1. Surface Water Hydrology Lecture 13: Infiltration
Readings:
Applied Hydrology Sections 4.3 and 4.4;
Handbook of Hydrology Sections 5.1 and 5.2
Soil texture and classification
Soil water properties, K(q), Y(q)
Infiltration
Green-Ampt method

2. Particle size measurement
Seives of progressively smaller size to get size
Distribution of soil

3. Soil Classification USDA particle size classification
< 0.002mm is clay
0.002 – 0.5mm is silt
0.5mm – 10mm is sand
> 10mm is gravel

4. USDA Soil Texture Triangle
A soil with 30% sand,
40% clay and 30% silt
is a Clay Loam
% Silt = %Sand - %Clay

5. Variation of Saturated Hydraulic Conductivity with Soil TextureK Se

6. Y K q q K
Interconnection of
Soil water properties Y

7. Double Ring Infiltrometer
Measure rate of fall in inner ring
Infilration

8. Infiltration by Horton’s method

9. Infiltration into a soil water column1 2

10. Green-Ampt method Relative saturation Incremental change
in soil water content
as wetting front passes

11. Green-Ampt Parameter Definitions
Relative saturation
Incremental change
in soil water content
as wetting front passes

12. Math for Green Ampt

13. Green- Ampt Parameters