Ground-water studiesl

Ground-water studiesl

A n international guide for reseurch and practice

Edited by R.

H.

A. A.

J. Ineson,

V.

A

Incorporating Supplement 2' (1973) und Supplement 2 (1975)

The Unesco Press Paris 1975

TITLES IN THIS SERIES / D A N S CETTE COLLECTION

1. The use of analog and digital computers in hydrology : Proceedings of the Tucson symposium, June 1966 / L’utilisation des calculatrices analogiques et des ordinateurs en hydrologie : Actes du colloque de Tucson, juin 1966. Vol. 1 and 2. (Co-edition IASH-Unesco/Coédition AIHS- Unesco.)

2. Water in the unsaturated zone: Proceedings of the Wageningen Symposium, June 1966 / ^L’eau clans la zone non saturée: Actes du symposium de Wageningen, juin 1966. Edited by / Edité par P. E. Rijtema and H. Wassink. Vol. 1 and 2. (Co-edition IASH-Unesco / Coédition AIHS-Unesco.)

3. Floods and their computation : Proceedings of the Leningrad Symposium, August 1967 / Les crues et leur Evaluation: Actes du colloque de Leningrad, aoirt 1967. Vol. 1 and 2. (Co-edition IASH-Unesco-WMO / Coédition AIHS-Unesco-OMM.)

4. Representative and experimental basins : A n international guide for research and practice.

Edited by C. Toebes and V. Ouryvaev. Published by Unesco. (Willalso appear in Spanish.) 4. Les bassins représentatifs et expérimentaux : Guide international des pratiques en matière de recherche. Publié sous la direction de C. Toebes et V. Ouryvaev. Publié par l’Unesco.

(A paraître également en espagnol.)

4. Penpesen~a~usxabe u 3?~~nepudien~u~zana~e bacceüna~. Mewdyxupodxoe pyxo- sodcTso no ucc&edosunuz& u npaxTuxe. IIog pe,qaKqneR I<. ToyGca il

5. Dischavge of selected rivers of the world / Débit de certains cours d’eau du monde / Caudal de algunos rios del mundo f PaczodaL soda^ ai36punna~x pex &upa. Published by Unesco / Publié par l’Unesco.

Vol. I: General and régime characteristics of stations selected Vol. I: Caractéristiques géné- rales et caractéristiques du régime des stations choisies / Vol. I: Curacteristicas generales y características del régimen de las estaciones seleccionadas 1 TOM I: 06uque U pexcufi-

xabe XapaxTepucTuxu u36pannaix CTanqUÜ.

Vol. II: Monthly und annual discharges recorded at various selected stations (from start of observations up to 1964) Vol. II: Débits mensuels et annuels enregistrés en diverses stations sélectionnées (de l’origine des observations d l’année 1964) 1 Vol. II: Caudales mensuales y anuales registrados en diversas estaciones seleccionadas (desde el comienzo de las observa- ciones hasta el año 1964)

1

* Vol. III: Mean monthly and extreme discharges (1965-1969)

1

extremos (1965-1969) J TOM III: Cpedxe-meczwnaie u 3xcTpedia&anbie paczod?>i 6. List of International Hydrological Decade Stations of the world

1

Décennie hydrologique internationale existant dans le monde / Lista de las estaciones del Decenio Hidrológico Internacional del mundo f Cnucox cmxquü Mexdyxupodxozo zudpo~ozu~ec~ozo deczTuneTuz 3e~wozo ulapa. (Published by Unesco / Publié pas 1 ’Unesco .)

7. Ground-water studies : An international guide for research and practice. Edited by R. H. Brown, A. A. Konoplyantsev, J. Ineson and V. S. Kovalevsky. (Willalso appear in French, Russian and Spanish / Paraîtra également en espagnol, en français et en russe.)

8. Land subsidence : Proceedings of the Tokyo symposium, September 1969 Affaissement du sol: Actes du colloque de Tokyo, septembre 1969. Vol. 1 and 2. (Co-edition IASH-Unesco / Coédition AIHS-Unesco.)

9. Hydrology of deltas: Proceedings of the Bucharest symposium, M a y 1969 / Hydrologie des deltas: Actes du colloque de Bucarest, mai 1969. Vol. 1 and 2. (Co-edition IASH-Unesco / Coédition AIHS-Unesco.)

10. Status and trends of research in hydrology / Bilan et tendances de la recherche en hydrologie.

Published by Unesco / Publié par l’Unesco.

11. World water balance: Proceedings of the Reading symposium, July 1970 / Bilan hydrique mondial: Actes du colloque de Reading, juillet 1970. Vol. 1-3. (Co-edition IASH-Unesco / Coédition AIHS-Unesco.)

B. YpbIBaeBa. M3AaHO K)HeCKO.

duTc% a0 1964 20aa).

(1965-1969 22.).

* 12. Research on representative und experimental basins: Proceedings of the Wellington (N.Z.)

symnposiiim, Deceniber 1970

1

* 13. Hydrometry: Proceedings of the Koblenz symposium, September 1970 / Hydrométrie : Actes du colloque de Koblenz, septembre 1970.

C o m p a n i o n volume Hors collection

Internatioiial legend for hydrogeological maps / Légende itrternationule cles curtes hydrogéologiques

1

Leyendu internacional pura mupus hiclrogeológicos / MealcdympodmsL ~ ~ e z e n d a x zudpo- z e o ~ ~ o z z ~ w c ? c u ~ i ?capTa&.

* To be published

1

Published by the Unesco Press, 7 Place de Fontenoy, 75700 Paris Printed by NICI, Gent

First edition with binder Supplement 1

ISBN 92-3-100960-5 Supplement 2 ISBN 92-3-101247-9

0 Unesco 1972, 1973, 1975 Printed in Belgium

Preface

The International Hydrological Decade (IHD) 1965-75 was launched by Unesco at the thirteenth session of its General Conference to promote international co-operation in research and studies and the training of specialists and technicians in scientific hydrology.

Its purpose is to enable all countries to make a fuller assessment of their water resources and a more rational use of them as man’s demands for water constantly increase in face of developments in population, industry and agriculture. In 1970 national committees for the Decade had been formed in 105 of Unesco’s 125 Member States to carry out national activities and to contribute to regional and international activitks within the programme of the Decade. The implementation of the programme is supervised by a Co-ordinating Council, composed of thirty Member States selected by the General Conference of Unesco, which studies proposals for developments of the programme, recommends projects of interest to all or a large number of countries, assists in the de- velopment of national and regional projects and co-ordinates international co-operation.

Promotion of collaboration in developing hydrological research techniques, diffusing hydrological data and planning hydrological installations is a major feature of the programme of the I H D , which encompasses all aspects of hydrological studies and research. Hydrological investigations are encouraged at the national, regional and international level to strengthen and to improve the use of natural resources from a local and a global perspective. The programme provides a means for countries well advanced in hydrological research to exchange scientific views and for developing countries to benefit from this exchange of information in elaborating research projects and in implementing reccnt developmmts in the planning of hydrological installations.

As part of Unesco’s contribution to the achievement of the objectives of the IHD the General Conference authorized the Director-General to collect, exchange and disseminate information concerning research on scientific hydrology and to facilitate contacts between research workers in this field. T o this end Unesco has initiated two collections of publica- tions, ‘Studies and Reports in Hydrology’ and ‘Technical Papers in Hydrology’.

The collection ‘Studies and Reports in Hydrology’ is aimed at recording data collected and the main results of hydrological studies undertaken within the framework of the Decade as well as providing information on research techniques. Also included in the collection will be proceedings of symposia. Thus, the collection willcomprise the com- pilation of data, discussion of hydrological research techniques and findings, and guidance material for future scientific investigations. It is hoped that the volumes willfurnish material of both practical and theoretical interest to hydrologists and governments participating in the I H D and respond to the needs of technicians and scientists concerned with problems of water in all countries,

The responsibility for the choice and presentation of facts and for opinions and views expressed lies with the organizations and authors cited in the foreword to each publicatioii in the collection. The designations employed and the presentation of the material in this guide do not imply the expresssion of any opinion whatsoever on the part of the Unesco Secretariat concerning the legal status of any country or territory, or of its authorities, or concerning the delimitations of the frontiers of any country or territory.

Contents

Introduction*

1 Principal features of the ground-water régime

1.1 1.1.1 1.1.2 1.1.3 1.2 1.2.1 1.2.2 1.3

Basic principles Origin of ground water Hydrological cycle

Surface water contrasted with ground water Concept of the ground-water régime Functioning of the ground-water régime Significance of ground-water movement

Practical steps for initial ground-water development References

2 Ground-water fundamentals

2.1 2.1.1 2.1.2 2.1.3 2.2 2.3 2.3.1 2.3.2 2.3.3

Geology

Lithology and structure

Development of fissures and joints Boundary conditions

Classification of water present in rocks Ground-water hydraulics

Laminar flow Turbulent flow

Unconfined and confined ground water References

3 Defining the ground-water régime

3.1 3.1.1 3.1.1.1 3.1.1.2 3.1.1.3 3.1 .I .4 3.1.1.5 3.2

Aquifer definition Methods Inventory

Field reconnaissance Photogeology Geophysics Drilling and logging

Dynamic factors influencing ground-water régime

Contents puge I Rev. 2 (1975)

Contents

3.2.1 3.2.2 3.2.2.1 3.2.2.2 3.2.2.3 3.2.2.4 3.2.3 3.2.3.1 3.2.3.2 3.2.4 3.2.5 3.2.6 3.2.6.1 3.2.6.2 3.2.6.3 3.2.6.4 3.2.7 3.2.8

General concepts Climatic factors Precipitation Evaporation Air temperature Atmospheric pressure Hydrologic factors Surface water Saline intrusion Biological-soil factors Zone of aeration Geological factors Seismic phenomena Volcanism

Other geologic processes Topographic relief Artiticial factors

General properties of unconfined régime References

4 Selection of areas for detailed studies

References

5 Defining the water balance

5.1 5.1.1 5.1.2 5.2 5.2.1 5.2.2 5.3 5.4 5.5

5.5.1 Dipping aquifers 5.5.2

5.5.3

5.5.4 Subsurface measurement of temperature 5.6

5.6.1 Scope of study 5.6.2

5.6.3 Balance area 5.1

5.7.1 5.7.2

General elements of the balance Basic data required for selection of areas Basic data required for ground-water inventory Determining the total water balance

Computing parameters of water balance and ground-water flow Requirements for determining water-balance elements

Computation of the unconfined ground-water balance Assessment of the ground-water component of streadow Computation of ground-water flow from subsurface temperatures Vertical conductivity of confining beds

Vertical flow near the land surface

Salt balance and the chemical composition of ground water

Expressions for compiling salt-balance elements related to unconfined ground-water flow

The ground-water régime under disturbed conditions The ground-water régime in areas of water development

Unconfined ground water and water balance in areas of irrigation and reclamation

References

6 Determining hydrodynamic parameters of ground-water flow

6.1 Aquifer tests 6.1.1

6.1.1.1 6.1.1.2

Aquifer response to changing discharge or head Profiles of flow in confined and unconfined aquifers Steady flow to a completely penetrating well

Contents page 2 Rev. 2 (1975)

Contents

6.1.1.3 6.1.1.4 6.1.1.5 6.3.1.6 6.1.1.7 6.1.2 6.1.3 6.2 6.2.1 6.2.2 6.2.3 6.2.4 6.3*

6.3.1 * 6.3.2*

6.3.3*

6.3.3.1*

6.3.3.2*

6.3.3.3*

6.3.4*

6.3.4.1*

6.3.4.2*

6.3.4.3*

6.3.4.4*

6.3.4.5 * 6.3.4.6*

6.3.4.7*

6.3.5*

6.3.6*

6.3.7*

6.4

Steady flow to a partially penetrating well Analysis of non-steady flow in the vicinity of wells Other solutions to aquifer-test configurations Aquifer test design

Field observations Recharge tests

Hydrological parameters of fissured and jointed rocks Determining aquifer parameters from water-level data Determining hydraulic diffusivity

Determining specific yield from moisture measurements in zone of aeration Computing areal recharge, infiltration and evapotranspiration

Assessing areal distribution of precipitation and evapotranspiration The uses of simulation models

Introduction Physical models Analogue techniques

Viscous-fluid parallel plate model Membrane model

Electrical analogue model Mathematical techniques Analytical solutions

Differential analyser solutions Type curve and similar techniques Graphical solutions

Numerical techniques Inverse problems

Mathematical techniques as optimizing tools

Computer programmes which solve electronic circuit problems Hybrid computers

Simulation of environmental isotope data

Estimating resistance to percolation through beds of surface-water bodies References *

7 Observations and instruments

7.1 7.1.1 7.1.1.1 7.1.1.2 7.1.1.3 7.1.1.4 7.1.1.5 7.1.1.6 7.1.2 7.2 7.2.1 7.2.1.1 7.2.1.2 7.2.1.3 7.2.1.4 7.3 7.4 7.4.1 7.4.1.1 7.4.1.2 7.4.2 7.4.3 7.4.4

Location of observation wells

Environments affecting the design of well networks Platform arcas

Mountain-folded areas Permafrost areas

Submontane terrains and valleys in arid regions Areas of alluvial and outwash plains

Karst areas

General provisions for location of observation wells Installing and testing observation stations

Wells

WellWishing and sealing operations Screen design

Screen installation

Testing of observation wells

Requirements of instruments and equipment for ground-water observations Observation criteria

Objectives of a water-level measurement programme General remarks

Frequency of observations

Measurement of ground-water flow velocity Observations of ground-water temperature Observations of ground-water quality

Contents page 3 Rev. 2 (1975)

Contents

7.4.4.1 7.4.4.2 7.4.4.3 7.4.4.4 7.4.5 7.4.6 7.5 7.6

Types of analyses Pore solutions Methods of sampling

Representation of chemical data

Observation of soil moisture in the zon- of a.;ration Observation-well management

Records and data display

Design and planning of observational networks (in preparation) References

8 Analysis and presentation of the data

8.1 8.1.1 8.1.2 8.1.3 8.1.4 8.2 8.3 8.3.1 8.3.2 8.3.3 8.3.4 8.4 8.4.1 8.4.2 8.5

Statistical techniques Correlation and regression Simple linear regression Multiple linear regression Graphical simple regression Presentation of data on maps

Forecasting changes in the ground-water régime The statistical method

The hydrodynamic method The water-balance method The analogy method

Compilation of results of ground-water investigations

Forms and arrangement of annual information on ground-water régime and balance

Summary of data on the régime, balance and total resources of ground water

Computer processing of ground-water data (in preparation) References

9 Application of geophysical techniques in ground-water investigations

9.1 9.1.1 9.1.2 9.1.2.1 9.1.2.2 9.1.2.3 9.1.2.4 9.1.3 9.1.3.1 9.1.3.2 9.2 9.2.1 9.2.2 9.2.2.1 9.2.2.2 9.2.2.3 9.2.2.4 9.2.3 9.2.4 9.2.5 9.2.6

Geophysical prospecting Introduction

Ground geophysical prospecting Electrical methods

Seismic prospecting Gravity prospecting Thermometry

Airborne geophysical prospecting Infra-red thermometry

Radio-wave methods

Geophysical logging of boreholes Introduction

Electrical logging Spontaneous potential log Resistivity logs

M u d resistivity measurement Fluid conductivity logs Caliper log

Sonic logging (velocity log) Temperature log

Water flow log or flowmeter

Contents pupe 4 Rev. 2 (1975)

Contents

9.2.7 9.2.8 9.2.8.1 9.2.8.2 9.2.8.3 9.2.9 9.2.10 9.2.1 1

Dip meter Nuclear logging Natural gamma-ray log Gamma-gamma logging Neutron logging

Direct observation logging

Combined logging in hydrogeology, examples of interpretation Stratigraphic correlations between boreholes

10 Nuclear techniques in ground-water hydrology

10.1 10.2 10.2.1 10.2.1.1 10.2.1.2 10.2.2 10.2.2.1 10.2.2.2 10.2.2.3 10.2.3 10.2.3.1 10.2.3.2 10.2.3.3 10.2.4 10.2.4.1 10.2.4.2 10.2.4.3 10.2.5 10.2.5.1 10.2.5.2 10.2.5.3 10.2.5.4 10.2.5.5 10.3 10.3.1 10.3.2 10.3.3 10.3.3.1 10.3.3.2 10.3.3.3 10.3.3.4 10.3.3.5 10.3.4 10.4

Introduction

Environmental isotope hydrology

Stable isotopes of hydrogen and oxygen in the hydrological cycle Isotopic variations in precipitation

Isotopic composition of ground water Tritium in the hydrological cycle History of tritium in the atmosphere Tritium in ground water

Infiltration studies

Carbon isotopes in the hydrological cycle Basis of carbon-14 dating of ground water Correcting for mineral carbonate Applicability

Project planning

Development of an isotope hydrology study Sampling

Costs of analyses Examples of application

Interconnexions between ground water and lakes Interconnexions between ground water and rivers Interconnexions between aquifers

Transit time and origin of water ín aquifers Flow velocity from 14C data

Artificial isotope hydrology Radioactive tracers Techniques Applications

Effective porosity of an aquifer Transmissivity

Dispersivity

Ground-water flow velocity Direction of ground-water flow Practical considerations Glossary

Further reading References

1 1 Well construction and spring development (in preparation)

12 Hydrology of zone of aeration (in preparation) 13 Analytical and investigational techniques for

non-indurated rocks (in preparation)

Contents page 5 Rev. 2 (1975)

Corirents

14 Analytical and investigational techniques for fissured and fractured rocks

14.1 14.1.1 14.1.2 14.1.3 14.1.4 14.1.5 14.1.6 14.1.7 14.2 14.2.1 14.2.1.1 14.2.1.2 14.2.1.3 14.2.2 14.2.2.1 14.2.2.2 14.2.2.3 14.2.3 14.2.3.1 14.2.3.2 14.2.4 14.2.4.1 14.2.4.2 14.2.4.3 14.2.4.4 14.2.5 14.2.6 14.2.7 14.3 14.3.1 14.3.2 14.3.2.1 14.3.2.2 14.3.3 14.3.3.1 14.3.3.2 14.3.3.3 14.3.3.4 14.3.3.5 14.3.4 14.3.4.1 14.3.4.2 14.3.4.3 14.3.4.4 14.3.4.5 14.3.4.6 14.3.5 14.3.5.1 14.3.5.2 14.3.5.3 14.3.6 14.3.6.2 14.3.6.3 14.3.6.4 14.3.6.1

The hydrogeology of fraclured and fissured rocks Introduction

Fractures and fissures Porosity

Hydrodynamics of fissures Permeability

Ground-water bodies Recharge

The hydrogeology of non-carbonate hard rocks Intrusive igneous rocks

Introduction Water-bearing granite

Springs, wells and boreholes in granite The hydrogeology of metamorphic rocks Fissures and fractures

Intensively metamorphosed rocks

Quartzite, amphibolite, and crystalline limestone Non-carbonate, indurated, sedimentary rocks Sandstones

Shales

Extrusive volcanic rocks Basalts

Trachytes and rhyolites Extrusive features Prospecting

The quality of water from fissured, non-carbonate rocks The influence of the climate, the environment and the relief Geological and hydrological criteria for siting of boreholes Hydrogeology of carbonate rock terrains

Introduction

Characteristic openings in carbonate rocks Different rock types

Types of openings

Natural controls of circulation The different zones of flow

Hydraulic conditions in carbonate rocks Permeability and transmissivity

Geographical and geological aspects Springs

Ground-water chemistry Dissolution of limestone Dissolution of dolomite Aggressivity of water Precipitation of CaC03

The effect of chemical phenomena in channel formation General water quality

Water resources

Recharge or replenishment Recharge rate : recharge index Resources

Field investigations

Geomorphological investigations Geological investigations Geophysical investigations Use of tracers

Conlenls pugc 6 Rev. 2 (1975)

Contents

14.3.6.5

14.3.7 Exploitation

14.3.7.1 Exploitation of springs

14.3.7.2 Exploiting the reservoir formations Use of boreholes and wells

References

15 Hydrogeological problems related to the quality of ground water (in preparation)

Appendixes

A B*

C D E F G

Selocted general references in ground-water hydrology List of definitions of terms used in text

Values of the function f(B1, z/L)

Values of the well function, W(u), for values of u between 10-15 and 9.5 The complementary error function, ikfc h

Standard units of deviation, t, and computed values of t/Vn

I List of symbols used in text

Contents page 7 Rev. 2 (1975)

List of tables

2.1.1 3.1.1.5 5.3a 5.3b 6.1.1.3a 6.1.1.3b 7.4.2a 7.4.2b 7.4.2~

7.4.4.1 8.1.2 8.1.3 9.1.2.1 9.1.2.2 9.1.2.3 9.2.8 10.2.1 10.3.1 14.1.4a 14.2.1.3a 14.2.1.3b 14.2.1.3~

14.2.2.2a 14.2.2b 14.2.2.2~

14.2.2.2d 14.2.3.1a 14.2.3. lb 14.2.3.1~

14.2.3.2a 14.2.4.1a 14.2.4. lb 14.3.5.1a 14.3.5.1 b 14.3.5.3b

Rock classification Borehole logging methods

Determination of Techarge rates for the unconfined ground-water régime at a. balance plot in an area near Moscow (U.S.S.R.)

Water balance for the unconfined ground-water régime at a plot in an arca nesr Moscow (U.S.S.R.)

Values of the seepage resistance function 5 Approximate velues of r,

Dye quantities used in measuring ground-water velocity Rhodamine dyes used as tracers in time-of-travel studies Recommended doses of salt tracers for injection into well Principal features of several types of wahr-quality analyses Data and computations for exampie of two-variable regression

Multiple regrsssion example: Baldwin Park, California, observation wcll Resistivity of waters and rocks

Elastic-wave velocity in rocks Density of the more common rocks

Content of radioactive elements in some types of sedimentary rocks Main environmental isotopes used in hydrology

Radioisotope tracers used in ground-water investigations Relation between water flow and width of fractures Yields and depths of wells in Maine

Characteristics of wells in South Africa Characteristics of wells in various regions

Hydraulic conductivity in different types of metamorphic rocks

Transmissivity (T) and storage coefficients (S) in the Brunswick shah, N e w Jersey Well yields in Connecticut

Mean yields in different types of metamorphic rocks Hydraulic conductivity and porosity in sandstones

Hydraulic conductivity for different fissure widths in sandstone Hydraulic conductivity in Tunisian sandstones

Porosity in shales

Hydraulic conductivitics and porosities of basalts in the United States of America Transmissivities and hydraulic conductivities of the basalt flow of the

Oujda region

Recharge rates in Mediterranean countries

Monthly variation in recharge rates in Hungary, average taken over a period of twenty-two years

Examples using formula 14.3(17)

List of tables page 1 Rev. 2 (1975)

List of illustrations

1.1.2 1.2a 1.2b 2.1.3 3.1.1.5a 3.1.1.5b 3.1.1.5~

3.2.2.1 3.2.3.2 4 5.2.la 5.2.lb 5.2.1~

5.3a 5.4a 5.4b 5.4c 5.5 5.5.1 5.5.2a 5.5.2b 5.5.4a 5.5.4b 5.6.2 5.1.2a 5.7.2b 5.1.2~

6.1.1 6.1.1.1 6.1.1.4a 6.1.1.4b

Schematic representation of the hydrological cycle Diagram showing divisions of subsurface water

Schematic cross-section showing occurrence of ground water Examples of aquifer boundaries

Schematic plot of well logs in unconsolidated rocks Schematic plot of well logs in consolidated rocks Actual resistivities of rocks

Relationship between recharge to and discharge (by evaporation) from unconfined ground water and the depth to water

lnterrelation between fresh and salt water in coastal aquifers

Features of interrelation between unconfined and confined ground waters Diagram of flow element for observation of soil moisture in the zone of aeration

Diagram of moisture changes in the soil prism during the time interval from Ti to Tz

Soil moisture profile in the zone of aeration

Dynamics of elements of uncon6ned ground-water balance for 1951-52 at a balance plot

Separation of components of streamflow Analysis of stream hydrograph separation

Stream hydrograph for gauging station at basin outlet Heat components affecting the earth’s surface Section of dipping aquifer

Section of semi-confining layer Type curves of the function f(/h, z/L)

Critical temperature gradients for the onset of convection in small-diameter wells filled with pure or saline water

Critical temperature gradients for the onset of convection in small-diameter wells filled with glycerol (98 per cent)

Vertical sections and notation for compiling salt-balance elements at a station

Diagram of lysimeter design

Sketch showing piezometer, position close to drain for assessing artesian discharge to drain

Diagram of head distribution in two-layer formations

Hydrograph from hypothetical observation well showing definition of drawdown

Schema of unsteady flow to a well Relation of W(u) and u to s and r2/t

Straight-line approximation of well function W(u)

List of illustrations page I Rev. 2 (1975)

List of illustrations

6.1.1.5 6.1.1.6 6.1.2a 6.1.2b 6.1.2~

6.2.1 6.2.2 6.2.3a 6.2.3b 6.2.3~

6.4a 6.4b 6.4~

6.4d 7.1.1.la 7.1.1.1b 7.1.2a 7.1.2b 7.1.2~

7.1.2d 7.2.la 7.2.lb 7.2.1.1 7.2.1.2a 7.2.1.213 7.2.1.3a 7.2.1.3b 7.4.2 7.4.3 7.4.4.4a 7.4.4.413 7.4.4.4c 7.4.4.4d 7.4.4.4e 7.4.4.4f 7.4.4.48 7.4.5a 7.4.5b 7.5a 7.5b 8.1.la 8.1.lb 8.1.2 8.1.4a 8.1.4b 8.3.2 9.1.2.la

Aquifer boundary conditions as reflected in departures of data plots from Theis-type curve

Pumping response as predicted in observation wells Profile of vertical recharge into unsaturatcd zone Dimensionless graph of infiltration

Section through double-ring infiltrometer

Element of two-dimensional unconfined ground-water flow Soil-moisture profiles for the zone of aeration

Semi-infinite unconfined ground-water flow

Graphs of variation in unconfined ground-water level and values of recharge from above

A section through three wells in line with a sloping aquiclude

Section view of parameters used in determining imperviousness of river bed Graph of the function '6

Observation piezometers for determining resistances to seepage through a bed of a canal

Section view with nomenclature for determining AL values for surface- water bodies in contact with two-layered ground-water reservoirs Typical diagrams of structure in representative basins

Arrangement of lines of observation wells in a river basin Location of observation wells in an experimental river basin Diagram of hydrodynamic zones

Schematic profile along an interfluvial line of observation wells on a balance plot

Diagram of inclined piedmont plain

Drive point screen and casing for observation well Design features of observation well

Details of well-sealing operations Well screen design features

Screen for use in consolidated rocks Installation of gravel-packed screen Flush-fitted screen installation

Graph of change in tracer concentrations in observation well Principal types of hydrogeothermal zones

Classification diagram for illustrating chemical composition of ground water

Example of semi-logarithmic diagram Logarithmic scales of solubilities

Analyses represented by three points plotted in trilinear diagram

Trilinear diagram for comparing chemical characteristics of individual water samples

Double trilinear diagram for comparing chemical characteristics of indivi- dual water samples

Analyses of four water samples represented by vertical bar graphs Arrangement of boreholes on microplots for soil-moisture sampling Location of boreholes for sampling along perimeters of polygons Graphs of ground-water régime

Frequency and duration of ground-watcr levels

Normal distribution of plotted points about the regression line

Plot used in demonstrating the effect of sample range on computed correla- tion coefficient

Plot of data from Table 8.1.2 and the computed regression line Four possible outcomes of plotting Y against X

Plot showing the two regression lines and the structural line

Diagram showing location of observation-well nodes in analysing two- dimensional flow

Curves giving the total porosity of a saturated non-argillaceous aquifer as a function of the formation factor F

List of illustrations page 2 Rev. 2 (1975)

List of illustrations

9.1.2.lb 9.1.2.1~

9.1.2.ld 9.1.2. le 9.1.2.lf 9.1.2.lg 9.1.2. lh 9.1.2.li 9.1.2.2a 9.1.2.2b 9.1.2.2~

9.1.2.2d 9.1.2.2e 9.1.2.22 9.1.2.2g 9.1.2.4 9.1.3.la 9.1.3.lb 9.2.2.1 9.2.2.2 9.2.3 9.2.5 9.2.8a 9.2.8b 9.2.10a 9.2.1 Ob 9.2.10~

9.2.1 Od 9.2.11 10.2.1.la 10.2.1.lb 10.2.1.2 10.2.2.la 10.2.2.lb 10.2.2.3 10.2.4.2 10.3.2 10.3.3.4a 10.3.3.4b 10.3.3.5 14.2.1.3 14.3.2.2a 14.3.2.2b 14.3.2.2~

14.3.2.2d

Quadripole AMNB configuration for resistivity measurements The depth of investigation increases with the distance AB

Electrical soundings, showing the dip of a bed with constant thickness Resistivity profile over a vertical fault

Tuldm Valley: interpretation cross-section

Tulúm Valley: map of the resistive fill and of the conductive basement Marismas. Curve giving the T D S as a function of the transversal resistance of the water-bearing formation

Yamaoussoukro: apparent resistivity map with AB = 400 m Example of a seismic refraction recording

Three layers separated by parallel planes ; refracted-ray paths and time- distance curve

Seismic reflection : reflected-ray paths and time-distance curve

Seismic reflection : galvanometric recording with indication of the arrivals of reflected waves

Wadi Azum Valley: seismic refraction sounding No. 1, time-distance curves Wadi Azum Valley: results of the seismic refraction soundings along section 213

Seismic reflection: variable density record section. The strip on the left side where the markers are interrupted corresponds to a fault

Finding an aquiferous formation by temperature measurement Infra-red scanning

Example of black and white thermal imagery Spontaneous potential and resistivity logs Devices used for resistivity logging

Caliper log and sonic log showing a fractured zone (a) in dolomites Temperature log showing water-bearing sands

Basic components of geophysical well-logging equipment

Diagram of installation for the investigation of saturated and unsaturated zones, in combination with well sinking by the method of embedding Theoretical logs : spontaneous potential, resistivity, gamma ray Theoretical gamma-ray and neutron logs

Correlation with natural gamma and neutron (n,n) logs

The relationship of six different geophysical logs to lithology, upper Brazos Riveï, Texas

Correlation between boreholes using geophysical logs

The annual mean 6 1 8 0 of precipitation as a function of the annual mean air temperature at surface

Deuterium and oxygen-1 8 correlation in precipitation and surface waters Deuterium and oxygen-18 correlation in two Saharian lakes going dry Tritium concentration in precipitation in Ottawa (Canada), Valentia (Ireland), and Vienna (Austria), from 1953 to 1970

Geographical distribution of the tritium concentration (in Tritium Units) in precipitation in 1963

Tritium content and soil moisture profiles at different times in a field experiment in Giessen (Federal Republic of Germany)

I4C sampling in the field

Instrument for borehole dilution measurements

Schematic diagram showing how the tracer concentration changes with time in a borehole dilution experiment

Arrangement of a set of detectors for determining vertical flow in a borehole

Diagram of water flow direction determination in a borehole Cross-section of sheeted terrain

Types of fissures

Caves of the Dent de Crolles Lehman Caves, Nevada Orgnac Cave

List of illustrations pugs 3 Rev. 2 (1975)

List of illustmtions

14.3.2.2e 14.3.2.2f 14.3.3.1a 14.3.3.1 b 14.3.3.2a 14.3.3.2b 14.3.3.5a 14.3.3.5b 14.3.3.52 14.3.3.5d 14.3.5.3a 14.3.5.3b 14.3.5.5~

Miremont Cave Lattice labyrinth

Karstified Eocene Limestone in the cutting of motor road near Zadar Diagram of karst system

Unconfined aquifer Confined aquifer Springs

Karstic springs of denudation Karstic springs of dams or faults Coastal springs

Discliayge from the Fontaine de Vaucluse in 1968 Determination of u

Unsteady flow in an anistropic aquifer

List of illustrations page 4 Rev. 2 (1975)

Introduction

During the International Hydrological Decade important water-resources problems were examined. The principal problems included the evaluation of the water resources of countries, studies of the interrelationship between surface and underground waters, establishment of the principles governing the ground-water régime, and the drawing of water balances.

A m o n g the objectives of the IHD was assistance in establishing regional water balances in individual countries and over continents, in long-term forecasting of changes in ground-water resources both under natural conditions and under the influence of man, and in establishing projects and programmes for the rational development of water resources.

These questions are of especial interest for developing countries with limited water resources. For the study and solution of these important problems extelisive methodolo- gical investigations to define the régime characteristics and water balances for the ground- water resource should be undsrtaken and a permanent network of water-data observation stations shoulct be established in all countries. Attention should be paid to the minimum amount of scientific investigation which needs to be undertaken within this network.

During the period of the IHD, methods of ground-water investigations were improved and modern instrumentation and the newest methods of processing and analysing data were introduced. Data obtained during the I H D programme should be analysed systematically and the techniques of forecasting changes in time should be established.

In organizing and implementing the foregoing investigations the experience of hydro- geologists should be made available from those countries where extensive research has been effectively conducted. This reason prompted the Co-ordinating Council of the IHD to approve, at its second session, the compilation of a guide for ground-water studies. The first draft of the guide, prepared by the U.S.S.R., was examined in February 1968 by a Unesco panel of experts, drawn together to evaluate the scope and arrangement of subject-matter and to accomplish the principal technical review and editing. The panel improved and developed a rcvised outline for the guide, representing in effect a modest expansion of that prepared by the U.S.S.R. The revised version was approved by the Co-ordinating Council at its fourth session in M a y 1968, and with some changes by the editors is reflected in the ‘Contents’ of this guide. The present guide has been compiled to this revised outline and inc1ud.a contributions from the U.S.S.R., United States of America, United Kingdom, Netherlands, France and the Federal Republic of Germany.

The present guide is for the use of persons responsible for organizing and conducting ground-water investigations particularly in developing countries. The guide contains discussions and recommendations concerning the organization and methods of under-

Introduction page I Rev. 2 (1975)

taking ground-water investigations

;

Recognizing the wide variety of natural conditions in which ground-water studies will be undertaken, only those recommendations of the guide which are applicable to a given set of conditions should be implemented. The guide provides examples of methods of observing and processing data, but such examples should not exclude the application of other accepted and approved methods.

The main purpose of this guide is to contribute to the development of ground-water investigations in different countries, to enlarge the body of knowledge concerning the natural laws relating to ground waters, to provide assistance for the more rational organization of detailed ground-water investigations on representative basins and at Decade stations, and to carry out other investigations related to the rkgime, water balance and resource of ground water.

It is dificult if not impossible to recognize each individual who contributed in some way to the process of structuring and shaping the content of the guide. It is appropriate, however, to acknowledge a number of the principal architects and authors responsibly associated with all phases of the effort. These include Mr. N. A. Bochin and Mr. R.

Tiburtini of the IWD Secretariat and the panel of experts for the guide comprising Mr. R. H. Brown (United States of America), Mr. G. Castany (Unesco Consultant), the late Dr. J. Ineson (United Kingdom), Mr. M. Y. Danilovich (U.S.S.R.), Dr. A. A. Kono- plyantsev (U.S.S.R.), Dr. V. S. Kovalevsky (U.S.S.R.), Professor W. Richter (Federal Republic of Germany), Prokssor H . Schoeller (France), Professor L. J. Tison (repre- senting IAHS), and Professor C. Voute (representing IAH).

Major contributors to the various chapters of the guide include Professors W. D . Babushkin, D. U. Kats, Drs. A. A. Konoplyantsev, V. S. Kovalevsky, A. V. Lebedev, Professor D. M. Shestakov and Dr. E. N. Yartseva (U.S.S.R.); Messrs. E. Cobb, N . J.

King, R. W. Stallman and H. E. Thomas (United States of America); and Professor W. Richter (Federal Republic of Germany).

Special recognition and thanks are due to several international scientists who ably undertook technical reviews of selected sections of the guide manuscript. These include Professor J. L. Bogardi (Hungary), Dr. E. C. Childs (United Kingdom) and Mr. D. A.

Kraijenhoff van de Leur (Netherlands).

Other contributions of material and reviews of additional selected sections were generously and effectively accomplished by : Professor H. Schoeller (France); Professor W. Richter and Dr. W. Lillich (Federal Republic of Germany); Messrs. J. P. Bell, A. G. P. Debney, R. A. Downing, D. A. Gray, G. P. Jones, and H. J. Richards (United Kingdom); Messrs. W. Back, H. H. Cooper, W. J. Drescher, R. F. Hadley, J. D . Hem, T. van Hylckama, J. Kimrey, C. L. McGuinness, J. Rollo, E. Sammel, E. Shuter and F. A. Swenson (United States of America); Mr. G. Y. Chernyak, Dr. N. M. Frolov, Messrs. A. I. Golovanov, I. P. Idarov, Professor B. I. Kudelin, Drs. O. V. Popov, 1. Y.

Sokolov, L. S. Yasvin and I. S. Zegtzer (U.S.S.R.); E. Bradley, R. M. Brown, R. Gon- fiantini, B. R. Payne, K. Przewlocki, G. Sauzay, C. K . Yen and Y. Yurtsever (IAEA);

R. G. Thomas (FAO), J. L. Astier and V. I. Ferronsky (IAEA).

Chief editors of the guide were Mr. R. H. Brown (United States of America) and Dr. A. A. Konoplyantsev (U.S.S.R.), assisted by the late Dr. J. Ineson (United Kingdom) and Dr. V. S. Kovalevsky (U.S.S.R.), all of w h o m contributed material to various chapters.

The guide in its present form is siiiiply a first attempt to reflect the combined thoughts of a number of international scientists drawn together under the common purposes of the THD. All participating countries are urged to maintain under continuing review their o w n hydrological and hydrogsological knowledge, experience and field techniques. As

Introduction poge 2 Rev. 2 (1975)

Introdidon

often as they recognize material suitable for inclusion in the guide, it should be prepared and submitted to the Secretariat for consideration for the preparation of amendments and additions to the guide.

The amendments and additions will be issued separately in loose-leaf form. Readers who wish to be informed of the appearance of new sections should return the card provided for this purpose. A m o n g the subjects proposed for future supplements are:

design and planning of ground-water networks; computer processing of ground-water data; well construction and spring development; hydrology of zone of aeration; analytical and investigational techniques for non-indurated rocks; hydrogeological problems related to the quality of ground water; artificial recharge; hydrogeological aspects of drainage; evaluation of ground-water resources

;

Introduction puge 3 Rev. 2 (1975)

1

1.1

Principal features of the ground-water régime

Basic principles

The term ground-water régime is used in the following discussion in its broader sense to refer to the general pattern of occurrence of ground water. Thus, it must necessarily include reference to the physical framework in which ground water occurs as well as to the hydrologic balance that results from natural and imposed recharge and discharge on a ground-water system.

Logically, a discussion of the ground-water régime should begin with a brief résumé of the origin of ground water so as to clarify the relationship of this resource to other modes of water occurrence.

1.1.1

Origin of ground water

According to Meinzer (I 923), ground water may be classified as being of either internal or external origin. Internal water (juvenile water) is derived from the interior of the earth as a new resource. External water is derived from atmospheric or surface water and m a y be trapped in rocks at the time the constituent material was deposited (connate water), or it may be absorbed into interstices some time after deposition (absorbed water).

For practical purposes, juvenile and connate water can be regarded as being largely academic curiosities. In rare instances they may contribute small quantities of minerals that might affect the local quality of the ground-water resource, but the volumes of water yielded by these sources are inconsequential relative to the volumes of water absorbed at the land surface. For that reason, the following discussion of the ground-water régime is based on the tentative assumption that the existing ground-water resource was initially absorbed from atmospheric or surface-water supplies (meteoric water) and that this resource is currently being recharged wholly from these sources. All other terrestrial and extraterrestrial sources of water can be safely ignored.

1.1.2

Hydrological cycle

Virtually all waters comprising a part of man’s environment are continuously being recycled in response to the forces exerted primarily by the sun’s energy and by the earth’s gravity. Water at or near the surface of the lithosphere tends to move upward into the atmosphere through processes of evaporation and transpiration. This moisture eventually falls back to the earth’s surface through processes of condensation and precipitation. This continuous recirculation of water is referred to as the hydrological cycle. Figure 1.1.2 is a

Growid-water studies

schematic representation after Parker et al. (1955). Detailed descriptions of the processes involved are presented by Meinzer (1923, 1942), Savarensky (1933), Lange (1950), Wundt (1953), Ovchinnikov (1955), Linsley et al. (1958), Todd (1959), Leopold and Langbein (1960), Keller (1961) and Schoeller (1962).

FIG. 1.1.2. Schematic representation of theLhydrologica1-cycle.

In this continuous cycle of water movement, the oceans provide the principal source of water, the atmosphere functions as the mover, and the land receives the primary benefit. Of the water that falls on the land, a part immediately returns to the atmosphere through evaporation, a part remains on the land surface, and a part enters the ground.

Water remaining on the surface contributes directly to the local surface-water régime.

Water entering the ground initially must generally satisfy the moisture-holding capacity of materials in the unsaturated zone before any increment is added to the ground-water régime. Thus, two gciieral modes of occurrence of water on and within the lithosphere are directly attributable to the circulation of water in the hydrological cycle. They are surface water and subsurface water. The latter includes water in both the unsaturated and saturated zones.

1.1 pugc 2

Principal features of the ground-wuter régime

1.1.3

Surfuce wuter contrasted with ground wuter

M a n is understandably most familiar with the surface-water régime as this resource is everywhere exposed to his direct observation. Even the untrained observer is generally aware of temporal and spatial variations in both quantity and quality of surfacewater supplies and commonly relates the origin of this resource to precipitation. Similarly, man’s use of surface water, the problems associated with its development and conservation, and the legal considerations that arise therefrom generally can be appreciated, if not fully understood, by the layman.

In contrast, water entering the ground passes out of direct contact with man’s senses and immediately assumes an aura of mystery to the non-technician. He may retain some intuitive comprehension of the occurrence of moisture in the soil‘ veneer and its relation- ship to precipitation or irrigation, but he has virtually no innate understanding of the movement of water through the zone of aeration and into the saturated zone. Consequent- ly, he cannot appreciate the general conditions of occurrence of this potential resource, nor the technical and legal problems associated with its location and development.

Partly because of man’s tendency to specialize and partly because of the marked contrast between the surface-water and subsurface-water environments, most workers in the past have concentrated their attention on one of these modes of water occurrence with only cursory reference to the other. As a result, the surface-water and subsurface- water régimes have commonly been treated as being separate and distinct. It should be stressed, therefore, that the two régimes are hydrologically interconnected and that they function together to form an integrated dynamic system in which water commonly moves alternately from one environment to the other on its way back to the oceans.

It is true that the two régimes are dissimilar in many respects, but because of their hydro- logic interdependence, it is technologically incorrect to treat them separately, except for purposes of classification, when evaluating the water resources of an area. This point is crucial to an understanding of the ground-water régime and willbe emphasized repeatedly in the following pages.

1.1 page 3

Principal features of the groicnd-water régime

1.2

Concept of the ground-water régime

In visualizing the ground-water régime the reader must be generally familiar with the divisions of subsurface water (Fig. 1.2a), and the principal modes of its occurrence (Fig.

1.2b). H e should also understand the definitions of certain basic terms which have been included in the Appendixes. To strengthen the preceding requisites, however, the reader must understand the geologic framework in which ground-water occurs and the hydraulics of ground-water movement. Discussions of these latter subjects are given in Chapters 2 aiid 3.

The concept of the ground-water régime is based on the fact that the local occurrence of ground water is not merely a product of chance, but the consequence of a finite com- bination of climatic, hydrologic, geologic, topographic, ecologic and soil-forming factors that together form an integrated dynamic system. These factors are interrelated in such a way that each provides some insight into the functioning of the total system and thus serves as an indicator of local conditions of ground-water occurrence. It is possible, therefore, to evaluate the general potential of an area for ground-water development by appraising as many of the factors listed above as practical and then by interpreting the

Land surface

?

2

:

Y Y

L

Y

e

O W c

N O c O

I Ø

._

2

U c

W S

N O

K O U U I 3 v U YI ._

c W c

N O

T

Belt of soil water

Intermediate belt

Capillary fringe

. - - -

Soil water

Intermediate vadose water

Fringe water W a t e r table

Ground water (phreatic water)

L W Y

- ;

.- 0 CI Y L U W c

.-

-

FIG. 1.2a. Diagram showing-divisions of subsurface water (after Meinzer, 1923).

I .2 page I

Gr6iir~E- water stirdies

local régime on the basis of known relationships among the factors and their eKect on the régime. The fundamental theory and field techniques for accomplishing this are discussed primarily in Chapters 5 and 6.

Most important among the preceding relationships are the physical characteristics of the framework in which the ground-water system occurs, the balance between ground- water recharge and discharge and the consequent hydrologic and lithologic implications that m a y be drawn, and the relationship among factors affecting the movement of ground water from the point(s) of recharge to the point@) of discharge. The manner in which water balances are drawn for ground-water systems is discussed primarily in Chapters 7 and 8.

Transpiration (xerophytes)

Transpiration (phreatophytes)

, - . . . .

-

I ---*

. Unconfined aquifer . . .

. .

. . .

. -

. ' C ' O N F I N E D A Q i I F E R , *

.

* .

. .

.

b . , . . G - R O U N D . W A T E R

. . . . .

FIG. 1.2b. Schematic cross-section showing occurrence of bround water.

1.2 pugc 2

Principal feutures of the ground-water régime

Obviously the ground-water régime must be viewed as a dynamic system in which water is absorbed at the land surface and eventually recycled back to that surface.

Water movement is through interconnected openings in the rocks that mantle the earth.

Thus, the framework in which ground water occurs is as varied as those rocks and as intricate as their deformation, which has progressed through geologic time. The possible combinations of variety and intricacy are virtually infinite and embrace most geologic disciplines, leading to the unavoidable conclusion that ground-water investigations at a given site almost always exhibit a certain uniqueness not completely amenable to wholly generalized prescriptions for their execution.

Ground water may be visualized as occurring in a subsurface reservoir, the boundaries of which are formed by adjacent less permeable or impermeable rocks. The reservoir may be open everywhere to the land surface (unconfined), or it may be capped in large part by impermeable ⁰¹ relatively impermeable rocks (confined). It may cover an extensive area or represent only an elongate ribbon of sand deposited in an ancient stream channel.

Matet ials forming the reservoir may be composed largely of unconsolidated sediments or of bed-rock; they may be uniformly permeable or vary widely in permeability both horizontally and vertically.

1.2.1

In developing an estimate of balance between recharge to and discharge from a ground- water régime the general manner in which that régime functions must be identified. The potential for recharge to the ground-water iégime in an area depends on the amount and pattern of annual precipitation in relation to the potential for evaporation and to the occurrence of any surface or subsurface inflow from adjacent areas. Most of this potential recharge is commonly intercepted by the soil veneer and eventually returned to the atmosphere through processes of evapotranspiration or dissipated though surface run-off. The amount that actually contributes to gi ound-water recharge varies seasonally and from year to year. Although perhaps difficult to quantify, it generally represents a comparatively small part of the total potential for recharge. Similarly, ground-water discharge may be difficult to quantify because of temporal variations, especially if it occurs at a number of scattered locations, either at the land surface in the form of springs, gaining streams, lakes, ponds, marshes or growths of phreatophytes, or at depth through permeable formations.

Thus the relationship between recharge and discharge under natural conditions is often obscured and not readily apparent from field observations. However, useful guide-lines that are generally applicable to specific problem areas can be drawn from the practical experience accumulated through &ld study of ground-water régimes in a variety of natural environments. These guide-lines may be sufnmarized as follows:

1. In relatively undeveloped areas long-term average discharge from a ground-water reservoir can be presumed to be in equilibrium with long-term average recharge.

2. As a consequence of 1, it follows that a large volume of ground-water discharge at the land surface is proof of corresponding high recharge to the system.

3. The potential for recharge in an area as determined, for example, by observing pre- cipitation, should not be confused with actual recharge. The two are telated only in that actual recharge cannot exceed the potential for recharge. Thus, desert areas characteristically receive low recharge because of low potential for recharge, but humid areas do not necessarily receive high recharge unless rocks underlying the land surface are highly permeable.

4. Surface-water discharge represents both run-off and ground-water discharge. The latter can be approximately equated with the low-flow natural discharge less inflow of streams not originating in the area.

Functioning of the ground-water régime

1.2 page 3