Changes in groundwater drought associated with anthropogenic warming
<p>Here we present the first empirical evidence for changes in groundwater drought associated with anthropogenic warming in the absence of long-term changes in precipitation. Analysing standardised indices of monthly groundwater levels, precipitation and temperature, using two unique groundwat...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-03-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/23/1393/2019/hess-23-1393-2019.pdf |
| Summary: | <p>Here we present the first
empirical evidence for changes in groundwater drought associated with
anthropogenic warming in the absence of long-term changes in precipitation.
Analysing standardised indices of monthly groundwater levels, precipitation
and temperature, using two unique groundwater level data sets from the Chalk
aquifer, UK, for the period 1891 to 2015, we show that precipitation deficits
are the main control on groundwater drought formation and propagation.
However, long-term changes in groundwater drought are shown to be associated
with anthropogenic warming over the study period. These include increases in
the frequency and intensity of individual groundwater drought months, and
increases in the frequency, magnitude and intensity of episodes of
groundwater drought, as well as an increasing tendency for both longer
episodes of groundwater drought and for an increase in droughts of less than
1 year in duration. We also identify a transition from a coincidence of
episodes of groundwater drought with precipitation droughts at the end of the
19th century, to an increasing coincidence with both precipitation droughts
and with hot periods in the early 21st century. In the absence of long-term
changes in precipitation deficits, we infer that the changing nature of
groundwater droughts is due to changes in evapotranspiration (ET) associated
with anthropogenic warming. We note that although the water tables are
relatively deep at the two study sites, a thick capillary fringe of at least
30 m in the Chalk means that ET should not be limited by precipitation at
either site. ET may be supported by groundwater through major episodes of
groundwater drought and, hence, long-term changes in ET associated with
anthropogenic warming may drive long-term changes in groundwater drought
phenomena in the Chalk aquifer. Given the extent of shallow groundwater
globally, anthropogenic warming may widely effect changes to groundwater
drought characteristics in temperate environments.</p> |
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| ISSN: | 1027-5606 1607-7938 |