Paolo Benettin

transcript

On the Integrated Response of Catchments: benchmark applications using chloride and isotopic tracers

Paolo Benettin

Workshop on coupled hydrological modling Padova | 23 – 24 April 2015

𝒑𝑸(𝑻, 𝒕)

Distribution of water parcels

𝐶 𝑡 = 𝑐 𝑇 𝒑𝑸 𝑻, 𝒕 𝑑𝑇

fundamental link between water age and water quality

spatially-integrated approach

NO FERTILIZATION

Measurements from the Hupsel Brook Catchment, NL

1 – slow transport response

TTDs and transport

outlet

2 – fast ‘reactivity’ during storms

CHLORIDE concentration measurements

• fast calibration

• easy exploration of the parameter space

spatially-integrated approach

simplification of the system, no physically-based

descriptions

‘soft’ models that capture the emergent transport

processes

suitable for hydrologic TRANSPORT and TTDs

effective integration of spatial complexity

integrated catchment response

from McDonnell et al., 2010, HP

realistic distributions ideal distributions

𝒑𝑸(𝑻, 𝒕)

smooth, easy to parameterize

irregular, time-variant

𝜕 [𝑆 𝑡 𝒑𝑺 𝑇, 𝑡 ]

𝜕𝑡+𝜕[𝑆 𝑡 𝒑𝑺 𝑇, 𝑡 ]

𝜕𝑇= −𝑄 𝑡 𝝎(𝑇, 𝑡) 𝒑𝑺(𝑇, 𝑡)

Age Master Equation (after Botter et al., GRL, 2011):

younger water

𝝎 (𝑇, 𝑡)

older water

𝒑𝑺(𝑇, 𝑡)

age tracking at catchment scale

age distribution of the water storage

StorAge Selection (SAS) functions

Random sampling: 𝑝𝑄(𝑇, 𝑡) = 𝑝𝑆(𝑇, 𝑡)

∞ S(t)

Q(t) Q(t)

𝐶𝑄 𝑡 = 𝐶𝑆 𝑇∞

𝑝𝑸 𝑇, 𝑡 𝑑𝑇

𝐶𝑄 𝑡 = 𝐶𝑆 𝑇∞

𝑝𝑺 𝑇, 𝑡 𝑑𝑇 = 𝐶 𝑆 𝑡

solute concentration at the catchment outlet

= 𝑀𝑆 𝑡 /𝑆(𝑡)

more on the RS

many RS compartments one non-RS compartment

𝝎 (𝑇, 𝑡) 𝝎 (𝑇, 𝑡) 𝝎 (𝑇, 𝑡)

two practical approaches

need for a full hydrologic model (internal fluxes) incorporates catchment characteristics (easier)

based on data

DRAWBACKS • dry deposition • concentration is often too low (noise) • effect of plants: output conc. higher

than input conc.

chloride as a tracer

MAIN SOURCES • atmosphere (coastal areas) • agriculture (KCl is widely used) • (road salting)

TRACER? • mostly yes • no degradation • nutrient for plants, but in very low

concentrations

outlet

chloride as a tracer

Hupsel Brook (NL)

Upper Hafren Plynlimon (UK)

fertilization fertilization

shorter (30-100 d) travel times

longer (2-3 y) travel times

Hupsel Brook

Benettin et al., 2013, WRR

Upper Hafren, Plynlimon

longer travel times

shorter travel times

Benettin et al., 2015, WRR

water stable isotopes

MAIN SOURCES • atmosphere • (deutered water for small experiments)

liquid 2H, 18O

depleted enriched

2H, 18O

lighter lighter

Deuterium Hubbard Brook WS3 (USA)

water stable isotopes

TRACER? • mostly yes • from precipitation to discharge • if snowmelt and evaporation have

minor impact

precipitation

EPFL lysimeter (CH)

Hubbard Brook WS3 (USA)

MOBILE WATER

MINERAL

dissolved Si and Na

Hubbard Brook WS3 NH, USA

hydrologic transport in a forested catchment

NS= 0.62

deuterium transport

travel time distributions

Silicon (Si)

Nov-2006 Nov-2007 Nov-2008

dry days:

many old particles

wet days:

many young particles

𝐶 𝑡 = 𝐶𝑒𝑞 1 − 𝑒−𝑘𝑻 𝑝 𝑄 𝑻, 𝑡 𝑑𝑻

𝐶𝑒𝑞 𝑐(𝑇)

1° order chemical kinetics:

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/𝑘 ~ 10 − 13 𝑑𝑎𝑦𝑠

Benettin et al., in review 18

non-RS compartment

Queloz et al., 2015a,b, WRR

Injection of fluorobenzoate (FBA) tracers

fractional AGE older younger

validation

measurements

simulations

mean age ~ 60-80 d ‘direct SAS approach’

• simple hydrochemical models generate complex age dynamics

• use of age distributions to model geogenic solutes

• multi-RS system can efficiently reproduce emergent transport dynamics

• deeper exploration of ‘direct SAS’ approach

• characterization of the age of evapotranspiration

• 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:

Paolo Benettin

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