Research on the processes of erosion and sedimentation, and their effects from human activities in onga river basin, kyushu, japan

RESEARCH ON THE PROCESSES OF
EROSION AND SEDIMENTATION, AND
THEIR EFFECTS FROM HUMAN
ACTIVITIES IN ONGA RIVER BASIN,
KYUSHU, JAPAN

Tran Anh Tu


RESEARCH ON THE PROCESSES OF EROSION AND
SEDIMENTATION, AND THEIR EFFECTS FROM
HUMAN ACTIVITIES IN ONGA RIVER BASIN,
KYUSHU, JAPAN

A Thesis Submitted
In Partial Fulfillment of the Requirements
For the Degree of
Doctor of Engineering

By
Tran Anh Tu

to the
DEPARTMENT OF CIVIL AND STRUCTURAL ENGINEERING
GRADUATE SCHOOL OF ENGINEERING
KYUSHU UNIVERSITY
Fukuoka, Japan
August, 2011


DEPARTMENT OF CIVIL AND STRUCTURAL ENGINEERING

GRADUATE SCHOOL OF ENGINEERING
KYUSHU UNIVERSITY
Fukuoka, Japan

CERTIFICATE

The undersigned hereby certify that they have read and
recommended to the Graduate School of Engineering for the acceptance
of this thesis entitled, ‘‘Research on the Processes of Erosion and
Sedimentation, and Their Effects from Human Activities in Onga
River Basin, Kyushu, Japan’’ by Tran Anh Tu in partial fulfillment of
the requirements for the degree of Doctor of Engineering.
Dated: August, 2011

Thesis Supervisor:
___________________________
Assoc. Prof. Yasuhiro MITANI, Dr. Eng.
Examining Committee:
___________________________
Prof. Noriyuki YASUFUKU, Dr. Eng.
___________________________
Prof. Yukihiro SHIMATANI, Dr. Eng.


ABSTRACT
The amount of sediment discharge in Japanese rivers is showing a very high
value in the world. This is considered to be affected not only by natural processes
such as landside and flooding under humid subtropical climates after the last glacial
period but also by human activities such as agriculture and mining. For management
and prediction of watershed sediment, it is important to know its long-term

sedimentation and relative factors. Thus, the thesis focuses on long-term natural
processes such as sedimentation and erosion through a case study in Onga River
Basin in northern Kyushu, Japan to clarify a sediment storage mechanism in the
Japanese catchment where many human activities since late Holocene were detected.
The contents of this dissertation are presented as follows
Chapter 1 introduces the overview of research background and objectives. It is
focused on the sedimentation and erosion for some thousands of years for the
drainage basin. For a long-term period, part of sediment lost due to discharge out of
the basin or to the sea. It is needed to concern on all processes in systematically such
as erosion, sedimentation and sediment delivery ration. This chapter also mentions to
overview of the comparison between sediment yield without and with human
activities.
Chapter 2 mentions the study area characteristics and methodology to calculate
the sediment erosion and deposition for long-term and short-term. Characteristics of
the basin focus on the geological units which were formed in Quaternary periods,
especially in Holocene. The sea level changes in Late Quaternary are considered in
relation to the marine sediment formed in this time such as Onga silt layer which
contained shell mounds and tephra. These records are the markers to identify the
relative age of the silt layer for analysis in chapter 3. The method is used to estimate
long-term erosion or denudation which is the function of mean altitude is described.
Long-term erosion calculation was also adopted in Japanese conditions as the
function of altitude of dispersion based on the data of sediments stored in the
reservoirs throughout Japan. For short-term erosion estimation, among some models,
RUSLE is proposed to use. The parameters of this model were also modified and
applied in some type of land-cover and landscape such as for farmlands and forests
in steep hill slope by many researches.
Chapter 3 explains in detail the processes to construct the palaeo-surfaces. At
iii

first, it is needed to define the boundaries between Pleistocene and Holocene, and
between Quaternary and Tertiary in the boreholes. The boundary between Quaternary
and Tertiary is defined easier than Pleistocene and Holocene if it is assumed that the
bedrock is the boundary. For Holocene and Pleistocene boundary, based on the
characteristics of geological units and sea level changes as mentioned in chapter 2,
the boundary is defined when upper most silt layer change to coarser grain size the
changes to the bottom. To support this viewpoint, some cross sections, shell mounds,
volcanic ash, geotechnical parameters and sediment comparisons are also used to
analyze in accompany with literatures. Beside boreholes, geological map and DEM
are used. Differences in resolution between DEM and geological map cause the
errors in some parts of the study area such as the Holocene geological boundaries
pass through the hill or mountain on DEM. The existed geological map in scale
1:200.000 needs to modify to adopt with DEM 50m resolution. The altitudes of
lower Holocene formations are interpolated to make continuous palaeo-surface.
Among some interpolated methods supported in GIS, Spline with tension is the
suitable method to do this work. It can give a ridge or valley, and the output is
exacted with the input in location of boreholes. Errors from interpolation are defined
by checking the thickness of sediment in comparison with maximum thickness in the
nearby boreholes. Errors are also modified based on the U-shape of the ancient
channels in lower reaches of the river.
Chapter 4 concentrates in the analysis of sediment storage and erosion in
long-term such as in Holocene and Quaternary. The volume storages are summed up
into the catchment 5, 6 7 and 8 and compares to its catchment area. The results show
a proportional correlation between sediment volume and its area. The annual average
deposition in Holocene was higher 30 times than that was in Late Pleistocene. From
the sediment storage, the average sedimentation rates in the basin are about 1.6
mm/year, and maximum is 2.0 mm/year, and average erosion rate varies from 0.114
to 0.163 mm/year. From the sediment budget result, the SDR in Holocene (8500 year
BP) of the Onga River varies from 0.0 to 0.1. A-values are higher in Tagawa than
orthers, while deposition in Iizuka region is higher. In Tagawa region the sediment

discharge ratio is higher than other regions. For examples, for catchments order 6,
minimum SDRs vary from 0.59 to 0.92, especially, these values can be up to 0.82
(Tagawa 1) and 0.92 (Tagawa 3). SDR high can cause some issues relate to the water
construction below the catchment as fast filling the dams.

iv


Chapter 5 focuses on the RUSLE model and compare it to long-term erosion
model (E) which is considered as the natural values. USLE/RUSLE model with
parameters such as R, K, LS and CP, adopted in Japanese condition, is applied to
calculate the ability of soil loss (A) in 1997. The product of R and LS is the
RULSE’s natural parameters which can be compared with the erosion from Ohmori’s
model. RLS consists of 48 % of total erosion from Ohmori’s model. It means the
sheet and rill erosion consists of 48% of total erosion in the catchment. On the other
hand, 52% of total soil loss is from other sources such as slope failures which may
deposit in hill slope. I Holocene, in system of total erosion, sediment storage in
channels, sediment storage in hill slope, surface erosion and sediment discharge out
of the Onga River basin, at least 48% of sediment is yielded from surface erosion can
be reach to the channel, and then (SDR) 10% of sediment in the channel can be
discharge out of the basin.. Beside natural processes, human impacts also are
classified by catchments. The impacts are clear in the catchment 6 and 7. In
catchment with stream order 5, there are also recognized the sediment caused by
human activities but in some area with slope angle over 13 degrees, the natural
sediment yield is dominant. A-values are near the E values because most of these
areas locate in near/in the forest. Sediment erosion (A) from agriculture and forestry
is about 69000±10% ton of soil loss per year higher than natural-base level.
Chapter 6 summarizes the content of the research.

v

ACKNOWLEDGEMENTS
With utmost sincerity and pleasure, I express my profound gratitude to my
mentor Associate Prof. Yasuhiro Mitani for his supervision, guidance, critical
comments. He gives a view of comprehensive and systematic research on the study
issues. His understanding and full supporting outside the study were very important
for daily life in Japan.
I would like to thank Prof. Noriyuki Yasufuku and Prof. Yukihiro Shimatani
who are the members of the Doctoral Examining Committee for their valuable
comments and suggestions to complete this dissertation.
I express my sincere thanks to Prof. Koichiro Watanabe for his recommendation
to this Course. I would like to thank Japan International Cooperation Agency (JICA)
and ASEAN University Network/ Southeast Asia Engineering Education
Development Network (AUN/SEED-Net) for supporting me the scholarship to
complete Special International Doctor Course. During the time I study and research
in Japan, JICA have not only thoughtfully cared me and my family in daily life but
also encouraged me in research.
My deeply thank go to Assistant Prof. Hiro Ikemi for the patience and
continuous support through all the research work. It is also thanks to other members
in the Environmental Geo-technology lab, who help me enthusiastically for daily
communications in Japanese.
I would also like to thank the Board of Rector of Ho Chi Minh University of
Technology who gave me a permission to attend this Course, and collogues who
have supported and shared my works during the time my research has been doing in
Japan.
I cannot find words to express my gratitude to my parents for their love and
support. To my wife, Thuy Duong, I extend my loved warmest and deepest thanks for
her great patience and endless support. Through the early morning, long evenings,
and overnight lab working, she has stood by me and gives helpful encouragement.

My lovely two children, Tu Han and Nhat Nam, are the greatest encouragement.

vi


TABLE OF CONTENTS
CERTIFICATE
ABSTRACT
ACKNOWLEDGEMENTS
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
Chapter 1 INTRODUCTION
1.1

Impacts of human activities on soil erosion and sedimentation

1

1.2

Long-term sedimentation, erosion and sediment discharge ratio

2

1.3

Objectives

4

1.4

Scope

4

1.5

Thesis layout

4

References
Chapter 2 STUDY AREA AND METHODOLOGY TO ESTIMATE EROSION
AND SEDIMENTATION
2.1

Study area

8

2.1.1 Geology and landforms

8

2.1.2 Sea level change
2.2

2.3

12

Method to estimate sedimentation and erosion

13

2.2.1 Method to estimate sedimentation

13

2.2.2 Method to estimate erosion

14

Erosion models

16

2.3.1 Universal Soil Loss Equation

16

2.3.2 Water Erosion Prediction Project Model

23

2.4

Unit conversion

24

2.5

Conclusions

25

References
Chapter 3 RECONSTRUCTION THE PALAEO-SURFACE BY USING GIS
3.1

Data

33

3.1.1 Digital elevation model

33

3.1.2 Geology map

34

3.1.3 Boreholes

35
vii

3.2

Reconstruction the palaeo-surfaces

35

3.2.1 Definition the geological boundaries

35

3.2.2 Preparation data in GIS

42

3.2.3 Interpolation methods

43

3.2.4 Processes to reconstruct the palaeo-surfaces

48

3.2.5 Errors

49

3.3

Checking the result from the field work

51

3.4

Conclusion

54

References
Chapter 4 SEDIMENT STORAGE AND EROSION IN QUATERNARY
4.1

Sediment storage

56

4.1.1 Sediment storage in Quaternary

56

4.1.2 Sediment storage in Holocene

58

4.2

Erosion

63

4.2.1 Erosion rate from sediment storage

63

4.2.2 Estimating erosion from long-term erosion model

63

4.3

Sediment budget

66

4.3.1 Sediment budget concepts

66

4.3.2 Long-term discharge

67

4.4

Conclusions

69

References

Chapter

5

SOIL LOSS

FROM

AGRICULTURE

AND

FORESTRY

ACTIVITIES
5.1

RUSLE model

73

5.1.1 Rainfall and runoff erosivity factor

73

5.1.2 Soil erodibility factor

76

5.1.3 Slope length factor

80

5.1.4 Slope steepness factor

82

5.1.5 Cover and practice factors

84

5.2

Erosion in forest areas

86

5.3

Soil loss from agriculture and forestry activities

89

5.4

Conclusions

93

References

Chapter 6 CONCLUSIONS

97

viii


LIST OF FIGURES
Figure 2-1 Onga River basin and its sub-catchments

9

Figure 2-2 Geological map of Onga River basin

10

Figure 2-3 Cross section along Onga River

11

Figure 2-4 Relative sea level change in the Japan from stage 5e to present

12

Figure 2-5 Example calculation of thickness from two DEMs in GIS

14

Figure 2-6 Schematic of a small watershed which the WEPP erosion model

23

Figure 2-7 Units conversion graph

25

Figure 3-1 DEM 50m displaces the Onga River basin

33

Figure 3-2 Quaternary geological units in Onga River basin

34

Figure 3-3 Distribution of boreholes

35

Figure 3-4 Flow chart to extract the geological boundary

36

Figure 3-5 Statistic of number of points change elevation from hill slope to gentle
area.

37

Figure 3-6 Q-T boundary is extracted from DEM

38

Figure 3-7 Modified Holocene boundary

38

Figure 3-8 Location of cross section A-A’

40

Figure 3-9 Cross section of Quaternary sediment in Onga town (A-A’)

40

Figure 3-10 Typical sediment grain sizes in the study area

41

Figure 3-11 Attributes of boreholes within Holocene boundary

42

Figure 3-12 Flow chart is used to define the Stream network, watershed and stream
order

43

Figure 3-13 Surface is interpolated by Spline with tension method

46

Figure 3-14 Surface is interpolated by IDW method

47

Figure 3-15 Surface is interpolated by Kriging method

47

Figure 3-16 Scheme to extract the sediment volume using GIS

48

Figure 3-17 Adjust negative number by linear interpolation along the channel

50

Figure 3-18 Detecting negative errors

50

Figure 3-19 Modifying the errors

51

Figure 3-20 Locations are checked the sediment thickness in stream order 5

52

Figure 3-21 Bottom exposes bedrock and gravels

53

Figure 3-22 Incision to bedrock and sediment cover

53

Figure 4-1 Quaternary sediments thickness

57

Figure 4-2 Relationship between catchment area and sediment storage in Quaternary
ix


58
Figure 4-3 Holocene sediment thickness

59

Figure 4-4 Relationship between catchment area and sediment storage in Holocene
60
Figure 4-5 Sediment accumulation rate in Holocene by catchment 6

60

Figure 4-6 Sediment buildup/time diagram

61

Figure 4-7 Denudation from mean altitude

64

Figure 4-8 Denudation from standard deviation of altitude

65

Figure 4-9 Sediment budget in the drainage basin

67

Figure 5-1 Example of calculating the EI30 for one rain storm

74

Figure 5-2 Relation between EI30 and I60 max in the study area

75

Figure 5-3 Distribution of R-value

76

Figure 5-4 Distribution of soil types in the Onga River basin.

77

Figure 5-5 Diagram defines the soil structure in Japan

78

Figure 5-6 Distribution of K-value

80

Figure 5-7 Distribution of L- value

81

Figure 5-8 Distribution of Slope value

82

Figure 5-9 Distribution of S-value.

83

Figure 5-10 Rice field in steep slope with practice management

84

Figure 5-11 Distribution of CP factor

85

Figure 5-12 Soil loss map in Onga river basin

86

Figure 5-13 Soil loss map in forest area

87

Figure 5-14 Aforestvs Eforest by catchment with stream order 5-7

88

*

Figure 5-15 Aforest vs E

forest

by catchment with stream order 5-7

88

Figure 5-16 Specific yield-A by catchment 6

90

Figure 5-17 Specific yield-E by catchment 6

90

*

Figure 5-18 Relation between A-E by catchment 5-7

91

Figure 5-19 Specific yield - A by catchment 5

92

Figure 5-20 Sediment loss - E by catchment 5

92

*

Figure 5-21 Relation between A-E by catchment 5

x

93


LIST OF TABLES
Table 2-1 LS factors in USLE and RUSLE

20

Table 4-1 Sediment erosion in Onga River Basin in Holocene (8500 years BP)

65

Table 4-2 Scenarios of SDR in Onga River Basin in Holocene (8500 years BP)

68

Table 4-3 SDR in Onga River Basin in Holocene (8500 years BP)

68

Table 5-1 R-value in each year from 1990 to 2010

74

Table 5-2 Permeability code for each soil type

78

Table 5-3 K-value for each soil type

79

Table 5-4 CP-factor from some study cases in Japan

84

Table 5-5 Erosion of each catchment in forest and agriculture areas

89

Table 5-6 Evaluating the errors for catchment 5

91

xi

CHAPTER 1

INTRODUCTION

1.1

Impacts of human activities on soil erosion and sedimentation
In globel scale, Meybeck & Vorosmarty (2005) concluded that the total river

basin area directly affected by human activities is of the same order of magnitude (>
40 Mkm2) as the total area affected over the last 18000 years. More than 80% of river
fluxes to oceans and to internal regions have been generated in less than 30% of the
continents in natural conditions. Human impacts are increasing this contrast since
major new sources of material are very concentrated in intensive agriculture areas,
mining and industrial districts, and megacities. Over the last 100 years, fluvial
systems have been largely impacted and modified by human activities and
anthropogenic controls, which are now to equaling the natural ones.
In small scale, a research in former Soviet Union showed a clear trend of
increasing suspended sediment yield during 1949-1985, and sediment loads have
increased by about 1.4 times since that time. These increased sediment loads reflect
the expansion of cultivation within the drainage basin (Bobrovitskaya, cf. Walling,
1999). Dedkov and Mozzherin (1984) (cf. Walling, 1999) analysis the covers
occupied by forest and cultivate to derive an approximate the magnitude of the
increasing sediment yield related to land disturbance by human activities. Förster &
Wunderlich (2009) estimated the sediment stores in the catchment from the thickness
of colluvial layers and its area for each soil types, and sediment eroded from the
remained thickness of erosive layer. They concluded that the sediment discharge ratio
in Holocene varies from 64.8% to 83.2% for the 301 km2 catchment, but land-use

history and human impact can’t be made. Macaire et al. (1997) calculated the
sediment budget for the Lac Chambon watershed in France for the last 15500 years.
They showed that a threefold increase in erosion over the last 1400 years due to the

1


impact of human-induced deforestation.
But, it doesn’t clear that the current erosion and deposition is over or under
‘natural value’ due to lack of long-term record of sediment transport for river in most
area of the world (Walling, 1999). Oguchi (1997) and Oguchi et al. (2001) also
mention that there is less known about sediment budget on timescale of more than
1000 years in Japan, and most of researches concentrate in the central and north
Japan.
1.2

Long-term sedimentation, erosion and sediment discharge ratio
Natural processes such as erosion, mass movement and water cycle produce

and transport sediment from one place to another as sedimentation in natural
conditions. Within a catchment, it is needed to clear the relation between erosion,
deposition and discharge to manage the catchment.
When human settles and disturbs the land surface without methods to protect
the soil erosion, it tends to accelerate the erosion (Syvitski et al. 2005). Currently, it
is possible to measure the erosion and monitor the sediment transportation within or
discharge out of a catchment, but it is impossible to measure directly for the past
time. Thus, for long-time period, sediment storage in some type of accommodations
such as reservoirs is a key which helps to know the average accumulation rate, and
then, know the erosion rate of the drainage basin upper that reservoir (Einsele and
Hinderer, 1998). This erosion values in a give time, which specific for a given

environment, can be compared with the values of other time span to know how
different the environment is. For examples, the Pleistocene and Holocene mechanical
denudation of entire Alps derived from the fillings of perialpine lakes, demonstrated
that the average denudation rate since the last glacial maximum (17 ka B.P.) was
about 5 times higher than the Holocene rate. In the Black Sea area, during the last
deglaciation (15 to 8 ka BP) the sediment yield of the rivers was two to four times
greater than at present (Einsele, 2000). Another example, in Japan, Ohmori (2003)
used the sediment storage in the reservoirs to establish the denudation model.

2


It is possible to estimate the long-term mechanical erosion rate from studies
in the landscape of particular area such as landform reconstruction. This rate can be
also grained from denudation-sedimentation-accumulation system of some size (lake,
larger basin) when the average accumulation rate cane be determined and the ratio of
the areas of sediment source and basin are known (Einsele, 2000). For instant,
Oguchi (1997) reconstructed five alluvial fans in Japan for Late-glacial period. The
sediment storage in fans was calculated from stratigraphical data. Sediment yield
from each source area (fans) was estimated based on digital elevation data and the
morphometric analyses of geomorphological maps, in which all hillslopes and fluvial
surfaces were classified. He estimated the supply source concluded that the ratio of
sediment storage in a fan to sediment supply is between 0.3 and 0.8. The maximum
storage ratio of 0.8 reflects the ratio of washload to total load for Japanese
mountainous rivers. This ratio has the same meaning with sediment delivery ratio
when the drainage basin is considered.
Sediment delivery ratio is the ratio of sediment delivered at the catchment
outlet to gross erosion within the basin. The magnitude of the delivery ratio for
particular basin will be influenced by a wide range of geomorphologic and
environmental factors including the nature, extent and location of the sediment

sources, relief and slope characteristic, the drainage pattern and channel conditions,
vegetation cover, land use and soil structure (Walling, 1983). Understanding the
sediment delivery process at the drainage basin scale remains a challenge in erosion
and sedimentation research. In the absence of reliable spatially distributed process
based models for the prediction of sediment transport at the drainage basin scale,
area-specific sediment yield (SSY; tkm-2 y-1) is often assumed to decrease with
increasing drainage basin area (A). However, over the last two decades several
studies reported a positive or nonlinear relation between A and SSY (de Vente et al.,
2007).
In this research, an interaction between sediment erosion and deposition in
the drainage basin is considered, in order to estimate the sediment delivery ratio for

3


the longer time span integrated to GIS and to clarify the human activities impact on
erosions as disturbance the land-cover. The Onga River basin locates in the south of
Japan on Kyushu Island is chosen as study area.
1.3

Objectives
For management and prediction of watershed sediment, it is important to

know its long-term sedimentation and relative factors. The objective of this research
are the development a systematic method integrated with GIS to estimate the natural
sedimentation and its relation to erosion through a case study in Onga River Basin in
northern Kyushu, Japan to clarify a sediment storage mechanism in the Japanese
catchment where many human activities since late Holocene were detected. There are
some objectives need to be done:
+

Reconstructing the Quaternary ground surface and Holocene ground surface
to estimate the sediment storage;

+

Estimating the natural sedimentation, erosion and sediment discharge of
watershed and its sub-watershed for watershed management of sediment

+

Separating the natural erosion and comparing with total erosion accelerated
by human to clarify the sediment yield from human activities;

1.4

Scope
The scope of this research is determining the relation between long-term

sedimentation, erosion and discharge and estimating the impact of human activities
on the land cover in the Onga river basin for watershed management.
1.5

Thesis layout
The thesis structure comprises a method for estimating the sediment volume

in the basin from the borehole data, geological map and DEM using GIS. It also
includes the sediment budget calculation for the drainage basin, and showing the
relation between sheet and rill erosion from RUSLE model and total erosion
estimated from denudation model. An evaluation of erosion produces from

agriculture and forestry activities is clarified. The thesis includes six (6) chapters and

4


is briefly described as:
Chapter One provides the overview of the researches on long-term and
short-term erosion and sedimentation, and on relation to pre-human impact in
comparison with human impact periods.
Chapter Two introduces the study area and methods to estimate the sediment
storage, erosion for long-term and short-term.
Chapter Three describes in detail how to make the palaeo-surfaces for
Holocene and Quaternary. The supplement method is applied to extract the Holocene
geological boundary from DEM for modifying the geological boundary. Borehole
analysis and evaluations have done to define the lower Holocene sediment layer and
lower Quaternary sediment layer. Among interpolation methods, the Spline method is
applied to give the suitable DEM of palaeo-surfaces.
Chapter Four calculates the accumulation rates for Holocene, Quaternary
and Late Pleistocene, erosion rate from the sediment storage and total erosion in the
basin. A relationship between sediment storage in each catchment and its area is
established. The sediment budget is applied to evaluate amount of sediment storage
in the hill slope, discharge to the channel and transport in and out of the
sub-catchment and whole catchment.
Chapter Five analysis the sheet and rill erosion using RUSLE and relation to
erosion caused by disturbance of human on the land cover in forestry and agriculture
activities. A relationship between parameters of RUSLE and the total erosion in Onga
River basin and its sub-catchments is proposed.
Chapter Six presents the conclusions of this study.

5

References

de By, R.A et al. (2001), Principles of Geographic Information Systems, ITC, The
Netherlands. ISBN:90-6164-200-0.
de Vente, J., Poesen, J., Arabkhedri, M. and Verstraeten, G. (2007), The sediment
delivery problem revisited, Progress in Physical Geography, Vol.31, p.155.
Einsele, G., (2000), Sedimentary basins: evolution, facies, and sediment budget,
Springer, 2rd edition, p.454, ISBN: 3-540-66193-x.
Einsele,

G.

and

Hinderer,

M.

(1998),

Quantifying

denudation

and

sediment-accumulation systems (open and closed lakes): basic concepts and first
results, Palaeogeography, Palaeoclimatology, Palaeoecology, Vol.140, pp.7-21.

Förster H., and Wunderlich J. (2009), Holocene sediment budgets for upland
catchments: The problem of soilscape model and data availability, Catena, Vol.77,
pp.143-149.
Hoffmann T. et al. (2007), Holocene floodplain sediment storage and hill slop
erosion within the Rhine catchment, The Holocene, Vol.17, No.1, pp.105-118.
Macaire J.J., et al. (1997), Sediment Yield during Late Glacial and Holocene Periods
in the Lac Chambon Watershed, Massif Central, France, Earth Surface Processes
and Landforms, Vol.22, pp.473-489.
Meybeck M. and Vorosmarty C. (2005), Fluvial filtering of land-to-ocean fluxes:
From natural Holocene variations to Anthropocene, C. R. Geosci., Vol.337,
pp.107-123.
Oguchi, T. et al. (2001), Fluvial geomorphology and paleo-hydrology in Japan,
Geomorphology Journal, Elsevier, Vol.39, pp.3-19.
Oguchi, T. (1997), Late Quaternary sediment budget in alluvialfan–source-basin
systems in Japan, Journal of Quaternary Science, Vol.12, No.5, pp.381-390.
Oguchi T. (1996), Late Quaternary hill-slope erosion rates in Japanese mountains
estimated from landform classification and morphometry, Zeitschrift fur
Geomorphologie Neue Folge Supplementary Band, pp.169-181.
Ohmori H. (2003), The paradox of Equivalence of the Davisian End-Peneplain and
Peckian primary peneplain, Concepts and Modelling in Geomorphology:
International perspective, pp.3-32.
Seidel J. and Mäckel R. (2007), Holocene sediment budgets in two river catchments

6


in the Southern Upper Rhine Valley, Germany, Geomorphology, Vol.92,
pp.198-207.
Syvitski J.P.M., et al. (2005), Impact of Humans on the Flux of Terrestrial Sediment
to the Global Coastal Ocean, Science, Vol.38, pp.376-380.

Wakamatsu, K., Matsuoka, M. and Hasegawa, K. (2006), GIS-based nationwide
hazard zoning using the Japan engineering geomorphologic classification map,
Proceedings of the 8th U.S. National Conference on Earthquake Engineering,
San Francisco, California, USA, Paper No.849.
Walling D. E. (1999), Linking land use, erosion and sediment yields in river basins,
Hydrobiologia, Vol.410, pp. 223–240.
Walling D. E. and Bradley S. B. (1988), The use of caesium-137 measurements to
investigate sediment delivery from cultivated areas in Devon, UK. Sediment
Budgets (Proceedings of the Porto Alegre Symposium), IAHS Publ. no.174.
Walling, D.E. (1983), The sediment delivery problem, Journal of Hydrology, Vol.65,
pp.209-237.

7


CHAPTER 2

STUDY AREA AND METHODOLOGY TO ESTIMATE
EROSION AND SEDIMENTATION
2.1. Study area
Onga River located in the northern Kyushu, Japan (Figure 2-1) its drainage
basin covers 1036 km2. In early-mid Holocene, the lower reach of this river acts as a
lagoon in which sedimentation occurred widely to form the plain named Nogata, and
some small plains are in the upper reaches. Currently, the precipitation in this area is
400 mm higher than other area in Japan, and causes many large floods (MLIT) which
are though to be one of major factors cause erosion and the main supply sources of
sediment, for example, the thickness of Holocene sediment in Nogata plain is up to
near 20 m (Shimoyama, 2002). Research on sedimentation and erosion of whole
drainage basin will contribute not only for geomorphology process studies but also
for current management of the river basin and understanding the human activities

impacts.Figure 2-1 shows the location of the Onga River basin in Fukuoka prefecture
and its sub-catchments on the Quaternary geological units. The Nogata plain
distributes from the river estuary though Onga town and Nakama city to Nogata city.
Other cities include Miyawaka, Iizuka and Tagawa. In this research, the river basin is
divided into 2 sub-catchments 7 and 6 sub-catchment 6. More information is
mentioned in the following sections.
2.1.1. Geology and landforms
In the estuary area, Quaternary deposits include most of the late Pleistocene
sediments belong to Wakamatsu formation in the eastern part. This formation
includes two members Shozugahama mud and Iwaya sand and gravel members. The
Shuzugahama mud (2m thick) is exposed along the coast composed of silt with small
amount of pebble and sand (Figure 2-3). The Iwaya sand and gravel member
(15-20m) made up mainly of pebble gavel and sand with silt (Ozaki et al., 1993).

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Figure 2-1 Onga River basin and its sub-catchments.

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Figure 2-2 Geological map of Onga River basin (modified from GSJ, 2005).

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Figure 2-3 Cross section along Onga River (Shimoyama, 2002)
a: Human fill up;, b: Sanrimatsubara sand layer, c: Koyanose layer, d: Onga silt layer, e:
Iwaya sand layer, f: Mid-terrace gravel, g: Heisan mud layer, h:Ancient terrace, and i:

Tertiary rock. (a∼d is Holocene, e∼h is Pleistocene)

In Nogata plain, there doesn’t expose any Pleistocene sediment on the surface,
except the area around the mountain belong to upper reaches. In this area there are
many tephra such as Kikai-Akahoya (K-ah), aged 6.3 ka years BP, occurs in marine
deposits (Machida, 1991); AT (AIRA – Tn tephra) which is dated around 21 – 22 ka
years BP; and Aso-4 tephra (70 ka years BP). Machida and Arai (1983) shown that
the K-ah thickness of volcanic ash is about less than 20 cm, AT ash thickness is 50
cm (Nakada & Lambeck, 1998). Otherwise, there are a lot of tephra of Aso-4 flows
in the upper reaches of the study area. The Aso-4 tephra interrupted when the sea
level drop between Obaradai and Misaki transgressions (Machida, 1991) and AT
formed when the sea level was lowest. The pre-Quaternary rocks include Paleogene
sedimentation, Cretaceous, Permian, and Carboniferous rocks, which consist of about
70% of the basin area. The K-ah ash occurs in the marine sediment, aged 6.3 ka year,
which is the geology record layer used to compare with other layers in the boreholes
in later analysis.

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2.1.2. Sea level change
Sea-level changes in Late Pleistocene-Holocene play a very important role to
define the ancient boundary surfaces as Holocene surface and Quaternary surface.
During the Last interglacial transgression or Shimo-sueyoshi transgression, the sea
level rose at peak in 130-120 ka years BP, near present sea level in the northern of
Kyushu (Kaizuka 1980). Shimoyama et al. (1999) explained that this ancient sea
level (marine top) in Onga, north-west of Kyushu, was -7.9 ± 1.5 m. In the Last
Glacial age, 20 -15 ka years BP, the sea level drop -140 to -120 m and reached the
lowest peak at around 18 ka years BP in comparison with today’s one (Kaizuka 1980
& Yasuda 1990) as shown in Figure 2-4. In Late-glacial, 13 ka – 10 ka years BP, the

sea level increased to -10m lower than that of today. After that the sea level withdrew
to -40 m around 11 ka to 10 ka year BP to form the coarse grain size along the
seashore (Umitsu, 1991). Example, 10 m thickness pebble in Hakata bay (Karakida
et al., 1994), which underlies by fine grain size; and about 5 meter sand without
shells in Onga River mouth. The sea-level rose to maximum around 6000 year BP
(Umitsu, 1991) or Jomon transgression.

Figure 2-4 Relative sea level change in the Japan (Machida, 2002) from stage 5e to present.
Ages in ka (1000 year). Abbreviations of volcanoes in Kyushu area: K, Kikai; At, Ata; A,
Aira; Kk, Kakuto and Kirishima; Kj, kuju; Ss, Shishimuta; L, low; H, high; MIS, Marine
Isotope Stage.

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In the late Jomon period, around 6000 BP, the sea level higher than present 2 to
3 meter (Karakida et al., 1994) to maximum +4.0m in north of Kyushu Island
(Pirazzoli, 1991), that made Onga village area become the lagoon and caused the
major deposition of the Hakata member (Karakida et al. 1994.). A research in Fukue,
an island located about 200 km to the southwest of Onga River, showed that the
mean sea level is above -11.4 m at about 7.900 yr BP, and from 8000 yr BP to 5000
yr BP, mean sea level rose with an average speed of 0.40 cm/yr. Then, minor
sea-level dropped, have been recognized in 5000-4000 BP and 3000-2000 BP
(Umitsu, 1991).
2.2. Method to estimate sedimentation and erosion
2.2.1. Method to estimate sedimentation
Sedimentation is a process of deposition of a solid material from a state of
suspension or solution in a fluid (usually air or water). Broadly defined it also
includes deposits from glacial ice and those materials collected under the impetus of
gravity alone, as in talus deposits, or accumulations of rock debris at the base of

cliffs. Estuaries or plains are filled with sediment brought in by tributaries streams,
but sedimentation in estuaries is also contributed by marine movement.
Sediments can accumulate in hill-slopes, alluvial fans, river channel, flood
plain, deltas and lakes bed deposits (Charlton, 2008). Colluvium is the type of
deposits on or at the base of slope. The sediment is discharged to the channel is call
alluvial. Terraces are the storage types formed from colluvial or fluvial in the past,
considered as fans. For examples, many authors calculate the volume of sediment in
fans and estimate the erosion rate and deposition in Quaternary (e.g. Oguchi, 1997;
Oguchi et al., 2001; de Moor and Verstraeten, 2008; Lewin et al, 2005; Harvey et al.,
1999). Sediment stored dominantly in the flood plains, and some of it distributes as
bottom layers.
In case of enough borehole data, the sediment volume can be calculated from
two DEMs in GIS, one is the upper DEM (uDEM) and another is the lower DEM
(lDEM). The results from minus two DEMs, respectively, give the prism thickness

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