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Introduction to Environmental Isotopes - Hydrology · PDF file Introduction to Environmental Isotopes Stefan Uhlenbrook and Jochen Wenninger UNESCO-IHE, VU Amsterdam and TU Delft,

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  • Introduction to Environmental Isotopes

    Stefan Uhlenbrook and Jochen Wenninger UNESCO-IHE, VU Amsterdam and TU Delft, Delft, Netherlands

    5 November 2009, Dutch Hydrology Meeting to receive the Darcy Lecture 2009, by Dr. Peter Cook, VU Amsterdam

  • Outline of This Lecture

    1. Introduction 2. How can environmental isotopes help to

    detect and quantify global change impacts on water?  Evaporation  Runoff generation  Groundwater  Precipitation

    3. Concluding Remarks

  • 2

    4

    3

    5

    6

    1

    0

    G lo

    ba l

    Te m

    pe ra

    tu re

    (° C

    )

    IPCC Projections 2100 AD

    N .H

    . T em

    pe ra

    tu re

    (° C)

    0

    0.5

    1

    -0.5

    1000 1200 1400 1600 1800 2000

    Lower Risk for Instabilities

    High Risk for Instabilities

    It is Getting Warmer!

    The context – ONE

  • 'climate colonialism'

     A massive land-grabbing scramble in Africa as foreign companies - some with foreign aid money support - rapidly establish enormous monoculture fields in tropical countries. Prof Seif Madoffe, SUA

    Sugar Cane – Kilombera Basin, Tanzania

    The context – TWO

  • Global Changes

     Climate (temperature, precipitation, radiation …)  Land use, land cover

     De-forestation / re-forestation  Urbanisation  Etc.

     Population (amount, density, structure, …)  Water use in space and time  Economic development  Change of diet (more meat => more water)  N- and P-fluxes to water bodies  Pollution (new substances etc.)  Change in composition of species  etc. etc. etc.

    …. and many interdependencies/feedbacks!

  • Picture from Fairless, 2007, Nature

    EIEIET ETES ES

    SS SS

    QR QR

    QR QR

    QS QS

    P P

    P P Impacts of land use change on hydrological processes P=Q+E+dS/dt

    Short-term dynamics (e.g. interception, flood generation) vs. long-term dynamics (e.g. groundwater recharge, base flow)

  •       PQQEEQEE ggfuTusssII dtdSdtdSdtdSdtdS  

     II EdtdS  Interception processes  sss QEdtdS  Surface water processes

     

      

      g g Qdt

    dS Groundwater processes

    Water Balance Equation: P=Q+E+dS/dt

    Where:

    Root zone moisture processes fuTu QEEdtdS 

    Possible changes in all variables due to climate and/or land changes!!

  • Weatherley catchment, South Africa

    How can Environmental Isotopes help??

  • Environmental Isotope – Basics

    16 O

    8

    Mass number (= protons + neutrons)

    Atomic number (= protons)

    18 O

    8

    8 protons (positive), 8 electrons (negative), 8 neutrons (neutral)

    8 protons, 8 electrons, 10 neutrons

    - Nuclides with same atomic number (i.e. an element) but different mass number are called isotopes

    - 92 natural elements have more than 1000 stable and radioactive isotopes

    - Protons and neutrons in the nucleus have approximately the same weight

    - Electrons (negative charge) are lighter and are located in electron shells

  • Some common environmental isotopes

    Source: Kendall, 1998

  • Picture from Fairless, 2007, Nature

    EIEIET ETES ES

    SS SS

    QR QR

    QR QR

    QS QS

    P P

    P P

    Investigation of different compartments of the water cycle using environmental isotopes

    P=Q+E+dS/dt

  • Meteoric Water Line (MWL): The Concept

    Source: IAEA

  • Observing evaporation using environmental isotopes in big systems

    Agarwaal et al., 2002

  • Transpiration Evaporation

    Soil moisture sensors

    Data Logger

    Soil

    Balance

    Percolation

    Rhizon water samplers

    Better Understanding of Evaporation Fluxes using Environmental Isotopes

    Wenninger et al., in preparation

  •  Evaporation is the driving factor in isotopic fractionation

     Transpiration and Percolation do not cause fractionation

     Quantification between fractionating and non-fractionating losses

     Conservation of mass and isotopes

    ztvpif mmmmmm 

    ppiizzttvvff xxxxxx  

    Isotope Mass Balance

    p; precipitation t; transpiration

    v; evaporation

    z; percolation

    i; f f; final WC i; initial WC

    Total

    j j m

    mx  piTotal mmm with:

    (e.g. Robertson et al. 2006, J. of Hydrol.)

  • Isotope Depths Profiles and Evaporation Line

    -70

    -60

    -50

    -40

    -30

    -20

    -10 -10 -8 -6 -4 -2

    Irrigated water Soil water percolated water MWL

    y = 3.8x-18.6

    R2 = 0.95

    GM WL

  • Comparison between different evaporation estimations: (a) measured using hydrometric data and HYDRUS 1D, and (b) calculated using isotope mass balance.

    (a)

    (b) (a)

    (b)

    New way to estimate evaporation fluxes?! Lysimeter A Lysimeter B

    Evaporation E (mm) 19 77

    Transpiration T (mm) 99 0

    T/Etotal ratio 84% 0

  • Picture from Fairless, 2007, Nature

    EIEIET ETES ES

    SS SS

    QR QR

    QR QR

    QS QS

    P P

    P P

    Investigation of different compartments of the water cycle using environmental isotopes

    P=Q+E+dS/dt

  • Studying hillslope processes with environmental isotopes

    Spring A (Zipfeldobel) Spring B (Zängerlehof II)

  • Investigation Period

    0 , 0

    0 , 4

    0 , 8

    1 , 2

    1 , 6

    2 3 . 1 0 . 9 9 2 9 . 1 0 . 9 9 0 4 . 1 1 . 9 9 1 0 . 1 1 . 9 9 1 6 . 1 1 . 9 9

    D is

    ch ar

    ge [l

    /s ]

    Z i p f e l d o b e l s p r i n g Z a e n g e r l e h o f I I s p r i n g

    E v e n t 1 E v e n t 2 E v e n t 3

    0

    2

    4

    6

    8

    Pr ec

    ip ita

    tio n

    [m m

    ]

    Spring A Spring B

    (Uhlenbrook, Didszun, Wenninger, 2008, Hydr. Sci. Journal)

  • Hydrochemical Dynamics: Dissolved Silica Spring A

    Spring B

    40

    60

    80

    100

    120

    140

    24.10.99 26.10.99 28.10.99 30.10.99 01.11.99S ta

    nd ar

    di ze

    d co

    nc en

    tra tio

    ns [%

    ]

    0,2

    0,6

    1,0

    1,4

    D is

    ch ar

    ge [l

    /s ]

    Silica Discharge

    40

    60

    80

    100

    120

    140

    24.10.99 26.10.99 28.10.99 30.10.99 01.11.99S ta

    nd ar

    di ze

    d co

    nc en

    tra tio

    ns [%

    ]

    0,2

    0,3

    0,4

    0,5

    0,6

    D is

    ch ar

    ge [l

    /s ]

    Silica Discharge

  • Hydrochemical Dynamics: Deuterium Spring A

    Spring B -100

    -90

    -80

    -70

    -60

    -50

    23.10.99 25.10.99 27.10.99 29.10.99 31.10.99

    δ D

    v- sm

    ov [‰

    ]

    0,2

    0,3

    0,4

    0,5

    0,6

    D is

    ch ar

    ge [l

    /s ]

    Deuterium Precip. Discharge

    -100

    -90

    -80

    -70

    -60

    -50

    23.10.99 25.10.99 27.10.99 29.10.99 31.10.99

    δ D

    v- sm

    ov [‰

    ]

    0,2

    0,6

    1,0

    1,4

    1,8

    D is

    ch ar

    ge [l

    /s ]

    Spring Precip. Incr. Mean Discharge

  • 0

    0,4

    0,8

    1,2

    1,6

    24.10.99 26.10.99 28.10.99 30.10.99

    D is

    ch ar

    ge [l

    /s ]

    direct Runoff

    deep GW

    Discharge

    shallow GW

    Results of Hydrograph Separation at both Springs/Hillslopes

    Spring A

    Spring B0,0

    0,2

    0,4

    0,6

    24.10.99 26.10.99 28.10.99 30.10.99 01.11.99

    D is

    ch ar

    ge [l

    /s ]

    direct Runoff

    deep & shallow GW Discharge

  • Example: Interpretation of Dominant Processes at the Hillslope Scale

    (Mc Donnell, 1990, WRR)

    (Picture: P. Mosley)

  • pre-event water

    event water

    Event (new) and prevent (old) water!

    “ … all nice, but we need measurements at catchment

    scale!”

    (Keith J. Beven)

    0

    5

    10

    15 20

    25

    30

    35

    0 10 20 30 40 50 60 Time

    St re

    am D

    is ch

    ar ge

    Quickflow, Stormflow

    Baseflow

  • The bench mark paper: Sklash & Farvolden, 1979: The role of ground- water in storm runoff. Water Resources Research.

  • Tracer-based Hydrograph Separation in the Weatherley Catchment, South Africa

    Wenninger, Uhlenbrook, Lorentz, 2008, Hydr. Sci. Journal

  • Picture from Fa

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