Small Scale Spatial Variability Of Water Infiltration And Its Influencing Factors

Contents

Acknowledgements

Abstract

1. Introduction.......................................................................................................................1

2. Review of literature...........................................................................................................4

2.1. Variability of hydraulic conductivity (Ks)......................................................................4

2.2. Role of vegetation cover.................................................................................................4

3. Methods.............................................................................................................................7

3.1. Site conditions ................................................................................................................7

3.2. Soil samples....................................................................................................................9

3.2.1.Soil dry bulk density.....................................................................................................9

3.2.2.Experimental design and infiltration measurements..................................................10

4. Results.............................................................................................................................12

4.1. Infiltration rates ............................................................................................................12

4.1.1. Infiltration rate of soil under shrub site .....................................................................12

4.1.2. Infiltration rate of soil under plantation forest site ....................................................13

4.2. Asymptotic infiltration..................................................................................................14

4.2.1. Asymptotic infiltration of soil under shrub area .......................................................14

Table 4.21: Asymptotic infiltration of soil under shrub area...............................................14

4.2.2. Asymptotic infiltration of soil under forest plantation ..............................................15

5. Discussion .......................................................................................................................18

Limitations of using ring infiltrometer ................................................................................19

6. Conclusions.....................................................................................................................20

References............................................................................................................................21

Acknowledgements

First of all, I would like to express my deepest gratitude with special thanks to

MSc. Phi Dang Son for his guidance and encouragement. Similarly, I am so grateful and

thankful to Prof. Lee McDonald for his guidance. To complete the research I also received

a lots of helps from Dr. Le, Dr. Bui Xuan Dung and Ms. Huyen who work in the

Laboratory of Vietnam Forestry University, therefore I would like to say thank you to all

of them for lending me the equipment to measure the parameters of my thesis. . Finally, I

would thank all friends and everybody who contributed to this thesis.

Abstract

This research was conducted to examine the small scale variability of infiltration

and the effect of the lower vegetation layer (under plantation forest and shrub) on the water

infiltration characteristics using the single ring infiltrometer method on Luot Mountain.

Infiltration rate was measured under plantation forest and shrub with 3 replicates for each

type of vegetation. Findings of this study showed the asymptotic infiltration rate of soil

under shrub area ranges from 1.6 to 2.5 higher than that under plantation forest. Soil

porosity and infiltration rate have a positive relationship.