In Focus – Special Book Series – serie

The importance of small towns is gaining increased recognition as a result of two developments. The first development concerns the possible role of small towns in migration flows and urbanization. Development of small towns, in the form of improved basic services and other amenities, has been promoted in order to abate the impact of urbanization on large urban centres and to alleviate service provision pressures in major urban centers, whilst stimulating rural economies and eventually prompting social transformations. The second development concerns the targets set by the SDGs in 2015. SDG6 requires countries to ensure universal and equitable water services by 2030. This inclusive target requires that the water services needs of small towns are considered in the expansion of sustainable and equitable water services.This book aims to contribute to the study of water services in small towns by critically examining different approaches and experiences of water supply in small towns. It brings together empirical testimonies of how the implementation of reductionist models and the perseverance of certain principles underlying these models in the water sector have yielded suboptimal results. Much remains to be done before achieving universal service coverage in small towns is likely. In order to do that, we should start speaking of small towns as a category on their own and continue the work in elaborating further what these are and how they work.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Water is life. But water is also a threat to life. During the past decade, the risks from water-related disasters are increasing and hamper sustainable development by causing political, social, and economic upheaval in many countries. Water-related disasters, such as floods, droughts, storm surges and tsunamis, account for 90% of all disasters in terms of number of people affected.The issue of “water and disasters” must be addressed if we hope to make sustainable development a reality. We must share our experiences and lessons learned, strengthen regional coordination and collaboration, and set common goals and targets in order to lay a foundation for weathering the water-related disasters to come, and make progress towards creating a better-prepared and more resilient society. All these elements should be translated into clear-cut messages and practical advice for decision makers to create effective policies and mechanisms that address water and disaster issues appropriately at all levels.The High Level Experts and Leaders Panel on Water and Disasters (HELP) was established to assist the international community, governments and stakeholders in mobilizing political will and resources. It promotes actions to raise awareness, ensure coordination and collaboration, establish common goals and targets, monitor progress, and take effective measures aimed at addressing the issues of water and disasters. Members of HELP solicited the 10 case studies on water and disasters that form this book.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

of high rate algal ponds as a result of process intensification. Anaerobic digestion devoted to biogas production continues to be the preferred strategy for the energy valorisation of the algal biomass, co-digestion with multiple high C/N ratio substrates gathering significant attention over the past years. The potential of algal biomass as a biosorbent for heavy metal removal (Cu, Ni, F) maintains its share in the research field of water bioremediation, while research on nutrient removal has focused on providing new insights on the mechanism of nitrogen and phosphorus removal from wastewater in algal–bacterial systems. Finally, it is worth noticing that breakthroughs in complementary fields of research such as nanotechnology or lighting technology are gradually being implemented in algal biotechnology, with new products such as nanoparticles for water disinfection or photobioreactors illuminated by low intensity LED panels.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book highlights the impacts of emerging pollutants (both organic and inorganic) in water bodies and the role and performances of different water and wastewater treatment approaches that are presently being employed in the field of environmental engineering. Some of these approaches are focused on ‘end-of-pipe’ treatment, while most of these approaches are focused on the application of novel physic-chemical and biological techniques for wastewater treatment and reuse. The goal of this book is to present the emerging technologies and trends in the field of water and wastewater treatment. The papers in this book provide clear proof that environmentally friendly (bio)technologies are becoming more and more important and playing a critical role in removing a wide variety of organic and inorganic pollutants from water. In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.This book highlights the impacts of emerging pollutants (both organic and inorganic) in water bodies and the role and performances of different water and wastewater treatment approaches that are presently being employed in the field of environmental engineering. Some of these approaches are focused on ‘end-of-pipe’ treatment, while most of these approaches are focused on the application of novel physic-chemical and biological techniques for wastewater treatment and reuse. The goal of this book is to present the emerging technologies and trends in the field of water and wastewater treatment. The papers in this book provide clear proof that environmentally friendly (bio)technologies are becoming more and more important and playing a critical role in removing a wide variety of organic and inorganic pollutants from water. In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.This book highlights the impacts of emerging pollutants (both organic and inorganic) in water bodies and the role and performances of different water and wastewater treatment approaches that are presently being employed in the field of environmental engineering. Some of these approaches are focused on ‘end-of-pipe’ treatment, while most of these approaches are focused on the application of novel physic-chemical and biological techniques for wastewater treatment and reuse. The goal of this book is to present the emerging technologies and trends in the field of water and wastewater treatment. The papers in this book provide clear proof that environmentally friendly (bio)technologies are becoming more and more important and playing a critical role in removing a wide variety of organic and inorganic pollutants from water. In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book focuses on mega-droughts of the past 20 years. Twelve cases from both developed and developing countries are elaborated in the book. Its intention is to draw lessons from the cases of extremely severe water shortages so that countries and stakeholders can be better prepared for extreme drought events in the future.Several recurrent themes emerge from the diverse case studies and descriptions of programs. For example, most chapters discuss the necessity to move from reactive (compensatory) to preventive policies. This theme has implications for use of insurance in developing countries, e.g. is insurance encouraging investments to help countries avoid disasters or is it acting mostly in a humanitarian way to compensate for losses to help people? Several authors point to the importance of risk assessment and to developing risk based policies for drought. This raises statistical issues of how such assessments of uncertainty and risks are done and how they relate to actual occurrence of events. Most chapters call for more inter-sectoral policies, policies which integrate water resources management approaches and to the necessity of raising public awareness of droughts in times of no drought. The issue of structural versus nonstructural is clear in most cases. While often cast as ‘either/or’ the message that emerges is more one of how do you integrate these approaches. Finally, a few chapters bring to light how prevention is needed for national security as well as water security.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Frontier technology in water treatment and pollutant removal is needed not only for maximizing water reuse but also for the rapid detection of contaminants in the recycled water. The UN announced the years 2018 to 2028 as the ‘International Decade for Action–Water for Sustainable Development’. To realize this mission, innovative and frontier technologies for water treatment and pollutant removal are important components. This book aims to serve as a platform for updating the scientific community with recent progress in this area, covering frontier technologies in analytical technique, physicochemical treatment, chemical treatment, and biological treatment.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

One of the major challenges in the world is to provide clean water and sanitation for all. With 3% fresh water reserves in the earth, there are more than 1 billion people who still lack access to clean drinking water. The declining water quality has not only reduced the life expectancy of humans, but it has also contributed to the deleterious negative impacts on aquatic/marine life, flora, fauna and the ecosystem. However, with rapid technological advancements and the availability of advanced scientific instruments, there has been substantial improvement in the design and operation of water and wastewater treatment systems. Recently, these sustainable eco-technologies have been designed and operated to offer the following advantages: (i) a smaller footprint, (ii) less maintenance, (iii) >99% removal of contaminants, (iv) provides the option for resource recovery, (v) less energy consumption, (vi) minimal use of chemicals, and (vii) less investment and operational costs. This book highlights the technologies used for the removal of pollutants such as dyes, uranium, cyanotoxins, faecal contamination and P/N compounds from water environments, and shows that ecotechnologies are becoming more and more important and playing critical role in removing a wide variety of organic and inorganic pollutants from water.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Hydrology: Advances in Theory and Practice, brings together contributions to both the theory and practice of hydrology, including chapters on (amongst other topics) flood estimation methods and hydrological modelling. The book also looks forward with a global hydrology research agenda fit for the 2030s, and explores how to make advances in hydrological modelling – based on almost 50 years of modelling experience.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

The global water and sanitation community is currently wrestling with the policy implications of two important realizations. The first is that it is quite possible for cities to actually run out of water–for the piped network to run dry. The second is that in many locations, basic water and sanitation interventions do not result in the large public health improvements that many water and sanitation professionals had hoped. As water and sanitation professionals work out the implications of these two realizations on policy and planning for water and sanitation improvements in the Global South, they will require an in-depth knowledge of local housing, water, and sanitation conditions, as well as a nuanced understanding of how households prioritize improvements in housing, water, and sanitation. The chapters in this book about Kathmandu illustrate the types of analyses of local conditions that are needed. Kathmandu holds many lessons for the global community about households’ responses to water scarcity and the management of water and sanitation services in periods of rapid urbanization and climate change.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Increasing urbanization and changing climate are two critical stressors that are adversely affecting the biophysical environment of urban areas in the Hindu Kush Himalaya. The book discusses various choices and options – from demand management to supply enhancement, understanding ecological footprints of towns to managing water at a bioregional scale. In doing so, it is vital to address issues of equity and empower local institutions in managing water. The focus for the future must be on building urban resilience by strengthening the adaptive capacities of affected communities while also understanding the limits to adaptation.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Today, multi-disciplinarity is the key to tackle challenges for the sustainable management of water resources, especially considering the increasing complexity in the water world. It is thus fundamental to link the mathematical laws describing water bodies and the new technologies given by the ICT and information science scientific communities. The 16 chapters in this book cover five main topics: numerical models to predict the water hydrodynamic in terms of flow fields and contaminant dispersion; problems related to floods in urban and coastal areas and to wastewater treatments; problems concerning water distribution networks; hydrological and climate change problems; and groundwater and erosion.The complexity of the problems and the different approaches used within the chapters of this book clearly show the multi-disciplinary nature of the researche focused on water bodies. Thanks to the vivacity of the hydroinformatics community, day by day fundamental advances are made in understanding complex phenomena related to water physics as well as in novel methodologies and tools to drive sustainable and efficient management of natural and artificial water systems.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Hydrology and water resources management in a changing world reflects important challenges for both researchers and practitioners in the public and private sectors. This book features contributions from all sectors on the following themes: water in urban areas; groundwater; floods; climate services; hydrological processes and models; hydropower; water consumption; environmental impact and water quality.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

The case for investment in water, sanitation and hygiene (WASH) has been convincingly made. WASH is essential for protecting public health, is a human right and investing in it is compelling from a fiscal and economic point of view. While the estimated $114 billion per year of capital investments required to meet universal access to safely managed water and sanitation services by 2030 is often portrayed as a hefty price tag, current best estimates of benefit-to-cost ratios leave little doubt about its value.What is less clear is how to allocate resources efficiently. There is limited evidence on the cost efficiency and cost effectiveness of various policy and implementation choices. The underlying drivers of demand for (new) technologies and solutions are, for example, poorly understood, as is beneficiaries’ willingness to pay (WTP), leading to open questions about pricing policies and sustainable business models.This is in contrast to other infrastructure sectors, such as energy and transport, where active literature on the economics and financing of services has been more helpful in defining national and international policy. Our objective with this book is to encourage the WASH sector to follow suit and start to effectively engage and research these issues.At the heart of this book therefore, are chapters which highlight some of the specificities, and challenges of conducting full economic evaluations of WASH interventions, provide a deeper understanding of potential solutions, and present new findings on costs and outcome measures, thereby contributing towards a fuller picture of WASH cost-effectiveness.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

The pressure on available freshwater resources due to urbanization and climate change impacts is increasing worldwide; so follows the need to explore unconventional resources. Water reuse and desalination are viable options for alternative water supplies, also for regions that had no need to consider these approaches in the past. However, these solutions need to be tailored to local conditions, be balanced against conventional supply options while minimizing any adverse health and environmental impacts. There is increasing interest in developing new planning tools, technological solutions and approaches in this field to foster safe and economically viable water reuse and desalination applications.The German Federal Ministry of Education and Research (BMBF) realized these needs at an early stage and launched the major funding initiative ‘WavE’ (www.bmbf-wave.de/en) in 2016 entitled ‘Future-oriented Technologies and Concepts to Increase Water Availability by Water Reuse and Desalination’ within the framework program ‘Research for Sustainable Development (FONA)’ and the research agenda on Green Economy. WavE is aimed at developing innovative technologies and management concepts to foster a sustainable increase in water availability. The aim is to provide sustainable solutions for national and international applications.This book reports research highlights from comprehensive research projects addressing contemporary approaches to evaluate new technologies and concepts in non-potable water reuse applications, multi-barrier concepts for potable and non-potable reuse applications, concepts for industrial reuse and resource recovery approaches for brine streams, as well as onsite desalination technologies for developing communities.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Climate change has altered hydrologic conditions, which directly affects water resources. In addition, increasing human activities have an impact on water resources, water environment and water ecology. Rivers are important channels of water cycle, the main source of fresh water for human consumption and an important renewed resource, which play essential roles in material cycle, energy flow and climate regulation. Reservoirs are important components of water conservancy constructions, and play vital roles in regional flood interception, water storage, and the regulation of water flow. It is of great significance to study the mechanism of the water cycle under the changing environment and build an optimized water resource management based on it.Rivers and reservoirs are faced with many problems, and it is necessary to study the optimal management of water resources in rivers, lakes and reservoirs, the hydrological mechanism and ecological environment process (including experimental and numerical simulation methods), the optimal operation of engineering facilities and their natural and social effects, as well as the mitigation of water security problems and ensuring the sustainability of the ecosystem through the integrated management of rivers and reservoirs.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Water treatment and reuse is the key strategy to address the problems of water shortages. This book deals with various problems and investigates different treatment technologies concerning water reuse. In response to the challenges of severe water shortages and the deterioration of water quality, the focus on cutting-edge technology and systems for water treatment and reuse is fast-growing worldwide. Progress is needed to provide high quality reclaimed water, minimize the risks to environment and human health, and support use of non-conventional water resources.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This chapters in this book highlight the breadth of smart water technologies and applications. From the use of classical machine learning and data transformation methods for process improvement, to data management and assimilation in models for better monitoring control, a selection of these chapters describes the acquisition and preparation of data as an initial step in its use as part of a digital framework for smart water applications. Importantly, several chapters examine the use of smart tools and contemporary AI technologies, such as neural networks and Internet of Things, that demonstrate value in non-conventional or remote environments. This collection demonstrates the innovation possible through the entire ‘pipeline’ of the process of applying smart water techniques, from data measurement and collection, through initial analysis to the application of machine learning and AI techniques and finally through to system deployment. Each of these steps plays an important role in the application of data science and AI techniques to water problems. Collectively, the book showcases the innovation required to leverage modern data science and AI approaches in the water sector and collectively point the way towards a future of new measurement techniques, innovative methodologies, and intuitive human interaction to truly ‘Make Water Smart’.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book emphasizes the growing interest in the design and operation of large wastewater treatment plants throughout the past decades. The outstanding role of LWWTPs nowadays results from the shift of the world’s population from rural to urbanized areas with centralized sewer systems. The urban population of the world has grown rapidly from 751 million in 1950 to 4.2 billion in 2018.Asia is home to 54% of the world’s urban population, followed by Europe and Africa with 13% each. Today, 55% of the world’s population lives in urban areas, a proportion that is expected to increase to 68% by 2050. Projections show that urbanization, combined with the overall growth of the world’s population could add another 2.5 billion people to urban areas by 2050, with close to 90% of this increase taking place in Asia and Africa. Topics covered in this book include operational data and research centred around large-scale applications of innovative technologies and approaches; topics connected with the design and operation of LWWTPs, such as data acquisition for design purposes, application of mathematical models, nitrogen removal optimization and financial sustainability. Emerging topics of interest are also examined, such as the removal of micropollutants and microplastics, greenhouse gas emissions, activated sludge granulation and the effect of street thawing salt on plants.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Safe drinking water and sanitation are very important for the survival of human life. With the rapid proliferation of industries, growth in population and different forms of pollution, i.e. in water, air, soil and sediments, the living environment and the ecosystem is constantly polluted. In this context, integrating different water resources for enhanced water quality and reuse is important to solve the persisting problems and challenges in developing and the developed nations. Integrated water management offers environmental, economic and social benefits because it aims at maximizing the existing resources and prevents further depletion of the ecosystem.The 22 chapters in this book cover the following aspects: (i) the performance of different bioreactor configurations for wastewater treatment, (ii) rain water harvesting, (iii) water/wastewater reuse, (iv) the application of mathematical models, neural networks and remote sensing for water quality monitoring, treatment plant performance prediction and water resource management, and (v) the implementation of the water-energy-agriculture concept in practice.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Could advances in geoinformatics, irrigation management and climate adaptive agronomic practices ensure the sustainability of water supply in agriculture?This book comprises 33 chapters that contribute to a broad discussion and demonstration of state-of-the-art multifunctional role of water resources in agriculture. The aim of the book to provide insights into novel modelling (monitoring, analyzing/visualizing and prediction) approaches, irrigation management and agronomic practices to investigate the adaptability of water supply and crop production systems to changing environment.The book presents characteristic examples of new technologies and decision support systems (e.g., artificial intelligence/optimization modelling approaches, Big Geo data) in water efficiency at different levels, including: water supply hydraulic infrastructure systems, water retention measures, less exposed to evaporation and better adapted to infiltration, solutions to reduce water demand and developing techniques for reusing water.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book deals with various problems and investigates different treatment technologies concerning water reuse. In response to the challenges of severe water shortages and the deterioration of water quality, the focus of cutting-edge technology and systems for water treatment and reuse is fast-growing worldwide. Progress is needed to provide high quality reclaimed water, minimize the risks to the environment and human health, and support the use of non-conventional water resources.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book brings together cutting-edge studies and reviews on the water-related health aspects of SARS-CoV-2, contributed by our research community. The contributions are related to the potential risk of waterborne COVID-19 transmission, household water uses, and hygiene during the pandemic, and surveillance of SARS-CoV-2 RNA in wastewater.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

The impact of climate change on water resources is a research area that is gaining prominence, and concerns the prediction of rainfall, temperature, streamflow/discharge, and other meteorological variables.This book is intended to help researchers and other relevant stakeholders working in this area. Its chapters deal with estimation of runoff, floods and droughts, intensity-duration frequency (IDF) curves and evapotranspiration (ET). In addition, some of the miscellaneous topics related to hydrology are also included.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Water is the primary medium through which climate change influences the earth's ecosystem and thus people's livelihoods and well-being. Globally, 83% of all disasters have been caused by extreme weather and climate-related events, such as floods, storms, and heatwaves, over the past decade. Together, these disasters have killed more than 410,000 people and affected a staggering 1.7 billion people in different parts of the world. With a 50% increase in the global population and a 30% increase in the urban population from 2000 to 2050, the world will continue to face enormous challenges in most contexts. In many cases, poor people and developing countries are most likely to be affected.The impacts of climate change will make the situation worse by creating extreme conditions with catastrophic outcomes. We may anticipate technological, economic, and sociological impacts resulting from climate change on water resources and processes.There are numerous global, regional, and national initiatives to address the technical and socio-economic challenges associated with the impacts of climate change on water. The Water and Society project, involving four countries in Africa, three from Asia, and one from Europe (www.WaSoProject.org), is an example and has inspired this book, which presents some water management challenges in Asia and Africa resulting from climate change. Selected studies on changes in water quantities and their socio-economic impacts, as well as examples of abatement activities and their effects, illustrate the challenges involved, their status, and solutions.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Over the next three decades — the typical planning period for large infrastructure — the world will have changed into a place that is predominantly water-scarce, yet also subject to more extreme flooding. The water world’s disjointed project-based approach to knowledge and capacity building needs to be replaced with a programmatic and professionalised structure applying a longer time horizon. Water management systems are becoming more complex and dynamic, and capacity development must take a systems approach. Though forecasting capabilities have increased significantly, the future remains uncertain, so planning should avoid locking in end results and investments, instead seeking an iterative approach facilitating adaptation and stepwise learning of what works. The chapters in this book call for institutionalising processes to learn from past experience, such as frames that monitor and evaluate policies and implementation programmes. Such approaches do necessitate much higher funding and a more coherent and longer operational time frame. Investing in capacity is economically sound, benefiting the individuals whose capacity is developed and society at large. In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book focuses on climate change and hydrological extremes, i.e. droughts and floods, which are globally important natural hazards with associated costly impacts on society and the environment. Floods and droughts result from the superposition of different processes at various space and time scales: physical processes in the atmosphere, catchments, the river systems, and anthropogenic activities. However, the characteristics of hydrological extremes have been altered due to climate change and variability, such that approaches for their detection, attribution, and the frequency of occurrence need to be revisited as they are no longer stationary processes. For more accurate estimation of hydrological extremes under nonstationary and uncertain conditions, there is a need for holistic assessments. Time–frequency analysis, hydrological modeling, physical-cause analysis, multivariate statistical analysis, and uncertainty analysis are powerful tools for detecting, attributing, and making frequency analysis of nonstationary hydrological extremes in a changing climate. Both nonstationarity and uncertainty of frequency analysis of extreme hydrological events should be integrated to reveal the possible operational alternatives to the assumption of stationarity in hydrological extremes frequency analysis.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

Acknowledging that resource efficiency as well as ecosystem protection are crucial goals to tackle has led to a deep rethinking in the way wastewater has been dealt with up to the 20th century. Indeed, pollution reduction to harmless levels has been the main focus of conventional wastewater treatment plants which have deployed effective and reliable solutions to get rid of suspended and dissolved pollutants. Nowadays, those same wastewaters are looked at as a mine of valuable resources that are to be harvested from the sewage through efficient technologies operated within water and resource recovery facilities (formerly known as wastewater treatment plants).Rethinking the way we deal with wastewater has become the new challenge and a key tool to implement the Circular Economy Action Plan, to address numerous UN Sustainable Development Goals, as well as to provide support tools to improve resilience to environmental and global threats, including climate change, water and food security, epidemic outbreaks and political instability.To tackle these challenging goals, new technologies as well as multidisciplinary tools are needed to pave the way toward a new water-economy, including: innovative technologies, integrated and risk-based approaches, and adequate regulatory and economic guidelines to promote technological uptake and societal acceptance.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book explores two frameworks for progressing structural change that supports safe, universal and equitable water, sanitation and hygiene (WASH): systems strengthening and the human rights to water and sanitation. As such, it elaborates and defines the intersection between these two areas. Whilst inherently interconnected, the two also represent different entry points for change, with opportunity for increased intentional integration to improve progress towards Sustainable Development Goal 6: Clean water and sanitation.Systems strengthening is widely recognised as foundational for ensuring access to sustainable, equitable WASH services in low- and middle-income countries, leaving no-one behind. Such systems comprise clear sector policy and strategy, effective institutional arrangements, sufficient sector financing, regular cycles of planning, monitoring and review and capacity development across the sector; as well as the people, interactions, power relations and behaviours that shape these elements.Equally, the human rights to water and sanitation provide numerous entry points for change, both in supporting people to claim and realise their rights and in supporting and advocating for governments at all levels to respond.Effective approaches to strengthen systems and realise the rights depend on inclusive processes that meaningfully involve people and advance equality, including gender equality. They facilitate mutual learning, capacity building and increased accountability, promote informed choice and place development in the hands of those it concerns.In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.

This book comprises six chapters prepared by the COST Action Circular City (https://circular-city.eu/). The Action aims to establish a network of researchers and stakeholders testing the hypothesis that: ‘A circular flow system that implements nature-based solutions (NBS) for managing nutrients and resources within the urban biosphere will lead to a resilient, sustainable and healthy urban environment.’ They are the starting point towards deeper exploration of how NBS can contribute to circular cities, gathering state-of-the-art knowledge of one of the biggest COST Actions so far. In Focus – a book series that showcases the latest accomplishments in water research. Each book focuses on a specialist area with papers from top experts in the field. It aims to be a vehicle for in-depth understanding and inspire further conversations in the sector.