Runoff Generation And Soil Erosion From Different Age Of Acaia Plantation Forest In Truong Son Commune Luong Son District Hoa Binh Province Viet Nam Master Thesis In Forest Science

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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL

DEVELOPMENT

VIETNAM NATIONAL UNIVERSITY OF FORESTRY

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CHIN KOLYAN

RUNOFF GENERATION AND SOIL EROSION FROM

DIFFERENT AGE OF ACACIA PLANTATION FOREST IN

TRUONG SON COMMUNE, LUONG SON DISTRICT, HOA BINH

PROVINCE, VIETNAM

MASTER THESIS IN FOREST SCIENCE

Hanoi, 2018

ii

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL

DEVELOPMENT

VIETNAM NATIONAL UNIVERSITY OF FORESTRY

--------------------

CHIN KOLYAN

RUNOFF GENERATION AND SOIL EROSION FROM

DIFFERENT AGE OF ACACIA PLANTATION FOREST IN

TRUONG SON COMMUNE, LUONG SON DISTRICT, HOA BINH

PROVINCE, VIETNAM

Major: Forest Science

Code: 8620201

MASTER THESIS IN FOREST SCIENCE

Signature: ………………………

Supervisor: Assoc. Prof. Dr. Bui Xuan Dung

Hanoi, 2018

i

ABSTRACT

Vegetation cover is the key factors that protect the soil, reduce surface runoff

and soil erosion. Present days, citizens are paying more attention to the industrial

plantation in Vietnam, especially Acacia magium plantation as it takes part in

improving the socio-economic condition. To propose a solution to mitigate the

impact of Acacia plantation, understanding about runoff generation and soil erosion

are needed. To determine the characteristic of runoff generation and soil erosion

derived at the different ages of Acacia plantation forest in Luong Son headwater of

Vietnam, four plots (15m2

) were set up. Of those, 2 plots (up-hill and down-hill) in

1-year-old Acacia plantation and 2 plots (up-hill and down-hill) in 5-years-old

Acacia plantation. The main finding includes: (1) runoff coefficient at Acacia 1-

year-old down and up was (0.36% - 0.46%) with the average 0.41%. And Acacia 5-

years-old, down and up was (0.35% - 0.39%) with the average 0.37%. It shows the

slightly different between the locations of two years due to the different ground

cover. However, t-test result showed that the difference between locations in years

one and year-5 are not significant (P-value = 0.31 and P-value = 0.96 respectively).

T-test also indicated that there was no significant difference in term of an runoff at

two different ages of Acacia plantation with (P-value = 0.95 > 0.05); (2) soil erosion

is significantly different between two years of Acacia plantation (P-value = 0.004 <

0.05). Total soil erosion in year-1 and year-5 were 21.84 ton/ha/6months and 14.20

ton/ha/6months, respectively that is classified as strong erosion (level IV) base on

TCVN5299:2009; (3) both runoff and soil erosion at 2 different ages of Acacia

plantation forest has strongly depended on the amount of precipitation (R2

range

from 0.52-0.85, with P-value = 0.00). This suggests that the amount of runoff and

soil erosion at Acacia 1-year-old was a greater amount of soil erosion because of

fewer vegetation covers we need to be more concerned and apply suitable

management for reducing the negative impact of Acacia plantation forest at the

headwater of Vietnam.

ii

TABLE OF CONTENT

ABSTRACT........................................................................................................ i

TABLE OF CONTENT......................................................................................ii

ABBREVIATIONS ........................................................................................... iv

LIST OF TABLES.............................................................................................. v

LIST OF FIGURES ........................................................................................... vi

CHAPTER I: INTRODUCTION..................................................................... 1

CHAPTER II: LITERATURE REVIEW........................................................ 5

2.1. Runoff generation and soil erosion globally................................................. 5

2.2. Runoff generation and soil erosion in Vietnam .......................................... 10

CHAPTER III: STUDY SITE AND METHODS .......................................... 13

3.1. Study site ................................................................................................... 13

3.2. Methods ..................................................................................................... 15

3.2.1. Plots design for an experiment ................................................................ 15

3.2.2. Measure runoff ....................................................................................... 19

3.2.3. Measure soil erosion ............................................................................... 20

3.2.4. Measure precipitation ............................................................................. 21

3.2.5. Soil moisture measuring ......................................................................... 21

3.2.6. Measure porosity of the soil.................................................................... 22

3.2.7. Soil texture ............................................................................................. 23

3.2.8. Vegetation observation ........................................................................... 25

3.2.9. Topographic survey ................................................................................ 25

3.3. Data analysis ............................................................................................. 25

CHAPTER IV: RESULTS ............................................................................. 26

4.1. Runoff generation at 2 different ages of Acacia plantation......................... 26

4.2. Soil erosion at 2 different ages of Acacia plantation .................................. 30

4.3. The relationship among runoff, soil erosion, and precipitation ................... 35

4.4. Suggested solution..................................................................................... 39

iii

CHAPTER V: DISCUSSION......................................................................... 41

5.1. Runoff generation at two different ages of Acacia plantation forest ........... 41

5.2. Soil erosion at two different ages of Acacia plantation forest .................... 44

CHAPTER VI: CONCLUSION..................................................................... 49

ACKNOWLEDGMENT ................................................................................... 50

REFERENCES

APPENDIX

iv

ABBREVIATIONS

1-Down Plot 1-down at Acacia 1-year-old

1-Up Plot 1-up at Acacia 1-year-old

5-Down Plot 5-down at Acacia 5-years-old

5-Up Plot 5-up at Acacia 5-years-old

API7 Antecedent precipitation index for 7 days

C Carbon

Cm3 Cubic centimeter

df Degree of freedom

FAO Food and Agriculture Organization

Fig. Figure

GIS Geography Information System

GPS Global position system

ha Hectare

N-P-K Nitrogen - Phosphorus - Potassium

P-value Probability

R

2 Coefficient of determination

RUSLE Revised Universal Soil Loss Equation

SPSS Statistical Package for the Social Sciences

USA United States of America

USDA US Department of Agriculture

v

LIST OF TABLES

Table 3.1. Observation plots characteristic at the study site ........................................ 17

Table 3.2. Soil texture at study site follow FAO classification 2006 ......................... 17

Table 4.1. The summary result from SPSS (Appendix table1) ................................... 30

Table 4.2. The summary result from SPSS (Appendix table 1). ................................. 34

Table 4.3. Summary of correlation analysis between runoff, soil erosion, and both

rainfall and soil moisture characteristics ........................................................................ 38

Table 4.4. TCVN5299: 2009 Method for determination of soil erosion by rainfall . 39

Table 5.1. Comparison the runoff coefficient with other studies (the unit for first

two columns are %/6months while the rests are a %/1 year) ...................................... 43

Table 5.2. Compare the soil erosion among Acacia plantation forest year-1, year-5

(ton/ha/6months) with other land types (ton/ha/year for the rest) ............................... 47