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  • ESTIMATING THE SATURATED HYDRAULIC CONDUCTIVITY OF A SOIL

    CONTAINING STONES

    Novák V., Kňava, K. Institute of Hydrology, Slovak Academy of Sciences,

    Bratislava, Slovakia

  • Slovakia, A = 49 019 km sq, Af = 0.41

  • High Tatras stony soils

    -Many mountaineous soils contain rock fragments (gravelly, stony soils), more than 2 mm in diameter

    -Most of forest soils over Slovakia are stony soils

    -Majority of published soil characteristics (physical, hydrophysical) are estimated for fine earth fraction (less than 2 mm in diameter)

  • FIRE 2005

  • 2007

  • 2008

  • 2009

  • EX NEXIF

    .lokality vybrané

    v

    súčinnosti s

    TANAP-om

    _IF(INTACT FOREST)

    Vyšné

    Hágy

    _EX(EXTRACTED FOREST)

    Danielov dom

    _NEX(NON-EXTRACTED-FOREST)

    Tatranská

    Lomnica /Jamy/

    _FIRE(ZHORENISKO)

    Nový Smokovec –

    Tatranské

    Zruby

    2005

  • 2009

  • Measuring stoniness

  • Measuring stoniness

  • -70.00

    -60.00

    -50.00

    -40.00

    -30.00

    -20.00

    -10.00

    0.00 0.00 0.10 0.20 0.30 0.40 0.50

    Pc

    z c

    m

    Site FIRE, High Tatras

  • -100

    -80

    -60

    -40

    -20

    0 0 0.5 1

    nr

    z c

    m Pores Stones Soil particles

    Site FIRE, High Tatras

  • Darcy´s law

    v

    “macroscopic”

    flow rate , m s1

    K –

    saturated hydraulic

    conductivity of the soil, m s1

    L

    length of the soil sample, m Δh –

    the difference between the water levels at the both ends of the soil column, m

    L hKv Δ=

    vK h

    L h

    LvK =→= Δ

    → Δ

    = 1

  • 1290.31

    670.30

    277.10

    321.28

    181.06

    1002.78

    238.76

    991.69

    0 200 400 600 800 1000 1200 1400

    1

    K cm.d-1

    44

    160

    54

    20

    19

    50

    46/45

    MK/30

    0 - 5

    c m

    10 -

    15 c

    m 40

    - 45

    c m

    Vertical distribution of saturated hydraulic conductivity of soil matrix K, measured on soil samples. Site Fire, H. Tatras.

  • Numerical experiment-

    alternative method of K stony soils estimation

    Representative elementary volume (REV) of stony soils is too big to be sampled and processed

    Numerical experiment (simulation of Darcy´s test) is good alternative to estimate K

    Two dimensional simulation model HYDRUS -2D was used

  • Darcy´s test •

    Volume of the REV is 1 cubic meter

    Cross section of the 2D simulation stony soil is 1 square meter

    Soil contains stones of 10 cm in diameter of given relative volume (area)

    Soil matrix is saturated with water, stones are non-conductive for water

    Unite hydraulic gradient is applied; the top and bottom of the REV is ponded with 10 mm of water

  • Water content for relative stone content 0.1

    red-

    saturated soil

  • Velocity for relative stone content 0.1 Red-high velocity Blue-low velocity

  • Water potential

    for relative stone content 0.1 Red-positive pressure Blue-negative

  • Rv_01_1_waterCONTENT.jpg

    Water content for relative stone content 0.1

  • Velocity Rv

    =0.1

  • Water potential Rv

    =0.1

  • Water content for relative stone content 0.2

  • Velocity

    Rv

    =0.2

  • Water potential

    Rv

    =0.2

  • Water content for relative stone content 0.2

  • Velocity

    Rv

    =0.2

  • Water potential

    Rv

    =0.2

  • Water content for relative stone content 0.3

  • Velocity

    Rv

    =0.3

  • Water potential

    Rv

    =0.3

  • Water content for relative stone content 0.3

  • Velocity

    Rv

    =0.3

  • Water potential

    Rv

    =0.3

  • Saturated hydraulic conductivities of soils K with different volumetric stone content Rv

    0.001

    0.01

    0.1

    1

    0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 Rv

    K c

    m .m

    in- 1

    1

    2

    3

    4

  • Cumulative water infiltration into stony soil with different stones content: Rv = 0, (1); Rv = 0.1, (2); Rv = 0.2, (3);

    Rv = 0.3, (4);

    Rv = 0.4,(5).

    Loamy sand, FIRE site, High Tatras, Slovakia.

    Cumulative Infiltration

    0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

    0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 t (min)

    I (c

    m )

    1

    2

    3

    4

    5

  • 0 - 100 cm

    21.5

    22.5

    23.5

    24.5

    25.5

    26.5

    27.5

    28.5

    29.5

    30.5

    31.5

    32.5 1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 10 3

    10 9

    11 5

    12 1

    12 7

    13 3

    13 9

    14 5

    15 1

    15 7

    16 3

    16 9

    17 5

    18 1

    18 7

    19 3

    19 9

    20 5

    21 1

    time, d

    W at

    er c

    on te

    nt , c

    m

    LAI 6 LAI 3 LAI 1.5

  • Závery Hydraulické

    vodivosti vodou nasýteného pórovitého prostredia (pôdy)

    K sa znižujú

    so zvyšujúcim pomerným objemom kameňov Rv nelineárne a

    ich hodnoty sú

    nižšie, ako vypočítané

    lineárnou

    závislosťou K = 1 -

    Rv . Závislosť

    medzi relatívnou nasýtenou hydraulickou vodivosťou

    a

    relatívnym obsahom skeletu Kr = f(Rv ) je vhodné

    vyjadriť lineárnou rovnicou typu Kr = 1- a Rv (rov.7),

    súčiniteľ

    a sa

    pohyboval v

    rozmedzí

    1.1 < a < 1.32 pre kamene guľového tvaru s

    priemerom 10 cm.

    Relatívne hydraulické

    vodivosti Kr pri danom pomernom obsahu kameňov Rv sa znižujú

    so znižujúcou sa nasýtenou hydraulickou

    vodivosťou pôdnej matrice a

    so zvyšovaním sa veľkosti dispergovaných kameňov.

  • Preliminary conclusion 1

    Hydraulic

    conductivity of porous media containing stones and saturated with water (soil)

    K decrease

    with

    increasing relative stone content (stoniness)

    Rv ; values of K are below linear relationship K = 1 -

    Rv .

  • Preliminary conclusions 2

    Relationship between relative saturated hydraulic conductivity Kr and stoniness Rv -

    Kr = f(Rv ) can be expressed by linear –

    type

    equation

    Kr = 1- a Rv ), coefficient

    a was found in the range 1.1 < a < 1.32 for spherical stones of 10 cm

    in diameter

  • Preliminary conclusions 3

    Relative hydraulic conductivities

    Kr for constant Rv are decresing with decresing saturated hydraulic conductivity of matrix Km , with diameter of stones and with unregularity in shape, size and distribution of stones.

    ESTIMATING THE SATURATED HYDRAULIC CONDUCTIVITY OF A SOIL CONTAINING STONES Foliennummer 2 Foliennummer 3 High Tatras stony soils Foliennummer 5 Foliennummer 6 Foliennummer 7 Foliennummer 8 Foliennummer 9 Foliennummer 10 Foliennummer 11 Foliennummer 12 Foliennummer 13 Foliennummer 14 Darcy´s law Foliennummer 16 Numerical experiment- alternative method of K stony soils estimation Darcy´s test Water content for relative stone content 0.1�red- saturated soil Velocity � Foliennummer 22 Foliennummer 23 Foliennummer 24 Foliennummer 25 Foliennummer 26 Foliennummer 27 Foliennummer 28 Foliennummer 29 Foliennummer 30 Foliennummer 31 Foliennummer 32 Foliennummer 33 Foliennummer 34 Foliennummer 35 Foliennummer 36 Saturated hydraulic conductivities of soils K with different volumetric stone content Rv Cumulative water infiltration into stony soil with different stones content: Rv = 0, (1); Rv = 0.1, (2); Rv = 0.2, (3); Rv = 0.3, (4); Rv = 0.4,(5). Loamy sand, FIRE site, High Tatras, Slovakia.� Foliennummer 39 Závery Preliminary conclusion 1 Preliminary conclusions 2 Preliminary conclusions 3