universiti putra malaysia effects of ...psasir.upm.edu.my/39955/1/fp 2013 12r.pdfof topographical...

UNIVERSITI PUTRA MALAYSIA

ABDAL SHAHRIVAR

FP 2013 12

EFFECTS OF TOPOGRAPHICAL FACTORS AND SOIL CHARACTERISTICS ON GULLY PROPERTIES IN KOHGILOYE

AND BOYER AHMAD PROVINCES, IRAN

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EFFECTS OF TOPOGRAPHICAL FACTORS AND SOIL

CHARACTERISTICS ON GULLY PROPERTIES IN KOHGILOYE AND

BOYER AHMAD PROVINCES, IRAN

By

ABDAL SHAHRIVAR

Thesis submitted to the School of Graduate Studies, Universiti Putra

Malaysia, in Fulfilment of the Requirements for the Degree of

Doctor of Philosophy

June 2013

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COPYRIGHT

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photographs and all other artwork, is copyright material of Universiti Putra Malaysia

unless otherwise stated. Use may be made of any material contained within the thesis

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may only be made with the express, prior, written permission of Unversiti Putra

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Copyright © Universiti Putra Malaysia

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Dedicated to my father’s soul

my precious mother

and

my wife

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Abstract of thesis presented to the senate of Universiti Putra Malaysia in fulfilment

of the requirements of the degree of Doctor of Philosophy

EFFECTS OF TOPOGRAPHICAL FACTORS AND SOIL

CHARACTERISTICS ON GULLY PROPERTIES IN KOHGILOYE AND

BOYER AHMAD PROVINCES, IRAN

By

ABDAL SHAHRIVAR

June 2013

Chairman: Christopher Teh Boon Sung, PhD

Faculty: Agriculture

Gully erosion is unequivocally an important form of soil erosion in the arid and semi-

arid regions of Iran. These lands, which are the main sources of income for farmers,

are being rapidly decimated. Moreover, nomadic livestock grazing in such regions is

heavily dependent on these lands. Sediments resulting from gully erosion can engender

a plethora of environmental problems, such as water quality problems in waterways,

rivers and lakes as well as decrease fertility of farmland. This study focuses on the

basic implications of the roles of gully watershed and certain physico-chemical soil

properties upon gully erosion in a semi-arid region of 210 km2. In this particular study,

the Abgendi watershed, which has the largest number of gullies, was selected. In this

area, all the gullies (53 gullies) were coded and 35 gullies were chosen randomly (using

random numbers in Excel, function of random between) and studied. Each of these

gullies has a small watershed, whose properties such as gully volume, gully length,

slope above gully, distance between head-cut and borderline, altitude difference, gully

watershed area and soil cover were determined. From the main waterway of the gully,

soil sampling from head-cut and two walls in two depths (0-30 cm and 30 cm to bottom

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of gully) was carried out. Physical characteristics of the soil, such as aggregate stability

(AS), mean weight diameter (MWD), clay, sand and silt, and soil chemical properties

such as electrical conductivity (EC), sodium adsorption ratio (SAR), organic carbon

(OC), cation exchange capacity (CEC), calcium (Ca), magnesium (Mg) and sodium

(Na) were determined. Moreover, in order to identify the main factors responsible for

the development of gully erosion, the gullies were classified according to gully volume

in three sizes: big, medium, and small gullies. The three gully volume groups were

compared to one another on the basis of their topographical factors such as gully

watershed areas, distance between head-cut and borderline, altitude difference of gully

watershed area, slope above head-cut and gully bottom slope and then they were

compared with the area without gullies (the control group) in terms of their soil’s

physico-chemical properties and soil cover such as percentages of vegetation cover,

stubble and gravel. The results of the investigation of the soil texture in the gully and

control areas indicated that the occurrence probability of gullies is low in soils which

tend to have high amount of sand. Soils with silt clay loam texture are the most

susceptible types of soils, while sandy loam and loam are the most resistant types to

gully erosion in the study area. The soil texture groups and mean values of gully

volume and length in soil texture groups in the top and sub-layer of gully head-cut and

walls showed that the occurrence probability of gullies in the soil with silt loam and

silt clay loam in the top layer, and clay loam and silt clay loam in the sub-layer is high.

In contrast, the occurrence probability of gullies in the soil with loam texture is low.

In other words, if a gully is formed in soils with clay loam and silt clay loam in the top

layer, the gully can be very large and long.

The results of the comparison between the gully volume groups and control area

indicated that some soil physical properties such as sand and proportion of sand / silt

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+ clay in both top and sub-layers of head-cut (at least one of the gully volume groups),

and sand, and proportion of sand / silt + clay in both top and sub-layers of the gully

walls (all three volume groups), were significantly lower than those of the same depths

in the control area. Furthermore, there was a positive correlation between the

percentage of clay in the top and sub-layers of the head-cut and gully volume at the

5% level (2-tailed). Likewise, the proportions of clay / (sand + silt) in the top -layers

of the head-cut were correlated positively with the volume and length of gully.

A comparison between the gully volume groups and the control area in terms of soil

chemical properties showed that, except for EC in the sub-layer of the gully walls (big

gully group) that was significantly higher than that in the same depth of the control

area, none of the chemical factors was significant. However, there was a significant

positive correlation between the volume and/or length of gully and Ca, Mg, EC in the

head-cut top layer, EC in the head-cut sub-layer, Mg in the gully walls top layer, and

EC and Ca in the gully walls sub-layer at the 5% level (2-tailed). However, comparison

between the gully volume groups in terms of soil chemical properties indicated that

soil chemical properties of the gully area were approximately uniform.

The result of the comparison between gully volume groups in terms of gully watershed

properties demonstrated that some topographical factors such as distance between

head-cut and borderlines, altitude difference and gully watershed area could explain

the different sizes among gully volume groups. The correlation between these

topographical factors and gully volume and length was strongly significant at 1% level.

The statistical analysis of gully watershed properties not only explained the gully

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volume and length but also explained the differences among the volume groups in the

gully area.

The percentage of the vegetation cover in the study area showed that, under these

circumstances, not only runoff generation is quickly formed, but raindrops can be

quickly dispersed throughout the soil particles as well. This process is attributed to

scarcity of soil cover. The result of comparison between control and gully area also

showed that the soil covers in the different sizes of gully were uniform, but the

vegetation cover of the control area was significantly higher than that in the gully area.

In order to develop a model, regressions between the gully length as a dependent

variable and other measured factors as independent variables were performed using a

stepwise method through SPSS. It should be mentioned that the same process was

carried out for the gully volume as the dependent variable and all the measured factors

as dependent variable. The gully length model indicated that gully length was affected

by the percentages of clay in the top layer of the gully head-cut and walls, gully

watershed area and distance between head-cut and borderline. Therefore, these three

factors turn out have the greatest impact on gully erosion. Among these effective

factors, the most important factor was distance between head-cut and borderline, with

a β coefficient of 0.517,whereas the least important factor was clay percentage of the

gully walls’ top layer, with a β coefficient of 0.246. On the other hand, the gully

volume model indicated that the gully volume was affected by distance between head-

cut and borderline and clay of the head-cut top-layer. Comparison of the two models

revealed that the gully length model could better explain the gully erosion development

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than the gully volume model for the simple reason that it had stronger R, R2 and

adjusted R2.

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Abstrak tesis yang dikemukakan kepada senat Universiti Putra Malaysia

sebagai memenuhi keperluan untuk ijazah Doktor Falsafah

CIRI-CIRI PEMBENTUKAN KESAN HAKISAN PEPARITAN KAWASAN

TADAHAN AIR DAN TANAH DI WILAYAH KOHGILUYEH

BOYERAHMAD, IRAN

Oleh

ABDAL SHAHRIVAR

Jun 2013

Pengerusi: Christopher Teh Boon Sung, PhD

Fackulti: Pertanian

Hakisan peparitan merupakan bentuk hakisan di kawasan kering dan separa-gersang

di negara Iran.Tanah, merupakan sumber pendapatan utama bagi petani sedang

menghadapi masalah kemusnahan.Sumber makanan ternakan nomad di kawasan-

kawasan tersebut sangat bergantung kepada tanah ini. Sedimen yang terhasil daripada

hakisan peparitan ini menyebabkan begitu banyak mencemarkan alam sekitar, seperti

masalah kualiti air pengairan, sungai dan tasik serta memusnahkan kesuburan tanah

ladang. Kajian ini memberi tumpuan kepada implikasi asas kesan hakisan peparitan

terhadap kawasan tadahan air dan keadaan fiziko-kimia tanah selepas dilanda hakisan

peparitan di kawasan kering dan separa gersang seluas 210 km². Dalam konteks kajian

ini, kawasan tadahan air Abgendi, yang mempunyai bilangan terbesar galur peparitan,

telah dipilih. Dalam kawasan ini, 35 galur peparitan telah dipilih secara rawak dan

dikaji. Setiap galur ini mempunyai satu titik kecil, keadaan tanah (seperti jumlah

sampah, parit panjang, cerun parit, jarak antara tahad tarahan tanah dan pinggiran,

perbezaan ketebalan sampah, kawasan tadahan air dan pelitub bumi) telah ditentukan.

Dari parit laluan air utama, sampel tanah daripada tahad tarahan dan dua tebing dalam

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dua kedalaman (0-30 cm dan 30 cm ke bawah dari peparitan) telah dijalankan. Ciri-

ciri fizikal tanah, seperti kestabilan agregat (AS), min diameter berat (MWD), tanah

liat, pasir dan kelodak, dan sifat-sifat kimia tanah seperti kekonduksian elektrik (EC),

nisbah penyerapan natrium (SAR), karbon organik (OC), keupayaan pertukaran kation

(CEC), kalsium (Ca), magnesium (Mg) dan natrium (Na), telah ditentukan. Selain itu,

untuk mengenal pasti faktor utama yang bertanggungjawab terhadap hakisan

peparitan, galur-galurnya dikelaskan mengikut saiz isi padu peparitan: iaitu galur

besar, galur sederhana, dan galur kecil. Kumpulan isipadu peparitan dikelaskan

mengikut saiz yang berbeza daripada galur dan kawasan tanpa galur (kumpulan

kawalan) dibandingkan daripada segi sifat-sifat fizik-kimia tanah, dan tanah litup

seperti peratusan tumbuhan pelindung, tunggul dan batu kelikir. Selain itu, kumpulan

isi padu glur peparitan dibandingkan dari segi kandungan galur kawasan tadahan air,

seperti peparitan kawasan tadahan air, jarak antara tahad tarahan dan sempadan,

perbezaan ketinggian tebing peparitan kawasan tadahan air, cerun tarahan dan cerun

bahagian bawah peparitan. Hasil daripada perbandingan antara kumpulan isipadu

peparitan dari segi keadaan kawasan tadahan air menunjukkan bahawa beberapa faktor

topografi seperti jarak antara tahad tarahan dan batas, perbezaan ketinggian dan

peparitan kawasan tadahan air menunjukkan saiz yang berbeza di kalangan kumpulan

isipadu peparitan. Korelasi antara faktor-faktor topografi dan isipadu galur dan

panjang galur adalah amat penting pada peringkat 1% (2-hujung).Hasil korelasi antara

jenis litup bumi (seperti tumbuhan perlindungan, tunggul dan batu kelikir) dan isipadu

galur peparitan dan panjang peparitan tidak signifikan.Walau bagaimanapun,

peratusan tumbuhan litup bumi dan tunggul kawasan kawalan berbanding dengan

kawasan peparitan adalah lebih tinggi. Satu perbandingan antara kumpulan isi padu

galur dan kawasan kawalan dari segi sifat-sifat kimia tanah menunjukkan bahawa,

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kecuali SPR dalam sub-lapisan tebing peparitan (kumpulan peparitan besar) yang jauh

lebih tinggi daripada itu dari segi kedalaman yang sama kawasan kawalan, tiada

faktor-faktor kimia (seperti SAR, OC, CEC, Na, Ca dan Mg) yang signifikan. Walau

bagaimanapun, terdapat korelasi positif yang signifikan antara isipadu galur atau

panjang peparitan (atau kedua-dua jumlah dan panjang) dan Ca, Mg, EC di lapisan

atas had tarahan, sub lapisan EC had tarahan, Mg di tebing atas lapisan peparitan, dan

EC serta Ca dalam lapisan tebing peparitan kecil di peringkat 5% (2-tialed). Keputusan

perbandingan antara kumpulan isi padu galur dan kawasan kawalan menunjukkan

bahawa beberapa sifat fizikal tanah, seperti pasir dan kadar pasir / kelodak + tanah liat

di atas dan lapisan sub-tahad tarahan (sekurang-kurangnya satu daripada jumlah

kumpulan isipadu galur), dan pasir, serta kadar pasir / kelodak + tanah liat dalam

kedua-dua lapisan atas sub-lapisan di bahagian tebing peparitan (kesemua tiga

kumpulan isipadu), adalah jauh lebih rendah daripada kedalaman yang sama di

kawasan kawalan. Selain itu, terdapat hubungan yang positif antara peratusan tanah

liat di atas dan sub-lapisan tahad tarahan dan isipadu pada tahap 5% (2-tialed). Begitu

juga, peratusan pasir dan kadar pasir / (tanah liat + kelodak) ada berkorelasi negatif

dengan isipadu dan panjang galur. Kurang bilangan galur jika tanahnya gembur dan

kelodak tekstur gembur di lapisan atas tahad tarahan, manakala bilangan yang paling

banyak peparitan mempunyai kelodak tanah liat gembur dan tanah liat gembur dalam

lapisan sub-tahad tarahan. Keputusan tekstur tanah dalam perbandingan dengan

kumpulan tekstur tanah menunjukkan bahawa panjang peparitan dan isipadu

meningkat dari tanah gembur kepada tanah liat gembur. Dalam kajian ini,

menunjukkan sebagai usaha untuk menyediakan model, regresi antara panjang

peparitan sebagai pembolehubah bersandar dan faktor ukuran lain sebagai

pembolehubah tak bersandar telah dijalankan menggunakan kaedah langkah demi

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langkah menggunakan SPSS. Model ini menunjukkan bahawa panjang peparitan

terjejas oleh peratusan tanah liat pada lapisan atas tahad tarahan dan tebing, peparitan

kawasan tadahan air dan jarak antara tahad tarahan dan pinggiran. Faktor yang paling

penting ialah jarak antara tahad tarahan dan pinggiran, dengan β pekali sama dengan

0,517, manakala faktor yang paling kurang penting ialah peratusan tanah liat lapisan

tebing peparitan, dengan pekali β sama dengan 0.246.

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ACKNOWLEDGEMENTS

First and foremost, I wish to express my utmost thanks and gratitude to Almighty Allah

SWT for his blessings and for giving me the ability and capacity to complete this

dissertation.

I wish also to express my most sincere gratitude and deepest appreciation to my

supervisor, Dr. Christopher Teh Boon Sung, for his kindness, continuous support,

fruitful advice and invaluable guidance, during the period of this study.

I am also very grateful to the members of my supervisory committee, Dr. Anuar Abdul

Rahim, Dr. Shamshuddin Jusop and Dr. Majid Soufi for their kindness support,

constructive comments, very helpful suggestions and insights which contributed to the

many aspects of this study and improved the quality of this dissertation.

I would like to acknowledge all the lecturers in UPM who taught me a lot of things

which improved my knowledge to conduct this study.

I would like to thank the UPM library management and support staff at the Department

of Land Management, Universiti Putra Malaysia for their help throughout my doctoral

study.

Last but not least, I wish to express my deepest gratitude to my beloved wife “Sara”,

and lovely children “Nima”, “Aryan” and “Andia” for their endless encouragement,

patience and sacrifices which had helped me to finish this study.

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfilment of the requirement for the degree of doctor of philosophy.

The members of the Supervisory Committee were as follows:

Christopher Teh Boon Sung, PhD

Senior lecturer

Faculty of Agriculture

Universiti Putra Malaysia

(Chairman)

Shamshuddin Jusop, PhD

Professor



(Member)

Anuar Abdul Rahim, PhD

Associate Professor



(Member)

Mijid Soufi, PhD

Manager

Agriculture Training and Research

Organization of Iran

(Member)

BUJANG BIN KIM HUAT, PhD

Professor and Dean

School of Graduate Studies


Date: 2 AUGUST 2013

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DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and

citations which have been duly acknowledged. I also declare that it has not been

previously, and is not concurrently, submitted for any other degree at Universiti Putra

Malaysia or at any other institution.

ABDAL SHAHRIVAR

Date: 4 June 2013

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TABLE OF CONTENTS

Page

DEDICATION iii

APSTRACT iv

ABSTRAK ix

ACKNOWLEDGEMENTS xiii

DECLARATION xvi

LIST OF TABLES xx

LIST OF FIGURES xxii

LIST OF ABBREVIATIONS xxv

CHAPTER

1 INTRODUCTION 1

1.1 Background 1

1.2 Problem and justification of study 4

1.3 Objectives of the study 6

2 LITERATURE REVIEW 7

2.1 Gully watershed characteristics affecting gully 7

2.2 Soil vegetation cover 13

2.3 Soil characteristics 15

2.3.1 Soil texture 16

2.3.2 Soil aggregate astability 17

2.3.3 Organic matter 18

2.3.4 SAR and EC 19

2.4 Soil mineralogy 21

2.5 Rainfall erosivity 22

2.6 Modelling 23

2.7 Environmental problems of gully erosion 27

2.8 Preventation and control of gully erosion 29

2.8.1 Gully control by biological structure 30

2.8.2 Gully control by mechanical structure 31

3 MATERIALS AND METHODS 33

3.1 Description of the study area 34

3.1.1 Abgendi watershed location 34

3.1.2 Abgendi watershed land-use 36

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3.1.3 Abgendi watershed climate 38

3.1.4 Soil mineralogy of the study area 40

3.2 Field data collection 41

3.2.1 Soil sampling 41

3.2.2 Method of measuring gully watershed 41

3.2.3 Methods of measuring vegetation cover 43

3.3 Methods of soil analysis 46

3.3.1 Particle size distribution 46

3.3.2 Aggregate stability 46

3.3.3 Mean weight diameter (MWD) 47

3.3.4 Electrical Conductivity (EC 47

3.3.5 Cation Exchange Capacity (CEC) 48

3.3.6 Sodium Adsorption Ratio (SAR) 49

3.3.7 Organic Carbon (OC) 49

3.4 Data analyses 49

4 RESULTS AND DISCUSSION 53

4.1 Soil mineralogy 53

4.2 Soil physical properties of gully head-cut and walls 54

4.2.1 Soil texture of gully 54

4.2.2 Gully volume and length based on soil texture groups 56

4.2.3 Comparison between top and sub-layers of gully 57

Head-cut in terms of soil physical properties

4.2.4 Comparison between top and sub-layers of gully walls 58

in terms of soil physical properties

4.2.5 Comparison between top layers of head-cut and walls 59


4.2.6 Comparison between sub-layer of head-cut and walls 61


4.2.7 Comparison between the top layer of gully volume 61

groups (head-cut) and control in terms of soil physical

properties

4.2.8 Comparison between the sub-layer of gully volume 63

groups (head-cut) and control in terms of soil physical

4.2.9 Comparison between the top layer of gully volume 64

groups walls and control in terms of soil physical properties

4.2.10 Comparison between the sub-layer of gully volume 66

groups walls and control in terms of soil physical properties

4.2.11 Correlation between the soil physical properties of 70

gully head-cut and walls with gully volume and length

4.3 Soil chemical properties 72

4.3.1 Comparison between top and sub-layer of gully head-cut 72

in terms of soil chemical properties

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4.3.2 Comparison between top and sub-layer of gully walls 73


4.3.3 Comparison between gully volume groups and control 74


4.3.4 Correlation coefficient between soil chemical properties 77

of gully head-cut top layer and gully volume and length

4.3.5 Correlation coefficient between soil chemical propertie 78

of gully head-cut sub layer and gully volume and length


of gully walls top layer with gully volume and length


of gully walls sub layer with gully volume and length

4.4 Gully watershed properties (topographical factors) 81

4.4.1 Comparison the gully volume groups in terms of gully 81

watershed properties

4.4.2 Correlation coefficient between gully watershed 85

properties and both gully volume and length

4.4.3 Comparison between gully volume groups in terms of 90

soil cover

4.4.4 Correlation between soil cover properties and gully 93

volume and length

4.4.5 Comparison between deep gullies and shallow gullies in 95

terms of gully watershed properties

4.5 Regression equation 98

4.5.1 Regression equation to predict gully volume regarding 98

the gully watershed, and soil chemical and physical properties

of gully head- cut and walls in the top and sub-layers

4.5.2 Regression equation to predict gully length regarding 100

the gully watershed, and soil chemical and physical properties

of gully head- cut and walls in the top and sub-layer

5 CONCLUSION 104

5.1 Recommendations 108

REFERENCES 109

APPENDICES 119

BIODATA OF STUDENT 194

LIST OF PUBLICATIONS 195

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