Evaluating effects of acacia plantation forest on surface runoff and erosion in luong son headwater of vietnam

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT VIETNAM NATIONAL UNIVERSITY OF FORESTRY FINAL THESIS EVALUATING EFFECTS OF ACACIA PLANTATION FOREST ON SURFACE RUNOFF AND EROSION IN LUONG SON HEADWATER OF VIETNAM Major: Natural Resources Management Faculty: Forest Resource and Environmental Management Student: Pham Quynh Trang Student ID: 1453092269 Class: K59 - Natural Resources Management Course: 2014 – 2018 Advanced Education Program Developed in collaboration with Colorado State University, USA Supervisor: Adjunct Associate Professor Dr Bui Xuan Dung Hanoi, 2018 i ACKNOWLEDGEMENT First and foremost, to be able to conduct this research, I would like to express my sincere respect to my supervisor - Assoc Prof Dr Bui Xuan Dung for his enthusiastic and patient support with invaluable comments In addition, I appreciated the support of other lectures during the time I analyzed the data Not only that, many thanks are due to my friends when I started to collect and analyze data They always give me the support whenever I needed In terms of difficulties, the transport to study sites was hard without my companions Lastly, I express my gratitude to local people who own the Acacia plantation model for allowing us to conduct this research in this site They also informed me about the weather which extremely support me to get the data Hanoi, October 2018 ii TABLE OF CONTENTS ACKNOWLEDGEMENT .ii TABLE OF CONTENTS iii LIST OF FIGURES v LIST OF TABLES vii ABSTRACT viii CHAPTER I: INTRODUCTION CHAPTER II: GOAL AND OBJECTIVES 2.1 Goal 2.2 Objectives CHAPTER III: STUDY SITE AND METHODS 3.1 Study site 3.2 Methods 3.2.1 Installing monitoring plot 3.2.2 Rainfall and soil physical characteristics 3.2.3 Runoff and soil erosion measurement 11 3.2.4 Vegetation observation 12 3.2.5 Topographic survey 12 3.2.6 Data analysis 13 CHAPTER IV: RESULTS 14 4.1 Soil physical factors, vegetation and precipitation characteristics on study sites 14 iii 4.1.1 Soil physical factors and vegetation on study sites 14 4.1.2 Precipitation characteristics 15 4.2 Runoff generation characteristics on study site 18 4.3 Soil erosion on study site 24 CHAPTER V: DISCUSSION 29 5.1 Surface runoff at bareland and different ages of Acacia 29 5.2 Soil erosion at bareland and different ages of Acacia 34 CHAPTER VI: CONCLUSION 41 CHAPTER VII: RECOMMENDATION 41 REFERENCES 44 APENDIX 49 iv LIST OF FIGURES Figure 3.1 The map of study site Figure 3.2 Location of five plots Figure 3.3 The model of plot and experiment conducted Figure 3.4 Rain gauge Figure 3.5 Measured poroxity 10 Figure 3.6 Determined amount of runoff 11 Figure 3.7 Took eroded soil and dried and in the Lab 11 Figure 3.8 GLAMA and Canopy Cover Free application 12 Figure 3.9 GPS and Compass application 12 Figure 3.10 Create box-plot by R-studio 13 Figure 3.11 Box-plot graph 13 Figure 4.1 Storm events 15 Figure 4.2 Precipitation, surface runoff and runoff coefficient at different ages of Acacia 18 Figure 4.3 Precipitation accumulation and runoff accumulation at different age of Acacia 20 Figure 4.4 Comparison of the runoff generation to forest cover change by bare land and four different Acacia tree-aged 21 Figure 4.5 Correlation between precipitation and surface runoff at different age of Acacia 22 Figure 4.6 Precipitation and soil eroded at different ages of Acacia 24 v Figure 4.7 Precipitation and soil erosion accumulation at different ages of Acacia 25 Figure 4.8 A comparison of soil erosion to forest cover change by bare land and four different Acacia tree-aged 26 Figure 4.9 Correlation between soil erosion and precipitation, surface runoff 27 Figure 4.10 Annual soil erosion at different ages of Acacia 28 Figure 5.1 Runoff coefficient of species on other study 30 Figure 5.2 The soil erosion annually at different Acacia ages 34 Figure 5.3 Annual soil erosion of vegetation types on other studies 36 Figure 6.1 Effect of Acacia plantation in different ages 42 vi LIST OF TABLES Table 4.1 Outline of five plots of different vegetation cover types 14 Table 4.2 Precipitation, API7 and rainfall intensity on study sites 16 Table 4.3 Vegetation on study site 17 Table 4.4 Surface runoff, runoff coefficient analysis between five plots 19 Table 4.5 Independent samples t-test for the effect of surface runoff to Acacia’s age 22 Table 4.6 Soil erosion analysis between five plots 25 Table 4.7 Independent samples t-test for the effect of soil erosion to Acacia ages 26 Table 5.1 TCVN 5299: 2009 - Method for determination of soil erosion by rainfall 36 Table 5.2 The soil erosion annually on other studies 37 vii ABSTRACT To assess soil losses and overland flow in Acacia plantations of different ages and evaluating erosion risk to surface cover by investigating the characteristics of surface runoff generation and soil erosion derived from bare land and Acacia Plantation forest model in Luong Son headwater of Vietnam Five plots (10 m2/plot) at different vegetation cover conditions (bare land, 4-month-old Acacia trees, 1-year-old Acacia trees, 2-year-old Acacia trees and 4-year-old Acacia trees) was set up and monitored over 75 storm events from September 2017 to August 2018 in Truong Son Commune, Luong Son district, Hoa Binh Province The main findings included: (1) Runoff coefficient was the highest at bare land (7.87%) and the lowest 4-year-old Acacia trees (0.40%); (2) The highest amount of soil loss accumulation during the observed time was induced from bare land plot (103.75 kg), the intermediate from 4-month-old Acacia (27.52 kg) 1-year-old Acacia (12.61 kg), 2-year-old Acacia (11.99 kg), and the lowest at 4year-old Acacia (14.19 kg); (3) Both the amount of runoff and soil erosion has a strong relationship with vegetation cover and precipitation (p year > year > year However, with the Acacia's 7-year life cycle, before starting a new cycle, need to clear be cutting and burning, Acacia is grown in headwater where has high and steep topography, which affects the soil and causes severe erosion As discussed above, the amount of erosion at my research site has exceeded the standard erosion threshold Therefore, Acacia trees can protect soil, but to determine whether or not to continue to develop Acacia plantation model in Luong Son headwater is still a question to be investigated further 40 CHAPTER VI CONCLUSION After surveying surface runoff 75 storm events, the conclusion of research pointed out: - Overland flow is the highest in bare land (runoff coefficient 7.87%), times higher than 4month-old-trees plot (1.81%); about times higher than 1-year-old Acacia trees plot (0.76%) and 2-year-old Acacia trees plot (0.73%), 23 times higher than 4-year-old Acacia trees plot (0.40%) The amount of runoff coefficient had the same direction as precipitation Acacia plantation plays an important role in controlling surface runoff - Soil erosion average is the highest in bare land (1.383 kg/10m2/storm) was 3.7 times greater than that of 4-month-old Acacia trees plot (0.366 kg/10m2/storm), about times higher than that of 1-year-old Acacia trees plot (0.168 kg/10m2/storm) and year-old Acacia trees plot (0.159 kg/10m2/storm), 29 times higher than that of 4-year-old Acacia tree plot (0.066 kg/10m2/storm) - Surface runoff and soil erosion had a strong relationship with precipitation Not only that, overland flow also had a strong relationship with soil erosion from bare land and four age levels of Acacia tree land: 4-month-old trees; 1-year-old trees, 2-year-old trees and 4-yearold trees - Main finding suggestion: Higher age of Acacia trees tends to the decrease of surface runoff and soil erosion due to lots of factors such as plant cover, porosity, rock cover, canopy cover, organic matter, etc - Determine whether or not to continue to develop Acacia plantation model in Luong Son headwater is still a question to be investigated further 41 CHAPTER VII RECOMMENDATION On the basis of the thesis results as well as the effect of Acacia plantation in different ages (Fig 6.1), Acacia plantation model should be encouraged, particularly for the degraded soils in order to minimize the amount of soil loss by erosion, thus avoiding slumping and promoting stability Figure 6.1 Effect of Acacia plantation in different ages Keeping suitable Acacia trees cover should be considered for soil and water conservation Currently, Acacia plantation has been applied successfully in Hoa Binh province as well as Truong Son commune (VAFS) However, as shown in figure 5.3 - section 5.2, only the 4-year-old tree permissive soil conservation standard, those below 4-year-old tree exceeded the standard and the ability of older trees to better control erosion To overcome this situation: + Planting grasses and shrubs: Bare land is easily washed away by wind and water, the two main causes of erosion When planting trees on the soil, the roots work to keep the soil in contact, helping to prevent the rain from causing landslides 42 + Keep soil covered year-round: Bare land is more susceptible to erosion than covered land Try to plant cover at least 40% of grazing land or more Use overlay or gravel These materials help the soil settle down, protecting seed and seedlings from being washed away This method also slows down the water absorption process, thus limiting the flow of water + Building retaining walls Severely eroded slopes will continue to collapse until they can be stabilized A retaining wall at the foot of the slope will help to block the soil and slow down the landslides It will help Acacia have enough time to grow and maintain the soil In brief, Acacia plantation model should continue to be designed, developed and expanded in the future with some improvements 43 REFERENCES Abraham Joel, Ingmar Messing, Oscar Seguel and Manuel Casanova, 2002 “Measurement of surface water runoff from plots of two different sizes” Swedish University of Agricultural Sciences, Department of Soil Sciences, PO Box 7014, SE750 07 Uppsala, Sweden University of Chile, Faculty of Agricultural Sciences, Department of Engineering and Soil, Casilla 1004, Santiago, Chile Al-Seikh, S., 2006 “The Effect of different water harvesting techniques on Runoff, Sedimentation, and soil characteristics.” M.Sc thesis, Hebron University Ayed G Mohammad, Mohammad A Adam, “The impact of vegetative cover type on runoff and soil erosion under different land uses” Range Science, College of Agriculture, Hebron University P.O Box 40, Hebron, Palestine Natural Resources Managements, College of Agriculture, Hebron University, Hebron, Palestine Benjamini, Y., 1988 “Opening the Box of a Boxplot” The American Statistician Vol 42, No (Nov., 1988), pp 257-262 Bo Ma, Xiaoling Yu, Fan Ma, Zhanbin Li & Faqi Wu, 2014 “Effects of Crop Canopies on Rain Splash Detachment” PLoS One 2014; 9(7): e99717 Bonell, M., 1998 “Possible effects of climate variability and change on tropical forest hydrology” Climatic change 39, 215–272 Bracken & Kirkby (2005) L.J Bracken, M.J Kirkby “Differences in hillslope runoff and sediment transport rates within two semi-arid catchments in southeast Spain Journal of Geomorphology, 68 (3–4) (2005), pp 183-200 View Record in Scopus” Bui Duc Thuan, 2018 - 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House, Hanoi 48 APENDIX Date 29/09/2017 30/09/2017 03/10/2017 04/10/2017 05/10/2017 07/10/2017 08/10/2017 09/10/2017 12/10/2017 17/10/2017 19/10/2017 25/10/2017 29/10/2017 06/11/2017 08/11/2017 09/11/2017 12/11/2017 15/11/2017 19/11/2017 20/11/2017 24/11/2017 05/04/2018 06/04/2018 15/04/2018 16/04/2018 22/04/2018 25/04/2018 27/04/2018 28/04/2018 30/04/2018 02/05/2018 05/05/2018 08/05/2018 11/05/2018 13/05/2018 16/05/2018 18/05/2018 19/05/2018 21/05/2018 26/05/2018 27/05/2018 28/05/2018 29/05/2018 31/05/2018 01/06/2018 02/06/2018 05/06/2018 06/06/2018 09/06/2018 10/06/2018 11/06/2018 12/06/2018 17/06/2018 18/06/2018 20/06/2018 27/06/2018 09/07/2018 10/07/2018 11/07/2018 14/07/2018 16/07/2018 18/07/2018 19/07/2018 Precipiatio n (mm) 18.50 11.00 29.50 9.50 13.50 33.00 13.50 0.75 182.00 3.50 5.50 7.00 0.50 1.00 3.00 2.50 9.00 3.00 14.50 7.00 4.50 0.90 10.20 12.50 16.50 33.00 49.20 27.00 2.10 36.00 31.50 28.50 29.50 55.00 9.40 11.00 42.00 6.00 41.50 34.20 85.00 5.00 20.00 15.90 15.00 69.00 53.00 6.00 13.80 6.20 8.40 4.30 20.00 125.00 2.00 45.80 9.30 28.00 58.60 62.70 109.00 34.00 197.00 Plot 1: Bare land Plot 2: 4-month-old trees Plot 3: 1-year-old trees SR1 Soil1 SR2 Soil2 SR3 Soil3 1.43 300.10 0.40 280.80 0.14 40.90 0.32 50.90 0.08 48.50 0.03 5.60 3.82 1225.40 0.72 320.10 0.23 51.80 0.10 52.60 0.03 56.90 0.01 9.30 0.53 160.00 0.19 56.80 0.04 6.80 4.50 1450.80 0.81 328.20 0.25 65.00 0.50 120.50 0.19 57.10 0.09 10.20 0.00 0.00 0.00 0.00 0.00 0.00 30.25 9165.00 5.52 1858.00 1.65 656.00 0.04 0.00 0.01 0.00 0.01 0.00 0.08 0.00 0.01 0.00 0.01 0.00 0.07 50.10 0.02 18.50 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.01 0.00 0.01 0.00 0.02 0.00 0.01 0.00 0.00 0.00 0.10 55.80 0.02 16.10 0.01 14.10 0.03 0.00 0.01 0.00 0.01 0.00 0.93 158.20 0.20 65.30 0.12 12.10 0.08 48.50 0.02 12.30 0.01 0.00 0.05 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.23 50.90 0.10 41.50 0.03 5.60 0.35 160.00 0.19 56.80 0.04 6.80 0.63 158.20 0.20 65.44 0.12 12.10 4.50 1439.00 0.81 328.23 0.25 65.54 5.25 1650.38 0.94 379.45 0.31 69.21 3.63 1028.35 0.62 292.22 0.23 47.46 0.00 0.00 0.00 0.00 0.00 0.00 4.58 1525.20 0.83 345.50 0.28 66.24 4.36 1385.50 0.82 331.16 0.25 65.30 4.06 1225.65 0.79 319.20 0.24 48.13 4.07 1244.27 0.81 323.41 0.24 49.95 5.79 1882.24 1.35 491.25 0.43 78.95 0.14 52.60 0.03 56.90 0.01 9.30 0.27 60.14 0.12 61.72 0.04 5.95 0.49 1485.40 0.88 362.45 0.30 67.60 0.08 0.00 0.01 0.00 0.01 0.00 5.18 1565.30 0.83 348.25 0.27 66.14 4.51 1499.10 0.82 333.75 0.26 65.87 12.70 4822.61 3.33 995.45 1.27 272.62 0.06 0.00 0.01 0.00 0.01 0.00 1.43 300.20 0.40 280.80 0.14 40.90 0.58 133.05 0.22 62.80 0.11 9.89 0.50 121.50 0.19 55.10 0.09 7.12 8.31 3614.74 2.30 657.71 0.93 195.85 5.76 1826.45 1.33 431.70 0.43 78.65 0.08 0.00 0.01 0.00 0.01 0.00 0.50 121.50 0.19 55.10 0.09 7.12 0.08 0.00 0.01 0.00 0.01 0.00 0.09 51.30 0.02 13.20 0.01 11.10 0.04 0.00 0.01 0.00 0.01 0.00 1.43 299.80 0.41 279.50 0.14 40.95 20.78 4845.03 6.89 1861.47 3.33 673.52 0.00 0.00 0.00 0.00 0.00 0.00 5.35 1665.83 1.03 398.25 0.37 71.14 0.10 55.60 0.02 16.10 0.01 14.10 4.00 1219.74 0.78 318.30 0.23 48.20 6.29 1958.82 1.95 561.25 0.46 82.95 7.91 6129.48 2.59 1335.20 1.16 421.40 13.94 4214.24 4.48 1242.18 3.24 1218.52 4.50 1482.40 0.82 327.60 0.25 67.45 35.25 9175.30 5.69 2038.16 1.85 816.03 49 Plot 4: 2-year-old trees Plot 5: 4-year-old trees SR4 Soil4 SR5 Soil 0.14 32.60 0.02 4.50 0.24 37.10 0.01 6.10 0.03 5.20 0.26 51.80 0.03 11.80 0.00 0.00 1.51 625.00 0.01 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 7.20 0.00 0.00 0.13 10.30 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.02 4.50 0.00 0.00 0.03 5.20 0.01 0.00 0.13 10.30 0.02 0.00 0.26 51.80 0.17 21.45 0.33 62.40 0.23 24.75 0.22 33.25 0.12 19.39 0.00 0.00 0.00 0.00 0.28 55.75 0.17 22.37 0.25 49.90 0.16 20.15 0.23 36.62 0.13 19.97 0.24 38.27 0.14 19.98 0.41 75.15 0.35 31.24 0.01 6.10 0.01 0.00 0.02 4.80 0.01 0.00 0.30 59.65 0.19 23.14 0.01 0.00 0.00 0.00 0.28 54.36 0.19 22.30 0.27 53.35 0.17 21.62 1.25 270.57 0.67 73.10 0.01 0.00 0.00 0.00 0.14 32.60 0.03 9.30 0.11 6.30 0.01 0.00 0.11 5.25 0.01 0.00 0.90 195.20 0.52 49.63 0.40 37.63 0.35 32.00 0.01 0.00 0.00 0.00 0.03 4.75 0.01 0.00 0.01 0.00 0.00 0.00 0.01 5.40 0.00 0.00 0.01 0.00 0.00 0.00 0.13 33.90 0.03 9.25 3.00 635.21 1.24 294.43 0.00 0.00 0.00 0.00 0.33 65.35 0.27 27.75 0.01 7.20 0.00 0.00 0.23 37.12 0.13 19.25 0.43 76.15 0.35 31.78 1.10 411.56 0.55 100.10 3.26 1204.76 0.89 352.64 0.26 62.71 0.17 21.52 1.81 783.28 1.55 342.77 20/07/2018 21/07/2018 22/07/2018 23/07/2018 24/07/2018 29/07/2018 31/07/2018 13/08/2018 18/08/2018 22/08/2018 24/08/2018 28/08/2018 18.90 126.20 42.00 33.00 25.00 85.00 42.50 35.00 110.00 37.00 28.50 104.00 2.70 23.95 6.34 5.11 3.26 12.07 6.34 5.10 21.56 5.72 0.82 4.16 Surface runoff (mm) Runoff coefficient (%) Soil erosion (kg/10m-2) Date 29/09/2017 30/09/2017 03/10/2017 04/10/2017 05/10/2017 07/10/2017 08/10/2017 09/10/2017 12/10/2017 17/10/2017 19/10/2017 25/10/2017 29/10/2017 459.67 5138.90 186.83 1558.20 605.80 6153.33 1867.30 1523.30 7372.17 872.52 389.50 1351.19 0.61 4.96 1.44 0.91 0.73 3.36 1.45 0.91 4.65 1.18 0.29 3.53 Plot N 5 75 75 75 75 54 75 75 75 75 54 75 75 75 75 54 308.30 908.79 412.23 344.20 434.80 1793.60 414.50 331.32 1760.25 378.22 64.45 1398.10 0.15 4.10 0.40 0.33 0.26 2.95 0.40 0.32 3.74 0.36 0.27 3.50 43.20 899.28 82.28 67.60 61.30 1896.93 83.20 65.50 2192.40 74.94 59.31 1349.59 Minimum Maximum 0 0 0 0 0 0 0 9.30 360.57 21.75 17.15 11.50 434.53 21.40 12.56 638.53 19.45 18.08 397.55 Std Deviation Mean 4.47 1.02 0.49 0.48 0.26 7.87 1.81 0.77 0.73 0.40 1.383 7.06 1.55 0.96 0.94 0.36 6.38 1.40 0.82 0.82 0.32 2150.91 2.547 2.192 2.146 0.638 27.522 12.608 11.989 3.572 0.366 0.168 0.159 0.066 0.531 0.410 0.399 0.137 Surface runoff (mm) 18.5 3.79 1.43 0.4 0.14 0.14 11 29.5 9.5 13.5 33 13.5 0.75 182 3.5 5.5 0.5 20.25 8.99 36.53 30.03 18.86 45.78 40.19 12.15 36.4 27.75 0.92 1.75 0.32 3.82 0.1 0.53 4.5 0.5 30.3 0.04 0.08 0.07 0.08 0.72 0.03 0.19 0.81 0.19 5.52 0.01 0.01 0.02 0.03 0.23 0.01 0.04 0.25 0.09 1.65 0.01 0.01 0.01 50 0.02 0.24 0.01 0.03 0.26 0.03 1.51 0.01 0.01 0.01 Plot Sum 0.03 1.15 0.27 0.17 0.12 0.86 0.27 0.15 0.97 0.22 0.15 1.00 334.99 76.24 36.92 35.76 14.19 590.06 135.94 57.60 54.60 21.87 103.753 API7 (mm) Plot 48.24 897.98 83.35 63.51 55.10 1801.20 81.45 61.80 2146.53 73.43 18.08 397.55 35.25 6.89 4.10 4.06 1.55 19.60 5.51 3.47 3.47 1.01 9.175 Total rainfall (mm) Plot 0.16 4.06 0.32 0.32 0.22 2.95 0.40 0.32 3.69 0.32 0.15 1.00 Plot Runoff coefficient (%) Plot Plot Plot Plot Plot 7.72 2.18 0.73 0.77 2.86 12.95 1.01 3.95 13.64 3.72 16.62 1.43 0.97 0.75 2.46 0.36 1.4 2.46 1.41 3.03 0.29 0.18 0.23 0.25 0.79 0.15 0.26 0.77 0.69 0.91 0.19 0.15 0.11 0.16 0.82 0.14 0.2 0.79 0.19 0.83 0.15 0.11 0.09 Plot 06/11/2017 08/11/2017 09/11/2017 12/11/2017 15/11/2017 18/11/2017 20/11/2017 24/11/2017 05/04/2018 06/04/2018 15/04/2018 16/04/2018 22/04/2018 25/04/2018 27/04/2018 28/04/2018 30/04/2018 02/05/2018 05/05/2018 08/05/2018 11/05/2018 13/05/2018 16/05/2018 18/05/2018 19/05/2018 21/05/2018 26/05/2018 27/05/2018 28/05/2018 29/05/2018 31/05/2018 01/06/2018 02/06/2018 05/06/2018 06/06/2018 09/06/2018 10/06/2018 11/06/2018 12/06/2018 17/06/2018 18/06/2018 20/06/2018 27/06/2018 09/07/2018 10/07/2018 11/07/2018 0 0.5 0.03 2.5 3.33 0.02 1.75 0.1 3.85 0.03 14.5 2.04 0.93 15.1 0.08 4.5 14.75 0.05 0.9 1.60 0.00 10.2 1.59 0.23 12.5 0.00 0.35 16.5 12.50 0.63 33 7.29 4.50 49.2 11.00 5.25 27 31.20 3.63 2.1 54.40 0.00 36 19.89 4.58 31.5 30.95 4.36 28.5 18.00 4.06 29.5 20.00 4.07 55 19.33 5.79 9.4 33.40 0.14 11 14.13 0.27 42 15.24 0.49 48.80 0.08 41.5 19.20 5.18 34.2 9.16 4.51 85 48.03 12.70 108.03 0.06 20 58.90 1.43 15.9 39.76 0.58 15 52.22 0.50 69 62.17 8.31 53 32.79 5.76 78.55 0.08 13.8 25.11 0.50 6.2 25.90 0.08 8.4 31.97 0.09 4.3 25.67 0.04 20 4.55 1.43 125 22.63 20.78 69.17 0.00 45.8 0.29 5.35 9.3 0.00 0.10 28 9.30 4.00 58.6 32.65 6.29 0.01 0.01 0.02 0.01 0.2 0.02 0.01 0.00 0.10 0.19 0.20 0.81 0.94 0.62 0.00 0.83 0.82 0.79 0.81 1.35 0.03 0.12 0.88 0.01 0.83 0.82 3.33 0.01 0.40 0.22 0.19 2.30 1.33 0.01 0.19 0.01 0.02 0.01 0.41 6.89 0.00 1.03 0.02 0.78 1.95 0.01 0.01 0.01 0.12 0.01 0.01 0.00 0.03 0.04 0.12 0.25 0.31 0.23 0.00 0.28 0.25 0.24 0.24 0.43 0.01 0.04 0.30 0.01 0.27 0.26 1.27 0.01 0.14 0.11 0.09 0.93 0.43 0.01 0.09 0.01 0.01 0.01 0.14 3.33 0.00 0.37 0.01 0.23 0.46 51 0 0.01 0.13 0.01 0.01 0.00 0.02 0.03 0.13 0.26 0.33 0.22 0.00 0.28 0.25 0.23 0.24 0.41 0.01 0.02 0.30 0.01 0.28 0.27 1.25 0.01 0.14 0.11 0.11 0.90 0.40 0.01 0.03 0.01 0.01 0.01 0.13 3.00 0.00 0.33 0.01 0.23 0.43 0.00 0.00 0.01 0.02 0.17 0.23 0.12 0.00 0.17 0.16 0.13 0.14 0.35 0.01 0.01 0.19 0.00 0.19 0.17 0.67 0.00 0.03 0.01 0.01 0.52 0.35 0.00 0.01 0.00 0.00 0.00 0.03 1.24 0.00 0.27 0.00 0.13 0.35 1.01 0.8 1.13 0.98 6.43 1.18 1.1 0.00 2.21 2.82 3.84 13.64 10.67 13.44 0.00 12.71 13.84 14.23 13.80 10.52 1.44 2.42 1.16 1.37 12.48 13.20 14.94 1.25 7.14 3.67 3.70 12.04 10.87 1.41 3.70 1.32 1.09 0.93 7.13 16.62 0.00 11.68 1.10 14.29 10.73 0.22 0.2 0.19 0.25 1.4 0.24 0.23 0.00 1.00 1.51 1.23 2.46 1.91 2.31 0.00 2.30 2.60 2.75 2.73 2.45 0.36 1.11 2.09 0.16 2.01 2.40 3.91 0.21 2.02 1.36 1.41 3.33 2.50 0.17 1.41 0.16 0.20 0.26 2.03 5.51 0.00 2.26 0.19 2.79 3.32 0.18 0.13 0.19 0.85 0.15 0.17 0.00 0.26 0.28 0.75 0.77 0.63 0.86 0.00 0.77 0.80 0.84 0.82 0.78 0.15 0.34 0.71 0.13 0.65 0.77 1.49 0.16 0.68 0.69 0.62 1.34 0.80 0.14 0.67 0.13 0.13 0.18 0.68 2.66 0.00 0.81 0.12 0.83 0.78 0.12 0.13 0.15 0.88 0.14 0.13 0.00 0.18 0.21 0.77 0.79 0.67 0.83 0.00 0.78 0.79 0.80 0.80 0.74 0.14 0.20 0.72 0.10 0.68 0.79 1.47 0.12 0.71 0.70 0.70 1.31 0.76 0.10 0.19 0.10 0.12 0.13 0.67 2.40 0.00 0.71 0.13 0.82 0.74 0.00 0.00 0.08 0.09 0.50 0.47 0.45 0.00 0.47 0.50 0.46 0.47 0.63 0.09 0.08 0.46 0.00 0.46 0.49 0.78 0.00 0.14 0.09 0.09 0.76 0.65 0.00 0.10 0.00 0.03 0.00 0.15 0.99 0.00 0.59 0.02 0.47 0.60 14/07/2018 16/07/2018 18/07/2018 19/07/2018 20/07/2018 21/07/2018 22/07/2018 23/07/2018 24/07/2018 29/07/2018 31/07/2018 13/08/2018 18/08/2018 22/08/2018 24/08/2018 28/08/2018 Date 29/9/2017 30/9/2017 3/10/2017 4/10/2017 5/10/2017 7/10/2017 8/10/2017 9/10/2017 12/10/2017 17/10/2017 19/10/2017 25/10/2017 29/10/2017 6/11/2017 8/11/2017 9/11/2017 12/11/2017 15/11/2017 18/11/2017 20/11/2017 24/11/2017 05/04/2018 06/04/2018 15/04/2018 16/04/2018 22/04/2018 25/04/2018 62.7 109 34 197 18.9 126.2 42 33 25 85 42.5 35 110 37 28.5 104 28.39 44.43 133.05 101.04 271.23 164.94 231.62 203.78 167.10 22.00 46.07 0.00 7.00 27.50 55.17 19.46 7.91 13.94 4.50 35.25 2.70 23.95 6.34 5.11 3.26 12.07 6.34 5.10 21.56 5.72 4.18 18.01 Total rainfall (mm) 18.5 11 29.5 9.5 13.5 33 13.5 0.75 182 3.5 5.5 0.5 2.5 14.5 4.5 0.9 10.2 12.5 16.5 33 49.2 2.59 4.48 0.82 5.69 0.61 4.96 1.44 0.91 0.73 3.36 1.45 0.91 4.65 1.18 0.82 4.16 API7 (mm) 3.79 20.25 8.99 36.53 30.03 18.86 45.78 40.19 12.15 36.4 27.75 0.92 1.75 0.5 3.33 1.75 3.85 2.04 15.1 14.75 1.60 1.59 0.00 12.50 7.29 11.00 1.16 3.24 0.25 1.85 0.15 4.10 0.40 0.33 0.26 2.95 0.40 0.32 3.74 0.36 0.29 3.53 Plot 300.1 50.9 1225.4 52.6 160 1450.8 120.5 45825 0 50.1 0 0 55.8 158.2 48.5 0.00 50.90 160.00 158.20 1439.00 1650.38 52 1.10 3.26 0.26 1.81 0.16 4.06 0.32 0.32 0.22 2.95 0.40 0.32 3.69 0.32 0.27 3.50 0.55 0.89 0.17 1.55 0.03 1.15 0.27 0.17 0.12 0.86 0.27 0.15 0.97 0.22 0.15 1.00 12.61 12.79 13.24 17.89 14.29 18.98 15.10 15.47 13.06 14.20 14.92 14.57 19.60 15.47 14.68 17.32 4.13 4.11 2.40 2.89 3.24 3.93 3.42 2.77 2.90 3.95 3.42 2.60 4.22 3.18 2.88 4.00 1.85 2.97 0.74 0.94 0.80 3.25 0.95 0.98 1.05 3.47 0.95 0.93 3.40 0.98 1.03 3.39 Soil erosion (g) Plot Plot Plot 280.8 40.9 32.6 48.5 5.6 4.5 320.1 51.8 37.1 56.9 9.3 6.1 56.8 6.8 5.2 328.2 65 51.8 57.1 10.2 11.8 0 9290 3280 3125 0 0 0 18.5 0 0 0 0 0 0 0 16.1 14.1 7.2 0 65.3 12.1 10.3 12.3 0 0 0.00 0.00 0.00 41.50 5.60 4.50 56.80 6.80 5.20 65.44 12.10 10.30 328.23 65.54 51.80 379.45 69.21 62.40 1.76 2.99 0.76 0.92 0.84 3.22 0.76 0.97 0.86 3.47 0.94 0.92 3.35 0.87 0.94 3.37 Plot 0.00 0.00 0.00 0.00 21.45 24.75 0.88 0.82 0.49 0.78 0.16 0.91 0.64 0.51 0.49 1.01 0.63 0.44 0.88 0.59 0.51 0.96 27/04/2018 28/04/2018 30/04/2018 02/05/2018 05/05/2018 08/05/2018 11/05/2018 13/05/2018 16/05/2018 18/05/2018 19/05/2018 21/05/2018 26/05/2018 27/05/2018 28/05/2018 29/05/2018 31/05/2018 01/06/2018 02/06/2018 05/06/2018 06/06/2018 09/06/2018 10/06/2018 11/06/2018 12/06/2018 17/06/2018 18/06/2018 20/06/2018 27/06/2018 09/07/2018 10/07/2018 11/07/2018 14/07/2018 16/07/2018 18/07/2018 19/07/2018 20/07/2018 21/07/2018 22/07/2018 23/07/2018 24/07/2018 29/07/2018 31/07/2018 13/08/2018 18/08/2018 22/08/2018 24/08/2018 28/08/2018 27 2.1 36 31.5 28.5 29.5 55 9.4 11 42 41.5 34.2 85 20 15.9 15 69 53 13.8 6.2 8.4 4.3 20 125 45.8 9.3 28 58.6 62.7 109 34 197 18.9 126.2 42 33 25 85 42.5 35 110 37 28.5 104 31.20 54.40 19.89 30.95 18.00 20.00 19.33 33.40 14.13 15.24 48.80 19.20 9.16 48.03 108.03 58.90 39.76 52.22 62.17 32.79 78.55 25.11 25.90 31.97 25.67 4.55 22.63 69.17 0.29 0.00 9.30 32.65 28.39 44.43 133.05 101.04 271.23 164.94 231.62 203.78 167.10 22.00 46.07 0.00 7.00 27.50 55.17 19.46 1028.35 292.22 47.46 33.25 19.39 0.00 0.00 0.00 0.00 0.00 1525.20 345.50 66.24 55.75 22.37 1385.50 331.16 65.30 49.90 20.15 1225.65 319.20 48.13 36.62 19.97 1244.27 323.41 49.95 38.27 19.98 1882.24 491.25 78.95 75.15 31.24 52.60 56.90 9.30 6.10 0.00 60.14 61.72 5.95 4.80 0.00 1485.40 362.45 67.60 59.65 23.14 0.00 0.00 0.00 0.00 0.00 1565.30 348.25 66.14 54.36 22.30 1499.10 333.75 65.87 53.35 21.62 9645.22 1990.89 545.23 541.14 146.20 0.00 0.00 0.00 0.00 0.00 300.20 280.80 40.90 32.60 9.30 133.05 62.80 9.89 6.30 0.00 121.50 55.10 7.12 5.25 0.00 7229.48 1315.41 391.70 390.40 99.25 1826.45 431.70 78.65 75.25 32.00 0.00 0.00 0.00 0.00 0.00 121.50 55.10 7.12 4.75 0.00 0.00 0.00 0.00 0.00 0.00 51.30 13.20 11.10 5.40 0.00 0.00 0.00 0.00 0.00 0.00 299.80 279.50 40.95 33.90 9.25 14535.10 5584.42 2020.56 1905.64 883.28 0.00 0.00 0.00 0.00 0.00 1665.83 398.25 71.14 65.35 27.75 55.60 16.10 14.10 7.20 0.00 1219.74 318.30 48.20 37.12 19.25 1958.82 561.25 82.95 76.15 31.78 6129.48 1335.20 421.40 411.56 100.10 10535.60 3105.45 3046.30 3011.90 881.60 1482.40 327.60 67.45 62.71 21.52 45876.50 10190.80 4080.16 3916.40 1028.30 459.67 308.30 43.20 48.24 9.30 20555.60 3635.14 3597.10 3591.90 1081.70 186.83 412.23 82.28 83.35 21.75 1558.20 344.20 67.60 63.51 17.15 605.80 434.80 61.30 55.10 11.50 9230.00 2690.40 2845.40 1801.20 651.80 1867.30 414.50 83.20 81.45 21.40 1523.30 331.32 65.50 61.80 12.56 18430.42 3520.50 3288.60 3219.80 957.80 872.52 378.22 74.94 73.43 19.45 1082.00 389.50 64.45 59.31 18.08 14892.80 3162.77 3221.25 2696.55 866.75 53 54 ... have conducted a study on: ? ?EVALUATING EFFECTS OF ACACIA PLANTATION FOREST ON SURFACE RUNOFF AND EROSION IN LUONG SON HEADWATER OF VIETNAM? ?? From there, step by step quantify these relationships... map of study site: a) Location of Hoa Binh province on Viet Nam map; b) Location of Luong Son district on Hoa Binh map; c) Location of Truong Son commune on Luong Son map 3.2 Methods 3.2.1 Installing... characteristics of the study site in Luong Son, Hoa Binh To evaluate amount of surface runoff in Acacia mangium plantation and bare land To evaluate soil erosion characteristics in Acacia mangium plantation