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A CASE STUDY ON SOIL EROSION RATE AND SEDIMENT YIELD OF A PROPOSED INFRASTRUCTURAL
DEVELOPMENT PROJECT
Ting Huong Siong
Master of Environmental Science (Land Use and Water Resource Management)
2013
Pusat Khidmat Maklumat Akademii: UNIVERSITI MALAYSIA SARAWAK
A CASE STUDY ON SOIL EROSION RÄTE AND SEDIMENT YIELD OF A PROPOSED INFRASTRUCTURAL
DEVELOPMENT PROJECT
TING HUONG SIONG
A thesis submitted in fulfilment of the requirements for the degree of
Master of Environmental Science
Faculty of Resource Science and Technology Universiti Malaysia Sarawak
2013
ACKNOWLEDGEMENT
I would like to express my sincerest and deepest appreciation to my supervisor, Prof.
Ir Dr. Law Puong Ling for his support and encouragement. His patience and generosity are
highly appreciated.
I would like to thank my former SLUSE coordinators, Dr. Lim Po Teen, Dr. Effendi
and current SLUSE coordinator, Dr. Tay Meng Guan for their encouragement and patience to
provide guidance and support. Last but not least, I would like to thank my wife, Tang Jock
Kie, and my family for their continuous support and during the course of this research.
1
ABSTRACT
Soil Erosion is a process of a portion of the soil profile or soil surface detachment to
the ambient environment. There are four major factors that affect erosion potential: soil
characteristics, vegetative cover, topography and climate. Predictions of soil erosion rate and
sediment yield during different construction stages were carried out at the proposed Project
site with respect to site clearing, earthworks/ sand filling and infrastructure works at light
industrial area, Kapit Division. The RUSLE and MUSLE were used to estimate the potential
erosion rate and the sediment yield, respectively during (i) pre-construction stage; (ii)
construction stage; and (iii) post-construction stage of the study area. During construction
stage, the disturbed soil surface would result from the site clearing, earthwork activities, and
slope grading would produce highest erosion rates and sediment yields as compared to other
construction stages. Significant amount of soil sediments would be washed and eroded
directly to the nearby watercourse, i. e., Batang Rajang and could result in deposition of the
sediments at the river bed and lead to degradation of the aquatic ecosystem. Erosion control
measures are recommended to minimize the potential erosion rates and sedimentation. A
comparison between "with BMP" and "without BMP" were carried out, and it was found that
a reduction of more than 65% for both erosion rate and sediment yield with the
implementation of BMPs. However, sediment control practices such as silt trap, silt fence and
check dam would minimize the adverse effects of erosion rates to a certain extent.
Keywords: Soil Erosion, Revised Universal Soil Loss Equation (RUSLE), Modified
Universal Soil Loss Equation (MUSLE), Best Management Practices (BMP)
ii
ABSTRAK
Hakisan Tanah adalah satu sebahagian proses daripada profil tanah atau permukaan tanah
detasmen untuk persekitaran ambien. Terdapat empat faktor utama mempengaruhi potensi
hakisan tanah: ciri-ciri tanah, perlindungan tumbuhan, topografi dan iklim. Ramalan untuk
kadar hakisan tanah dan hasil enapan dalam peringkat pembinaan yang berbeza telah
dijalankan di cadangan pembersihan tapak, kerja-kerja tanah / pengisian pasir dan kerja-kerja
infrastruktur di kawasan perindustrian ringan, Daerah Kapit. RUSLE dan MUSLE telah
digunakan untuk menganggar kadar hakisan yang berpotensi dan basil pengenapan masing-
masing di seluruh i) peringkat pra-pembinaan ii) peringkat pembinaan; dan iii) peringkat
operasi di kawasan kajian. Semasa pembinaan, tanah terganggu dan terdedah yang
disebabkan oleh kerja-kerja pembersihan tapak, kerja tanah, dan penggredan cerun telah
menghasilkan kadar hakisan yang tertinggi dan penghasilan sedimen jika dibandingkan
dengan peringkat pembinaan yang lain. Jumlah besar tanah yang didedahkan akan dibasuh
dan dihakiskan terus ke arah saluran air yang berdekatan, iaitu Batang Rajang, dan akan
mengakibatkan pemendapan sedimen di dalam air sungai, pencemaran dan degradasi alam
sekitar terutamanya ekosistem akuatik. Oleh itu, langkah-langkah kawalan hakisan telah
dicadangkan untuk mengurangkan kadar hakisan yang berpotensi dan deposisi pemendapan.
Satu perbandingan antara BMP dan tanpa BMP telah dijalankan dan menunjukkan dengan
jelasnya pengurangan melebihi 65 peratus untuk kedua-dua kadar hakisan dan hasil
pengenapan dengan pelaksanaan BMPs. Amalan kawalan sedimen seperti perangkap
kelodak, pagar kelodak dan empangan semakan akan mengurangkan kesan-kesan buruk
daripada hakisan tanah kepada persekitaran ambien. Untuk mencapai keberkesanan optimum
BMPs di tapak pembinaan, semua langkah-langkah kawalan dinasihatkan supaya diperiksa
dan diselenggarakan dengan tetap masa.
iii
Kata-kata kunci: Hakisan Tanah, Semakan Tanah Universal Kehilangan Persamaan (RUSLE),
Ubahsuai Tanah Universal Kehilangan Persamaan (RUSLE), Amalan Pengurusan Terbaik (BMP)
iv
Pusat Khidmat Maklumat Akademie. UNIVERSM MALAYSIA SARAWAK
TABLE OF CONTENTS
Acknowledgement
Abstract
Table of Contents
List of Appendices
List of Tables
List of Figures
Chapter 1- Introduction
1.1 Introduction
1.2 Problem Statement
1.3 Objectives of Study
1.4 Scope of Study
1.4.1 The Study Area
1.4.2 Topography
1.4.3 Geology and Soil
1.4.4 General Climate
Chapter 2- Literature Review
i 11
V VI
vii
viii
1
3
6
7
7
9
9
9
2.1 Soil Erosion 12
2.1.1 Types of Soil Erosion 13
2.2 Soil Erosion Modeling 17
2.2.1 Universal Soil Loss Equation (USLE) 18
2.2.2 Revised Universal Soil Loss Equation (RUSLE) 19
2.2.3 Modified Universal Soil Loss Equation (MUSLE) 23
Chapter 3- Methodology
3.1 Identification of Study Area 27
3.2 Scope of Study 28
3.3 Prediction of Soil Erosion Rates and Sediment Yield 28
3.3.1 Revised Universal Soil Loss Equation (RUSLE) 28
3.3.1.1 Rainfall Erosivity, R 29
3.3.1.2 Soil Erodibility Factor, K 30
3.3.1.3 Slope Length and Slope Steepness Factor, LS 32
3.3.1.4 Cover Management Factor, C 37
3.3.1.5 Erosion Control Practice Factor, P 38
V
3.3.2 Modified Universal Soil Loss Equation
3.3.2.1 MUSLE
3.3.2.2. Peak Flow
3.3.2.3 Volume of Runoff
3.4 Best Management Practices (BMP) for Erosion Control
3.4.1 Silt Trap / Sediment Trap
3.4.2 Silt Fence
3.4.3 Check Dam
Chapter 4- Results and Discussion
4.1 Introduction
4.2 Prediction of Erosion Rate
4.2.1 Mean of Rainfall Intensity and Rainfall Factor, R
4.2.2 Soil Erodibility, K
4.2.3 Slope Length and Slope Steepness Factor, LS
4.2.4 Cover Management Factor, C
4.2.5 Erosion Control Practice Factor, P
4.2.6 Estimation of Peak Discharge, Qp
4.2.7 Volume of Runoff, V
4.2.8 Prediction of Erosion Rates and Sediment Yields
4.3 Summary
Chapter 5- Conclusion
References
List of Appendices
39
39
40
42
46
47
48
48
50
50
51
51
54
56
57
58
65
67
70
71
73
Appendix A Meteorological Data A-I
Appendix B Soil Investigation Data A-4
Particle Size Distribution
Hand Auger Log
Organic Matter Content
Appendix C Construction Drawing A-5
Slope Protection Works
vi
List of Tables
3.1 Cover Management Factors, C (Construction Site) 37
3.2 Erosion Control Practice Factor, P 39
3.3 Runoff Coefficients (Rational Equation) 41
3.4 Runoff Curve Numbers (Undeveloped Land) 43
3.5 Hydrology Soil Groups 45 Estimated Relative Erosion Sediment Control Effectiveness for Different 3.6 Best Management Practices (BMP) 46
4.1 Particles Size Analyses for Samples Collected from 6 Boreholes (BH) 53
4.2 Estimated Soil Erodibility, K (Nomograph) 54
4.3 LS Factors for Each Slope during Pre-Construction Stage 55
4.4 LS Factors for Each Slope during Construction / Operation Stages 56
4.5 Cover Management Factors, C 57
4.6 Erosion Control Practices Factor, P 58
4.7 Runoff Coefficient 59
4.8 Runoff Peak Flow, Qp 64
4.9 Curve Number of Runoff 65
4.10 Runoff Coefficient 66
4.11 Summary of Erosion Rates (without BMP) in Different Construction 68 Stages
4.12 Summary of Sediment Yield (without BMP) in Different Construction 68 Stages
4.13 Summary of Erosion Rates (with BMP) in Different Construction Stages 69
4.14 Summary of Sediment Yield (with BMP) in Different Construction 69 Stages
vii
List of Figures
1.1 Locality Plan of Study Area
1.2 Site Plan of Study Area
1.3 Topography of Study
2.1 Sheet Erosion
2.2 Rill Erosion
2.3 Gully Erosion
2.4 Types of Erosion
2.5 The Wind Erosion to an Open Field
3.1
3.2
3.3
3.4
3.5
3.6
4.1
4.2
4.3
Soil Erodibility Nomograph
Details of Slope Elevation, Length and Steepness
Design Platform Level
Segment Area and Slope Lengths during Pre-Construction Stage
Slope Lengths During Construction and Post-Construction Stage
Typical Details of Check Dam Analysis on the Runoff Flow Pattern on Existing Topography During Pre-construction Stage
8
8
11
14
14
15
16
17
31
33
34
35
36
49 60
Analysis on the Runoff Flow Pattern During Construction Stage 61 Catchment Areas on Existing Topography During Pre-construction 62 Stage
4.4 Catchment Areas During Construction Stage 63
viii
CHAPTER 1
INTRODUCTION'
1.1 Introduction
Soil Erosion is a process whereby a portion of the soil profile or soil surface is
detached to the ambient environment. It can be occurred by the natural physical forces
of water and wind or disturbances of human activities on the land. Rapid growth in
industrial production, urban development, mono-cropping and cultivation to support
the demand of rapid-growth of population and world economic has led to the
acquirement of more land especially the forest area. Deforestation and land clearing
are the major attributions to industrial development.
The forest, which serves as temporary water storage, biological diversity
conservation, production of ecosystem goods, carbon storage, and soil protection has
been rapidly destroyed that leading to significant soil erosion. The removal of soil-
trapping trees during the process of deforestation near waterways causes the upper
layer of soil more vulnerable to the water and wind erosion. Sediments and soil
carried by the runoff after rainfall from cleared lands can damage the river, lake and
marine and destroy the ecosystems. Several effects may caused by excessive erosion
such as reduction of soil productivity, landscape degradations which are complex and
have diverse nature and land dimensions, and production of sediments that may result
damages of downstream.
1
Soil erosion has become the major environmental problems in Malaysia. The
coastal zone between Sungai Sementa and Sungai Puloh in Malaysia has been
severely eroded up to 120-200 meters since 1963 at a rate of 5 to7 meters per year
(Port Klang ICM Project Management Office, 2004). The eroded soil flows to the
waterways causes the sedimentation and siltation to the waterways and makes it
shallow and reduces the flood carrying capacity of the river. When the trees are
removed, the land no longer absorbs the water when it rains, the water flows more
quickly to the waterways, causing erosion and flashfloods. The floods that break the
river banks worsen the soil erosion problems by changing the path of the river.
In order to control the erosion effectively and protect the natural environments,
the factors of influencing soil erosion should be defined. The mitigation measures,
control plans and Best Management Practices (BMP) should be planned and
implemented in order to reduce the soil erosion and sedimentation problems
especially at the construction site. Department of Irrigation and Drainage Malaysia
(DID) has introduced a design guidelines and manual named Urban Stormwater
Management Manual for Malaysia (MSMA) in year 2001 purposed for project
developers, planners, engineers, and contractors to engage in planning, designing and
implementing the BMP that to be adopted on construction site. In 2011, DID has
further published a new specific design guideline and manual entitled Guideline for
Erosion and Sediment Control in Malaysia (DID, 2011). Besides, Department of
Environment (DOE), Malaysia has established the requirement of Erosion Sediment
Control Plan (ESCP) to all the projects which involve soil disturbing activities and
site preparation in year 2011 as part of the EIA approval under the Environmental
Impact Assessment (EIA) Order, 1987.
2
Thus, the mathematical model, such as Universal Soil Loss Equation (USLE)
or Revised Universal Soil Loss Equation (RUSLE) is an important tool in
management system by predicting the erosion processes, and conservation planning
and design for sediment control. Universal Soil Loss Equation (RUSLE) is one of the
presently used models to predict the potential soil erosion hazard resulted from human
activities such as rural and urban extension, industrial developments .
1.2 Problem Statement
Rapid increase in construction industrial involving varieties of construction
activity such as construction practices and materials, waste, vehicles, and equipment
management have potential to pollute stormwater and contamination to the waterways.
Erosion is a major environmental problem for most of the construction projects
especially those construction projects located in sensitive areas such as the highland,
near rivers and streams. Water is the most significant agent of soil erosion, and the
removal of vegetative cover which breakdown and loosen the soil structure and
organic matte often reduce infiltration and accelerate runoff and the entrainment of
soil particles. Malaysia, which influences by the tropical climate with high rainfall
intensity has led to several erosion problems. The soil-trapping forest which protects
the soil to be washed away by the runoff is removed during the construction which in
turn leading to the erosion. Surface runoff generated from high climatic conditions
and steep terrains are highly erosive to the exposed soil surface within the
construction area, eg. New Light Industrial Estate located at Kapit Division. The
eroded soil has caused sedimentation and siltation to the waterways and destroyed the
water ecosystems.
3
Ngoi and Choo (2012) mentioned some of the erosion and sediment hazards
caused by uncontrolled construction activities:
1) Changes in water runoff, earth movement and accumulation of
sedimentation;
2) Water pollution and change in river bed levels due to accumulation of
sediments washed from the construction site; and
3) Damages to the aquatic life habitat and hydrology which affect the
fishery and agriculture industries.
As stated in DID's Urban Stormwater Management Manual for Malaysia
(MSMA, 2001), gullies are the major source of erosion at the exposed construction
site. Downcutting of any slope is the dominant gully enlargement process as gullies
increase in size more rapidly on fill materials instead of cut slopes. In 1996, DOE
categorized the impacts on soil erosion, sedimentation, siltation, and deposition into
"On-site" and "Off-site":
1) On-Site
a. Loss of topsoil and resulting costs to communities,
b. Undermining of roads and utilities,
c. Sediment and mud on roads with associated traffic problems and road
safety issues,
d. Clogged drains and increased nuisance flooding,
e. Sedimentation and bank damage on construction sites,
f. Increased down-time on construction and building sites after storm
events,
4
Pusat Khidmat Maklumat Akadem ik UMVERSTTI MALAYSIA SARAWAK
g. Unsightly appearance of construction works,
h. Sedimentation and accelerated loss of capacity in sediment basins, and
i. High cost for reconstruction and maintenance.
2) Off-site
a) Sedimentation in reservoirs and other storage structures, with resulting
loss of water storage capacity;
b) Instability of stream channels caused by increased runoff and sediment
loads: channel change and bank erosion may affect adjacent buildings
and other infrastructure;
c) Siltation and sedimentation of rivers will cause a reduction in channel
capacity leading to greater frequency of floods;
d) Proliferation of exotic weeds within watercourses due to the high
nutrient content of silt and sediments;
e) Smothering of aquatic and marine flora and fauna as high turbidity in
rivers excluding light penetration affecting fish life;
f) Land degradation caused by gully erosion and sediment deposition;
g) Increased pollution of rivers and streams;
h) Loss of navigable reaches of a river or watercourse;
i) Adverse ecological effects of high sediment loads, deposition, and
dredging and de-silting of waterways;
j) Decline or total loss of recreational and commercial fishing,
particularly as a result of increased turbidity; and
k) Reduced recreational and aesthetic value of riverbanks and waterways.
5
1.3 Objectives of Study
The objectives of this study are to estimate and compute soil erosion rates
during pre-construction, construction, and post construction of the proposed site
clearing, earthworks/ sandfilling and infrastructure works at light industrial area.
To reduce the environmental impacts associated with soil erosion, the erosion
control and the best management practices are recommended to reduce the effects of
soil erosion from the construction site. In this study, the percentage of reduction by
implementation of control measures is going to be defined.
The specific aims of the study are to:
1) Identify a study area - the Proposed Site Clearing, Earthworks, Sand
Filling and Infrastructural Works of Light Industrial Area for Food
Processing located at Kapit Division, Sarawak;
2) Collect project details and relevant information, i. e. locality and site
plans, geology and geotechnical information, structural design of slope
protection works, soil investigation data, etc.;
3) Literature review - annual soil erosion rates, best management practices
(BMP), etc.;
4) Tabulate slopes of construction site base on topography data, and estimate
other relevant parameters of Revised Universal Soil Loss Equation
(RUSLE);
5) Estimate soil erosion rates by using RUSLE;
6) Recommend appropriate BMP; and
6
7) Estimate soil erosion rates by using RUSLE and tabulate percentage of
erosion reduction by implementing BMP.
1.4 Scope of Study
This study estimates the erosion rates and sediment yield on the disturbed soil
surfaces during; i) pre-construction stage; ii) construction stage; and iii) post-
construction stage. A series of data shall be collected from an undergoing project,
Proposed Site Clearing, Earthworks, Sand Filling and Infrastructural Works of Light
Industrial Area for Food Processing located at Kapit Division.
1.4.1 The Study Area
The study area is located on the south bank of Batang Rajang, approximately
2.3km west of Kapit Township as shown in Figure I. I. It encompasses an area of
approximately 9.34ha (23.07 acres). The study area is accessible by car and other
motor vehicles via Jalan Bleteh, Kapit. The study area is a classified as Mixed Zone
Land and is in the category of Country Land. Figures 1.1 and 1.2 show the locality
and site plan of the study area, respectively.
7
Batang Rajang
, I*-_ Project Site
: 'ý. '"ýkýý ýý . -ý _.
Figure 1.1: Locality Plan of Study Area
Figure 1.2: Site Plan of Study Area
f-
8
V---
1.4.2 Topography
The study area has undulating terrain and the elevation ranges from 4m to 76m
with reference from TBM 1 (RL=37.91m) as shown in topographical map (Figure
1.3). The undulating terrain eases towards the riverbank and continues towards the
south of the study area where the elevation is progressively higher.
1.4.3 Geology and Soil
The geological deposits of the study area are mainly of rocks from tertiary
period with Paleocene and Eocene sedimentary deposits. The rock formation is of the
Kapit Member of Belaga Formation, consisting primarily of shale, slate, phyllite and
sandstone with marlstone, calcerous sandstone, conglomerate and limestone lenses
with weak regional metamorphism. The study area is covered mainly by skeletal soils
(Kapit Series) and red-yellow podzolic soils (Kapit Series) consisting of very shallow
to moderately deep loamy sands to clays. The soils are formed on sedimentary, acid
igneous and metamorphic rocks and are distributed in areas of steep and mountainous
land (Appendix A- Soil Map).
1.4.4 General Climate
Characteristic features of the climate in the regional and the study area are
uniform temperature, high humidity and high rainfall, typical of equatorial regions.
Winds are generally light. There are two monsoon regimes, i. e. the Southwest
9
Monsoon (May to September) and the Northeast Monsoon (November to March). The
Northeast Monsoon brings heavy rainfall and the Southwest Monsoon normally
signifies relatively drier weather. Due to the proximity of the Equator, East Malaysia
is not directly exposed to the monsoons, wherefore there is a more climatic conditions
show less seasonal variance and peaks compared to other south-east Asian regions.
10
CHAPTER 2
LITERATURE REVIEW
2.1 Soil Erosion
Soil erosion is a natural process that is essential for soil formation which
occurred throughout geological history. It is an unavoidable phenomenon associated
on sloping land. Soil erosion is mainly caused by water that does not infiltrate into the
soil and direct runs over the soil surface resulting erosion damages over the sloping
land, and removes most of the topsoil that contains nutrients.
The human activities such as deforestation and resulting soils depleted may
boost the natural progress of soil erosion. Natural soil erosion rate could not haved
occurred constantly with consistent rates: for example, and soils and semi-arid soils
which have less protective vegetative covers may erode at average rates of 10-50
times greater than those humid climate soils (Miller and Donahue, 1990).
Soil erosion has caused more than 80% of land degradation, of which 56% are
due to water-induced soil erosion (Oldeman, 1992). UN Environmental Program
reported that crop productivity on about 20 million hectares could be reduced to zero
annually due to the soil induced degradation or soil erosion (UNEP, 1991). Without
proper soil erosion and sediment control measures, soil erosion from construction
sites may loss of 8-80 tones/ha/year, which is 20 times greater than the loss from the
agricultural land (NRCS, 1999). Soil erosion has become the major environmental
problems in China. Approximately 400 million tons of sediment settles in the Lower
12
Yellow River annually (Ministry of Water Resources, the People's Republic of China,
2011).
2.1.1 Types of Soil Erosion
According to New South Wales Department of Primary Industries (NSWDPI
n. d. ), there are six major types of soil erosion:
(i) Splash or Raindrop Erosion:
It is the first stage of erosion that resulted from the raindrop impacts on
bare soil surface and destructs surface soil aggregates is termed as splash
erosion. The splashed soil particles will fill up the void of soil aggregates,
so the soil will be sealed and infiltration process will be reduced. Thus,
surface runoff is introduced.
(ii) Sheet Erosion:
Removal of thin layers of soil by the impacts of the raindrop and shallow
surface water flow is termed as sheet erosion (Figure 2.1). The soil
particles that are removed by sheet erosion contain most of the organic
matters and nutrients of the soils. It occurs where there is little vegetative
cover that can anchor the soil.
13
Figure 2.1: Sheet Erosion
Source: (Ritter, 2012)
(iii) Rill Erosion:
A form of water erosion where a numerous of shallow drainage less than
300mm depth and straight channels are produced. Rill erosion (Figure 2.2)
is common in freshly cultivated soil where the soil aggregates is loosened.
This type of erosion starts to develop when surface water concentrates to
flow on the same channels and erodes the soil.
Figure 2.2: Rill Erosion
Source: (Ritter, 2012)
14