dc.description.abstract |
Groundwater abstraction from the transboundary
Indo-Gangetic Basin comprises 25% of global groundwater
withdrawals, sustaining agricultural productivity in Pakistan,
India, Nepal and Bangladesh. Recent interpretations of
satellite gravity data indicate that current abstraction
is unsustainable1–3, yet these large-scale interpretations
lack the spatio-temporal resolution required to govern
groundwater e ectively4,5. Here we report new evidence
from high-resolution in situ records of groundwater levels,
abstraction and groundwater quality, which reveal that
sustainable groundwater supplies are constrained more by
extensive contamination than depletion. We estimate the
volume of groundwater to 200m depth to be >20 times the
combined annual flow of the Indus, Brahmaputra and Ganges,
and show the water table has been stable or rising across 70%
of the aquifer between 2000 and 2012. Groundwater levels
are falling in the remaining 30%, amounting to a net annual
depletion of 8.0 3.0 km3.Within 60% of the aquifer, access
to potable groundwater is restricted by excessive salinity or
arsenic. Recent groundwater depletion in northern India and
Pakistan has occurred within a longer history of groundwater
accumulation from extensive canal leakage. This basin-wide
synthesis of in situ groundwater observations provides the
spatial detail essential for policy development, and the
historical context to help evaluate recent satellite gravity data. |
en_US |