The thesis presents a two-dimensional Risk Assessment Method (RAM) where the assessment of risk to the groundwater resources incorporates both the quantification of the probability of the occurrence of contaminant source terms, as well as the assessment of the resultant impacts. The approach emphasizes the need for a greater dependency on the potential pollution sources, rather than the traditional approach where assessment is based mainly on the intrinsic geo-hydrologic parameters. The risk is calculated using Monte Carlo simulation methods whereby random pollution events were generated to the same distribution as historically occurring events or a priori potential probability distribution.
Integrated mathematical models then simulate contaminant concentrations at the predefined monitoring points within the aquifer. The spatial and temporal distributions of the concentrations were calculated from repeated realisations, and the number of times when a user defined concentration magnitude was exceeded is quantified as a risk.
The results of the applications of the method are presented in the form of tables, graphs and spatial maps. Varying the model grid sizes indicates no significant effects on the simulated groundwater head. The simulated frequency of daily occurrence of pollution incidents is also independent of the model dimensions. However, the simulated total contaminant mass generated within the aquifer, and the associated volumetric numerical error appear to increase with the increasing grid sizes.
Table of Contents
1. INTRODUCTION
1.1 PREAMBLE
1.2 BACKGROUND
1.2.1 Motivation
1.2.2 Problem Statement
1.2.3 Research Questions
1.2.4 Hypothesis
1.3 GROUNDWATER IN HARD ROCK AREAS.
1.3.1 Vadose Zone In Hard Rocks
1.3.2 Water Harvesting In Hard Rock Region
1.4 INTEGRATED GROUNDWATER MANAGEMENT
1.4.1 Issues of Concern
1.5 INTEGRATED ASSESSMENT, MODELLING TOOLS
1.6 SCOPE AND AIM OF THE PRESENT STUDY.
1.7 RESEARCH QUESTIONS
1.8 RESEARCH OBJECTIVES.
2. REVIEW OF LITERATURE
2.1 GENERAL
2.2 OVERVIEW OF WATER RESOURCES
2.2.1 Hard Rock Hydrogeology
2.3 REVIEW OF Hard Rock Aquifers
2.4 RENEWABLE WATER RESOURCES OF KARNATAKA
2.5 CLIMATE CHANGE AND GROUNDWATER
2.5.1 REVIEW OF MORPHOMETRIC ANALYSIS
2.5.2 REVIEW OF RUNOFF ESTIMATION
2.6 REVIEW OF HYDROGEOCHEMICAL STUDIES
2.7 REVIEW OF GROUNDWATER PROSPECT ZONES
2.8 REVIEW OF GROUNDWATER FLOW AND RECHARGE MODELS
2.9 REVIEW OF MANAGED AQUIFER RECHARGE
3. STUDY AREA AND COLLECTION OF DATA
3.1 GENERAL:
3.2 DETAILS OF THE STUDY AREA
3.3 COLLECTION OF DATA
3.3.1 Primary Data
3.3.2 Secondary Data
3.3.3 Evaluation Of Data
3.4 GEOMORPHOLOGY SETUP
3.4.1 Physiography
3.4.2 Pediments
3.4.3 Pediment Inselberg Complex
3.4.4 Geology
3.4.5 Gneisses
3.4.6 LINEAMENTS
3.4.7 Pediplains
3.4.8 Valley Fills
3.4.9 Drainage
3.4.10 Climate Temperature
3.4.11 Rainfall
3.5 DATA PRODUCTS
3.5.1 Digital Elevation Model (DEM) Data
3.6 HYDROMETEOROLOGICAL DATA
3.6.1 Wind Speed and Wind Direction
3.6.2 Relative Humidity
3.6.3 Potential Evapotranspiration
3.6.4 Monthly Minimum and Maximum Temperature
3.7 SOILS IN THE STUDY AREA
3.7.1 Clayey Soil
3.7.2 Loamy Skeletal
3.7.3 Red Loamy Soil
3.7.4 Red Soils
3.7.5 Red Sandy Soils
3.7.6 Red Gravelly Soils
3.8 AGRICULTURAL LAND
3.8.1 Kharif Crop
3.8.2 Double Crop
3.8.3 FOREST PLANTATIONS
3.8.4 Degraded Forest
3.8.5 Wastelands
3.8.6 Barren Rocky/Stony Waste
3.8.7 Land With Or Without Scrub
3.8.8 Grass Lands / Grazing Lands
3.9 HYDROLOGICAL FEATURES
3.10 HYDROGEOLOGY
3.10.1 Behaviour of Ground Water Level
3.10.2 Aquifer Parameters
4. METHODOLOGY, MORPHOMETRIC ANALYSIS AND RUNOFF ESTIMATION
4.1 INTRODUCTION.
4.2 METHODOLOGY FOR PREPARATION OF THEMATIC MAPS
4.3 WATERSHED DELINEATION
4.3.1 Drainage Map
4.3.2 LAND USE/ LAND COVER MAP
4.4 METHODOLOGY FOR MORPHOMETRIC ANALYSIS
4.4.1 Stream Order
4.4.2 Stream Length
4.4.3 Mean Stream Length
4.4.4 Stream Length Ratio
4.5 RUNOFF ESTIMATION
4.5.1 S C S Curve Number
4.5.2 Antecedent-Moisture (AMC)
5. HYDROGEOLOGICAL ANALYSIS
5.1 INTRODUCTION
5.2 BEHAVIOR OF GROUND WATER LEVEL
5.2.1 Depth to Water Level
5.2.2 Ground Water Level Fluctuations
5.3 AQUIFER PARAMETERS
5.3.1 Shallow Zone
5.3.2 Moderately Deep Zone
5.3.3 Deeper Aquifers
5.4 PUMPING TEST
5.4.1 PURPOSE OF CONDUCTING AQUIFER TESTS
5.4.2 Models for Analysing The Pumping Test
5.4.3 Radial Flow
5.4.4 In Situ Pumping Tests
6. RISK ASSESSMENT OF GROUNDWATER QUALITY
6.1 INTRODUCTION
6.2 GROUNDWATER POLLUTION
6.3 CONTAMINANT TRANSPORT PROCESS
6.4 ONE-DIMENSIONAL TRANSPORT MODEL
6.5 RISK ASSESSMENT METHOD (RAM)
6.5.1 Pre-Processing Of Pollution Sources
6.6 GROUNDWATER SAMPLING AND ANALYSIS
6.7 IMPORTANT QUALITY PARAMETER ANALYSIS
6.7.1 Specific Conductivity
6.7.2 pH
6.7.3 Total Dissolved Solids
6.7.4 Total Alkalinity
6.7.5 Chloride
6.7.6 Total Hardness
6.7.7 Calcium
6.7.8 Magnesium
6.7.9 Sulphate
6.7.10 Sodium
6.7.11 Nitrate
6.7.12 Potassium
6.7.13 Iron
6.7.14 Turbidity
6.7.15 Fluoride
6.8 WATER QUALITY INDEX
6.9 GROUNDWATER QUALITY REGRESSION MODEL
6.10 REGRESSION ANALYSIS
7. ELECTRICAL RESISTIVITY AND GROUNDWATER PROSPECT Zones
7.1 GROUNDWATER INVESTIGATION
7.2 ELECTRICAL RESISTIVITY
7.2.1 Basic Principles
7.2.2 Electrical Resistivity Tomography (ERT)
7.2.3 Physical Base
7.3 VERTICAL ELECTRICAL SOUNDING
7.4 Schlumberger Electrode Configuration
7.5 Resistivity in Hard Rock Terrains
7.6 RESISTIVITY SURVEYS IN THE STUDY AREA
7.6.1 Curve Matching Method
7.6.2 ISO-Resisitivity Maps
7.6.3 Iso-Thickness Maps
7.6.4 Total Longitudinal Conductance Map
7.7 GROUNDWATER PROSPECT MAPPING
7.7.1 Generation Of Spatial Database
7.7.2 Geological/Lithological Map
7.7.3 Land Use/Land Cover Map
7.7.4 Slope Map
7.7.5 Soil Map
7.7.6 Rainfall
7.8 DEMARCATION OF GROUNDWATER POTENTIAL ZONES
7.8.1 WEIGHTED OVERLAY ANALYSIS
8. SUSTAINABLE GROUNDWATER MANAGEMENT
8.1 SUSTAINABLE WATER MANAGEMENT
8.2 GROUND WATER RECHARGE
8.3 GROUND WATER DEVELOPMENT SCENARIO
8.4 GROUNDWATER BALANCE EQUATION
8.4.1 Data for Groundwater Draft
8.4.2 Conventional Mass Balance Method
8.5 NATIONAL WATER POLICY ON GROUNDWATER
8.6 MODFLOW - GROUND WATER MODEL
8.6.1 MODFLOW Simulation
8.6.2 MODFLOW Input Data
8.6.3 Water Table Fluctuation
8.7 MODELLING WITH MODFLOW
8.7.1 CONCEPTUAL MODELLING
8.7.2 Define Property Zones
8.7.3 Boundary Conditions
8.7.4 Define Model Grids
8.7.5 Model Translation and Simulation
8.8 MODEL CALIBRATION
9. SUMMARY AND CONCLUSIONS
9.1 GENERAL
9.2 DEVELOPMENT OF A SAFETY STATUS WARNING INDEX
9.3 DISCUSSIONS AND CONCLUSIONS
9.4 RECOMMENDATIONS
Research Objectives and Themes
This thesis aims to address the critical decline of groundwater resources in the hard rock terrain of Bengaluru North Taluk by developing an integrated management framework. By evaluating hydrogeological, geological, and climate-related data, the research generates specific metrics to inform sustainable water use, evaluate groundwater quality, and assess contamination risks, ultimately providing policymakers with a scientific basis for managing artificial recharge and improving resource sustainability at a local scale.
- Integrated assessment of groundwater using risk assessment and modeling tools.
- Geomorphological and hydrogeological analysis of hard rock terrain.
- Utilization of Remote Sensing and GIS for mapping potential groundwater zones.
- Development of a Safety Status Warning Index for sustainable groundwater exploitation.
- Evaluation of water quality using physicochemical parameters and WQI mapping.
- Application of mathematical modeling (MODFLOW) for groundwater flow simulation.
Excerpt from the Book
GROUNDWATER IN HARD ROCK AREAS.
Groundwater is a distinguished component of the hydrologic cycle. Physiography, the thickness of weathered zone, porosity, permeability, the density of fractures, and joints play a vital role in the occurrence and movement of groundwater in hard rock terrain. Due to heterogeneity within the rock formation, it is very uncertain about the quantity of groundwater available for exploitation.
From a technical standpoint, though hard rock areas occupy a greater part of our country, very little knowledge exists about the “the vadose zone”, that spans the region between the ground surface and fluctuating water table. There is no much reliable information about the unsaturated zone that exists over hard rock formations. It is, therefore, essential to have quantitative knowledge of the dynamics of water storage & water release mechanism from the vadose zone (unsaturated zone) that are considered important in the formulation and implementation of artificial recharge works in water shortage and drought-prone hard rock regions in the country.
It would be necessary therefore for anyone to know first the nature, movement, and occurrence of groundwater in hard rocks. Some salient characteristics of occurrence of groundwater in hard rock are listed below –
Summary of Chapters
CHAPTER 1 INTRODUCTION: Outlines the research context, problem statement for hard rock terrains, and the research objectives.
CHAPTER 2 REVIEW OF LITERATURE: Reviews previous HYDROGEOCHEMICAL STUDIES and related scholarship on hydrogeology and groundwater management.
CHAPTER 3 STUDY AREA AND COLLECTION OF DATA: Describes the physical, climatic, and hydrological characteristics of the Bengaluru North region.
CHAPTER 4 METHODOLOGY, MORPHOMETRIC ANALYSIS AND RUNOFF ESTIMATION: Details the GIS-based morphometric and drainage analysis techniques used.
CHAPTER 5 HYDROGEOLOGICAL ANALYSIS: Examines groundwater levels and results from pumping tests in the study area.
CHAPTER 6 RISK ASSESSMENT OF GROUNDWATER QUALITY: Evaluates groundwater contamination through sampling, WQI calculation, and regression models.
CHAPTER 7 ELECTRICAL RESISTIVITY AND GROUNDWATER PROSPECT Zones: Explores the use of geophysical resistivity methods and GIS for mapping potential aquifer zones.
CHAPTER 8 SUSTAINABLE GROUNDWATER MANAGEMENT: Documents the development of flow models and managed aquifer recharge scenarios.
CHAPTER 9 SUMMARY AND CONCLUSIONS: Concludes the thesis with a review of findings, recommendations, and the Safety Status Warning Index.
Keywords
Groundwater, Sustainability, Hard Rock Terrain, Hydrogeology, GIS, Remote Sensing, MODFLOW, Aquifer, Morphometric Analysis, Risk Assessment, Bengaluru North, Water Quality Index, Groundwater Recharge, Soil Properties, Numerical Modeling
Frequently Asked Questions
What is the primary goal of this research?
The primary goal is the development of an integrated approach for groundwater sustainability and management in a hard rock terrain, specifically focusing on the Bengaluru North region.
What specific problem does this study address?
The study addresses the critical decline of groundwater levels, bore well drying, and deterioration of groundwater quality due to over-exploitation and rapid urbanization in Bengaluru North Taluk.
Which scientific methods are primarily used?
The research employs Remote Sensing and GIS for mapping, electrical resistivity tomography for subsurface investigation, and numerical flow modeling using the MODFLOW software package.
What is meant by an "integrated approach"?
An integrated approach means looking beyond the aquifer itself to consider surface water links, catchment-level management, and cross-sectoral interplay with economics, energy, and climate policies.
How is water quality assessed in this study?
Water quality is assessed by collecting numerous samples for physical and chemical analysis, computing a Water Quality Index (WQI), and mapping these results using spatial analysis.
What are the key thematic areas covered in the main section?
The work covers morphometric analysis, hydrogeological analysis, groundwater quality risk assessment, electrical resistivity surveys, and the development of sustainable management models.
How does the Safety Status Warning Index work?
The index uses four specific criteria—groundwater level decline, vertical land balance, water contamination level, and surface water reduction—to classify regions based on their safety status, ranging from "Best" to "Worst".
Why is understanding the "vadose zone" important in this research?
The vadose zone (unsaturated zone) governs the fluctuation of water levels in hard rock aquifers; understanding it is essential for formulating effective artificial recharge strategies.
- Quote paper
- Nanjundi Prabhu (Author), 2020, An Integrated Approach towards Ground Water Sustainability and Management for a Hard Rock Terrain, Munich, GRIN Verlag, https://www.grin.com/document/1245569
