Infiltration (water resources engineering)

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

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(), ()
•Infiltration
•Green-Ampt method

2. Particle size measurement
http://www.soils.agri.umn.edu/academics/classes/soil2125/doc/s2chp1.htm
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 = 100 - %Sand - %Clay

5. K
S
e
Variation of Saturated Hydraulic
Conductivity with Soil Texture

6. Interconnection of
Soil water properties
K




K

7. Double Ring Infiltrometer
Measure rate of fall in inner ring
Infilration
http://www.alwi.com/wastewater.php

8. Infiltration by Horton’s method
 
kt
cc effff


0

9. Infiltration into a soil water column









21
21
zz
hh
Kf
1
2 LF

10. Green-Ampt method
ri
r
eS





Relative saturation
i
Incremental change
in soil water content
as wetting front passes

11. Green-Ampt Parameter Definitions
ri
r
e
S





Relative saturation
i
Incremental change
in soil water content
as wetting front passes

12. Math for Green Ampt

13. Green-
Ampt
Parameters