Infiltration.

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

1. INFILTRATION A M R K A D R Y S A Y E D , 6 t h NOV. 20201 Bsc Degree of Civil Engineering D r . S amia A boul Fetouh Mohamed Assistant Professor at Irrigation and Hydraulics Faculty of E g i n e e r i n g , Ain Sham un i versity Environmental and Water R esources Diploma

2. O u t l i n e s Introduction Infiltration definition Soil water zones F a c t o r s a f f e c t s o n t h e Infiltration How t o m e a s u r e the infiltration M odels for estimating infiltration

3. I n t r o d u c t i o n In f i l t r a t i o n i s a m ain component of the water cycle Infiltration causes the soil water Surface water percentage Water cycle Those images are quoted from ScienceDirect W e b s i t e. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/hydrological-cycle

4. Infiltration Defi n t i o n I n filtration that process by which precipitation moves downward through the surface of the earth . I n f i l t r a t i o n replenishes soil moisture, recharges aquifers . I n f i l t r a t i o n 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 C h a r a c t e r s t i cs of the soil Condition of the soil surface Current moisture con t e n t Vegetation cover Soil t e m p r ature Intensity W a t e r q u ality

7. How t o m e a s u r e the infiltration Using flooding type of the i n f i ltrometers Single ring infiltrometers D ouble ring infiltrometers P l o t t h e infiltration capacity Vs. Time. T he m e a sure - ments end when the inf i ltration rate is fixed. It May takes from 2-3 h r s .

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 T e s t R e s u l t s

9. Using Rai nfall simulator W a t e r b u g get equation I m a g e i s q u e t e d f r o m 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. H y d r o g r a p g h a n a lysis Estimation of infiltration capacity of a s m a l l w a t e r shed can be obtained by analysing measured run o f f h y d r o g r a p g h a n d c o r responding rainfall records .

11. M odels for estimating infiltration HORTON’S INFILTRATIO N M ODEL GREEN-AMPT MODEL HUGGINS-MONKE MODEL HOLTAN MODEL

12. HORTON’S INFILTRATIO N M ODEL G raphical e q u a t i o n d rived by Horton 1930. It indicates that if the rainfall supply exceeds the infiltration capacity

13. Those e figures are quoted from Introduction to Hydrology 4th Edition b o o k b y J o n a t h a n c h a n g

14. GREEN-AMPT MODEL Wetted Zone Wetting Front Ponded Water Ground Surface Dry Soil G r e e n a n d A m p t (1991) proposed a s i m p l i f i e d p i c t u r e of the infiltration. Using two starting aspects of continuity and Darcy low.

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

16. Initial effective saturation ≤ S e ≤ 1 Effective porosity     Initial Effective Saturation (Brooks and Corey ,1964) Source : R a w l s , Brakensiek , and Miller, 1983

17. Ponding Time Potential Infiltration Actual Infiltration Rainfall Accumulated Rainfall Infiltration Time Time Infiltration rate, f Cumulative Infiltration, F Up to the time of ponding, all rainfall has infiltrated ( i = rainfall rate)

18. Question

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