Download - Física e Conservação do Solo
![Page 1: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/1.jpg)
Física e Conservação do Solo
Gerd Sparovek (LSO/Esalq)
segundo semestre de 2006
![Page 2: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/2.jpg)
![Page 3: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/3.jpg)
![Page 4: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/4.jpg)
A erosão do solo: Processo
Desprendimento -> Transporte -> Deposição
![Page 5: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/5.jpg)
A erosão do solo: Processo
Desprendimento -> Transporte -> Deposição
Desagregação:Forças de adesão e coesão em função do tamanho dos agregados
Quantidade de energia disponível
Diminuição da quantidade de energia
![Page 6: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/6.jpg)
A erosão do solo: Processo
Desprendimento -> Transporte -> Deposição
Desagregação:Forças de adesão e coesão em função do tamanho dos agregados
Quantidade de energia disponível
Diminuição da quantidade de energia
Impacto da gota de chuva
EnxurradaEnxurrada
![Page 7: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/7.jpg)
![Page 8: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/8.jpg)
![Page 9: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/9.jpg)
![Page 10: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/10.jpg)
![Page 11: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/11.jpg)
![Page 12: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/12.jpg)
![Page 13: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/13.jpg)
![Page 14: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/14.jpg)
![Page 15: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/15.jpg)
![Page 16: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/16.jpg)
![Page 17: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/17.jpg)
![Page 18: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/18.jpg)
The theory: spherical drop on a rigid surfaceHuang, C.; Bradford, J.M.; Cushman, J.H. (1982) A numerical study of raindrop
impact phenomena: the rigid case. Soil Science Society of America Journal 46: 14-19.
Basic fluid dynamic equations: Momentum or Navier-Stokes equation:
PVVtV
∇−
=⎟⎠⎞
⎜⎝⎛∇+
∂∂ →→
→
ρ1
o
Continuity equation
0=∇→
Vo Where: →
V velocity vector P pressure ρ density of the liquid t time o∇ divergence operator
∇ gradient operator
The problem domain
•Use techniques of material engineering that study high speed liquid-solid impact phenomena (turbine blades, airplane wings, and windows).•Mechanistic approach rather than ‘black box’ as usual in agriculture.•Calculated the compressive stress from the impact and the shearing stress from the lateral jetting.
![Page 19: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/19.jpg)
Time: 0.4 µ s Velocity(Z = 0.025) = 0.26 to 1.09
Time: 0.8 µ s Velocity(Z = 0.025) = 0.19 to 1.56
Time: 4.8 µ s Velocity(Z = 0.025) = 0.13 to 1.59
Time: 10.6 µ s Velocity(Z = 0.025) = 0.11 to 2.01
Time: 17.8 µ s Velocity(Z = 0.025) = 0.17 to 1.88
The time history of velocity:Raindrop of 4 mm traveling at 10 m s-1
(fall velocity normalized to 1)
High speed lateral jet stream:•large shearing stress at the surface•tensile failure on surface irregularities
![Page 20: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/20.jpg)
![Page 21: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/21.jpg)
Time: 0.8 µ s Time: 4.8 µ s
Maximum pressure vs time
The time history of pressure:Raindrop of 4 mm traveling at 10 m s-1
(reference pressure = 50 kPa, normalized to 1)
High initial pressure:extremely high (1,200 kPa) pressure at the very instant of impacthigh capacity to deform plastic surfaces
Soil shear stress: 2 to 20 kPa
![Page 22: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/22.jpg)
low shear strength τ = 2.6 kPa
![Page 23: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/23.jpg)
high shear strength τ = 20.9 kPa
![Page 24: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/24.jpg)
Water velocity ≈ 0.5 - 1.0 m s-1 (Kew)Laminar flow water shear stress ≈ Pa (τw)Soil strengths ≈ kPa (τs)
Kewτw
τs
![Page 25: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/25.jpg)
Water velocity ≈ 0.5 - 1.0 m s-1 (Kew)Laminar flow water shear stress ≈ Pa (τw)Soil strengths ≈ kPa (τs)
Kewτw
τs
Sediment load vs. detachment The turbulent bursts
![Page 26: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/26.jpg)
![Page 27: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/27.jpg)
A erosão do solo: Formas
Desprendimento -> Transporte&Deposição
Muito seletivoImpacto da gota Laminar
Dispersa (não recorrente) SulcosEnxurrada
Concentrada (recorrente) Voçorocas efêmeras
Voçorocas permanentes
Pouco seletivo
![Page 28: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/28.jpg)
Muito seletivoImpacto da gota Laminar
Dispersa (não recorrente) SulcosEnxurrada
Concentrada (recorrente) Voçorocas efêmeras
Voçorocas permanentes
![Page 29: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/29.jpg)
![Page 30: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/30.jpg)
![Page 31: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/31.jpg)
![Page 32: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/32.jpg)
Time: 0.4 µ s Velocity(Z = 0.025) = 0.26 to 1.09
Time: 0.8 µ s Velocity(Z = 0.025) = 0.19 to 1.56
Time: 4.8 µ s Velocity(Z = 0.025) = 0.13 to 1.59
Time: 10.6 µ s Velocity(Z = 0.025) = 0.11 to 2.01
Time: 17.8 µ s Velocity(Z = 0.025) = 0.17 to 1.88
Water velocity ≈ 0.5 - 1.0 m s-1 (Kew)Laminar flow water shear stress ≈ Pa (τw)Soil strengths ≈ kPa (τs)
Kewτw
τs
![Page 33: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/33.jpg)
![Page 34: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/34.jpg)
![Page 35: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/35.jpg)
![Page 36: Física e Conservação do Solo](https://reader033.vdocuments.site/reader033/viewer/2022051205/58668fa01a28abbe3f8b7784/html5/thumbnails/36.jpg)