A quick presentation describes infiltration as an abstraction in the hydrological water cycle.

1. INFILTRATION
AMR KADRY SAYED , 6th NOV. 20201
Bsc Degree of Civil Engineering
Dr. Samia Aboul Fetouh Mohamed
Assistant Professor at Irrigation and Hydraulics
Faculty of Egineering , Ain Sham university
Environmental and Water Resources Diploma

2. Outlines
 Introduction
 Infiltration definition
 Soil water zones
Factors affects on the Infiltration
 How to measure the infiltration
 Models for estimating infiltration

3. Introduction
 Infiltration is a main component of the water cycle
 Infiltration causes the soil water
Surface water percentage Water cycle
Those images are quoted from ScienceDirect Web site. https://www.sciencedirect.com/topics/earth-and-
planetary-sciences/hydrological-cycle

4. Infiltration Defintion
Infiltration that process by which precipitation moves
downward through the surface of the earth.
Infiltration replenishes soil moisture, recharges
aquifers.
Infiltration ultimately supports stream flows During
dry period.

5. depth
Wetting Zone
Transmission
Zone
Transition Zone
Saturation Zone
Wetting Front
q
• Process of water penetrating from
ground into soil
• Four zones
Saturated, transmission, wetting, and
wetting front
Moisture zones during the infiltration (Hillel, 1980)

6. Factors affects on Infiltration
Characterstics of the soil
Condition of the soil surface
Current moisture content
Vegetation cover
Soil temprature
Intensity
Water quality

7. How to measure the infiltration
 Using flooding type of the infiltrometers
Single ring infiltrometers Double ring infiltrometers
• Plot the
infiltration
capacity Vs.
Time.
• The measure -
ments end when
the infiltration
rate is fixed.
• It May takes
from 2-3 hrs.

8. Time Since
start
(minutes)
Infiltration
Depth
(cm)
Time
interval
(mins)
Incremental
Depth
(cm)
Infiltration
Rate fp
(cm/hour)
5 1.75 5 1.75 21
10 3 5 1.25 15
15 3.95 5 0.95 11.4
25 5.5 10 1.55 9.3
45 7.25 20 1.75 5.25
60 8.3 15 1.05 4.2
75 9.3 15 1 4
90 10.2 15 0.9 3.6
110 11.28 20 1.08 3.24
130 12.36 20 1.08 3.24
Test Results
0 50 100 150 200
0
2
4
6
8
10
12
14
0
5
10
15
20
25
0 50 100 150 200
Depth
(cm)
Infiltration
(
cm/hr
)
Time ( Hr )
INFILTRATION VS. TIME
RELATIONSHIP
Infilteration Rate fp
( cm/hour )
Cummulative Infilteration
Depth (cm)

9. Using Rainfall simulator
• Water bugget equation
Image is queted from a researche gate web site.
https://www.researchgate.net/figure/The-Guelph-portable-rainfall-simulator-a-being-
used-to-generate-runoff-from-a-1-1-m_fig1_228505914

10. Hydrograpgh analysis
Estimation of infiltration capacity of a small watershed can be
obtained by analysing measured runoff hydrograpgh and
corresponding rainfall records.

11. Models for estimating infiltration
HORTON’S INFILTRATION MODEL
GREEN-AMPT MODEL
HUGGINS-MONKE MODEL
HOLTAN MODEL

12. HORTON’S INFILTRATION MODEL
• Graphical equation drived by Horton
1930.
• It indicates that if the rainfall supply
exceeds the infiltration capacity

13. Thosee figures are quoted from Introduction to Hydrology 4th Edition book by Jonathan chang

14. GREEN-AMPT MODEL
Wetted Zone
Wetting Front
Ponded Water
Ground Surface
Dry Soil
0
h
L
q

n
i
q
q
z








 1
F
K
f
q














q

q

F
Kt
F 1
ln
• Green and Ampt (1991) proposed a
simplified picture of the infiltration.
• Using two starting aspects of continuity
and Darcy low.

15. Wetted Zone
Wetting Front
Ground Surface
Dry Soil
L
q

n
i
q
q
z
q

= increase in moisture
content as wetting front
passes

 = Suction head at “sharp”
wetting front Conductivity, K
L = Wetted depth
K = Conductivity in wetted
zone
Ponded Water
0
h
0
h = Depth of water ponding
on surface (small)
 GREEN-AMPT equation parameters

16. r
e n q
q 

Initial effective saturation
0 ≤ Se ≤ 1
Effective porosity
𝑠𝑒 =
𝜃 − 𝜃𝑟
𝑛 − 𝜃𝑟
Δ𝜃 = 𝜃𝑒(1 − 𝑠𝑒)
Initial Effective Saturation (Brooks and Corey ,1964)
Source : Rawls, Brakensiek , and Miller, 1983

17. Ponding Time
i
f  p
t
i
F *









 1
F
K
f
q











 1
* p
t
i
K
i
q

Potential
Infiltration
Actual Infiltration
Rainfall
Accumulated
Rainfall
Infiltration
Time
Time
Infiltration
rate,
f
Cumulative
Infiltration,
F
i
p
t
p
p t
i
F *

)
( K
i
i
K
tp



q

Up to the time of ponding, all rainfall has
infiltrated (i = rainfall rate)

18. Question

19. Thank you,,,