Showing papers on "Water scarcity published in 2017"

Water scarcity assessments in the past, present, and future

Abstract: Water scarcity has become a major constraint to socio-economic development and a threat to livelihood in increasing parts of the world. Since the late 1980s, water scarcity research has attracted much political and public attention. We here review a variety of indicators that have been developed to capture different characteristics of water scarcity. Population, water availability and water use are the key elements of these indicators. Most of the progress made in the last few decades has been on the quantification of water availability and use by applying spatially explicit models. However, challenges remain on appropriate incorporation of green water (soil moisture), water quality, environmental flow requirements, globalization and virtual water trade in water scarcity assessment. Meanwhile, inter- and intra- annual variability of water availability and use also calls for assessing the temporal dimension of water scarcity. It requires concerted efforts of hydrologists, economists, social scientists, and environmental scientists to develop integrated approaches to capture the multi-faceted nature of water scarcity.

Water scarcity hotspots travel downstream due to human interventions in the 20th and 21st century

Abstract: Water scarcity is rapidly increasing in many regions. In a novel, multi-model assessment, we examine how human interventions (HI: land use and land cover change, man-made reservoirs and human water use) affected monthly river water availability and water scarcity over the period 1971–2010. Here we show that HI drastically change the critical dimensions of water scarcity, aggravating water scarcity for 8.8% (7.4–16.5%) of the global population but alleviating it for another 8.3% (6.4–15.8%). Positive impacts of HI mostly occur upstream, whereas HI aggravate water scarcity downstream; HI cause water scarcity to travel downstream. Attribution of water scarcity changes to HI components is complex and varies among the hydrological models. Seasonal variation in impacts and dominant HI components is also substantial. A thorough consideration of the spatially and temporally varying interactions among HI components and of uncertainties is therefore crucial for the success of water scarcity adaptation by HI.

Wastewater Reuse in Agriculture: A Review about Its Limitations and Benefits

Abstract: For centuries, wastewater has been improperly used in agriculture, presenting potential risks to public health and the environment. In the context of scientific development, and confronted by an increasing water crisis, wastewater reuse merits consideration because the practice helps decrease water use pressure and moderates water pollution. Thus, this article presents a literature review that addresses the effects, both positive and negative, of wastewater use in agriculture, emphasizing the effects on the soil environment. The literature review reveals that, until the 1990s, research studies promoted the use of wastewater for irrigation purposes from a treatment approach, while proposing “end of pipe” conventional solutions. However, more recent research studies (2012–2016) reveal that agricultural reuse significantly affects soil texture properties, while also causing possible alterations of the biomass and microbiota. In addition, research in this period has been oriented to the quantitative evaluation of microbiological risk.

The challenges of water, waste and climate change in cities

Abstract: Cities play a prominent role in our economic development as more than 80 % of the gross world product (GWP) comes from cities. Only 600 urban areas with just 20 % of the world population generate 60 % of the GWP. Rapid urbanization, climate change, inadequate maintenance of water and wastewater infrastructures and poor solid waste management may lead to flooding, water scarcity, water pollution, adverse health effects and rehabilitation costs that may overwhelm the resilience of cities. These megatrends pose urgent challenges in cities as the cost of inaction is high. We present an overview about population growth, urbanization, water, waste, climate change, water governance and transitions. Against this background, we discuss the categorization of cities based on our baseline assessments, i.e. our City Blueprint research on 45 municipalities and regions predominantly in Europe. With this bias towards Europe in mind, the challenges can be discussed globally by clustering cities into distinct categories of sustainability and by providing additional data and information from global regions. We distinguish five categories of sustainability: (1) cities lacking basic water services, (2) wasteful cities, (3) water-efficient cities, (4) resource-efficient and adaptive cities and (5) water-wise cities. Many cities in Western Europe belong to categories 3 and 4. Some cities in Eastern Europe and the few cities we have assessed in Latin America, Asia and Africa can be categorized as cities lacking basic water services. Lack of water infrastructures or obsolete infrastructures, solid waste management and climate adaptation are priorities. It is concluded that cities require a long-term framing of their sectoral challenges into a proactive and coherent Urban Agenda to maximize the co-benefits of adaptation and to minimize the cost. Furthermore, regional platforms of cities are needed to enhance city-to-city learning and to improve governance capacities necessary to accelerate effective and efficient transitions towards water-wise cities. These learning alliances are needed as the time window to solve the global water governance crisis is narrow and rapidly closing. The water sector can play an important role but needs to reframe and refocus radically.

Water Footprint Assessment: Evolvement of a New Research Field

Abstract: This paper reviews the evolvement of water footprint assessment (WFA) as a new research field over the past fifteen years. The research is rooted in four basic thoughts: (1) there is a global dimension to water management because water-intensive commodities are internationally traded, so we must study virtual water trade and the effects of countries externalizing their water footprint; (2) freshwater renewal rates are limited, so we must study the development of consumption, production and trade patterns in relation to these limitations; (3) supply-chain thinking, previously uncommon in water management, can help to address sustainable water use from the perspective of companies and final consumers; and (4) a comprehensive approach requires the consideration of green in addition to blue water consumption, the traditional focus in water management, and the analysis of water pollution in the same analytical framework as well. The quick emergence of the new field and wide uptake of the water footprint concept in society has generated substantial discussion about what the concept in narrow sense and the research field in broader sense can offer and what not. The paper reflects on the main issues of debate.

Desalination and water reuse to address global water scarcity

Abstract: The act of ensuring freshwater is considered the most essential and basic need for humanity. Although the planet is water-rich in some terms, the freshwater sources available for human consumption and beneficial uses are very limited. Excess population growth, industrial development coupled with improving living standards have caused an unprecedented need for freshwater all over the world. Regions once rich in water resources are struggling to meet the ever increasing demands in recent years. In addition, climate change and unsustainable management practices have led to a situation called “drought” in many regions. Water supplies in drought conditions can be addressed by taking two major approaches related to management and technology development. The management approaches include demand mitigation and supply enhancement. Demand mitigation can be done by implementing water conservation practices, and by enforcing a mechanism to influence user-responsible behavior through higher water fares and other billing routes. Supply enhancement can be achieved by utilizing the methods available for water reclamation, reuse and recycle including rain harvesting. This paper provides a critical insight of the causes for drought and the issues caused by persistent drought conditions followed by discussion of management and technological approaches required to maintain adequate water resources around the world. Challenges and opportunities involved in implementation of desalination and water reuse technologies in addressing global water scarcity are discussed in detail with case studies

Renewable energy integrated desalination: A sustainable solution to overcome future fresh-water scarcity in India

Abstract: Fossil fuels such as coal, petroleum, and natural gas have been used as the major sources of energy in the recent past. However, the negative environmental impacts associated with the emission of the greenhouse gases from these conventional energy sources forced to realize the importance of renewable energy resources. At the same time, the average annual exponential rate of population growth in India needs increasing amounts of fresh-water for the basic necessities. This might result in water scarcity as the overall population in India is expected to increase to 1.60 billion by 2050. It has been forecasted that, by the year 2040, India will rank 40th in the world in terms of water scarcity. To meet the rising fresh-water demand, desalination is an intelligent and sustainable option for India, which has a very long coastline measuring 7517 km. In this paper, an attempt has been made to provide a comprehensive review of water scarcity in India and suggest a possible solution, which is implementing desalination technologies coupled with renewable resources. The paper reviews the ground water scenario in India and the global desalination market. We summarize the energy consumption in various desalination processes and provide a brief outlook of the desalination techniques in India. Apart from this, desalination using non-conventional sources such as solar, wind, and geothermal energy is discussed. In addition, factors affecting the environment due to desalination and the potential counter measures are presented. This review aims to provide an awareness of the projected water crisis in India, in the coming decades, and is also aimed to help the policy makers for selecting an appropriate desalination technology.

The measurement of water scarcity: Defining a meaningful indicator

Abstract: Metrics of water scarcity and stress have evolved over the last three decades from simple threshold indicators to holistic measures characterising human environments and freshwater sustainability. Metrics commonly estimate renewable freshwater resources using mean annual river runoff, which masks hydrological variability, and quantify subjectively socio-economic conditions characterising adaptive capacity. There is a marked absence of research evaluating whether these metrics of water scarcity are meaningful. We argue that measurement of water scarcity (1) be redefined physically in terms of the freshwater storage required to address imbalances in intra- and inter-annual fluxes of freshwater supply and demand; (2) abandons subjective quantifications of human environments and (3) be used to inform participatory decision-making processes that explore a wide range of options for addressing freshwater storage requirements beyond dams that include use of renewable groundwater, soil water and trading in virtual water. Further, we outline a conceptual framework redefining water scarcity in terms of freshwater storage.

Human–water interface in hydrological modelling : current status and future directions

Abstract: Over recent decades, the global population has been rapidly increasing and human activities have altered terrestrial water fluxes to an unprecedented extent. The phenomenal growth of the human footprint has significantly modified hydrological processes in various ways (e.g. irrigation, artificial dams, and water diversion) and at various scales (from a watershed to the globe). During the early 1990s, awareness of the potential for increased water scarcity led to the first detailed global water resource assessments. Shortly thereafter, in order to analyse the human perturbation on terrestrial water resources, the first generation of largescale hydrological models (LHMs) was produced. However, at this early stage few models considered the interaction between terrestrial water fluxes and human activities, including water use and reservoir regulation, and even fewer models distinguished water use from surface water and groundwater resources. Since the early 2000s, a growing number of LHMs have incorporated human impacts on the hydrological cycle, yet the representation of human activities in hydrological models remains challenging. In this paper we provide a synthesis of progress in the development and application of human impact modelling in LHMs. We highlight a number of key challenges and discuss possible improvements in order to better represent the human-water interface in hydrological models.

Quality matters for water scarcity

Abstract: Quality requirements for water differ by intended use. Sustainable management of water resources for different uses will not only need to account for demand in water quantity, but also for water temperature and salinity, nutrient levels and other pollutants.

Drought Tolerance and Water Use of Cereal Crops: A Focus on Sorghum as a Food Security Crop in Sub-Saharan Africa

Abstract: Sub-Saharan Africa (SSA) faces twin challenges of water stress and food insecurity – challenges that are already pressing and are projected to grow. Sub-Saharan Africa comprises 43 % arid and semi-arid area, which is projected to increase due to climate change. Small-scale, rainfed agriculture is the main livelihood source in arid and semi-arid areas of SSA. Because rainfed agriculture constitutes more than 95 % of agricultural land use, water scarcity is a major limitation to production. Crop production, specifically staple cereal crop production, will have to adapt to water scarcity and improved water productivity (output per water input) to meet food requirements. We propose inclusion and promotion of drought-tolerant cereal crops in arid and semi-arid agro-ecological zones of SSA where water scarcity is a major limitation to cereal production. Sorghum uniquely fits production in such regions, due to high and stable water-use efficiency, drought and heat tolerance, high germplasm variability, comparative nutritional value and existing food value chain in SSA. However, sorghum is socio-economically and geographically underutilized in parts of SSA. Sorghum inclusion and/or promotion in arid and semi-arid areas of SSA, especially among subsistence farmers, will improve water productivity and food security.

Asia’s glaciers are a regionally important buffer against drought

Abstract: The high mountains of Asia—encompassing the Himalayas, the Hindu Kush, Karakoram, Pamir Alai, Kunlun Shan, and Tian Shan mountains—have the highest concentration of glaciers globally, and 800 million people depend in part on meltwater from them. Water stress makes this region vulnerable economically and socially to drought, but glaciers are a uniquely drought-resilient source of water. Here I show that these glaciers provide summer meltwater to rivers and aquifers that is sufficient for the basic needs of 136 million people, or most of the annual municipal and industrial needs of Pakistan, Tajikistan, Turkmenistan, Uzbekistan and Kyrgyzstan. During drought summers, meltwater dominates water inputs to the upper Indus and Aral river basins. Uncertainties in mountain precipitation are poorly known, but, given the magnitude of this water supply, predicted glacier loss would add considerably to drought-related water stress. Such additional water stress increases the risk of social instability, conflict and sudden, uncontrolled population migrations triggered by water scarcity, which is already associated with the large and rapidly growing populations and hydro-economies of these basins. Glaciers in the high mountains of Asia provide a uniquely drought-resilient source of water, supplying summer meltwater sufficient for the basic needs of 136 million people. Glaciers are often considered as valuable, but not critical, contributors to water supply. But Hamish Pritchard now shows that glaciers are a key source of water for much of the high-mountain region of Asia. Estimates of relevant quantities such as mountain precipitation have uncertainties that are difficult to quantify, but the author's findings suggest that some basins, including the Aral and Indus, which have a combined population of over 360 million, are dominated by glacially sourced water contributions during drought years. Extensive glacier loss, which may occur in a warming climate, could therefore exacerbate water stresses in an already heavily taxed system.

Climate change impacts in the Middle East and Northern Africa (MENA) region and their implications for vulnerable population groups

Abstract: The Middle East and North Africa (MENA) region emerges as one of the hot spots for worsening extreme heat, drought and aridity conditions under climate change. A synthesis of peer-reviewed literature from 2010 to date and own modeling work on biophysical impacts of climate change on selected sectors shows that the region is highly affected by present and future climate change. These biophysical impacts paired with other pressures and a lack of resilience in some countries cause high vulnerabilities within these sectors and for social dimensions in the MENA region. The agricultural sector, of which 70 percent is rain-fed, is highly exposed to changing climatic conditions. This is of critical importance as the agriculture sector is the largest employer in many Arab countries and contributes significantly to national economies. Impacts will be high in a 2 °C world, as, e.g., annual water discharge, already critically low, is projected to drop by another 15–45% (75% in a 4 °C world) and unusual heat extremes projected to affect about one-third of the land area with likely consequences for local food production. As a consequence, deteriorating rural livelihoods associated with declining agricultural productivity will continue to contribute to migration flows, often to urban areas as already observed. The region could be heavily challenged by both rising food and water demand given its projected increase in population that may double by 2070. As a result, the regions already substantial import dependency could increase and thus its vulnerability to agricultural impacts well beyond its country borders. A severe and sustained pressure on resources could contribute to further social unrest in the already unstable political environment that currently characterizes parts of the region. While the particular societal responses to such changes are hard to foresee, it is clear that extreme impacts would constitute unprecedented challenges to the social systems affected.

Valuing water for sustainable development

Abstract: Achieving universal, safely managed water and sanitation services by 2030, as envisioned by the United Nations (UN) Sustainable Development Goal (SDG) 6, is projected to require capital expenditures of USD 114 billion per year ( 1 ). Investment on that scale, along with accompanying policy reforms, can be motivated by a growing appreciation of the value of water. Yet our ability to value water, and incorporate these values into water governance, is inadequate. Newly recognized cascading negative impacts of water scarcity, pollution, and flooding underscore the need to change the way we value water ( 2 ). With the UN/World Bank High Level Panel on Water having launched the Valuing Water Initiative in 2017 to chart principles and pathways for valuing water, we see a global opportunity to rethink the value of water. We outline four steps toward better valuation and management (see the box), examine recent advances in each of these areas, and argue that these four steps must be integrated to overcome the barriers that have stymied past efforts.

The exposure of global base metal resources to water criticality, scarcity and climate change

Abstract: Mining operations are vital to sustaining our modern way of life and are often located in areas that have limited water supplies or are at an increased risk of the effects of climate change. However, few studies have considered the interactions between the mining industry and water resources on a global scale. These interactions are often complex and site specific, and so an understanding of the local water contexts of individual mining projects is required before associated risks can be adequately assessed. Here, we address this important issue by providing the first quantitative assessment of the contextual water risks facing the global base metal mining industry, focusing on the location of known copper, lead, zinc and nickel resources. The relative exposure of copper, lead-zinc and nickel resources to water risks were assessed by considering a variety of spatial water indices, with each providing a different perspective of contextual water risks. Provincial data was considered for water criticality (CRIT), supply risk (SR), vulnerability to supply restrictions (VSR) and the environmental implications (EI) of water use. Additionally, watershed or sub-basin scale data for blue water scarcity (BWS), the water stress index (WSI), the available water remaining (AWaRe), basin internal evaporation recycling (BIER) ratios and the water depletion index (WDI) were also considered, as these have particular relevance for life cycle assessment and water footprint studies. All of the indices indicate that global copper resources are more exposed to water risks than lead-zinc or nickel resources, in part due to the large copper endowment of countries such as Chile and Peru that experience high water criticality, stress and scarcity. Copper resources are located in regions where water consumption is more likely to contribute to long-term decreases in water availability and also where evaporation is less likely to re-precipitate in the same drainage basin to cause surface-runoff or groundwater recharge. The global resource datasets were also assessed against regional Koppen-Geiger climate classifications for the observed period 1951–2000 and changes to 2100 using the Intergovernmental Panel on Climate Change’s A1FI, A2, B1 and B2 emission scenarios. The results indicate that regions containing copper resources are also more exposed to likely changes in climate than those containing lead-zinc or nickel resources. Overall, regions containing 27–32% (473–574 Mt Cu) of copper, 17–29% (139–241 Mt Pb + Zn) of lead-zinc and 6–13% (19–39 Mt Ni) of nickel resources may have a major climate re-classification as a result of anthropogenic climate change. A further 15–23% (262–412 Mt) of copper, 23–32% (195–270 Mt) of lead-zinc and 29–32% (84–94 Mt) of nickel are exposed to regional precipitation or temperature sub-classification changes. These climate changes are likely to alter the water balance, water quality and infrastructure risks at mining and mineral processing operations. Effective management of long-term changes to mine site water and climate risks requires the further adoption of anticipatory risk management strategies.

Assessing the Governance Capacity of Cities to Address Challenges of Water, Waste, and Climate Change

Abstract: The challenges of water, waste, and climate change in cities are overwhelming and underpin the importance of overcoming governance issues impeding adaptation These “governance challenges” typically have fragmented scopes, viewpoints, and responsibilities As there are many causes leading to this uncertainty and disagreement, there is no single best approach to solve these governance challenges In fact, what is necessary is iterative and requires governance capacity to find dynamic long-term solutions that are supported by flexible interim targets, so as to anticipate emerging barriers and changing situations The literature contains a plethora of governance gaps, barriers, and capacities, which sometimes overlap, are contradictory and case-specific, and reflect disciplinary scopes We argue that a balanced set of well-developed conditions is needed, to obtain the governance capacity that enables effective change Therefore, we aim to obtain deeper understanding of the key conditions determining the urban water governance capacity, by developing an integrated empirical-based approach that enables consistent city comparisons and facilitates decision-making We propose a governance capacity framework focusing on five governance challenges: 1) water scarcity, 2) flood risk, 3) wastewater treatment, 4) solid waste treatment and 5) urban heat islands Nine governance conditions, each with three indicators, are identified and empirically assessed using a Likert-type scoring method The framework is illustrated by a case study on Amsterdam, the Netherlands We conclude our approach shows great potential to improve our understanding of the key conditions determining the governance capacity to find solutions to the urban challenges of water, waste, and climate change

Nanotechnology for water purification: applications of nanotechnology methods in wastewater treatment

Abstract: Providing clean and affordable drinking water is one of the modern-times challenges. The world’s growing population causes water scarcity, and pollutants contaminate whatever water sources are left. Nanotechnology has provided innovative solutions for water purification. This chapter reviews nanotechnology-enabled water-treatment processes, showing how they transform our water supply and wastewater treatment. The following topics are discussed: different nanomaterials, properties, mechanisms, advantages compared to existing methods, limitations, research needs for commercialization, and toxicities of nanomaterials.

Reservoir Evaporation in the Western United States: Current Science, Challenges, and Future Needs

Abstract: One way to adapt to and mitigate current and future water scarcity is to manage and store water more efficiently. Reservoirs act as critical buffers to ensure agricultural and municipal water deliveries, mitigate flooding, and generate hydroelectric power, yet they often lose significant amounts of water through evaporation, especially in arid and semiarid regions. Despite this fact, reservoir evaporation has been an inconsistently and inaccurately estimated component of the water cycle within the water resource infrastructure of the arid and semiarid western United States. This paper highlights the increasing importance and challenges of correctly estimating and forecasting reservoir evaporation in the current and future climate, as well as the need to bring new ideas and state-of-the-art practices for the estimation of reservoir evaporation into operational use for modern water resource managers. New ideas and practices include i) improving the estimation of reservoir evaporation using up-to-dat...