Impact of climate change on water sources and river-floodplain mixing in
the natural wetland floodplain of Biebrza River
Abstract
The origins of river and floodplain waters (groundwater, rainfall,
and snowmelt) and their extent during overbank flow events strongly
impact ecological processes such as denitrification and vegetation
development. However, the long-term sensitivity of floodplain water
signatures to climate change remains elusive. We examined how the
integrated hydrological model HydroGeoSphere and the Hydraulic
Mixing-Cell
method could help us understand the long-term impact of climate change
on water signatures and their spatial distribution in the protected
Biebrza River Catchment in northeastern Poland. Our model relied on
20th century Reanalysis Data from 1881 to 2015 and an ensemble of
EURO-CORDEX simulations for RCP 2.6, 4.5, and 8.5 from 2006 to 2099.
The historical component of the simulations was subjected to extensive
multiple-variable validation from 1881 to 2019. The results show that
the extents of water sources were rather stable in the floodplain
in the 1881-2015 period. The projected future impacts were variable
with each analyzed RCP, but in all cases, different significant trends
were present for the spatial distribution of water sources and for
the river-floodplain mixing. However, the total volume of water from
different sources was less sensitive to climate change than the dominant
sources and spatial distribution of water. The simulation results
highlight the impact of climate change on the extent of water sources
in temperate zone wetlands with significant implications for ecological
processes and management. These results also underscore the urgent
need to leverage such modeling studies to inform protective and
preservation
strategies of floodplain wetlands.
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