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On the Integrated Response of Catchments: benchmark applications using chloride and isotopic tracers
Paolo Benettin
Workshop on coupled hydrological modling Padova | 23 โ 24 April 2015
age T
๐๐ธ(๐ป, ๐)
Distribution of water parcels
time
๐ถ ๐ก = ๐ ๐ ๐๐ธ ๐ป, ๐ ๐๐
โ
0
fundamental link between water age and water quality
spatially-integrated approach
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NO FERTILIZATION
Measurements from the Hupsel Brook Catchment, NL
1 โ slow transport response
TTDs and transport
NL
outlet
2 โ fast โreactivityโ during storms
CHLORIDE concentration measurements
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โข fast calibration
โข easy exploration of the parameter space
spatially-integrated approach
simplification of the system, no physically-based
descriptions
โsoftโ models that capture the emergent transport
processes
suitable for hydrologic TRANSPORT and TTDs
effective integration of spatial complexity
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integrated catchment response
from McDonnell et al., 2010, HP
realistic distributions ideal distributions
๐๐ธ(๐ป, ๐)
smooth, easy to parameterize
irregular, time-variant
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๐ [๐ ๐ก ๐๐บ ๐, ๐ก ]
๐๐ก+๐[๐ ๐ก ๐๐บ ๐, ๐ก ]
๐๐= โ๐ ๐ก ๐(๐, ๐ก) ๐๐บ(๐, ๐ก)
Age Master Equation (after Botter et al., GRL, 2011):
younger water
๐ (๐, ๐ก)
1
older water
๐๐บ(๐, ๐ก)
age tracking at catchment scale
age distribution of the water storage
StorAge Selection (SAS) functions
age T
RS
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Random sampling: ๐๐(๐, ๐ก) = ๐๐(๐, ๐ก)
โ S(t)
Q(t) Q(t)
๐ถ๐ ๐ก = ๐ถ๐ ๐โ
0
๐๐ธ ๐, ๐ก ๐๐
๐ถ๐ ๐ก = ๐ถ๐ ๐โ
0
๐๐บ ๐, ๐ก ๐๐ = ๐ถ ๐ ๐ก
solute concentration at the catchment outlet
= ๐๐ ๐ก /๐(๐ก)
S(t)
more on the RS
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many RS compartments one non-RS compartment
๐ (๐, ๐ก) ๐ (๐, ๐ก) ๐ (๐, ๐ก)
two practical approaches
need for a full hydrologic model (internal fluxes) incorporates catchment characteristics (easier)
based on data
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DRAWBACKS โข dry deposition โข concentration is often too low (noise) โข effect of plants: output conc. higher
than input conc.
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chloride as a tracer
MAIN SOURCES โข atmosphere (coastal areas) โข agriculture (KCl is widely used) โข (road salting)
TRACER? โข mostly yes โข no degradation โข nutrient for plants, but in very low
concentrations
NL
outlet
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chloride as a tracer
Hupsel Brook (NL)
Upper Hafren Plynlimon (UK)
fertilization fertilization
shorter (30-100 d) travel times
Q [
mm
/h]
longer (2-3 y) travel times
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Hupsel Brook
Benettin et al., 2013, WRR
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Upper Hafren, Plynlimon
longer travel times
shorter travel times
Benettin et al., 2015, WRR
water stable isotopes
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MAIN SOURCES โข atmosphere โข (deutered water for small experiments)
liquid 2H, 18O
vapor
depleted enriched
2H, 18O
heavy
lighter lighter
Deuterium Hubbard Brook WS3 (USA)
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water stable isotopes
TRACER? โข mostly yes โข from precipitation to discharge โข if snowmelt and evaporation have
minor impact
precipitation
EPFL lysimeter (CH)
Hubbard Brook WS3 (USA)
MOBILE WATER
MINERAL
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dissolved Si and Na
Hubbard Brook WS3 NH, USA
hydrologic transport in a forested catchment
NS= 0.62
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deuterium transport
travel time distributions
Silicon (Si)
Nov-2006 Nov-2007 Nov-2008
dry days:
many old particles
wet days:
many young particles
๐ถ ๐ก = ๐ถ๐๐ 1 โ ๐โ๐๐ป ๐ ๐ ๐ป, ๐ก ๐๐ป
โ
0
๐ถ๐๐ ๐(๐)
1ยฐ order chemical kinetics:
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age-dependent transport
14-year dataset dissolved silicon and sodium
NS= 0.42 - 0.76
Silicon (Si) Sodium (Na)
NS= 0.34 - 0.66
1/๐ ~ 10 โ 13 ๐๐๐ฆ๐
Benettin et al., in review 18
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non-RS compartment
Queloz et al., 2015a,b, WRR
Injection of fluorobenzoate (FBA) tracers
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ET
Q
fractional AGE older younger
validation
con
cen
trat
ion
[m
g/l
]
measurements
simulations
Q [
mm
/h]
mean age ~ 60-80 d โdirect SAS approachโ
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โข simple hydrochemical models generate complex age dynamics
โข use of age distributions to model geogenic solutes
โข multi-RS system can efficiently reproduce emergent transport dynamics
โข deeper exploration of โdirect SASโ approach
โข characterization of the age of evapotranspiration
โข move on to complex transport dynamics (e.g. nitrates)
Summary Future perspectives
acknowledgments
Plynlimon data:
Ype van der Velde
Hupsel Brook data:
Hubbard Brook data:
K.J. McGuire, S.W. Bailey, JP Gannon, M. Green, J. Campbell, G. Likens, D. Buso
ENAC/IIE/ECHO lab Pierre Queloz
Lysimeter data:
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