Climate Change Science: Causes, Effects and Solutions for Global Warming

Climate Change Science: Causes, Effects and Solutions for Global Warming presents unbiased, state-of-the-art, scientific knowledge on climate change and engineering solutions for mitigation. The book expands on all major prospective solutions for tackling climate change in a complete manner. It comprehensively explains the variety of climate solutions currently available, including the remaining challenges associated with each. Effective, complementary solutions for engineering to combat climate change are discussed and elaborated on. Some of the more high-risk proposals are qualitatively and quantitatively compared and contrasted with low-risk mitigation actions to facilitate the formulation of feasible, environmentally-friendly solutions.

The book provides academics, postgraduate students and other readers in the fields of environmental science, climate change, atmospheric sciences and engineering with the information they need for their roles. Through exploring the fundamental information currently available, exergy utilization, large-scale solutions, and current solutions in place, the book is an invaluable look into how climate change can be addressed from an engineering-perspective using scientific models and calculations.

• Provides up-to-date, comprehensive research on the causes and effects of climate change – both manmade and natural
• Explains the scientific data behind climate change from an interdisciplinary perspective
• Describes the future effects of climate change and the necessity for immediate implementation
• Presents environmentally-friendly solutions and critically analyzes benefits and drawbacks

• Language: English
• Publisher: Elsevier Science
• Release date: May 21, 2021
• ISBN: 9780128241820

Book preview

Climate Change Science

Causes, Effects, and Solutions for Global Warming

Edited by

David S-K. Ting

Professor in the Department of Mechanical, Automotive and Materials Engineering at the University of Windsor, ON, Canada

Jacqueline A. Stagner

Engineering Undergraduate Programs Coordinator at the University of Windsor, ON, Canada

Contents

Cover

Title page

Copyright

Dedication

Contributors

Preface

Acknowledgments

1: Enhancing crop water productivity under increasing water scarcity in South Africa

Abstract

1. Introduction

2. Understanding water productivity

3. The value of water markets in water scarce regions

4. Improving water productivity from a WEF nexus perspective

5. Recommendations

6. Conclusions

2: Can renewable energy sources be a viable instrument for climate change mitigation? Evidence from EU countries via MCDM methods

Abstract

Nomenclature

1. Introduction

2. Literature review

3. Research methods

4. Data and descriptive statistics

5. Climate change mitigation profile of EU countries

6. Empirical results

7. Conclusion and policy implications

3: Carbon emission as a result of forest land change in Islamabad, Pakistan

Abstract

1. Introduction

2. Aim & research questions

3. Materials and methods

4. Results and discussion

5. Conclusion

Acknowledgment

4: Integrated coastal management enhances coastal resilience to climate change—The East Asia experience

Abstract

1. Introduction

2. ICM system

3. ICM adoption in the East Asian Seas region

4. Climate change impacts on the coastal area

5. ICM strengthens environmental and societal resilience

6. Conclusion

5: Underground methanation, a natural way to transform carbon dioxide into methane

Abstract

1. Introduction

2. Power to gas

3. Underground methanation

4. Conclusions

Acknowledgment

6: Analysis of plant oil-based fuel characteristics for green supply chains

Abstract

1. Introduction

2. Model structure: fuel-related properties of plant oils

3. Conclusions

7: The effects of couple layout on thermoelectric generator performance

Abstract

Nomenclature

1. Introduction

2. Methodology

3. TEG model establishment and validation

4. Effects of layout on the TEG performance

5. Conclusions

Acknowledgment

8: Spatio-temporal patterns for human-based architecture to solve metropolitan collapse in Latin America

Abstract

1. Introduction

2. Architecture as an intelligent living organism

3. Realizing spatio-temporal architecture

4. Developing the spatio-temporal architecture in Latin America (case study)

5. Conclusion

9: The nexus of climate change and urbanization

Abstract

1. Introduction

2. Part 1: how urbanization impacts climate change

3. Part 2: how climate change impacts urban life

4. Part 3: Fundemental climate change mitigation strategies in cities

5. Summary

10: Bioshading system design method (BSDM)

Abstract

1. Introduction

2. Related work

3. Bioshading system design method

4. Architecture domain—definition process

5. Nature domain—abstraction process

6. Artifact domain—emulation process

7. Discussion

8. Conclusions

11: Green science: smart building technology to mitigate global energy and water crises

Abstract

1. Introduction

2. Material, methods, and simulation

3. Results and discussion

4. Electricity transformation

5. Conclusions

Acknowledgments

12: How green energy giants increase their revenues? Impacts on global warming

Abstract

1. Introduction

2. Stock market data variation

3. Influencing factors for share price variation

4. Results, evaluation, and discussion

5. Conclusions

Index

Copyright

Elsevier

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Notices

Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.

Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

Library of Congress Cataloging-in-Publication Data

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British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library

ISBN: 978-0-12-823767-0

For information on all Elsevier publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Candice Janco

Acquisitions Editor: Marisa LaFleur

Editorial Project Manager: Ruby Gammell

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Typeset by Thomson Digital

Dedication

To everyone who strives to make a positive impact in conserving our environment, one starfish at a time.

Contributors

Yomna K. Abdallah,     Universitat Internacional de Catalunya, iBAG—UIC Barcelona (Institute for Biodigital Architecture and Genetics), Barcelona, Spain

Natalia A. Alonso,     Universitat Internacional de Catalunya, iBAG—UIC Barcelona (Institute for Biodigital Architecture and Genetics), Barcelona, Spain

Isabel Amez,     Etsi Minas y Energía, Universidad Politécnica de Madrid, Madrid, Spain

Figen Balo,     Department of Industrial Engineering, Firat University, Elazığ, Turkey

Sanchita Baral,     Department of Business Development and Technology, Aarhus University, Herning, Denmark

Danilo Bonga,     Partnerships in Environmental Management for the Seas of East Asia (PEMSEA), Quezon, Philippines

Loke-Ming Chou,     National University of Singapore, Singapore

Thia-Eng Chua,     Partnerships in Environmental Management for the Seas of East Asia (PEMSEA), Quezon, Philippines

Alberto T. Estévez,     Universitat Internacional de Catalunya, iBAG—UIC Barcelona (Institute for Biodigital Architecture and Genetics), Barcelona, Spain

Fazıl Gökgöz,     Faculty of Political Sciences, Ankara University, Ankara, Turkey

Sergio Gonzalez,     Etsi Minas y Energía, Universidad Politécnica de Madrid, Madrid, Spain

Paul Henshaw,     Turbulence & Energy Laboratory, University of Windsor, Windsor, ON, Canada

Md. Faruque Hossain,     College of Architecture and Construction Management, Kennesaw State University, Marietta, GA, United States

Umer Khayyam,     Department of Development Studies, School of Social Sciences and Humanities (S³H), National University of Sciences and Technology (NUST), Islamabad, Pakistan

Carla Leitão,     Rensselaer Polytechnic Institute, Troy, NY, United States

Bernardo Llamas,     Etsi Minas y Energía, Universidad Politécnica de Madrid, Madrid, Spain

Tafadzwanashe Mabhaudhi,     Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal (UKZN), Pietermaritzburg, South Africa

Sylvester Mpandeli

Water Research Commission Pretoria, South Africa

School of Environmental Sciences, University of Venda, Thohoyandou, South Africa

Luxon Nhamo

Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal (UKZN), Pietermaritzburg, South Africa

Water Research Commission Pretoria, South Africa; Water Research Commission, Pretoria, South Africa

Maria João de Oliveira,     Instituto Universitário de Lisboa (ISCTE-IUL), DINÂMIA’CET, Lisboa, Portugal; Iscte-Instituto Universitário De Lisboa (ISCTE-IUL), DINÂMIA’CET, Lisboa, Portugal

Marcelo F. Ortega,     Etsi Minas y Energía, Universidad Politécnica de Madrid, Madrid, Spain

Vasco Rato,     Iscte-Instituto Universitário de Lisboa (ISCTE-IUL), ISTAR_iscte, Lisboa, Portugal

Arezou Sadoughi,     Department of Sustainable Technology and the Built Environment, Appalachian State University, Boone, NC, United States

Laura Sanchez-Martin,     Etsi Minas y Energía, Universidad Politécnica de Madrid, Madrid, Spain

Lutfu S. Sua,     School of Entrepreneurship and Business Administration, Auca, Bishkek, Kyrgyz Republic

Mohammadsoroush Tafazzoli,     School of Design and Construction, Washington State University, Pullman, WA, United States

David S-K. Ting,     Department of Mechanical, Automotive and Materials Engineering at the University of Windsor, Windsor, ON, Canada

Xi Wang,     Turbulence & Energy Laboratory, University of Windsor, Windsor, ON, Canada

Sarah Waseem,     Department of Development Studies, School of Social Sciences and Humanities (S³H), National University of Sciences and Technology (NUST), Islamabad, Pakistan

George Xydis,     Department of Business Development and Technology, Aarhus University, Herning, Denmark

Engin Yalçın,     Institute of Social Sciences, Ankara University, Ankara, Turkey

Preface

The push for large-scale interventions of the entire atmosphere that drives the Earth’s climate system is gaining ground. The educated can sit on the sideline and assume that this is but far-fetched science fiction that will never take place. After all, who in their right mind would take a risky action such as setting up an atomic explosion in the outer atmospheric layer in an effort to reduce the solar radiation reaching the surface of the earth? Then again, human beings have been proven to do crazy things when overcame by fear. Let us be reminded of the 2020 toilet paper crisis for many years to come, hopefully to better prepare us in preventing, mitigating, and/or dealing with the next impasse. As Andersen (2017) put it, Many fear that, when global leaders finally realize the peril of climate change, they will jump at engineering projects without any evidence base, risking side effects of unknown magnitude. The idea of controlling and engineering the vast population of the human race is more real than just entertaining movies. What about engineering human beings to become meat intolerance in order to eliminate greenhouse emissions from the livestock industry? Not to mention shrinking future generations into smaller beings so that they consume less. These and other forms of human engineering are entering mainstream scientific discussion; see (Liao, 2017), for example.

According to Reader (2021), The emphasis, perhaps overemphasis, of carbon dioxide’s role in actual climate change may well moderate as more data becomes available, but only in so far as the role of other contributing factors to actual changing climates need to be clarified, measured, and embedded in better predictive models. What other contributing factors are there? Let us be enlightened by astrophysicist Khabibullo Abdusamatov who supervised the Astrometria project of the Russian section of the International Space Station and headed Space research laboratory at the Saint Petersburg-based Pulkovo Observatory of the Russian Academy of Sciences. Abdusamatov concluded that, Global warming results not from the emission of greenhouse gases into the atmosphere, but from an unusually high level of solar radiation and a lengthy - almost throughout the last century - growth in its intensity. It is no secret that when they go up, temperatures in the world’s oceans trigger the emission of large amounts of carbon dioxide into the atmosphere. So the common view that man’s industrial activity is a deciding factor in global warming has emerged from a misinterpretation of cause and effect relations. This, by no means, excuses us from good stewardship of the beautiful planet that we reside in, and share with abundant and fascinating species. Case in point, Swithinbank et al. (2019) delineated how Christian theology promotes sustaining the environment and fosters grassroots social movements for sustainable development.

Even so, how can we make a positive impact without resorting to large-scale interventions? The impending challenge seems overwhelming for a layperson, at least it appears that individual efforts are not going to make a dent. Is there then nothing we can do? The answer to this vital question is in the Starfish Story by Loren Eiseley. Here is our edited version that conveys the salient message.

One day a man was walking along the beach when he noticed a boy picking up stranded starfish and throwing them into the sea. Approaching the boy he asked, Young man, what are you doing? The boy replied, If I don’t throw the starfish back, they’ll surely die. The man exclaimed, But there are thousands of them. What difference does it make? The boy smiled as he threw another starfish into the sea, It makes a difference to this one.

This one-starfish volume aims at disseminating the open-minded state-of-the-art scientific knowledge on climate change and the engineering solutions for mitigating it. It promotes the discussion of big ideas, such as erecting a net along the beach to prevent the up-washing of the starfish to the shore, or analogously, a global-scale solar shield. The uncertain after effects of these methods should not be whitewashed; for example, the title of the article by Langin (2018), A solar shield could save us from climate change. But its sudden collapse would doom the planet, alone says it all. On the same topic, Sillmann et al. (2015) sound the alarm, The danger of declaring a climate emergency is further exacerbated when one considers the political stakes of doing so. Emergencies are by no means simple geophysical occurrences, but rather the outcome of highly complex interactions between the natural environment, political interests and social norms. In the context of considerable scientific uncertainty - and hence the multiple possible interpretations of scientific results and arguments - climate emergencies will be declared on largely political grounds. This interlinking of scientific uncertainty and political opportunism should caution against implementing SRM (solar radiation management) as a climate emergency measure, a conclusion we reach on the basis of sound scientific arguments, good governance and ethical principles.

More so, this volume or forum calls for small, more certain and low-risk actions. Every earth inhabitant can execute these seemingly inconsequential actions, that is, all beach and starfish lovers can have the pleasure to save some starfish. Let the collective effort speak for itself.

Case in point, we need food, food is intimately interrelated with precious water, and both food and water are directly influence by climate change. Mabhaudhia, Nhamo, and Mpandeli disclose rainwater harvesting and soil water conservation as options to enhance crop water productivity in Chapter 1.

How do we know if a solution to alleviate climate change is working in real life? Gökgöz and Yalçin recommend the multi criteria decision-making approach to assess climate change mitigation performance, where such an appraiser is conducted for the European Union countries in Chapter 2.

Deforestation is bad. Unfortunately, this obvious fact is often buried under the name of progress. Such is the case in Pakistan, as detailed by Khayyam and Waseem in Chapter 3, where they call for the halting of massive urbanization at the expense of deforestation.

Forget not the vulnerable coastline. In Chapter 4, Chou, Chua, and Bonga enlighten us with integrated coastal management system for strengthening coastal resilience, beautifying coastal cities and municipalities for future generations to enjoy. Integrated within this system includes the conservation of natural resources and maintenance of environmental quality for sustaining the ecosystem.

Is there a well-founded way to store carbon dioxide underground? What about converting it into methane via the hydrogen and carbon dioxide reaction? Amez, Sanchez-Martin, Ortega, and Llamas reveal this ingenious idea in Chapter 5. What makes this idea practically attractive is its direct integration into the power to gas technology, where the excess electricity during low demand is exploited to produce hydrogen or methane in the existing natural gas networks.

As we are on the topic of fuel, we cannot escape being confronted with the fact that the politically incorrect combustion of fuel will continue to drive us into the future. According to Sua and Balo, plant oil-based fuels can green the supply chains that are powered primarily via fuel combustion. They analyze a multitude of plant oils with respect to diesel and gasoline for the logistics industry in Chapter 6.

Waste heat is given for just about all engineering systems and hence, it is of significant environment benefit to harnessing it for electricity. Thermoelectric generator (TEG) is a gadget for such purpose. In Chapter 7, Wang, Henshaw, and Ting illustrate how to better configure the underlying layouts of the n-type and p-type couples to further TEG performance.

How do we sustain a dynamic city that changes continuously with time? Alonso, Estévez, and Abdallah propose making its architecture alive in Chapter 8. Imitating organisms develop in space and time the spatio-temporal architecture adjusts itself in response to the dynamic interaction between the inhabitants and the environment.

Pandemic and climate change alike, they tend to have a larger impact on more populated areas. In Chapter 9, Tafazzoli and Sadoughi explain that intensely developed cities substantially contribute to climate change, and are more adversely affected by climate change. Mitigation should initiate with the identification of the specific characteristics of the city.

Ever heard of bioshading system design methodology (BSDM)? Oliveira, Rato, and Leitão explain in Chapter 10 that BSDM is an architectural problem-based methodology that exploits nature to design responsive shading systems. Enjoy the inspiration instilled by the ladybug.

It is evident that smart building plays a critical role on our road toward a greener future. Hossain demonstrates that capitalizing active photovoltaic panels along a building exterior curtain wall can power the entire building in Chapter 11. Furthermore, we can employ static electricity to harness cloud water and treat it with ultraviolet to meet the building water demand.

Money is the fuel for realizing dreams, and money is required for fulfilling big green dreams. The final chapter, Chapter 12, by Baral and Xydis disseminates how possible major factors such as strategic decision, financial activity, management change, and dividend affected the share prices of six different green energy giants between 2013 and 2018. Readers would appreciate the challenge in attempting to unify markets’ reactions under a multi-objective system using technical indicators.

The distinct yet complementary aspects brought forth in the 12 chapters aim at enlightening the reader. Furthermore, this volume aspires to stimulate better understanding of the causes and effects of climate change, forging the way for increasingly more potent and ecofriendly solutions.

References

Andersen SO. We can and must govern climate engineering. Nature. 2017;551:415.

Langin, K. (2018). A solar shield could save us from climate change. But its sudden collapse would doom the planet. Science. doi: 10.1126/science.aat0811.

Liao, S. M. (2017). Tackling climate change through human engineering. In A. De Grey (Ed.), The next step: exponential life (pp. 274–293). BBVA OpenMind.

Reader, G. T. (2021). Energy: a reasonable mix? In D. S-K. Ting, R. Carriveau (Eds.), Sustaining tomorrow via innovative engineering, World Scientific Publishing.

Sillmann, J., Lenton, T.M., Levermann, A., Ott, K., Hulme, M., Benduhn, F.s, et al. (2015). Climate emergencies do not justify engineering the climate. Nature Climate Change, 5(4), 290–292. doi: 10.1038/nclimate2539.

Swithinbank, H. J., Gower, R., Foxwood, N. (2019). Sustained by faith? The role of Christian belief and practice in living sustainably. In W. L. Filho, A. C. McCrea (Eds.), Sustainability and the humanities (pp. 375–391), Springer International Publishing.

Acknowledgments

This volume is the fruit of contributions from many fronts, not to mention the grace from above. The editors are indebted to the publishing team led by Peter J. Llewellyn, who truly deserves a special mention. Ruby Gammell has also been instrumental. This volume would have been The Emperor’s New Clothes without the quality scholarships of the expert authors who meticulously weaved the 12 beautiful chapters. A heartfelt Thank You goes to the reviewers who checked every thread, seriously boosted the quality of the manuscript.

David S-K. Ting

Professor in the Department of Mechanical, Automotive and Materials Engineering at the University of Windsor, ON, Canada

Jacqueline A. Stagner

Engineering Undergraduate Programs Coordinator at the University of Windsor, ON, Canada

1: Enhancing crop water productivity under increasing water scarcity in South Africa

Tafadzwanashe Mabhaudhia,*

Luxon Nhamoa,b

Sylvester Mpandelib,c

a    Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal (UKZN), Pietermaritzburg, South Africa

b    Water Research Commission, Pretoria, South Africa

c    School of Environmental Sciences, University of Venda, Thohoyandou, South Africa

∗Corresponding author

Abstract

Agricultural productivity in South Africa is threatened by the increasing water scarcity as the country is ranked among the 30 driest countries in the world. The challenge is exacerbated by population growth, migration, changing diets, and increasing frequency and intensity of drought, which increase pressure on already depleted and scarce water resources. The multiple challenges have negatively affected crop water productivity in the country. This study explored the opportunities to increase crop water productivity (output per unit water consumed) under water scarcity conditions in South Africa. Although irrigation may provide immediate options to improve crop water productivity in response to droughts and mid-season dry spells, there should be considerations on the availability and accessibility of water and energy for irrigation requirements. The country also faces energy supply challenges and irrigation expansion could aggravate the existing challenges if not well-managed. Groundwater use and water marketing are considered as options to alleviate water scarcity challenges, but the extent to which they can bring relief on the stressed water resources is not yet known. Tapping into groundwater also requires reliable energy resources, which brings into the fore the need for a water-energy nexus planning to enhance agricultural and water productivity. These issues are critical for a sector that is dominated by poorly resourced smallholder farmers. Options to enhance crop water productivity include rainwater harvesting and soil water conservation technologies.

Keywords

climate risks

drought

adaptation

rainwater harvesting

water security

1. Introduction

In South Africa, climate change impacts are being felt mostly through either drought or floods, with the former being of primary concern to agriculture (Mpandeli et al., 2019; Nhamo, Mabhaudhi, & Modi, 2019a). At the same time, demand for water continues to grow due to increasing population, urbanization, industrialization, and agriculture expansion (Cosgrove & Loucks, 2015). The challenge of increasing water scarcity is not only prompted by quantitative or qualitative scarcity, but also by inefficient use and poor management (Srinivasan, Lambin, Gorelick, Thompson, & Rozelle, 2012). Thus, water resource management has become topical and has dominated global debates on sustainable development. This highlights the importance of water as an indispensable resource for human wellbeing, economic development, biodiversity protection, and sustainable development (McClain, 2013). This also calls for adopting new and innovative approaches and policies to support efficient, equitable, and sustainable water resources management in order to sustainably increase food production. Therefore, there is an urgent need for adopting new and innovative approaches and policies (Kumwenda, van Koppen, Mampiti, & Nhamo, 2015; Russo, Alfredo, & Fisher, 2014).

In South Africa, the challenge of water scarcity is aggravated by its semi-arid conditions, and a water profile that is fast changing from water scarce to water stressed (Matchaya, Nhamo, Nhlengethwa, & Nhemachena, 2019). The country’s annual average rainfall is 450 mm, which is well below the world average of 860 mm (Botai, Botai, & Adeola, 2018). Rainfall in South Africa is unevenly distributed, with about 50% of the rain falling on 15% of the land, resulting in most areas failing to have reliable water resources for domestic, industrial, and agricultural consumption (Mpandeli et al., 2019). The majority of smallholder farmers reside mainly in most of the remaining 85% of the country where rainfall is severely scarce (van Koppen et al., 2017). Although South Africa is classified as food secure, it is either in relation to the production of sufficient food or in the availability of resources to import enough food for its populace at a national level, yet about 28.3% of households remain at risk of hunger and 26% are actually food insecure (Chakona & Shackleton, 2019). The country’s National Development Plan (NDP) acknowledges the role of agriculture and rural development as important sectors when it comes to food security, employment creation, economic growth, and poverty reduction (NDP, 2013). Interventions in the agriculture sector have potential to provide rural communities with resources and opportunities to live a healthier and more productive life, while at the same time contributing to sustainable development post-Covid-19 and toward the country’s gross domestic product (GDP).

Current agricultural practices require large amounts of water and agriculture remains the biggest user of water in South Africa using more than 60% of the available freshwater resources (Donnenfeld, Crookes, & Hedden, 2018). As a result, addressing water and food challenges in South Africa requires dynamic institutions and actions to balance increasing water productivity with environmental management (Mabhaudhi et al., 2018). Agricultural production and livelihoods in water scarce countries like South Africa, can be sustained provided that priority is given on improving water productivity (Nhamo, Mabhaudhi, & Magombeyi, 2016); this requires technological development (Cai, Magidi, Nhamo, & van Koppen, 2017).

Technological developments in the agriculture and water sectors are always important pathways toward sustainability and food and water security and balance resource management and development (Cosgrove and Loucks, 2015). Technology, particularly hydrological and water management tools, and models have emerged as essential components of water management. Examples of technologies that are transforming the agriculture and water sectors include the development of smart plants that are more drought tolerant through genetic modification and genome editing (Khan et al., 2019; Tripathi, Ntui, & Tripathi, 2019). Some plants can also be engineered to use more efficient photosynthetic pathways that fully use the sun’s available energy (Khan et al., 2019). This development holds promise for the hot climates and water scarce regions. Remote sensing has also become an important component of irrigation management, particularly in irrigation scheduling (Mpandeli et al., 2019; Nhamo et al., 2020a). Developments in precision farming mean that freely available remote sensing products can be used to pinpoint areas of wet and dry zones in cultivated fields as well as for estimating crop water requirements (Alvino & Marino, 2017). Such information is vital for variable irrigation scheduling. Mobile applications and related social media platforms have become important tools to disseminate agrometeorological and market information to farmers in near real-time, which is critical for better farm management and productivity (Inwood & Dale, 2019).

Available agricultural water management options to improve water and food productivity can be informed through nexus planning to determine their sustainability in South Africa (Nhamo et al., 2020b). Through scenario planning, it is feasible to sustainably increase the irrigated area (Gutzler et al., 2015). This is possible through transboundary water cooperation, inter-basin transfer, water marketing, agricultural land intensification, and extensification (Matchaya et al., 2019). Transformative approaches encompass low consumption of energy, low pollutant emission, and high efficiency in resource use, and are restorative and regenerative in nature, reducing losses in the whole value chain (Mpandeli et al., 2018; Nhamo et al., 2018). Post-COVID-19 interventions to rebuild the economy and society in South Africa requires policy-makers to embrace transformative approaches as they inform sustainable development, economic development, and the attainment of the constitutional promise of a better life for all.

Thus, this study addressed the available options to improve agricultural water productivity under increasing water scarcity in South Africa. Water productivity is considered in the context of both rain-dependent and irrigated agricultural production systems. The study outlined the meaning and implications of increased water productivity and then systematically considered the limits and opportunities for its improvement.

2. Understanding water productivity

The terms of water use efficiency (WUE) and water productivity (WP) are generally and incorrectly interchangeably used, but they do not mean the same, although they are related (van Halsema & Vincent, 2012; Koech & Langat, 2018). The relationship between WUE and WP is based on that the increase of WUE generally leads to better WP and it works to the farmer’s favor by improving economic return from the investments in irrigation water supply (Levidow et al., 2014). While the two terms seek to address the notion of more crop per drop, they are now being incorrectly used interchangeably as they are closely linked (Mabhaudhi, Chibarabada, & Modi, 2016). Irrigation engineers, crop physiologists, and water managers hold different perspectives on the correct terminology (Molden et al., 2010). Water specialists came-up with a conceptual framework for communicating water productivity (Mabhaudhi et al., 2016). The indices for WUE and WP in an agronomic sense have been used widely to quantify the notion more crop per drop (Molden et al., 2010; Nhamo et al., 2016). Water use efficiency is the ratio of biomass or yield to water applied (Eq. 1.1) while WP is defined as the ratio of biomass or yield to actual water used (Eq. 1.2) (Molden et al., 2010; Nhamo et al., 2016).

(1.1)

(1.2)

where, Ya and Ba is the actual yield and biomass (kg), respectively and ETa is the actual evapotranspiration (mm ha−1 or m−3) or water consumed. For the calculation of WUE, water applied suggests water entering the systems and is silent on the unproductive loss of water such as runoff, deep percolation, capillary rise, and changes in subsurface flow, since it is challenging to quantify these. The confusion between WUE and WP usually emanates from the confusion in the definition and value of the denominator whereby water consumption (ET) is confused with water applied or diverted from a scheme (van Halsema and Vincent, 2012). The premise of WP is informed by the need to address the challenge of low irrigation and water use efficiencies and high yield gaps and increasing, coupled with increasing water scarcity (van Halsema and Vincent, 2012). In this chapter, we adopt the term water productivity.

2.1. Spatial distribution of water resources in South Africa

South Africa’s land area is huge and diverse, with a highly variable rainfall regime, which is characterized by a semi-arid climate (Botai et al., 2018). South Africa is the world’s 30th driest country, with low but highly variable and unevenly rainfall pattern (both inter- and intra-annually). Its runoff is erratic, with high evaporation and shallow and heavily silted dam basins (Kohler, 2016). Annual rainfall varies from less than 100 mm year−1 to the west of the country, to over 1500 mm in the east. Average rainfall is about 450 mm per annum (Fig. 1.1) (Chami & Moujabber, 2016; Schoeman & Van der Walt, 2004). More than 60% of the country’s river flow originates from only 20% of the total land area requiring large-scale inter-basin transfers (Chami and Moujabber, 2016). In terms of surface runoff, an important source for the flow of rivers, and the recharge of wetlands, lakes, dams, and aquifers, only about 8% of South Africa’s land produces about 50% of the total surface runoff (Botai et al., 2018; Schoeman and Van der Walt, 2004). This uneven distribution of rainfall in South Africa determines the distribution patterns of water resources in the country.

Figure 1.1   Average annual rainfall across South Africa. ARC-ISCW, Schoeman & Van der Walt, 2004.

2.2. Considerations in improving water productivity

The key principles to be considered in strategies to improve water productivity at any spatial scale include (Kijne, 2003):

1. increase the marketable yield of the crop for each unit of water transpired by it,

2. reduce field related outflows (runoff, drainage, seepage, percolation, and evaporative), and

3. increasing the effective use of rainfall, stored water, and water of marginal quality.

These principles apply on any agricultural system, whether the crop is grown under rainfed or irrigated conditions and is applicable at any spatial scales. However, these options and practices differ from place to place and may need different approaches and technologies at varying spatial scales (Sayer et al., 2013).

2.3. Options to improve water productivity at all levels

Information on the spatial distribution of water resources and use, crop production and water productivity are critical for informed water management, particularly in water scarce regions where there is need to improve on water productivity. Available information on crop water productivity and evapotranspiration (ET) indicates substantial spatial variation throughout the country, for example, maize with 18–29 kg ha−1 mm−1 and wheat 15–24 kg ha−1 mm−1 (Brauman, Siebert, & Foley, 2013). The high variability is influenced by variations in crop management conditions and environmental conditions in the country. Although it has been challenging to accurately estimate crop