EVALUATING THE EFFECTS OF INVASIVE ALIEN PLANTS ON WATER AVAILABILITY AND ...

118 Pages·2014·4.96 MB·English

EVALUATING THE EFFECTS OF INVASIVE ALIEN PLANTS ON WATER
AVAILABILITY AND USABILITY OF LAKE WATER INGAUTENG PROVINCE

by
LAMECK RWIZI

Submitted in accordance with the requirements for

the degree of
MASTER OF SCIENCE

In the subject
ENVIRONMENTAL MANAGEMENT

at the

UNIVERSITY OF SOUTH AFRICA

Supervisor: Dr Luxon Nhamo

AUGUST 2014
DECLARATION

I, Lameck Rwizi, hereby declare that the research reported herewith on the topic “Evaluating
the Effects of Water Hyacinth on Water Availability and Usability of Lake Water in
Gauteng Province”, is my own work and that all the sources used or quoted in this
dissertation have been indicated and acknowledged by means of complete referencing.

……………………………………………
Signed (Author)

Date: ………………………………….

…………………………………………………
Signed (Supervisor)
Date:

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ACKNOWLEDGEMENTS
Firstly, I would like to express my sincere gratitude to the Almighty God for bringing me this
far and for always been with me.
I wish to express my profound gratitude to my substantive supervisor Dr. Luxon Nhamo, who
despite his busy schedule was able to guide me through this research until the final write up. I
really appreciate his effort, guidance, encouragement and discrete council in times of
confusion.
I would also like to convey my sincere thanks to Ekurhuleni Metropolitan Municipality and
its Wetland Team including Mr. Christopher Muthombeni for providing me with permission
to conduct my research in Middle Lake, Civic Lake and Kleinfontein Lakes in Benoni, and
information regarding the aquatic weeds contained in this lakes.
The Agricultural Research Commission (ARC) in Pretoria is also acknowledged for its
contribution in providing the meteorological data variables from 2000 – 2012.
I also thank my brother Tandanai, for assisting me with statistical analysis of my research
without him this work could have been impossible to accomplish.
Lastly, I acknowledge my indebtedness to my wife Nhamo, my sons Ephraim, Joyful and
Nokutenda for the support and understanding they offered me during trying times when I
conducted the research.

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ACRONYMS

ANOVA Analysis of variance
CARA Conservation of Agricultural Resources Act
CBD Convention on Biological Diversity
DEA Department of Environmental Affairs
DEM Digital Elevation Model
DWAF Department of Water Affairs and Forestry
EMM Ekurhuleni Metropolitan Municipality
ET Evapotranspiration
GIS Geographical Information Systems
GPS Geographical Positioning System
IAS Invasive Alien Species
IPCC Intergovernmental Panel on Climate Change
IPPC International Plant Protection Convention
IUCN International Union for the Conservation of Nature.
NIR Near Infrared Radiation
NISC National Invasive Species Council
SAPIA South African Plant Invaders Atlas
TIR Thermal Infrared Radiation
UNEP United Nations Environmental Programme
WfW Working for Water Programme

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TABLE OF CONTENTS

DECLARATION ...................................................................................................................................... i
ACKNOWLEDGEMENTS .................................................................................................................... ii
ACRONYMS ......................................................................................................................................... iii
TABLE OF CONTENTS ........................................................................................................................iv
LIST OF TABLES ................................................................................................................................ viii
LIST OF FIGURES ................................................................................................................................. ix
ABSTRACT ............................................................................................................................................ x
CHAPTER: 1 ....................................................................................................................................... - 1 -
1. INTRODUCTION ....................................................................................................................... - 1 -
1.1 INTRODUCTION ....................................................................................................................... - 1 -
1.2 RESEARCH BACKGROUND ................................................................................................... - 3 -
1.3 PROBLEM STATEMENT.......................................................................................................... - 4 -
1.4 RATIONALE FOR DOING THE RESEARCH ......................................................................... - 5 -
1.5 RESEARCH QUESTIONS ......................................................................................................... - 6 -
1.6 AIM AND OBJECTIVES ........................................................................................................... - 6 -
1.6.1. Aim ...................................................................................................................................... - 6 -
1.6.2. Objectives ............................................................................................................................ - 6 -
1.7 DESCRIPTION OF THE STUDY AREA .................................................................................. - 7 -
1.7.1 Precipitation and Temperature ........................................................................................... - 10 -
1.7.2 The Southern Dolomite Outcrop ....................................................................................... - 10 -
1.7.3 Land use and vegetation .................................................................................................... - 11 -
CHAPTER: 2 ..................................................................................................................................... - 13 -
2. RESEARCH PROBLEM THEORY ......................................................................................... - 13 -
2.1 INVASIVE SPECIES: THE CONCEPT AND INVASION PROCESS ................................... - 13 -
2.2 FACTORS CONFERRING INVASIVENESS ......................................................................... - 14 -
2.3 INVASION PROCESS.............................................................................................................. - 15 -
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2.4 GEOGRAPHICAL RANGE AND IMPACT OF THE PROBLEM IN SOUTH AFRICA ...... - 15 -
2.5 IMPACTS OF INVASIVE ALIEN PLANTS ........................................................................... - 18 -
2.6 THE LEGAL FRAMEWORK REGARDING INVASIVE ALIEN PLANTS IN SOUTH
AFRICA .................................................................................................................................... - 20 -
2.6.1 Constitution of the Republic of South Africa, 1996 (Act 108 of 1996) ............................ - 21 -
2.6.2 Conservation of Agricultural Resources Act (Act 43 of 1983) (CARA) .......................... - 21 -
2.6.3 National Environmental Management Act (Act 107 of 1998) (NEMA) ........................... - 22 -
2.6.4 National Environmental Management: Biodiversity Act (NEMBA) (Act 10 of 2004) ..... - 27 -
2.6.5 National Environmental Management: Protected Areas Act (NEMPAA) (Act 57 of 2003) ... -
27 -
2.7 INTERNATIONAL CONVENTIONS ..................................................................................... - 28 -
2.7.1 The Convention on Biological Diversity ........................................................................... - 28 -
2.7.2 The International Plant Protection Convention ................................................................. - 29 -
2.8 EVALUATION OF THE SOUTH AFRICAN LEGISLATIVE AND INSTITUTIONAL
CONTEXT REGARDING IAS ................................................................................................. - 29 -
2.9 REPRODUCTION OF THE WATER HYACINTH ................................................................ - 32 -
2.10 THE WATER HYACINTH ENVIRONMENTAL PROBLEMS ............................................. - 32 -
2.11 CONTROL MEASURES .......................................................................................................... - 33 -
2.11.1 Manual and Mechanical Control ....................................................................................... - 34 -
2.11.2 Chemical Control ............................................................................................................... - 35 -
2.11.3 Biological Control ............................................................................................................. - 35 -
2.12 IMPLICATIONS FOR POLICY ............................................................................................... - 37 -
2.13 POTENTIAL UTILISATION OF WATER HYACINTH ........................................................ - 37 -
2.14 CLIMATE CHANGE AND INVASIVE ALIEN SPECIES: IMPLICATIONS FOR
ECOSYSTEMS ......................................................................................................................... - 39 -
2.14.1 Effects of rising CO on biological invasions ..................................................................... - 41 -
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2.14.2 Changes in land use and land cover ................................................................................... - 42 -
2.14.3 Global commerce ............................................................................................................... - 42 -
2.14.4 Does global change favour invasive over native species? ................................................. - 43 -
2.14.5 Critical research and management needs to improve forecasting and combating alien plants
invasion risk in an era of climate change .......................................................................................... - 43 -
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2.15 THE USE OF GEOGRAPHICAL INFORMATION SYSTEMS AND REMOTE SENSING
DATA IN MONITORING ALIEN INVASIVE SPECIES ....................................................... - 44 -
2.16 SUMMARY .............................................................................................................................. - 45 -
CHAPTER: 3 ..................................................................................................................................... - 47 -
3. RESEARCH DESIGN AND METHODOLOGY ..................................................................... - 47 -
3.1 INTRODUCTION ..................................................................................................................... - 47 -
3.2 STUDY METHODOLOGY ...................................................................................................... - 47 -
3.3 DAM LEVEL CHANGE DETECTION USING REMOTE SENSING AND GEOGRAPHICAL
INFORMATION SYSTEMS .................................................................................................... - 48 -
3.4 DATA COLLECTION AND DESIGN ..................................................................................... - 49 -
3.5 REASONS FOR MODELLING THE AQUATIC HYDROLOGICAL SYSTEM .................. - 50 -
3.6 STATISTICAL MODELS TO DETERMINE DISTRIBUTION OF IAS ................................ - 52 -
3.7 STATISTICAL TECHNIQUES ................................................................................................ - 55 -
3.7.1 Regression Analysis and Correlation Analysis.................................................................. - 55 -
3.7.2 When to apply Regression Analysis? ................................................................................ - 55 -
3.7.3 Scatter Plots ....................................................................................................................... - 56 -
3.7.4 Multiple Regression Analysis ............................................................................................ - 57 -
3.7.5 Multiple Regression Objectives ......................................................................................... - 58 -
3.7.6 Assessing Statistical Assumptions ..................................................................................... - 58 -
3.7.7 Sample Size and Generalisability ...................................................................................... - 58 -
3.7.8 Multiple Regression correlation and Analysis of Variance (ANOVA) ............................. - 59 -
3.7.9 Testing Significance of the model and ANOVA ............................................................... - 60 -
3.8 WHEN TO USE MULTIPLE REGRESSION .......................................................................... - 61 -
3.9 INTERPRETING THE REGRESSION VARIANTS ............................................................... - 62 -
3.10 ASSESSING MULTICOLLINEARITY ................................................................................... - 63 -
3.10.1 How to deal with multicollinearity .................................................................................... - 64 -
3.11 SUMMARY .............................................................................................................................. - 64 -
CHAPTER: 4 ..................................................................................................................................... - 65 -
4. RESULTS AND DISCUSSIONS ............................................................................................. - 65 -
4.1 INTRODUCTION ..................................................................................................................... - 65 -
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4.2 WATER HYACINTH CHANGE DETECTION, IMPACT ANALYSIS AND MONITORING ... -
65 -
4.3 WATER LAKE LEVEL ANALYSIS ....................................................................................... - 68 -
4.4 FOCUS GROUP RESULTS ..................................................................................................... - 71 -
4.5 WATER HYACINTH SPATIAL AND TEMPORAL VARIATIONS .................................... - 72 -
4.6 ANALYSIS OF WATER AVAILABILITY AND USABILITY OF LAKES ......................... - 75 -
4.7 MULTIPLE REGRESSION ANALYSIS OF HYDROLOGICAL VARIABLES, MODELLING
AND CLIMATIC VARIABILITY ........................................................................................... - 77 -
4.7.1 Overview of hydrological variables .................................................................................. - 78 -
4.7.2 Correlation analysis of hydrological variables .................................................................. - 78 -
4.7.3 Forecasting hydrological model: Multiple regression analysis ......................................... - 79 -
4.7.4 Trend analysis to reveal impact of hydrological factors on aquatic weeds ....................... - 80 -
4.7.5 Trend test ........................................................................................................................... - 80 -
4.8 SUMMARY .............................................................................................................................. - 84 -
CHAPTER 5 ...................................................................................................................................... - 86 -
5. CONCLUSIONS AND RECOMMENDATIONS .................................................................... - 86 -
5.1 CONCLUSIONS ....................................................................................................................... - 86 -
5.2 RECOMMENDATIONS........................................................................................................... - 88 -
REFERENCES .................................................................................................................................. - 90 -
APPENDICES ................................................................................................................................. - 103 -
Appendix 1: Hydrological variables ................................................................................................. - 103 -
Appendix 2: Authorisation Letter. ................................................................................................... - 106 -
Appendix 3: Ethics Letter ................................................................................................................. - 107 -

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LIST OF TABLES
Table 1.1: Invasive alien plants found in Benoni area ......................................................................... - 9 -
Table 2.1: Methods for the control of water hyacinth ....................................................................... - 34 -
Table 2.2: Possible general impacts of climate change elements on prevalence of invasive alien
speciesa .............................................................................................................................................. - 40 -
Table 3.1: General ANOVA table for multiple regressions ............................................................. - 61 -
Table 4.1: Descriptive statistics of area not covered by water hyacinth ............................................ - 68 -
Table 4.2: Correlations of lake area among the three lakes ............................................................... - 68 -
Table 4.3: Descriptive statistics of hydrological variables ............................................................... - 78 -
Table 4.4: Correlation matrix ............................................................................................................ - 79 -
Table 4.5: Hydrological Coefficients ................................................................................................ - 79 -
Table 4.6: Pearson correlation ........................................................................................................... - 79 -
Table 4.7: ANOVA ........................................................................................................................... - 80 -
Table 4.8: Evapotranspiration model summary ................................................................................. - 81 -
Table 4.9: ANOVA Table of Evapotranspiration .............................................................................. - 81 -
Table 4.10: Multiple regression coefficients ..................................................................................... - 81 -

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LIST OF FIGURES
Figure 1.1: Location of the lakes in Ekurhuleni Municipality and in South Africa ............................ - 7 -
Figure 1.2: The map of Benoni showing the study lakes .................................................................... - 8 -
Figure 2.1: The Water-master machine clearing invasive plants in the Kleinfontein Lake. ............. - 14 -
Figure 2.2: The distribution of invasive alien plants in South Africa. .............................................. - 16 -
Figure 2.3: The water hyacinth creating watery graves across Middle Lake in Benoni................... - 19 -
Figure 2.4: The Water hyacinth weevil (Neochetina eichhorniae) ................................................... - 36 -
Figure 2.5: Impact of climate change on invasions, and feedbacks from invaders to global change - 41 -
Figure 3.1: Flow chat of major steps in the study methodology ....................................................... - 52 -
Figure 4.1: Area covered by water hyacinth in the Kleinfontein Lake.............................................. - 66 -
Figure 4.2: Area covered by water hyacinth in the Civic Lake ......................................................... - 66 -
Figure 4.3: Area covered by water hyacinth in the Civic Lake ......................................................... - 67 -
Figure 4.4: Area covered by water hyacinth in the Civic Lake ......................................................... - 67 -
Figure 4.5: Area of lakes covered by water hyacinth from 2002 to 2012 ......................................... - 69 -
Figure 4.6: Comparison of mean yearly surface water area per lake ................................................ - 70 -
Figure 4.7: Kleinfontien Lake totally covered by water hyacinth in 2010 ........................................ - 71 -
Figure 4.8: Middle Lake partly covered by water hyacinth ............................................................. - 72 -
Figure 4.9: Frequent colonisation of water hyacinth on lake edges in Middle Lake ........................ - 73 -
Figure 4.10: Bank of the Middle Lake infested by water hyacinth .................................................. - 73 -
Figure 4.11: Recreation around the study lakes, Benoni Golf Course.............................................. - 74 -
Figure 4.12: Recreation along Rynfield Lake ................................................................................... - 75 -
Figure 4.13: Recreation around the study lakes, Benoni Golf Course .............................................. - 75 -
Figure 4.14: Surfing in Rynfield Lake ............................................................................................... - 76 -
Figure 4.15: Algal blooms and water hyacinth in the Middle Lake ................................................. - 77 -

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