Title: Holocene and future response of suspended sediment yield to land use and climate change: a case study for the Meuse basin
Authors: Ward, Philip J.
van Balen, Ronald T.
Verstraeten, Gert
Renssen, Hans
Vandenberghe, Jef #
Issue Date: Apr-2008
Publisher: EGU
Host Document: Geophysical Research Abstracts vol:10
Conference: EGU General Assembly location:Vienna date:13-18 April 2008
Article number: EGU2008-A-03034
Abstract: The suspended sediment yields (SY) of rivers are affected by changes in both land
use and climate. However, the relative influence of these factors is poorly understood,
partly due to the scarcity of observations of SY. In this study we investigate the relative
importance of changes in land use and climate (represented by the rainfall erosivity
factor) on millennial timescales in the Meuse basin (northwest Europe). We use
a spatially distributed soil erosion and sediment delivery model (WATEM/SEDEM)
to simulate long-term (50-year) SYs in two time-periods: (a) 4000-3000 BP (minimal
anthropogenic influence), and (b) 1000-2100 AD (includes land use change and
human induced climate change). Changes in rainfall erosivity are based on the output
of a climate model (ECBilt-CLIO-VECODE); for the period 2001-2100 AD the
model is forced in line with the SRES A2 and B1 emissions scenarios of the IPCC.
These scenarios lie towards the higher and lower end of the full SRES scenario range
respectively. For the period 4000-3000 BP the basin is assumed to be almost fully
forested; for 1000-2000 AD land use is reconstructed using CORINE data, historical
sources, and a simple land use model; for the future scenarios land use is based on future
scenario data from EURURALIS. Whilst rainfall erosivity increases by only 3%
between the periods 4000-3000 BP and 1000-2000 AD, mean annual SY shows more
than a three-fold increase (from 91,513 Mg.a−1 to 306,040 Mg.a−1 respectively). For the older time-period the results are consistent with geological data. Almost all of
this increase can be attributed to the large scale conversion from forest to agriculture
between the two time-periods. Furthermore, SY shows a significant increasing trend
over the period 1000-1900 AD (Mann-Kendall, p<0.0001), with a peak SY value
of 388,062 Mg.a−1 in the 19th Century in response to continuing deforestation. In
the 20th Century, reforestation and rapid urbanisation resulted in a decrease in SY
to 281,163 Mg.a−1. Sensitivity analyses, whereby rainfall erosivity and the percentage
of forest were altered individually, show that as the percentage cover of forest
decreases, the relative effects of changes in rainfall erosivity increase. For the nearfuture
(21st Century) the results are highly sensitive to the scenario (climate and land
use) used; the A2 climate change scenarios lead to higher SYs than the B1 scenarios.
However, whilst rainfall erosivity is expected to rise rapidly over the coming century,
our simulations using future climate and land use scenarios suggest that SY will decrease
in relation to the 20th Century. On the other hand, if changes in future land use
are excluded, significant increases in SY can be expected under both climate change
scenarios. Interestingly, in none of the future simulations is the modelled SY greater
than the peak value of the 19th Century.
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Division of Geography & Tourism
# (joint) last author

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