Alluvial Aquifer Processes

Milan Dimkic

• Publisher: IWA Publishing
• Year: 2021
• ISBN:
  9781789060911
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

The global population is expected to grow from more than seven billion at present to nine billion by the year 2050. As a result, resource issues are becoming increasingly severe. The questions raised in connection with natural resources are practical, but also philosophical and political.

Alluvial groundwater is becoming increasingly important for the drinking water supply, but also for agriculture and other human needs. Human civilisations developed in alluviums during the Holocene. Armies, roads, trade and agglomerations largely concentrated in river valleys. Alluviums are resource treasuries (water, forests, farmland, etc.), but at the same time, they are exposed to pressures from the population and economy. These threats to alluvial plains and alluvial aquifers require very careful planning and persistent implementation of protection measures.

Sudden social and natural changes increasingly lead the world into a tangle of global events and problems whose outcomes are not easy to perceive, let alone influence. One of the factors that can help is knowledge or, in other words, expertise focusingon a single problem or area. The ability to synthesise information and master comprehensive models is also extremely important.

This book, a monograph, is a modest attempt to contribute to the understanding of planetary water management, groundwater and certain natural processes in alluviums. It comprehensively encompasses current topics associated with the state, processes and problems of alluvial aquifers and is devoted to professionals, experts, professors and students in advanced stages of learning.

The book is a continuation of sorts of another book released in 2008 by IWA Publishing, Groundwater Management in Large River Basins, edited by Milan A. Dimki?, Heinz-Jürgen Brauch and Michael Kavanaugh.

© IWA Publishing 2021. Alluvial Aquifer Processes Editor: Milan Dimkić doi: 10.2166/9781789060904_0001

Chapter 1

Introduction

The development of water management can be divided into three distinct stages. Stage 1 – abundance, in which water use and water pollution are low compared to the quantity and quality of available water resources. Stage 2 – overexploitation, in which water use is considerable and water quality substantially disturbed. Stage 3 – aiming at sustainable development, which requires water management to ensure good status of water resources and safeguarding of water quantity and quality for the future.

Global population is expected to grow from more than seven billion at present to nine billion by the year 2050. As a result, resource issues are becoming increasingly severe. Estimates suggest the water demand could grow from the current 3000–4000 km³/year to about 5000 km³/year by 2050.

The questions raised in connection with natural resources are practical, but also philosophical and political. The use and management of resources certainly need to be local, regional and global. We are witnessing tumultuous social, economic and political shifts and changes. The demographic growth is increasing the global drinking water demand. At the time of writing, the COVID-19 pandemic has already taken hundreds of thousands of lives and is likely to have grave economic and uncertain political consequences.

Climate change occurs periodically on our planet and lasts for a long time. Ice ages and interglacial periods alternated in the Pleistocene and Holocene. However, changes have been quite rapid over the past decades. The Intergovernmental Panel on Climate Change indicated in its AR5 Synthesis Report that each of the past three decades has been consecutively warmer than any other decade since 1850. Further warming will cause certain wet regions to become wetter and some presently arid regions drier. This could have a dramatic effect on a number of regions, if not the entire world.

It is becoming increasingly difficult to conserve our planet's nature. Water, air and soil are mostly threatened by humankind. By way of illustration, an expedition noted plastic waste on the bottom of the Mariana Trench (at a depth of some 10,000 m, the lowest point on Earth).

Optimal water governance in variable social and climate conditions is a topical issue worldwide, which largely remains unresolved.

There is an abundance of water on our planet. However, 97.5% is saline water of the seas and oceans. The remaining 2.5% is fresh water, of which slightly more than three-quarters is ice. The liquid phase accounts for 23% of fresh water, of which 22% is groundwater. Rivers and lakes make up about 0.3% of our planet's fresh water resources. The Food and Agriculture Organisation (FAO) estimates that the volume of fresh groundwater is 10.53 million km³ (FAO, 2016). However, global water resources are not evenly distributed.

How should water scarcity be addressed? Viewed in broad terms, by meeting the water demand and conserving our planet's water resources. However, the water-food-energy counterpoint needs to be taken into account in an appropriate fashion.

The sustainability and conservation of water resources are highly complex. In addition to social, economic and political factors, there are significant natural constraints – local, regional and global.

The response to these various challenges is certainly multifaceted. Above all, the answers should be founded upon a sound understanding of natural and social processes, as well as the condition of water resources. In turn, this requires sufficient knowledge about the water sector and the various concerns in the field of water. To that end, our society needs to ensure the availability of required scientific, professional, institutional and operational capacities. Ever present in this regard is the matter of designing appropriate policies, which are efficient and implementable.

Dispersion of the use of water resources can facilitate adaptation to change. This includes the use of groundwater and surface water, seawater desalination, wastewater recycling, and water storage (primarily in aquifers but also in surface reservoirs).

Agriculture needs to focus on crops compatible with water availability in a given community. Climate change will improve conditions (e.g. two harvests per year) in some places and aggravate them in others. Farmers in certain regions will have to opt for other crops. Where irrigation is applied, water use efficiency will need to be maximised.

Alluvial groundwater is becoming increasingly important for drinking water supply, but also for agriculture and other human needs. Estimates show that groundwater meets about half of the municipal water demand. Half of that groundwater comes from alluviums. The advantages of alluvial aquifers are that they are close to consumers and that the extracted groundwater is renewable.

Human civilisations developed in alluviums during the Holocene. Armies, roads, trade and agglomerations were largely concentrated in river valleys. Alluviums are resource treasuries (water, forests, farmland, etc.), but at the same time they are exposed to pressures from the population and economy. These threats to alluvial plains and alluvial aquifers require very careful planning and persistent implementation of protection measures.

Sustainable management and conservation of alluvial aquifers requires the understanding and identification of alluvium formation and sedimentation conditions (input of materials and mechanisms of erosion, transport and accumulation), as well as the connection of a given aquifer with other aquifers, surface water and other geologic formations. All of these factors are determined by their origin. They differ both globally and locally, so the origin and characteristics of shallow aquifers developed in Quaternary sediments are relevant for the protection, conservation and sustainable use of groundwater resources. Even though Quaternary sediments are rather fragmented, in addition to their significance for the population and water supply, they help us understand and reconstruct paleo climate conditions during the Quaternary period.

Sudden social and natural changes increasingly lead the world into a tangle of global events and problems whose outcomes are not easy to perceive, let alone influence. One of the factors that can help is knowledge or, in other words, expertise focussed on a single problem or area. The ability to synthesise information and master comprehensive models is also extremely important.

This book, a monograph, is a modest attempt to contribute to the understanding of planetary water management, groundwater and certain natural processes in alluviums.

The book is a continuation of sorts of another book released in 2008 by IWA Publishing – ‘Groundwater Management in Large River Basins’, edited by Milan A. Dimkić, Heinz-Jürgen Brauch and Michael Kavanaugh.

The book comprises 11 chapters and 4 appendices. In essence, each chapter was written in a stand-alone manner but care was taken to ensure that they are complementary and in holistic harmony. The chapters following this introductory one can be divided into three groups.

GROUP I

This group comprises a single, rather voluminous chapter – Chapter 2. It does not purport to offer prescriptions for water governance or management of groundwater or alluvial water resources. Still, the intent is to bring the reader closer to the main natural, administrative (at different levels), economic, financial and institutional features and processes associated with water management, in particular alluvial groundwater management. Chapter 2 describes general positions in respect of water governance and analyses water availability and the water-food-energy nexus. It discusses three levels of water management – global, regional and local, from administrative, economic, financial, scientific, technical and planning perspectives. It was an honour to incorporate a section on the efforts of the International Commission for the Protection of the Danube River (ICPDR), written by its Executive Secretary Mr. Ivan Zavadsky and his associate Miss Jelena Krstajić.

Chapter 2 emphasises the main concepts and processes associated with the transformation of groundwater quality and contains an overview of the processes discussed in other chapters of the book.

The final section of Chapter 2 includes a very good example of how the expansion of human activity and settling juxtaposes the conservation of alluvial groundwater resources.

GROUP II – GENERAL CHAPTERS

This group comprises Chapters 3, 4 and 11, which discuss the natural background of processes that take place in alluvial aquifers, which are described in the remainder of the book.

Chapter 3: Alluvial Aquifers – The Legacy of the Quaternary Period

This chapter provides insight into the formation of alluvial aquifers, particularly at moderate latitudes. Special attention is devoted to alternating ice ages and interglacial periods of the Pleistocene and the consequences of erosion, alluvial sedimentation, and mechanical and chemical properties (e.g. the oxic state of an aquifer). In essence, the chapter comprises three parts.

•The first part is general and contains an overview of known geologic and cosmic conditions that have determined the mega processes on our planet in the Quaternary period. Phenomena and occurrences relevant to the origin and formation of alluvial sediments are also covered.

•The second part illustrates (we hope) how the age of alluvial deposits is determined.

•The third part reports original investigations aimed at connecting high mountains in the upper basin of the Sava River (a tributary of the Danube) with polycyclic sedimentation in the Sava alluvium, particularly at Belgrade's water supply source that relies on groundwater. The studied processes have had a dominant effect on the creation of conditions for the development of a groundwater source, particularly its yield, the aquifer's purification potential and the oxic state of the groundwater.

Chapter 4: Oxic State of Alluvial Aquifers

Chapter 4 discusses the effect of the oxic state of an alluvial aquifer on the direction and rate of the processes discussed in the book. An aquifer's oxygen balance depends on the oxidation-reduction of organic and inorganic substances, groundwater flow rate, and hydrogeologic, hydrologic and similar conditions. It is evident that fine sediment tends to be deposited along the lower courses of large rivers and that, almost as a rule, the prevailing conditions are less oxic. The chapter brief...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• The Editor
• Preface
• Chapter 1: Introduction
• Chapter 2: Water management in large alluvial plains
• Chapter 3: Alluvial aquifer – The legacy of the quaternary period
• Chapter 4: Oxic conditions of alluvial aquifers
• Chapter 5: Iron incrustation of water wells
• Chapter 6: Pharmaceutical attenuation processes during filtration in groundwater
• Chapter 7: Removal of pesticides from groundwater by filtration
• Chapter 8: Transformation of nitrogen compounds in groundwater
• Chapter 9: Methods for trace analysis of pharmaceuticals and pesticides in water and sediment samples
• Chapter 10: Artificial aquifer recharge and the compression of layers of a hydrogeological complex due to groundwater abstraction
• Chapter 11: Drought and alluvial groundwater resources
• Appendix 1: Surface tension, capillarity and viscosity
• Appendix 2: Determining the coefficient of filtration based on data on the granulometric composition of soil
• Appendix 3: Chemical structure and selected properties that influence the fate of pesticides in the environment
• Appendix 4: The chronology of the quaternary period
• Index