insignificant change in streamflows in the watersheds drained by the upper Brahmaputra River but a perceptible increase in river discharges in the watersheds drained by the middle Brahmaputra River and its tributaries, particularly within the upper and lower catchments of the middle Brahmaputra Basin. Copyright © 2012 John Wiley & Sons, Ltd.