Groundwater Resource Assessment for Town Water Supply in South Africa. The Case of Steynsrus in the Free State Province

Table of Contents

CHAPTER 1 INTRODUCTION

1.1 RESEARCH FRAMEWORK

1.2 WATER SUPPLY BACKGROUND

1.3 PROBLEM STATEMENT

1.4 METHODOLOGY

1.5 AIMS AND OBJECTIVES

1.6 STRUCTURE OF DISSERTATION

CHAPTER 2 LITERATURE REVIEW

2.1 INTRODUCTION

2.2 OVERVIEW OF GROUNDWATER RESOURCE ASSESSMENT

2.3 GROUNDWATER RESOURCE ASSESSMENT CONCEPTS

2.3.1 Groundwater Occurrence

2.3.2 Groundwater Flow and Storage

2.3.2.1 Borehole sustainability and aquifer parameters

2.3.3 Groundwater Recharge

2.3.3.1 The Chloride Mass Balance Method (CMB)

2.3.3.2 Qualified guesses

2.3.4 Borehole Sustainable Yields

2.3.5 Groundwater Quality

2.3.5.1 Interpretation of chemical data

2.3.5.1.1 Piper and Durov diagrams

2.3.5.1.2 Schoeller diagram

2.3.5.1.3 Groundwater salinity

2.3.5.2 Statistical analysis

2.4 SUSTAINABLE DEVELOPMENT

2.5 GROUNDWATER ASSESSMENT CASE STUDIES

2.6 SUMMARY

CHAPTER 3 SITE DESCRIPTION

3.1 OVERVIEW AND ECONOMIC DEVELOPMENT

3.2 PHYSIOGRAPHY AND DRAINAGE

3.3 RAINFALL AND CLIMATE

3.4 VEGETATION AND LAND USE

3.5 WATER RESOURCES

3.5.1 Surface Water

3.5.2 Local Groundwater

3.5.3 Groundwater Potential

3.5.4 Water Use in the Moqhaka Local Municipality

3.6 GEOLOGY AND GEOHYDROLOGY

3.6.1 General Geology

3.6.2 Geohydrology

3.7 SUMMARY

CHAPTER 4 DESKTOP STUDY

4.1 INTRODUCTION

4.2 REMOTE SENSING AND MAP ANALYSIS

4.2.1 Borehole Siting

4.3 BOREHOLE INFORMATION

4.4 SUMMARY

CHAPTER 5 GEOPHYSICAL INVESTIGATIONS

5.1 INTRODUCTION

5.2 MAGNETIC SURVEY

5.2.1 Results and Discussion

5.3 SUMMARY

CHAPTER 6 DRILLING AND GEOLOGICAL CHARACTERISATION

6.1 INTRODUCTION

6.2 PERCUSSION DRILLING

6.2.1 Lithology

6.2.2 Unsuccessfully Drilled Boreholes

6.3 SUMMARY

CHAPTER 7 PUMP TESTING AND AQUIFER PARAMETERS

7.1 INTRODUCTION

7.2 AQUIFER TESTING

7.2.1 Blow Yields

7.2.2 Step Discharge Test

7.2.3 Constant Discharge Test

7.2.3.1 Diagnostic plots

7.2.4 Recovery Test

7.2.5 Aquifer Parameters

7.2.5.1 Cooper-Jacob method

7.2.5.1.1 Validity of Assumptions of Cooper-Jacob method

7.2.5.1.2 Estimation of Transmissivity using Cooper-Jacob method

7.2.5.2 RPTSOLV program

7.3 SUMMARY

CHAPTER 8 EXPLOITABLE GROUNDWATER RESOURCE

8.1 INTRODUCTION

8.2 RECHARGE ESTIMATION

8.2.1 Chloride Mass Balance Method

8.2.2 Qualified Guesses

8.3 GROUNDWATER RESOURCE SUSTAINABLE YIELD ESTIMATES

8.3.1 Borehole Recommended Yields

8.3.2 Water Balance

8.4 SUMMARY

CHAPTER 9 HYDROCHEMISTRY

9.1 INTRODUCTION

9.2 STATISTICAL ANALYSIS

9.2.1 Univariate Statistics

9.2.2 Quality of Inorganic Chemistry Data

9.3 GROUNDWATER QUALITY

9.3.1 Irrigation Suitability

9.4 HYDROGEOCHEMICAL CHARACTERISTICS

9.5 SUMMARY

CHAPTER 10 CONCLUSIONS AND RECOMMENDATIONS

10.1 INTRODUCTION

10.1.1 Geophysics Survey

10.1.2 Geology and Geohydrology

10.1.3 Aquifer Parameters

10.1.4 Groundwater Quality

10.1.5 Groundwater Sustainable Use

10.1.6 Additional Findings

10.2 RECOMMENDATIONS

Research Goals and Topics

The dissertation aims to assess the groundwater resources for water supply to the town of Steynsrus. The primary goal is to investigate whether current and projected future groundwater resources are sufficient to meet the municipal water demands for the year 2030, while ensuring the sustainable use of the aquifer system.

• Assessment of groundwater occurrence using magnetic geophysical methods.
• Geological characterization and analysis of aquifer lithology from drilling logs.
• Evaluation of aquifer hydraulic and storage properties through constant discharge pump testing.
• Estimation of exploitable groundwater resources, including recharge and water balance calculations.
• Analysis of hydrogeochemical characteristics to determine water quality suitability for domestic consumption.

Extract from the Book

Summary of Chapters

CHAPTER 1 INTRODUCTION: Outlines the research background, the water scarcity problems in Steynsrus, and the primary objectives of the study.

CHAPTER 2 LITERATURE REVIEW: Reviews the fundamental concepts of groundwater assessment, including occurrence, recharge methods, and sustainable development principles in fractured rock aquifers.

CHAPTER 3 SITE DESCRIPTION: Provides a detailed physical and socio-economic overview of the Steynsrus area, including climate, geology, and existing water resources.

CHAPTER 4 DESKTOP STUDY: Details the collection and evaluation of existing reports, geological maps, and satellite imagery to define drilling targets.

CHAPTER 5 GEOPHYSICAL INVESTIGATIONS: Examines the magnetic methods used to locate and verify potential groundwater structures.

CHAPTER 6 DRILLING AND GEOLOGICAL CHARACTERISATION: Documents the percussion drilling of boreholes and the analysis of lithological logs for characterizing the subsurface.

CHAPTER 7 PUMP TESTING AND AQUIFER PARAMETERS: Discusses the execution of aquifer tests and the determination of key hydraulic properties such as transmissivity and storativity.

CHAPTER 8 EXPLOITABLE GROUNDWATER RESOURCE: Presents the estimates for recharge and water balance to evaluate the sustainability of the groundwater supply.

CHAPTER 9 HYDROCHEMISTRY: Analyzes the chemical composition of the groundwater and its suitability for domestic use according to national standards.

CHAPTER 10 CONCLUSIONS AND RECOMMENDATIONS: Synthesizes the study's findings and offers management recommendations for the Moqhaka Local Municipality.

Keywords

Borehole sustainable yield, Geohydrological characterisation, Groundwater assessment, Groundwater flow, Groundwater occurrence, Aquifer parameters, Karoo fractured-rock aquifers, Water balance, Water quality, Steynsrus, Magnetic survey, Lithology, Hydrochemistry, Pump testing.

Frequently Asked Questions

What is the primary focus of this research?

This research focuses on performing a comprehensive groundwater resource assessment to determine if groundwater can reliably supply the town of Steynsrus to meet its projected 2030 water demands.

Which regional water management area does the study cover?

The study area falls within the Middle Vaal Water Management Area, specifically within the quaternary catchment C60E.

What is the main objective regarding the municipal water supply?

The objective is to estimate the sustainable yield of existing and newly drilled boreholes to determine if groundwater is sufficient as a sole or supplementary water source for the town.

What scientific methods were employed to characterize the aquifer?

The study utilized remote sensing, magnetic geophysical surveys, percussion drilling, aquifer pump testing, and hydrochemical analysis of water samples.

What does the literature review establish regarding Karoo aquifers?

The review establishes that Karoo aquifers are primarily fractured-rock systems where groundwater flow is controlled by secondary features such as faults, joints, and dolerite intrusions.

How are the sustainable yield estimates determined in this study?

Sustainable yields are estimated using the FC program, which incorporates pump testing data, drawdown observations, and recovery data to ensure long-term aquifer viability.

Why were the magnetic data from the original consultant questioned?

The magnetic data were evaluated as "bad data" because they showed unrealistic magnetic intensities and single-point anomalies that did not align with conventional geological expectations.

What is the conclusion regarding the town's future water security?

The study concludes that current groundwater resources are insufficient to meet projected 2030 demands, indicating a significant supply deficit that requires further water management strategies.