EXPERIMENTAL STUDY ON INFILTRATION USING DOUBLE-RING

INFILTROMETER

MORAMMAD FARHAN BIN SALLEH

A thesis submitted in fulfillment

of the requirements for the

award of the degree of

Bachelor of Civil Engineering

Faculty of Civil & Environmental Engineering

University College of Engineering and

Technol Malaysia

NOVEMBER, 2006

ABSTRACT

Kolej Universiti Kejuruteraan & Teknologi Malaysia (KUKTEM) is located in

Pahang Darul Makniur. Infiltration can be define as the rate of water soaking into the

soil and the unit used to calculate the infiltration rate is mm/hour. The calculation of the

infiltration rate entering the soil, a double-ring infiltrorneter is used for the experiment.

Three locations have been selected as the study area which is nearby the laboratory of

Civil and Environmental Faculty, in front of KUKTEM's mosque and KUKTEM's

football field. For each location, three points have been chosen based on the distance of

the point with distance between 5m-lOrn as an experimental point. After performing the

experiment, soil samples have been gathered and analyzed in the laboratory using the

sieve analysis experiment. The calculation that is using in this experiment is Horton's

Equation. The analysis indicated that the soil for the three selected areas is sandy soil.

The infiltration rate at KUKTEM's football field is lower compared to the other two

selected areas.

V

ABSTRAK

Kolej Universiti Kejuruteraan dan Teknologi Malaysia (KUKTEM) terletak di

Pahang Darul Makmur. Penyesapan bermaksud kadar air masuk ke dalam tanah dan unit

yang digunakan untuk mengira kadar resapan ialah mm/jam. Pengiraan kadar resapan air

ke dalam tanah, alat double-ring infiltrometer digunakan untuk eksperimen. Tiga tempat

telah dipilih sebagai kawasan kajian iaitu berdekatan makmal kejuruteraan awam dan

sumber alam, depan masjid KUKTEM dan padang bolasepak KUKTEM. Untuk setiap

kawasan kajian, tiga tempat dipilih mengikut jarak antara tempat iaitu jarak antara 5m-

10m sebagai kawasan eksperimen. Selepas eksperimen, sampel tanah setiap eksperimen

diambil dan dianalisis di makmal dengan ekperimen ayakan. Pengiraan yang digunakan

dalam eksperimen un ialah persamaan Horton. Analisis menunjukkan tanah ketiga-tiga

kawasan kajian bercirikan pasir. Kadar penyesapan air ke tanah di kawasan padang

bolasepak KUKTEM Iebih rendah berbanding dengan di dun kawasan kajian yang lain.

vi

TABLE OF CONTENTS

CHAPTER SUBJECT PAGE

FRONT PAGE i DECLARATION DEDICATION ACKNOWLEDGEMENT iv

ABSTRACT v ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x LIST OF FIGURES xi LIST OF SYMBOLS xiii

LIST OF APPENDICES xv

CHAPTER I INTRODUCTION

1.1 General i 1.2 Problem statement 2 1.3 Objective 3 1.4 Scope of study 3

CHAPTER II LITERATURE REVIEW

vi'

2.1 Infiltration 4

viii

2.2 Factors affect infiltration 5

2.2.1 Soil properties 5

2.2.2 Residence time 7

2.2.3 Infiltration rate 8

2.2.4 Vegetation 8 2.3 Engineering Classification of Soil 8 2.4 Particle-Size Distribution Curve 9 2.5 Unified Soil Classification System 10 2.6 Time of Ponding 15 2.7 Infiltration method 16

2.7.1 Horton equation 16

2.7.2 Modified Horton equation 18

2.7.3 Green-Ampt equation 1

2.7.4 Holtan equation 21 2.8 Double-ring infiltrometer 23

2.8.1. Introduction 23 2.9 Summary 25

CHAPTER III METHODOLOGY

3.1 Introduction 27 3.2 Methodology 28 3.3 Study area 29 3.4 Infiltration equation 31 3.5 Laboratory Test 31 3.6 Sieve analysis 31

3.6.1 Apparatus 32

3.6.2 Procedure 32 3.7 Field infiltration test 33

3.7.1 Apparatus 34

3.7.2 Procedure 35

CHAPTER IV RESULT AND ANALYSIS

4.1 Introduction 36 4.2 Analysis of Data 37

4.2.1 Sieve Analysis 37 4.2.2 Infiltration rate 43

4.3 Summary of Analysis 50

CHAPTER V CONCLUSION AND RECOMMENDATION

5.1 Introduction 51 5.2 Conclusion 52 5.3 Recommendation 53

REFERENCES 54

APPENDIX A - C 56

ix

LIST OF TABLES

TABLE 'TITLE PAGE

2.1 Unified Soil Classification (USC) System 11

(from AS'TM D 2487), 2003

2.2 Flowchart group names for gravelly and sandy soil 14

2.3 Horton Parameters for Bluegrass Turf 18

2.4 Tentative Estimates of the Vegetation Parameter a in the 22

Infiltration Equation

5.1 Table of Horton Equation for Location A, B and C 52

x

LIST OF FIGURES

NO.FIGIJRE TITLE PAGE

2.1 Plasticity chart 12

2.2 Infiltration curve 17

2.3 Doublc4ting Infiltrometer Equipment 23

3.1 Flow chart of methodology 28

3.2 Nearby the Civil and Environmental Engineering Lab 29 3.3 In front of KUKTEM's mosque 30

14 KUKTEM's football field 30

3.5 Sieve Analysis Mechanical Shaker 32

Doublc'Ring Infiltrometer 34

4.1 Particle size distribution for sample Al at location A 38 4.2 Particle size distribution for sample A2 at location A 39 4.3 Particle size distribution for sample A3 at location A 39 4.4 Particle size distribution for sample B at location B 40 4.5 Particle size distribution for sample 132 at location B 40 4.6 Particle size distribution for sample 133 at location B 41 4.7 Particle size distribution for sample C at location C 41 4.8 Particle size distribution for sample C2 at location C 42 4.9 Particle size distribution for sample C3 at location C 42 4.10 Infiltration curve for sample Al at location A 45 4.11 Infiltration curve for sample A2 at location A 46 4.12 Infiltration curve for sample A3 at location A 46 4.13 Infiltration curve for sample BI at location 13 47 4.14 Infiltration curve for sample B2 at location B 47 4.15 Infiltration curve for sample B3 at location 8 48

xi

xli

4.15 Infiltration curve for sample B3 at location B 48

4.16 Infiltration curve for sample Cl at location C 48

4.17 Infiltration curve for sample C2 at location C 49

4.18 Infiltration curve for sample C3 at location C 49

LIST OF SYMBOLS

D10 = Effective size

C = Uniformity coefficient

D60 = diameter corresponding to 60% finer.

C = Coefficient of gradation

= Sorting coefficient

t ponding time

I time

= infiltration capacity, (mm/hr)

ff = final infiltration capacity, (mm/hr)

fo initial infiltration capacity, (mm/hr)

k = exponential decay constant, (hr')

t time from beginning of rainfall. (hr)

K = hydraulic conductivity

H0 depth of flow ponded at the surface

Sw = effective suction at the wetting front

L = depth from the surface to the wetting front

f infiltration rate

F = accumulative infiltration

xlii

A parameter

xiv

B parameter

a he infiltration capacity [(inihr)/in."] of the available storage (index of

surface-connected porosity)

S. = available storage in the surface layer (A -horizon in agricultural soils, that is

about the first six in.) (in. of water equivalent)

mm/hr = millimeter/hour

mm = millimeter

hr =hour

LIST OF APPENDICES

APPENDIX TITLE PAGE

A.l Infiltration data for sample Al at location A 57

A.2 Infiltration data for sample A2 at location A 58

A.3 Infiltration data for sample A3 at location A 60

A.4 Infiltration data for sample B! at location B 61

A.5 Infiltration data for sample B2 at location B 62

A.6 Infiltration data for sample B3 at location II 64

A.7 Infiltration data for sample C at location C 66

A.8 Infiltration data for sample C2 at location C 67

A.9 Infiltration data for sample C3 at location C 68

B. 1 Sieve Analysis data for sample Al at location A 70

B2 Sieve Analysis data for sample A2 at location A 70

B.3 Sieve Analysis data for sample A3 at location A 71

B.4 Sieve Analysis data for sample 131 at location B 71

B.5 Sieve Analysis data for sample 132 at location B 72

B4 Sieve Analysis data for sample B3 at location B 72

B.7 Sieve Analysis data for sample C at location C 73

B.8 Sieve Analysis data for sample C2 at location C 73

B.9 Sieve Analysis data for sample 0 at location C 74

C. 1 Infiltration curve at location Al 76

C.2 Infiltration curve at location A2 76

C.3 Infiltration curve at location A3 77

C.4 Infiltration curve at location BI 77

C.5 Infiltration curve at location B2 78

C.6 Infiltration curve at location 133 78

xv

xvi

C.7 Infiltration curve at location C

79

C.8 Infiltration curve at location C2

79

C.9 Infiltration curve at location C3

80

CHAPTER I

INTRODUCTION

1.1 General

Infiltration is the process when the water soaking into the soil. Infiltration rate is

simply how fast water enters the soil and is usually measured in inches or millimeters

per hour. This rate depends on soil texture (amount of sand, silt, and clay) and soil

structure, Soils in good condition have well developed structure and continuous pores to

the surface. As a result, water from rainfall or snowmelt readily enters these soils.

Soil is a reservoir that stores water for plant growth. The water in soil is

replenished by infiltration. The infiltration rate can be restricted by poor management.

Under these conditions, the water does not readily enter the soil and it moves down

slope as runoff or ponds on the surface, where it evaporates. Thus, less water is stored in

the soil for plant growth, and plant production decreases, resulting in less organic matter

in the soil and weakened soil structure that can further decrease the infiltration rate.

Another important of infiltration is in construction. The infiltration experiment

will be done at any area to definite that the area safe for construction. The results

summarize about the texture and porosity of the soils. Good soil structure improves

infiltration. Soils with good structure have more pores for the movement of water than

soils with poor structure.

2

Commonly used methods for determining infiltration capacity are hydrograph

analyses and inflitrometer studies. Infiltrometers are usually classified as rainfall

simulators or flooding devices. In the former, artificial rainfall is simulated over a test

plot and the infiltration is calculated from observations of rainfall and runoff, with

consideration given to depression storage and surface detention (W. K. Johnson, 1974).

Infiltrometers are usually tubes and rings inserted in the ground level of soil.

Water is applied and maintained at a constant level and observations are made of

the rate of replenishment required (W.Viessman and Jr.Gary L.Lewis, 2003). Estimates

of infiltration based on hydrograph analyses have the advantage over infiltrometers of

relating more directly to prevailing conditions of precipitation and field. Several

methods have been developed and are in use (Charley, A. Pabst, and J.Peters, 1995).

1.2 Problem Statement

In this infiltration study, the infiltration test will determine the types of soil in

KUKTEM area. The result from the experiment will analyze the types of soil and the

effects for the development at the surrounding KUKTEM area. This study will

determine how fast the water infiltrates into the soil in KUKTEM area. So we will know

the properties of soil in the area which the rates of infiltration that can prevent flood

from happen and for the future development. For the preventing flood happen, the soil

Properties must be study before any development will be constructed at KUK'II M area.

3

1.3 Objective

The objectives of study are;

I. To determine types of soils for study area.

2. To obtain infiltration curve using Horton's Equation.

3. To determine the infiltration parameter using Horton's Equation.

4. To compare the values of infiltration parameter among different locations.

1.4 Scope of study

This study will be used Double-Ring Infiltrometer that is prepared by Faculty of

Civil and Environmental Engineering KUKTEM. Three main locations are chosen to

collect the data. The locations are nearby the Civil and Environmental Engineering Lab,

in front of KUKTEM's mosque and KUKTEM's football field. The calculation for

infiltration measurement in this study is using Horton's Equation.

CHAPTER II

LITERATURE REVIEW

21 Infiltration

Infiltration process is the largest process of rainfall losses in area. The term

infiltration refers to the process by which rainwater passes through the ground surface

and fills the pores of the underlying soil ( A.Osman Akan and Robert J. Houghtalen,

1992). Surface and subsurface of soil conditions influence the infiltration rates. The

surface conditions determine the availability of water, while the subsurface conditions

govern the ability of the available water to infiltrate (A.Osman Akan and Robert J.

Houghtalen, 1992). The rate of rainfall means the availability of water at the ground

surface, The infiltration capacity means as the maximum rate at which water can

infiltrate into the soil. Its mean the ability of available water to infiltrate.

Infiltration is the process when the water penetrating or enter into the soil from

the ground surface. There are many factors that influence the infiltration rate such as the

condition of the soil surface and its vegetative cover, the properties of the soil, such as

its porosity and hydraulic conductivity, and the current moisture content of the soil. Soil

strata with different physical properties may overlay each other, forming horizons; for

example, a silt soil with relatively high relatively high hydraulic conductivity may

overlay a clay zone of low conductivity. Also, soils exhibit great spatial variability even

within relatively small areas such as a field. As a result of these great spatial variations

and the time in soil properties that occur as the soil moisture content changes, infiltration

5

is a very complex process that can be described only approximately with mathematical

equations (Veil Te Chow, 1988).

2.2 Factors affect infiltration

The proportion of water from rainfall or snowmelt that enters the soil depends on

residence time (how long the water remains on the surface before running oft) and the

infiltration rate. These are affected by vegetation and many soil properties.

2.2.1 Soil properties

The properties that affect infiltration and cannot be readily changed by

management include:

i. Texture

Water moves more quickly through the large pores and spaces in a sandy soil

than it does through the small pores in a clayey soil. Where the content of

organic matter is low, texture plays a significant role in the susceptibility of the

soil to physical crusting.

ii. Clay mineralogy

Some types of clay develop cracks as they dry. These cracks rapidly conduct

water to the subsurface and seal shut once the soil is wet.

iii. Minerals in the soil

High concentrations of sodium tend to inhibit the development of good structure

and promote the formation of surface crusts, which reduce the infiltration rate.

Calcium improves soil structure.

iv. Soil layers

Subsurface soil, including a subsoil of dense clay, cemented layers, and highly

contrasting layers, such as coarse sand over loam, can slow water movement

through soil and thus limit infiltration.

V. Depth

Soil depth controls how much water the soil can hold. When soil above an

impermeable layer, such as bedrock, becomes saturated, infiltration ceases and

runoff increases. The properties that affect infiltration and can be readily

changed by management or a shift in vegetation.

vi. Organic matter and soil biota

Increased plant material, dead or alive, generally improves infiltration. As

organic matter is broken down by soil organisms, it binds soil particles into

stable aggregates that enhance pore space and infiltration.

vii. Aggregation and structure

Good soil structure improves infiltration. Soils with good structure have more

pores for the movement of water than soils with poor structure. if aggregates are

stable, the structure remains intact throughout a rainstorm.

viii. Physical crusts

Physical crusts form when poorly aggregated soils are subject to the impact of

raindrops and/or to ponding. Particles broken from weak aggregates can clog

pores and seal the surface, thus limiting water infiltration.

7

ix. Biological crusts

Biological crusts can eithernerease or reduce the infiltration rate. Theft effect on

the infiltration rate depends on many other factors, including soil texture.

X. Pores and channels

Continuous pores connected to the surface convey water. Such organisms as

earthworms, ants, and termites increase the number of pores. Termites, however,

can decrease the infiltration rate by reducing the amount of litter cover, and some

ant species seal the surface around their nests.

xi. Soil density

A compacted zone close to the surface restricts the entry of water into the soil

and often results in surface ponding. Increased bulk density reduces pore space

and thus the amount of water available for plant growth.

xii. Water-repellent layer

As shrubs and an underlying thick layer of litter bum in a hot fire, very high

temperatures can occur directly beneath the shrubs. The heat forces a gas from

the burning plant material into the soil. When it cools, the gas forms a water-

repellent layer that limits infiltration. This feature is temporary, although it may

persist for a number of years. Some soils can be slightly water repellent when

dry.

2.2.2 Residence time

The length of time that water remains on the surface depends on the slope, the

roughness of the soil surface, and obstructions to overland flow, such as plant bases and

litter. Consequently, plant communities with large amounts of basal area cover, such as

8

grasslands tend to slow runoff more than communities with small amounts of basal

cover,, such as shrub lands.

2.2.3 Infiltration rate

The infiltration rate is generally highest when the soil is dry. As the soil becomes

wet, the infiltration rate slows to the rate at which water moves through the most

restrictive layer, such as a compacted layer or a layer of dense clay. Infiltration rates

decline as water temperature approaches freezing. Little Or no water penetrates the

surface of frozen or saturated soils.

2.2.4 Vegetation

A high percentage of plant cover and large amounts of root biomass generally

increase the infiltration rate. Different plant species have different effects on infiltration.

The species that form a dense root mat can reduce the infiltration rate. In areas of and

and semiarid rangeland, the infiltration -limiting layer commonly is confined to the top

few millimeters of the soil, particularly in the open spaces between plant canopies.

These areas receive few inputs of organic matter, which build soil structure. Also, the

impact of raindrops in these areas can degrade soil structure and form physical crusts.

2.3 Engineering Classification of Soil

Different soils with similar properties may be classified into groups and sub-

groups according to their engineering behavior. Classification systems provide a

common language to concisely express the general characteristics of soils, which are

infinitely varied, without detailed descriptions. Currently, two elaborate classification

systems are commonly used by soils engineers. Both systems take into consideration the

particle-size distribution and Atterberg limits. They are the American Association of

State Highway and Transportation Officials (AASHTO) classification system and the

Unified Soil classification system. The AASHTO classification system is used mostly by

state and country highway departments. Geotechnical engineers generally prefer the

Unified system.(Braja M.Das,2006)

2.4 Particle-Size Distribution Curve

A particle-size distribution curve can be used to determine the following four

parameters for a given soil.

1. Effective size (L)jo): This parameter is the diameter in the particle-size

distribution curve corresponding to 10% finer. The effective size of a granular

soil is a good measure to estimate the hydraulic conductivity and drainage

through soil.

2. Uniformity coefficient (Ce) This parameter is defined as

cu = /to (2l)

D10

where D60 = diameter corresponding to 60% finer.

10

3. Coefficient of gradation (Ce) This parameter is defined as

930

(2.2) D60 X D10

4. Sorting coefficient (So) : This parameter is another measure of uniformity and is

generally encountered in geologic works and expressed as

So = Jp (2.3)

D25

The sorting coefflecient is not frequenly used as a parameter by geotechnical

engineers. (Braja M. Das, 2006)

23 Unified Sil Classification System

The original form of this system was proposed by Casagrande in 1942 for use in

the airfield construction works undertaken by the Army Corps of Engineers during

World War H. In cooperation with the U.S Bureau of Reclamation, this system was

revised in 1952. At present, it is used widely by engineers ( ASTM Test Designation D-

2487). The Unified Soil Classification System is presented in Table 2.1. -

11

Table 2.1 : Unified Soil Classification (USC) System (from ASTM D 2487), 2003

r Divisions MajorGroupSymbol

Gravels Clean GW Cu> 4 and I <Cc < 3c 50% or more Gravels <4/ > of course

Gravels GM P1<4 or plots below "A" line fraction

Course-Grained retained on with ______ 11)

GC P1>7 and plots on or above "A" Soils the 4.75 mm Fines More than 50% (No. 4) sieve line ((Figwc 2.1) retained on the O075mm Sands Clean SW Cu>6 and l<zCc<3c

s Cu <6 and/or 1 > Cc >3c (No 200) sieve 50% or more an

of course fraction passes Sands SM P1 <4 or plots below "A" line

the 475 with(Figure

SC P1>7 and plots on or above "A" (No 4) sieve Finesline (Figure 11)

CL P1<4 or plots on or above "A" line (Figure 2.1)

ML P1>7 and plots below "A" line Silts and Clays _______ (Figure 2.1) Liquid Limit 50% or less . ..

- limit - oven d Liquid dried Fine-Grained

OL

- <0.75

Soils -Liquid limit - not dried

More than 50% ___________________ _______ ; OL zone passes the 0.075 Tflffi CH P1 plots on or above "A"

(No. 200) sieve(Figure 2.1)

Silts and Clays MH P1 plots below "A" In -6

Liquid Limit greater than

(Figure)

Liquid limit = oven dried 50%

OHLiquid limit - not dried

OH zone

Highly Organic Soils PT Primarily organic matter, dark in colour and organic odor

Prefix: G Gravel, S Sand, M Silt, C Clay, 0 Organic Suffix: W Well Graded, P = Poorly Graded, M = Silty, L = Clay, LL < 50%, H = Clay, LL>5%