Global Water Demand Research Articles

Optimal location of an intake at a reservoir prone to salt diffusion

There are two main factors which prompt to look for an alternative to traditional approaches to the provision of drinking water. They are climate change and population growth.Climate change and its increasing scale are no longer in doubt. It tends to increase the frequency and intensity of droughts. Changes in average water availability in most Central Asian river basins are estimated to be drastically big for the next 30 years. And, groundwater recharge may also be affected with a reduction in the availability of groundwater for drinking water in some regions.Water use has been increasing worldwide by about 1% per year since the 1980s, driven by a combination of population growth, socio-economic development and changing consumption patterns. Global water demand is expected to continue increasing at a similar rate until 2050, accounting for an increase of 20 to 30% above the current level of water use, mainly due to rising demand in the industrial and domestic sectors.These obliging to redefine the strategy for the use of water resources to ensure sustainable drinking water supply forcing the use of all available water resources even those that were not previously taken into account, for example, off stream storage reservoirs.Research, development and innovation play an important role in supporting informed decision-making. Therefore, further scientific and engineering studies are also needed for the development of financially affordable, safe and efficient infrastructure services in the areas of drinking water supply, sanitation and hygiene and its components.The article considers a particular reservoir the bottom of which is composed of saline soils operating in regular filling and emptying and subject to significant wind effects. The research conducted allowed to find a place of water intake location which provides a minimum salt content in the water abstracted.

Water Treatment: Are Membranes the Panacea?

Alongside the rising global water demand, continued stress on current water supplies has sparked interest in using nontraditional source waters for energy, agriculture, industry, and domestic needs. Membrane technologies have emerged as one of the most promising approaches to achieve water security, but implementation of membrane processes for increasingly complex waters remains a challenge. The technical feasibility of membrane processes replacing conventional treatment of alternative water supplies (e.g., wastewater, seawater, and produced water) is considered in the context of typical and emerging water quality goals. This review considers the effectiveness of current technologies (both conventional and membrane based), as well as the potential for recent advancements in membrane research to achieve these water quality goals. We envision the future of water treatment to integrate advanced membranes (e.g., mixed-matrix membranes, block copolymers) into smart treatment trains that achieve several goals, including fit-for-purpose water generation, resource recovery, and energy conservation.

Water scarcity: regional analyses in the Czech Republic from 2014 to 2018

Research background: Water is a scarce natural resource essential for life and also many economic activities. Scarcity of drinking water is a problem that is ad-dressed at national and international levels. Global water demand continues to rise, but the quantity and quality of water resources is declining in many regions. Recent surveys of the population of the Czech Republic show that the most serious global problems are waste accumulation, water pollution, lack of drinking water and air pollution. Average temperatures continue to rise across Europe due to climate change and water is expected to become increasingly scarce in many areas. An adequate supply of good-quality water is a pre-requisite for economic and social development, and thus it is necessary to learn to save water and better manage our available resources in this area.
 Purpose of the article: The purpose of this study was to investigate to what degree environmental problems ? especially the issue of drinking water scarcity ? have been evaluated in the Czech Republic from 2014 to 2018 and whether the fear of a lack of drinking water has motivated water conservation.
 Methods: A regional analysis of water availability in the Czech Republic and the possible causes of water scarcity has been carried out. Subsequently, selected socio-economic factors that could have an impact on the assessment of drinking water scarcity are analyzed using Gamma and Kendall's Tau and logistic regression. The analyzed time period is from 2014 to 2018. Microdata was taken from the Centre for Research of Public Opinion, and selected regional-level statistics from the Czech Statistical Office have been added to this data to supplement it.
 Findings & Value added: The perception of drinking water shortages is not only influenced by indicators representing the volume and price of water in each region, but can also be determined by other socio-economic factors such as income, gender, age and education.

Analysis of groundwater level trend and groundwater drought using Standard Groundwater Level Index: a case study of an eastern river basin of West Bengal, India

Global water demand has far exceeded the total available water resources which in turn have put a serious concern on food security. Changes in the land use and land cover scenario and rapid population growth are putting unavoidable stress over the water resources of the nation. The Indian aquifer system is facing an acute crisis due to the unscientific abstraction of groundwater for agricultural, industrial and domestic sector by the 1.3 billion growing population. To investigate the groundwater degradation, 20 wells from a river basin of West Bengal have been selected to study their seasonal groundwater level trend using Mann–Kendall test statistics from 1996 to 2018 where 60% of the wells are showing a decline in water level particularly in post-monsoon season. These wells are mainly located near the agricultural land where extraction of groundwater from submersible pumping wells is extensive as observed from socio-economic survey. Agglomerated hierarchical cluster analysis has been executed to classify the wells based on their magnitude of fluctuation. The wells have been classified in four clusters where cluster I consists most of the wells about 15 numbers whose fluctuation ranged between 1.8 and 4.33 m below groundwater level (mbgl). Finally, Standard Groundwater Level Index has been applied to understand the groundwater drought years. Well locations like Simlapal, Bheduasol and Neradeul have a higher frequency of drought years. The recharge potential of the wells is now decreasing day by day. Such kind of studies is required and will help the stakeholders to focus on sustainable management of this valuable water resource.

The Effects of Different Irrigation and Field Management Practices Using AquaCrop Model on Yield and Water Productivity

World population is prospected to increase to 9.8 billion people in 2050 and global food and water demands can also be presumed to rise concurrently. Regarding these future demands and considering climate change and depletion in water sources; new approaches, management strategies, and models are needed. In this study, the AquaCrop model, which may simplify the complexities of the real-system assessments, is used as an analytical tool to predict the effects of different management practices within winter wheat, spring wheat, winter barley, and maize in a specific location (middle Guadiana sub-catchment, Spain). The primary drivers from the model were determined as actual evapotranspiration (ET a ), yield (Y), and water productivity (WP). Model runs were executed within three different management strategies; which are irrigation technologies, irrigation strategies, and mulching practices. Thereafter, the yield gaps (Y g ) and water productivity gap (WP g ) were analyzed, and water scarcity/shortage degrees were compared. The results of this study showed that the AquaCrop model is a sophisticated model to estimate ET a , Y, and WP parameters. Yield productions in deficit irrigation were mostly more than supplementary irrigation. Full irrigation showed the highest yield within non-limited water conditions; however, some adverse effects of the full irrigation strategy such as salinity should not be ignored. Mulching practices positively affected the ET a reduction. Full irrigation and no mulching scenario showed the worst impacts on the water resources system. Supplementary irrigation and synthetic mulching practices depicted the least surface water resource deterioration. Deficit irrigation and synthetic mulching practices resulted in remarkable water savings with fewer yield losses compared to the scenario with the highest yield production levels.

Full-Scale Seawater Reverse Osmosis Desalination Plant Simulator

Reverse Osmosis (RO) is an evolving membrane-based technology for water desalination that started to gain increased popularity in the light of the increased global water demand due its high efficiency and low carbon footprint. This paper presents a full-scale Seawater Reverse Osmosis (SWRO) desalination plant simulator using MATLAB/Simulink, which is a user-friendly and commonly used simulation software. The simulator has been validated using the operational data from a local plant and it allows simulating the system behavior under different operating conditions with high flexibility and minimal cost. It can be used to analyze the plant performance under different operating conditions, and for research for health monitoring applications and in the cybersecuity area.

ГЛОБАЛЬНІ ВОДНІ РЕСУРСИ: ВИКЛИКИ ХХІ СТОЛІТТЯ

The article provides an analytical overview of the state of global water resources and their use in the world. The focus is on the most important component of water resources – freshwater, which on the planet is only 2.5 % of the total. The most accessible renewable water resources are river runoff, which is distributed unevenly on the surface of the planet: Asia (32 %), South America (28 %), North America (18 %), Africa (9 %), Europe (7%), Australia and Oceania (6 %). Along with the characteristics of the known components of freshwater resources (river runoff, groundwater, glaciers), attention is also focused on trends in attracting unconventional sources (recovered wastewater or gray water, desalinated, specially collected rainwater). The total use of fresh water in the world is only 9 % of the total river flow of the planet. At the same time, the problem of water scarcity was included in the list of the World Economic Forum 2015, as one of the global risks in terms of the potential impact on human society in the next decade. Among the causes of global water, scarcity are geographical and socio-economic. Geographical reasons are the spatial and temporal (seasonal) mismatch of the demand for fresh water and its availability. Socio-economic reasons are the growth of the world’s population, urbanization, improving living standards, changes in consumption patterns, and an increase in irrigated land. The latter has become key to the growth of global water demand. Experts forecast that the limited access to fresh water in 2050 can be felt by 3.3 billion more people than in 2000. The article gives examples of a methodology for the hydrological assessment of water scarcity (calculation of the ratio of the volume of annual renewable water resources to the population) and the methodology of economic and geographical assessment. Other approaches to assessing water resources by creating new paradigms (water – blue, green, virtual, water footprint) have been characterized. Throughout the history of mankind, there have been many conflicts related to water. Active water cooperation between countries today reduces the risk of military conflicts. This conclusion was made after studying transboundary water relations in more than 200joint river basins, covering 148 countries. The right to safe water and sanitation is a fundamental right of everyone (UN, 2010). Therefore, among the 17 sustainable development goals adopted by the UN for implementation for the period 2015-2030, Global Goal 6 “Clean Water and Good Sanitary Conditions” is aimed at ensuring sustainable management of water resources and sanitation for all. This will save people from diseases, and society will be given the opportunity to be more productive in economic terms.

Multi-effect distillation plants for small-scale seawater desalination: thermodynamic and economic improvement

The growing global demand for fresh water coupled to the increasing interest in renewable energies and waste heat recovery has resulted in flourishing attention to the multi-effect distillation process for seawater desalination. The low operating temperature makes this technology attractive in the case of low temperature heat sources such as geothermal, solar or waste heat recovery. The low energy density of these heat sources requires small-scale desalination systems whose layout and operation may differ from large-scale plant. In this work, new plant configurations for a small-scale multi-effect distillation system are proposed and analyzed from a thermodynamic and economic point of view. Each configuration tends to better exploit the energy content of the various streams by improving heat recovery, according to an increasing layout complexity. These configurations were studied in two layouts, differing in the way seawater and brine fed the various effect. The feed mass flow in each effect was varied to maximize the recovery ratio by imposing the maximum salt concentration in the brine related to calcium sulphate precipitation. Numerical simulations were conducted in Aspen Plus environment by varying the top brine temperature with a fixed bottom brine temperature of 40 °C. The electrolyte non-random two liquid equation of state was adopted to evaluate saltwater properties and an inter-model comparison with a validated algebraic model was carried out. The configurations implementing seawater preheating increased the performance ratio up to 10% due to the better exploitation of the energy content of distillate streams. The proposed solutions with the maximization of the recovery ratio demonstrated to be cost-effective with respect to the base multi-effect distillation configuration when thermal energy cost became relevant. In the case of negligible thermal energy cost (waste heat recovery) the base configuration was the preferable solution in terms of water cost, despite the lower performance ratio.

The Role of Improving Water Use Efficiency in Irrigated Agriculture for Enhancing the Production and Productivity of the Crops

Water scarcity and the increasing global demand for water in many sectors, including agriculture, has become a global concern .The rapid growth world population and the adverse impacts of climate change lade to growing computation for water use by industrial and urban users for agriculture to secure enough food. Irrigated agriculture is an important role in total agriculture and provides humanity with wide range of agricultural products, including fruits, vegetables, grains and cereals. Effective management of water use is the only way to save water for the increasing irrigated agriculture. Different approaches have been adopted to reduce the damage caused by drought; among these approaches is water productivity or water use efficiency WUE. A crop with high WUE should have greater yield than crop with low WUE. Keywords : water use efficiency, drought, irrigated agriculture, plant improvement DOI : 10.7176/JNSR/9-23-03 Publication date: December 31 st 2019

Global to regional scale evaluation of adaptation measures to reduce the future water gap

The global water gap, water demand minus water supply, is expected to increase through 2100, negatively affecting agriculture, industry and households. Adaptation measures are necessary, but projections on their effectiveness and costs are currently unavailable. Here, we present an adaptation evaluation framework aimed at closing the water gap, which is applied offline at the global scale, and made available for regional decision making as a web service. It includes climate change and socioeconomic scenarios over the 21st century as drivers for global projections of water supply and demand. The transient water gap was calculated for 1604 water provinces globally and we determined the water gap reduction that could be achieved by three increasingly involved sets of adaptation measures. The median annual adaptation costs amount to 1.4–1.6% of the GDP per affected water province. The interactive web-based simulation allows users to include information that is not available at the global scale.

Nanofertilisers. An outlook of crop nutrition in the fourth agricultural revolution

With the world’s population expected to exceed nine billion by 2050, scientists are working to develop new ways to meet rising global demand for food, energy and water without increasing the strain on natural resources. Organisations including the World Bank and the U.N. Food and Agriculture Organisation are calling for more innovation to address the challenges of the agri-food sector. The wide use of synthetic fertilisers has led to negative impacts on the environment and on farmer economies. Innovative cost-effective and eco-compatible strategies are needed in the modern and in the future precision agriculture. This goal could be achieved by reducing the amount of fertilisers applied on crops, in particular, by finding new techniques to distribute the necessary plant nutrients taking into account water and land scarcity, climate change and ecosystems. Nanotechnology is one of six keyenabling technologies that contribute to smart, sustainable competitiveness and inclusive growth in many sectors. It is expected that properly designed nanostructures will allow controlled release of nutrients to synchronise the release with crops nutritional needs. However, the deliberate introduction of nano-sized materials in agricultural activities raises concerns over the possible implications for human health and the environment. The introduction of nanotechnologies in agriculture still need deepen basic and applied knowledge, however several promising results were achieved, so far. The paper presents an overview on the most recent insights and the perspectives of applied research.

Public knowledge, contaminant concerns, and support for recycled Water in the United States

Water recycling is one potential solution to meeting the growing global demand for water in an age of dwindling freshwater supplies. However, public opposition has played a key role historically in blunting the broad implementation of water recycling technologies across the United States. Addressing public concerns and overcoming this opposition is critical to the political viability of water recycling programs as a response to growing water insecurity. This analysis builds on existing research on Americans’ attitudes toward water recycling in three ways. First, it explores public understanding of basic elements of water recycling and identifies important gaps in public knowledge. Second, it examines the factors that most concern Americans about water recycling. Finally, it investigates how knowledge, specific concerns, and a range of other factors, including Americans’ environmental priorities, local context, partisan leanings, and demographic characteristics, combine to influence attitudes toward recycled water. The results identify several promising targets for future educational outreach efforts to build public support for water recycling projects. Policy-relevant knowledge is the single most important predictor of support for water recycling. Yet, there is a stark knowledge gap between a highly informed few and an unaware majority. Bridging this gap could greatly increase support for water recycling. Concerns about sewage contamination were most corrosive to support for water recycling, making them a prime target for further outreach. Finally, our results suggest that future educational campaigns may seek to decouple water scarcity and climate change in the public mind to avoid exacerbating existing cleavages.

Low-recovery, -energy-consumption, -emission hybrid systems of seawater desalination: Energy optimization and cost analysis

Ultraconcentrated seawater disposal is detrimental to marine biota, and carbon emissions from desalination processes are detrimental to the atmosphere. These detrimental effects are expected to increase, given the continuously growing global water demand and the associated water stress problems caused by water scarcity and population and economic growth. Along with political inclination to impose strict environmental regulations and a carbon tax on the price of freshwater, developing low-energy-consumption, low-carbon-emission desalination systems operating at low recovery is the future of SW desalination. Such desalination systems can be achieved by integrating electrodialysis, which does not have driving force limitations, with nanofiltration and brackish water reverse osmosis (RO), which provide low-energy-consumption desalination regions, to decrease energy consumption below that of current state-of-the-art RO systems. In this study, iterative optimization algorithms were developed for hybrid desalination systems. As a result, energy consumptions as low as 1.3 kWh/m3 were achieved at recoveries <30%. Despite the higher cost of freshwater production compared with that of state-of-the-art RO systems, owing to utilization of larger membrane areas, the hybrid systems reduced carbon dioxide emissions and brine concentrations from 63 to 26 and 41 to 34%, respectively.

A New Perspective on Terrestrial Hydrologic Intensity That Incorporates Atmospheric Water Demand

AbstractHydrologic intensity is often quantified using precipitation without directly incorporating atmospheric water demand. We develop a hydrologic intensity index called the surplus deficit intensity (SDI) index that accounts for variation in supply and demand. SDI is the standardized sum of standardized surplus intensity (mean of daily surplus when supply &gt; demand) and deficit time (mean of consecutive days when demand &gt; supply). Using an observational ensemble of global daily precipitation and atmospheric water demand during 1979–2017, we document widespread hydrologic intensification (SDI; +0.11 z‐score per decade) driven primarily by increased surplus intensity. Using a climate model ensemble of the United States, hydrologic intensification is projected for the mid‐21st century (+0.86 in z‐score compared to 1971–2000), producing greater apparent intensification when compared to an index that does not explicitly incorporate demand. While incorporating demand had a minor effect on observed hydrologic intensification, it doubles hydrological intensification for the mid‐21st century.

The decline of water consumption in Spanish cities: structural and contingent factors

ABSTRACT As cities will concentrate most of the world’s population and economic activities, so urban water demand will account for a large proportion of global water demand in the future. In contrast, recent empirical evidence indicates that water consumption in many cities of the developed world is declining. In this article, this decline in consumption is studied for the major Spanish cities, and some of the drivers of this decline (economic, technological and behavioural) are explored. Contingent events such as droughts and economic crises may intensify the decline in consumption, as shown for the case of Barcelona.

The snow and rainfall impact on the Verde spring behavior: A statistical approach on hydrodynamic and hydrochemical daily time-series

The wide regional aquifer system springs are one of the most important sources of freshwater, especially because of the ever-increasing global water demand. Thus, these springs must be protected and managed in a sustainable manner. To this purpose, a detailed knowledge about the corresponding aquifer systems hydrodynamic is vital.In this general framework, the Majella carbonate aquifer is one of the most important as well as heterogenous aquifer systems in Central Italy. It is characterized by high elevation, a heterogeneous hydraulic conductivity distribution and groundwater flow, and its recharge is mainly due to both rainfall and snowmelt. Its most important spring is the Verde spring, located in the eastern side, exploited for drinking and hydroelectric purposes.The main objectives of this research are (1) to get a deeper insight into the hydrogeological conceptual model of the Verde spring, combining multiparameter input and output time-series, and (2) to quantify each inflow effect on the Verde spring parameters by a methodological approach that is quite uncommon in literature: comparing univariate and bivariate statistical analyses of both raw and residual (non-systematic component) time-series.The results obtained highlighted that the snowmelt is the most important inflow of the Majella aquifer system. The snow cover melting leaks slowly large amount of water into the aquifer and creates smoothly significative modifications to the spring discharge, electrical conductivity and temperature, in terms of groundwater volume increase and dilution. Contrariwise, although the rainfall inflow volume and the corresponding spring parameters changes are very limited, the transient behavior of the rainfall inflow allowed identifying different recharge modes. These recharge modes depend on several flow paths in the unsaturated zone, characterized by different water volumes brought toward the saturated zone, sizes, hydraulic conductivities, and distances from the Verde spring.

Author Correction: Flexibility and intensity of global water use

In the version of this Analysis originally published, in the section ‘Trends in global water demand’, the percentage increase in agricultural area equipped for irrigation was incorrect: the text ‘rose by 48% from 270 to 400×106 ha’ should have read ‘rose by 50% from 220 to 330×106 ha’; this has now been corrected.

Analysis of Water Resource Benefits Due to Power Grid Interconnections Using the Virtual Water Method

The global water demand and supply situation is becoming increasingly severe due to water shortage and uneven distribution of water resources. The highest water demand in the energy sector is attributable to power generation. With cross-country and cross-continental power grid interconnections becoming a reality, electricity trading across countries and the creation of new opportunities for re-allocation of water resources are possible. This study expands the concept of virtual water and proposes a generalized virtual water flow in an interconnected power grid system to accurately estimate water resource benefits of clean power transmission from both the production and the consumption sides. By defining the water scarcity index as a price mechanism indicator, the benefits of water resources allocation through power grid interconnections are evaluated. Taking the Africa-Asia-Europe interconnection scenario as an example, the total water saving would amount to 88.95 million m3 by 2030 and 337.8 million m3 by 2050. This result shows that grid interconnections could promote the development of renewable energy and expand the benefits of available water resources.

Bio-desalination of brackish and seawater using halophytic algae

Global demand for water is rising. A sustainable and energy efficient approach is needed to desalinate brackish sources for agricultural and municipal water use. Genetic variation among two algae species, Scenedesmus species (S. sp.) and Chlorella vulgaris (C. vulgaris), in their tolerance and uptake of salt (NaCl) was examined for potential bio-desalination of brackish water. Salt-tolerant hyper-accumulators were evaluated in a batch photobioreactors over salinity concentration ranging from 2 g/L to 20 g/L and different nutrient composition for their growth rate and salt-uptake. During algae growth phase, the doubling time varied between 0.63 and 1.81 days for S. sp. and 3.1 to 5.9 for C. vulgaris. The initial salt-uptake followed pseudo first order kinetics where the rate constant ranged between −3.58 and −7.68 day−1 reaching up to 30% in a single cycle. The halophyte algae S. sp. and C. vulgaris that were selected for pilot-scale studies here represent a promising new method for desalination of brackish waters. Halophytic technologies combined with the potential use of algae for biofuel, which offsets energy demand, can provide a sustainable solution for clean, affordable water and energy.

Simulation of groundwater level fluctuations in response to main climate parameters using a wavelet–ANN hybrid technique for the Shabestar Plain, Iran

In recent decades, increasing global water demand, coupled with the effects of climate change, has led to increased variation in groundwater level depletion. In this work, the effect of climate parameters is investigated with respect to groundwater levels in the Shabestar Plain, Iran. In the first step, the best models for the study region were selected from the general circulation models provided under the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change. To increase the spatial resolution of the precipitation data, downscaling of the models was performed using the Long Ashton Research Station weather generator for three representative concentration pathway (RCP) scenarios (RCP2.6, RCP4.5, RCP8.5) for the future period 2020–2049. The results of these models illustrated an increase in temperature and a decrease in precipitation for the study region. In the next step, an artificial neural network (ANN) technique for studying aquifer behavior was used. To increase the efficiency of the model, spatial and temporal preprocessing of data was performed using k-means clustering and wavelet transform de-noising, respectively. A fuzzy inference system was also used as a tool for estimating groundwater extraction and reducing uncertainty of illegal extraction. The results of ANN for five selected observation wells showed correlation coefficients of 0.92, 0.86, 0.76, 0.57 and 0.94 for the simulation. The model simulation under the three above-mentioned scenarios and the trend in groundwater decline in the Shabestar Plain for the base and future periods illustrated that the groundwater level dynamics were not related solely to climate parameters and that the impact of anthropogenic factors would be high.