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One key challenge of water resources management is the identification and processing of the information necessary for decision-making. This article aims to provide avenues for translating a ‘water scarcity–water reuse’ (WS–WR) situation into an information system. It is dedicated to supporting an integrated assessment in decision-making with the final goal of optimising water scarcity risk reduction and water reuse sustainability. The approach combines the following two strands: (1) specific interpretation of systems thinking and (2) systemic characterisation and interlinkage of indicators. The result is an analytical concept that translates the WS–WR situation into an information system consisting of two structured components, a multi-layer (ML) and a lane-based (LB) approach. While the multi-layer approach supports the description of the elements of the biophysical and information systems such as endpoints and descriptors, respectively, the lane-based approach aids in understanding the importance of indicators within the entire system and their distribution across risk and sustainability realms. The findings from a generic exemplification of the analytical concept depict the feasibility of identifying system-based endpoints representing the WS–WR situation and their translation via descriptors to an interlinked indicator set to jointly assess water scarcity risk and sustainability of the water reuse measures. Therefore, this analytical concept supports addressing the water resources management information challenge via a structured representation of the system’s complexity and the quantification and visualisation of interlinkages between the social, economic, and environmental dimensions of water scarcity risk and water reuse sustainability.

Water scarcity is a serious socio-environmental challenge for sustainable development which is recognized as a potential cause of social conflict within and between countries. It is expected to intensify due to increasing water demands from increasing populations, rapid urbanization, industrialization, and climate changes. With predictions of dire global water scarcity, attention is turning to Unconventional Water Resources (UWRs) which are considered as supplementary water resources that need specialized processes to be used as water supply. The literature encompasses a vast number of studies on various UWRs and their usefulness in certain environmental and/or socio-economic contexts. Considering the increasing importance of UWRs in the global push for water security, the current study intends to offer a nuanced understanding of the existing research on UWRs by summarizing the key concepts in the literature. The number of articles published on UWRs have increased significantly over time and most publications were authored from researchers based in the USA or China, India, Iran, and Spain. Here, twelve general types of UWRs including fog, dew, rainwater harvesting, and cloud seeding as Atmospheric Unconventional Water (AUW); artificial recharge, fossil water as Unconventional Ground Water (UGW); iceberg water and virtual water as Transferred Unconventional Water (TUW), and wastewater, desalinated water, and agricultural drainage water as Processed Unconventional Water (PUW), were used to assess their global distribution, showing that climatic conditions are the main driver for the application of certain UWRs. Overall, the literature review demonstrated that, even though UWRs provide promising possibilities for overcoming water scarcity, current knowledge is patchy and points towards UWRs being, for the most part, limited in scope and applicability due to geographic, climatic, economic, and political constraints. Future studies focusing on improved quantitative documentation and demonstration of the physical and socio-economic potential of various UWRs could help in strengthening the case for some, if not all, UWRs as avenues for the sustainable provision of water.Keywords: Water scarcity; UWRs; distribution maps; literature review

Circular Economy principles seek to apply a “multiple use” approach with focus on returning the resource to further systems. Water and wastewater treatment systems rarely consider all three dimensions of sustainability in terms of environmental, social, and economic parameters. Wastewater holds important resources that are useful for further use, for instance in irrigation for agriculture, groundwater recharge, sludge reuse, biomass harvesting, and energy production. We postulate that using circular economy principles in wastewater treatment systems, i.e., using treated wastewater for subsequent purposes, can increase the sustainability of wastewater treatment system, in particular for achieving the United Nations Sustainable Development Goal 6 and one of its targets on increasing the proportion of safely treated wastewater. We further postulate that using treatment systems that allow for multiple (re)use options achieves higher sustainability. In two examples from Latin America and Asia (India) we illustrate how circular economy principals applied to wastewater treatments holds potential to address environmental, social, and economic development.

Constructed Wetlands (CWs) are a nature-based solution for the treatment of wastewater. The CWetlands – the Constructed Wetlands Knowledge Platform – intends to help understand how CWs can support achieving the Sustainable Development Goals. The platform is based on more than 100 attributes of CWs including criteria for design criteria, operation, efficiency, climate and other geographical factors. This study aims at developing an attribute value extraction mechanism tool in R to extract meaningful information from peer-reviewed journal articles in a reliable and fast way. • The tool focuses on the extraction of eighteen different extractable attributes gathered in 4 classes, which describe the main characteristics of CW systems. • The process contains 4 sub-processes: 1–2) the papers are accessed and pre-processed, 3) the attributes are extracted by two data mining techniques: Keyword Match and Web Scrap, and 4) the values are exported to a database. • For the development and testing of the tool, 13 articles were used. The tool achieved a mean success rate of 79% in 30 min; less compared with the 480 min needed with a manual approach. In further versions, the tool is expected to obtain a higher success rate in all attributes. Method name: Attribute value extraction mechanism, Keywords: Nature-based solutions, Text mining, Natural processing, R, Database

Water resources and their properties highly vary in both space and time and their observations have high uncertainties. The characterization of this variability requires long-term spatially distributed observations, that allow the recognition of spatio-temporal patterns and changes. Unlike other engineering activities that typically can be satisfied with a one-time surveying of the designated area prior to the development planning, water management requires continuous monitoring records capturing the historical variability of the hydrological conditions. The need for a sustained data collection often without the immediate use, places water resources management in a difficult position. The justification of operating monitoring networks in the absence of pressing objectives, particularly at long-time scales, is often challenging, but water managers need to convince policy makers that water management decisions require the knowledge of how the hydrological processes varied over time. Without sufficiently long and up-to-date data series, adequate water management planning, ecosystem monitoring, and early warning systems are severely limited.

This chapter is the collection of several examples, both in thematic and geographical sense, which manifest the need to address water and land management in an integrated way. It reviews irrigation and soil management techniques, performance assessment of irrigation as well as water delivery scheduling for irrigated agriculture. Water scarcity and drought may even jeopardize that irrigation infrastructure could be deployed to offset threatening economic losses. The chapter emphasizes the need for careful afforestation planning to avoid aggravating water shortage downstream. Finally, constructed wetlands are introduced as a low cost wastewater treatment technology with other positive spin off effects.

The 2030 Agenda for Sustainable Development sets a series of ambitious challenges for the global community. These Sustainable Development Goals (SDGs) include targets for access to safe drinking water and sanitation and better water management, as well as goals for addressing inequality and discrimination, including the overarching aims of ‘leaving no one behind’ and ‘reaching the furthest behind first’. These are challenges that, to date, have proven difficult to meet, partly because they are complex, but also due to political inertia. The global context for this agenda may be characterized as ‘crisis is the new normal’, with political insecurity, social, economic and environmental challenges on a daunting scale. This calls for redoubled efforts and carefully selected approaches towards achieving transformative change.The issues underlying both water-related goals and leaving no one behind intersect in several ways. Both water supply and sanitation, and issues of equality for all people and for specific disadvantaged groups in particular, are recognized through international human rights instruments and agreements. However, these have not been enough to bring about the necessary changes. To some extent, the issues share both root causes and similar challenges. The same people who are being left behind are those who could benefit most from improved access to water and sanitation. Improved access to water and sanitation, water management and governance, and the multiple benefits they bring, can contribute significantly to positive transformation for marginalized people. Benefits include better health, savings in time and money, dignity, improved access to food and energy, and greater opportunities in terms of education, employment and livelihoods. These benefits, directly and indirectly, separately and in combination, contribute to improving the lives of all, but can be particularly transformative for people in vulnerable situations. At the same time, engaging with marginalized groups can enhance the achievement and sustainability of water-related goals. This process of engagement can also be transformative in giving a voice to those rarely heard, in turn creating space for vital water-related knowledge and experience that might otherwise be lost.As the sixth in a series of annual, thematic reports, the 2019 edition of the United Nations World Water Development Report (WWDR) examines how improved water resource management and access to water supply and sanitation services can help address the causes and alleviate the impacts of poverty and social inequity. It provides insights and guidance in helping identify ‘who’ is being left behind, and describes how existing frameworks and mandates, such as the 2030 Agenda and the SDGs and human rights-based approaches, can help ‘reach the furthest first’, through improved water management.The report assesses the issues and offers potential responses from technical, social, institutional and financial perspectives, while taking account of the many different challenges faced in rural and urban settings. With the world witnessing the highest levels of human displacement on record, an entire chapter has been dedicated to the exceptional challenges faced by refugees and forcibly displaced people with respect to water and sanitation. We have endeavoured to produce a balanced, fact-based and neutral account of the current state of knowledge, covering the most recent developments, and highlighting the challenges and opportunities provided by improved water management in the context of human development. Although primarily targeted at national-level decision-makers and water resources managers, as well as academics and the broader development community, we hope this report will also be well received by those interested in poverty alleviation, humanitarian crises, human rights and the 2030 Agenda.This latest edition of the WWDR is the result of a concerted effort between the Chapter Lead Agencies, FAO, OHCHR, UNDP, UNESCO-IHP, UN-Habitat, UNHCR, UNU-INWEH, UNU-FLORES, WWAP and the World Bank, with regional perspectives provided by UNECE, UNECLAC, UNESCAP and UNESCWA. The Report also benefited to a great extent from the inputs and contributions of several other UN-Water members and partners, as well as of dozens of scientists, professionals and NGOs, who provided a wide range of relevant material.On behalf of the WWAP Secretariat, we would like to extend our deepest appreciation to the afore-mentioned agencies, members and partners of UN-Water, and to the writers and other contributors for collectively producing this unique and authoritative report that will, hopefully, have multiple impacts worldwide. Léo Heller, Special Rapporteur on the human rights to safe drinking water and sanitation, deserves specific recognition for having generously shared his knowledge and wisdom in the early critical phases of the report’s production process.We are profoundly grateful to the Italian Government for funding the Programme and to the Regione Umbria for generously hosting the WWAP Secretariat in Villa La Colombella in Perugia. Their contributions have been instrumental to the production of the WWDR.Our special thanks go to Audrey Azoulay, Director-General of UNESCO, for her vital support to WWAP and the production of the WWDR. The guidance of Gilbert F. Houngbo, President of IFAD, as Chair of UN-Water has made this publication possible. Last but not least, we extend our most sincere gratitude to all our colleagues at the WWAP Secretariat for their professionalism and dedication, without whom the report would not have been completed.

Monitoring the qualitative status of freshwaters is an important goal of the international community, as stated in the Sustainable Development Goal (SDGs) indicator 6.3.2 on good ambient water quality. Monitoring data are, however, lacking in many countries, allegedly because of capacity challenges of less-developed countries. So far, however, the relationship between human development and capacity challenges for water quality monitoring have not been analysed systematically. This hinders the implementation of fine-tuned capacity development programmes for water quality monitoring. Against this background, this study takes a global perspective in analysing the link between human development and the capacity challenges countries face in their national water quality monitoring programmes. The analysis is based on the latest data on the human development index and an international online survey amongst experts from science and practice. Results provide evidence of a negative relationship between human development and the capacity challenges to meet SDG 6.3.2 monitoring requirements. This negative relationship increases along the course of the monitoring process, from defining the enabling environment, choosing parameters for the collection of field data, to the analytics and analysis of five commonly used parameters (DO, EC, pH, TP and TN). Our assessment can be used to help practitioners improve technical capacity development activities and to identify and target investment in capacity development for monitoring. Electronic supplementary material The online version of this article (10.1007/s10661-020-8224-3) contains supplementary material, which is available to authorized users.

In northern Togo where rainfed maize is one of the major crops grown, agriculture is subject to frequent yield losses due to erratic rainfall. To ensure food availability and improve agricultural productivity, it is necessary to produce maize during the dry season under irrigation. A sound application of full and deficit irrigation requires a thorough understanding of the crop parameters and yield response to water. Thus, this study investigated the effect of full and deficit irrigation on maize plant above-ground biomass, leaf area index, canopy cover, plant height, and grain yield. A field experiment was carried out from December 2017 to April 2018 in northern Togo at the agronomic research institute. Full irrigation (FI), 80% FI, and 60% FI treatments were applied. The results showed that in the late-season stage, the differences in biomass between FI and 60% FI were significant (p < 0.05). On average, FI had the greatest grain yield (2 200.4 kg/ha), while the lowest grain yield was recorded under 60% FI (1 068.3 kg/ha). The grain yield differences between FI and 60% FI were significant. Nevertheless, the grain yield differences between FI and 80% FI were not significant (p > 0.05). 80% FI had water use efficiency (WUE) (0.22 kg/m3) similar to that of FI (0.21 kg/m3), on average. The results of this study illustrate that deficit irrigation must be carefully managed since slight differences in the application volumes affect the biomass and yield of maize significantly. Under a moderate level of deficit irrigation (vegetative and reproductive growth stages) the biomass and the grain yield of maize are reduced. However, a moderate level of deficit irrigation during the vegetative growth stage could result in similar values of WUE to that of FI.Keywords: evapotranspiration, deficit irrigation, water use efficiency, crop yield, maize

In many parts of the world wastewater is not treated at all or only to a limited extend because there are no resources available to establish an efficient wastewater treatment plant and there are also insufficient resources for operation and maintenance costs. Constructed wetlands (CWs) are nature-based solutions to treat wastewater in a highly cost-efficient manner. They can be very efficient and effective when well designed and maintained. Latin America is rich in saline natural wetlands. These can be used as prototypes for CWs treating saline process or wastewater. Similar to natural saline wetlands CWs can deliver several ecosystem services. This review focuses on saline wetlands and will first present the protagonists, the salt-tolerant plant species belonging to the halophytes with respect to their physiological and biochemical functions in wetlands. In a second step, their remediating activities which are used in many ways by local people will be shown in an exemplary manner. A number of CWs established in different regions, including Latin America, will be introduced as case studies. Halophytes are already being used in a number of CWs as biofilter but their usage could be increased, for example to treat aquaculture effluents and the biomass has a high potential for valuable compounds (i.e. metabolites) or for bioenergy production. Lastly, aspects of sustainability and ecosystem services of saline natural and constructed wetlands are shown with an emphasis on charting a way forward for the future holistic implementation of saline systems in Latin America.

While the world is facing unprecedented transitions and threats we need to deeply rethink the relationships between water and energy use, food production, and ecosystem protection. This includes the development and deployment of ambitious, out-of-the-box solutions towards sustainable development. This paper is based upon recent discussions before and during the 2nd World Irrigation Forum in Chiang Mai, Thailand. This paper takes stock of current knowledge and analyses the most recent trends in water, irrigation and the environment. It discusses the requirements for strategic approaches and the contributions of irrigation and drainage to Sustainable Development Goals. Firstly, we concentrated on renewed and more balanced relationships between water, energy, food and ecosystems in the context of irrigation and drainage management. Secondly, we assessed the positive and negative impact of agricultural water use in order to demonstrate and improve its performance. Given exacerbated competition and water resource scarcity, a better understanding of the positive effects and valuable ecosystem services provided by irrigation and drainage systems could pave the way to maximizing benefits and safeguarding the environment. Lastly, we tried to address the role of stakeholders in irrigation governance. This includes active contribution to policy-making and planning, incentives, and most importantly, capacity development.

Wastewater management in Latin America faces great challenges to reach a sustainable state. Although enough infrastructure has been built to treat around 40% of wastewater, only between 15&ndash, 20% is effectively treated, and abandoned or defective infrastructure is a common sight. Data about current conditions at specific sites is quite fragmented, when existing. This leads to challenges in management, decision making and planning for sustainable options. We argue that a main obstacle is the lack of a regionally relevant sustainability assessment framework that allows for a holistic understanding of wastewater management as a nexus problem. We therefore developed a comprehensive framework to (1) understand current conditions (2) involve stakeholders and (3) point to pathways to improve wastewater management in the Americas. Building on literature review and stakeholder involvement, we constructed a multi-scalar extended dataset framework that is adaptable to different study sites using specific criteria. Sustainability was assessed through a &ldquo, distance-to-target&rdquo, approach. Social and economic variables were the lowest ranking in both cases, with technical variables generally performing better. Although some dimensions of sustainability are performing acceptably, others, such as social and economic, are general low to very low performing. This means, when looked at in an integrated manner, neither of the wastewater management systems analysed can be considered sustainable. Here we present the approach itself, the results of its application in two pilot sites in Latin America, and our recommendation to shift waste water management into sustainability.

Decision-makers face major challenges when trying to reduce risks of water scarcity sustainably through measures of water reuse. One of these challenges is the lack of interconnectedness between risk assessment for water scarcity and sustainability assessment for water reuse. Therefore, this paper aims to explore the conceptual integration of risk and sustainability assessments (RSA) in a framework for decision support in ‘water scarcity – water reuse’ situations. This article follows a three steps approach: (i) defining and interpreting the ‘water scarcity – water reuse’ situation as a coupled human and natural system; (ii) identifying and defining key concepts relevant for risk and sustainability assessment, and (iii) constructing the integrated RSA Framework for decision support. As a result, the latter provides a conceptualisation of a simultaneous assessment of water scarcity as a risk and the sustainability of water reuse measures according to the social, economic, and environmental dimensions. It contemplates an analysis phase and an evaluation phase to provide unified information on the level of water scarcity risk and water reuse sustainability. The resulting indicates that the integration of risk and sustainability in one joint assessment for decision support is conceptually feasible. It hence paves the way towards a comprehensive and consistent methodological operationalisation and empirical application.

Attempts to monitor the quality of freshwater resources on a global scale unveil huge data lacks. Involving citizens in data collection has potential to resolve this lack of water quality data. However, it is widely unclear which factors drive the success of citizen science activities. Based on a systematic literature review of 56 peer-reviewed research articles, we identify three sets of factors for successful citizen science projects in water quality monitoring: (i) attributes of citizens (knowledge and experience in collecting data, awareness of environmental problems, motivation, and socio-economic background of citizens), (ii) attributes of institutions (motivation, type of organization, consistent and adequate funding), and (iii) the interactions between citizens and institutions (supporting structure, communication and feedback). These three sets of factors enable a systematic analysis and design of citizen science projects in the future.

In the 1990s, the emergence of Integrated Management Approaches to water, land and waste established a widely accepted understanding on integration of environmental systems. Nexus Approaches try to often build on these. This paper assesses i) the intended goals and features of three Integrated Management Approaches (Integrated Natural Resources Management - INRM, Integrated Water Resources Management - IWRM and Integrated Solid Waste Management - ISWM) and two Nexus Approaches (Water-Energy-Food (WEF) Nexus and Water-Soil-Waste (WSW) Nexus), and ii) how target systems and their integration are viewed in each of the Integrated Management Approaches. From this we assess commonalities and some lessons-learned for the Nexus. The method is based on a systematic literature review and a document analysis. From 1652 articles 52 peer reviewed papers were analysed. The results show that in terms of goals the Nexus Approaches are very similar to Integrated Management Approaches with the addition of clearly wanting to address governance and policy aspects e.g. in the WEF Nexus. Nexus Approaches try to move away from a single-resource centric view (e.g. WSW Nexus) and intend to go beyond resources towards sectors (e.g. WEF Nexus). It cannot be confirmed, that integration is clearly addressed in the analysed Integrated Management Approaches and what integration means is hardly defined. To provide some clarity for Nexus Approaches we propose a concept to describe integration by using “categories of integration” and the term “aspect” which includes systems, subsystems and other aspects alike.

Despite of all efforts, soil and land degradation is increasing across sub-Saharan Africa (SSA). One reason for this is that many homes in SSA have no access to modern energy supply. Most of the energy used for cooking and heating comes from firewood, charcoal, crop residues, or even dung. Since biomass collection for energy use is not counterbalanced by soil nutrient increasing measures these habits results in significant vegetation and soil degradation, and decreasing water supply in wells and rivers. As a consequence, the provision of water, food, and energy is not ensured in many regions of SSA. The entry shows that food, energy and water security are interlinked as a Gordian knot. At the heart of these interlinkages is the Nexus of water, soil, and waste. Solutions to food and water issues in SSA must involve the establishment of land use systems which produce more food and bioenergy based on a sustainably enhanced productivity of soils and land. It is discussed that multifunctional land use systems based on agroforestry concepts meet these needs. As an innovative strategy to improve soils and land in SSA, the integration of non-food bioenergy systems across the landscape on degraded soils and on soils with medium to low productivity is suggested. It is demonstrated how the productivity of these sites could be increased by integrating waste from households and farms into the biomass production cycle. Finally, the potential impacts of implemented multifunctional land use systems on environmental, social, and socioeconomic aspects are illustrated.

The assessment of biophysical crop suitability requires datasets on soil and climate. In this study, we investigated the differences in topsoil properties for the dominant soil mapping units between two global soil datasets. We compared the ISRIC World Soil Information Center’s World Inventory of Soil Emissions Potential 5 by 5 arc min Soil Map of the World (ISRIC-WISE 5by5 SMW ) with the Harmonized World Soil Database (HWSD) in 0.5 arc min. We also incorporated annual mean temperature and mean precipitation from two global climate datasets that were the WorldClim measurement-based climate dataset and the Kiel Climate Model (KCM) modelled results of global climate from 1960 to 1990. We then applied a fuzzy logic approach using different combinations and resolutions of the datasets to determine the effects on the extent and distribution of suitable areas for 15 crops. We only used the spatially dominant soil class in the mapping units in the soil databases (resampled to the same resolution of 5 arc min), and we found that the estimates of topsoil properties (0–20 cm in ISRIC-WISE and 0–30 cm in HWSD) of the seven analysed parameters were up to 40% lower in most of the HWSD than in the ISRIC-WISE 5by5 SMW. Results from the KCM are 0.1 °C (1%) lower in mean global annual temperature and 20% higher in average global annual precipitation compared with the WorldClim data. The HWSD-based runs resulted in 10% less crop-suitable land than the ISRIC-WISE 5by5 SMW-based results. The KCM simulations predicted 1% less crop-suitable land than the WorldClim model. Despite generalizations, our results demonstrate that discrepancies in crop suitable areas are largely due to the differences in the soil databases rather than to climate.

The Sustainable Development Goals have placed integrated resources management, such as integrated water resource management, at the heart of their targets. The upcoming “International Decade for Action—Water for Sustainable Development”, 2018–2028 has highlighted the importance of promoting efficient water usage at all levels, taking into account the water, food, energy, and environmental nexus. While integrated resource management approaches have been defined and applied for decades, nexus approaches are more recent. For these latter approaches to be implemented on the ground, their system boundaries need to be clarified. While the Water–Energy–Food Nexus focuses on sectors, the Water–Soil–Waste Nexus addresses linkages between environmental resources—namely water, soil and waste—to tackle sustainable management. In this paper, we analyzed integrated management systems and how their system boundaries are defined. From this we determined that in order for system boundaries to be applicable, they should be clear, wide and flexible. Based on this, we propose the boundary of the Water–Soil–Waste Nexus system. We use two case studies to exemplify the usefulness of these system boundaries.

Soil parameters represent key data input for crop suitability analysis. Soil databases are complex offering soil mapping units made up of various component soils. In the case of the Harmonized World Soil Database there can be up to 8 component soils per unit. In roughly 1/3 of soil mapping units, the additional component soils take up more than 50% of the pixel share value. The soil parameter value estimate, such as pH, salinity and organic carbon content, may differ between the value of the dominant soil component and the weighted average of the values of all component soil. Understanding the effect of these differences on crop model outputs may allow quantifying the error. In this study, we show the changes in crop suitability of 15 crops while using the parameter value estimates of the dominant soils versus a weighted average of the component soils. In the case of the latter, global crop suitability amounts to 54.5% of the earth’s land surface–1% more than when using the values of just dominant soils. Intrinsic regional differences in the quality of the soil database influence the distribution of crop suitability classes especially in areas where share values of the dominant soil are low. The uncertainty range for the use of dominant versus component soils on the overall global crop suitability could be considered to be 1%, while that of each suitability class can amount to up to 4%.