Showing papers on "Water scarcity published in 2013"

The Millennium Drought in southeast Australia (2001–2009): Natural and human causes and implications for water resources, ecosystems, economy, and society

Abstract: [1] The “Millennium Drought” (2001–2009) can be described as the worst drought on record for southeast Australia. Adaptation to future severe droughts requires insight into the drivers of the drought and its impacts. These were analyzed using climate, water, economic, and remote sensing data combined with biophysical modeling. Prevailing El Nino conditions explained about two thirds of rainfall deficit in east Australia. Results for south Australia were inconclusive; a contribution from global climate change remains plausible but unproven. Natural processes changed the timing and magnitude of soil moisture, streamflow, and groundwater deficits by up to several years, and caused the amplification of rainfall declines in streamflow to be greater than in normal dry years. By design, river management avoided impacts on some categories of water users, but did so by exacerbating the impacts on annual irrigation agriculture and, in particular, river ecosystems. Relative rainfall reductions were amplified 1.5–1.7 times in dryland wheat yields, but the impact was offset by steady increases in cropping area and crop water use efficiency (perhaps partly due to CO2 fertilization). Impacts beyond the agricultural sector occurred (e.g., forestry, tourism, utilities) but were often diffuse and not well quantified. Key causative pathways from physical drought to the degradation of ecological, economic, and social health remain poorly understood and quantified. Combined with the multiple dimensions of multiyear droughts and the specter of climate change, this means future droughts may well break records in ever new ways and not necessarily be managed better than past ones.

Expansion of global drylands under a warming climate

Abstract: . Global drylands encompassing hyper-arid, arid, semiarid, and dry subhumid areas cover about 41 percent of the earth's terrestrial surface and are home to more than a third of the world's population. By analyzing observations for 1948–2008 and climate model simulations for 1948–2100, we show that global drylands have expanded in the last sixty years and will continue to expand in the 21st~century. By the end of this century, the world's drylands (under a high greenhouse gas emission scenario) are projected to be 5.8 × 10 6 km 2 (or 10%) larger than in the 1961–1990 climatology. The major expansion of arid regions will occur over southwest North America, the northern fringe of Africa, southern Africa, and Australia, while major expansions of semiarid regions will occur over the north side of the Mediterranean, southern Africa, and North and South America. The global dryland expansions will increase the population affected by water scarcity and land degradations.

Nanotechnology for a safe and sustainable water supply: enabling integrated water treatment and reuse.

Abstract: Ensuring reliable access to clean and affordable water is one of the greatest global challenges of this century. As the world’s population increases, water pollution becomes more complex and difficult to remove, and global climate change threatens to exacerbate water scarcity in many areas, the magnitude of this challenge is rapidly increasing. Wastewater reuse is becoming a common necessity, even as a source of potable water, but our separate wastewater collection and water supply systems are not designed to accommodate this pressing need. Furthermore, the aging centralized water and wastewater infrastructure in the developed world faces growing demands to produce higher quality water using less energy and with lower treatment costs. In addition, it is impractical to establish such massive systems in developing regions that currently lack water and wastewater infrastructure. These challenges underscore the need for technological innovation to transform the way we treat, distribute, use, and reuse water t...

Water conservancy projects in China: Achievements, challenges and way forward

Abstract: China's water policies in the past decades have relied heavily on the construction of massive water conservancy projects in the form of dams and reservoirs, water transfer projects, and irrigation infrastructure. These facilities have brought tremendous economic and social benefits but also posed many adverse impacts on the eco-environment and society. With the intensification of water scarcity, China's future water conservancy development is facing tremendous challenge of supporting the continuous economic development while protecting the water resources and the dependent ecosystems. This paper provides an overview of China's water conservancy development, and illustrates the socioeconomic, environmental and ecological impacts. A narrative of attitude changes of the central government towards water conservancy, as well as key measures since the 1950s is presented. The strategic water resources management plan set by the central government in its Document No. 1 of 2011 is elaborated with focus on the three stringent controlling “redlines” concerning national water use, water use efficiency and water pollution and the huge investments poised to finance their implementation. We emphasize that realizing the goals set in the strategic plan requires paradigm shifts of the water conservancy development towards maximizing economic and natural capitals, prioritizing investment to preserve intact ecosystems and to restore degraded ecosystems, adapting climate change, balancing construction of new water projects and rejuvenation of existing projects, and managing both “blue” (surface/groundwater) and “green” water (soil water).

A global water scarcity assessment under Shared Socio-economic Pathways – Part 2: Water availability and scarcity

Abstract: . A global water scarcity assessment for the 21st century was conducted under the latest socio-economic scenario for global change studies, namely Shared Socio-economic Pathways (SSPs). SSPs depict five global situations with substantially different socio-economic conditions. In the accompanying paper, a water use scenario compatible with the SSPs was developed. This scenario considers not only quantitative socio-economic factors such as population and electricity production but also qualitative ones such as the degree of technological change and overall environmental consciousness. In this paper, water availability and water scarcity were assessed using a global hydrological model called H08. H08 simulates both the natural water cycle and major human activities such as water abstraction and reservoir operation. It simulates water availability and use at daily time intervals at a spatial resolution of 0.5° × 0.5°. A series of global hydrological simulations were conducted under the SSPs, taking into account different climate policy options and the results of climate models. Water scarcity was assessed using an index termed the Cumulative Abstraction to Demand ratio, which is expressed as the accumulation of daily water abstraction from a river divided by the daily consumption-based potential water demand. This index can be used to express whether renewable water resources are available from rivers when required. The results suggested that by 2071–2100 the population living under severely water-stressed conditions for SSP1-5 will reach 2588–2793 × 106 (39–42% of total population), 3966–4298 × 106 (46–50%), 5334–5643 × 106 (52–55%), 3427–3786 × 106 (40–45%), 3164–3379 × 106 (46–49%) respectively, if climate policies are not adopted. Even in SSP1 (the scenario with least change in water use and climate) global water scarcity increases considerably, as compared to the present-day. This is mainly due to the growth in population and economic activity in developing countries, and partly due to hydrological changes induced by global warming.

Growing water scarcity in agriculture: future challenge to global water security

Abstract: As water is an essential component of the planetary life support system, water deficiency constitutes an insecurity that has to be overcome in the process of socio-economic development. The paper analyses the origin and appearance of blue as well as green water scarcity on different scales and with particular focus on risks to food production and water supply for municipalities and industry. It analyses water scarcity originating from both climatic phenomena and water partitioning disturbances on different scales: crop field, country level and the global circulation system. The implications by 2050 of water scarcity in terms of potential country-level water deficits for food self-reliance are analysed, and the compensating dependence on trade in virtual water for almost half the world population is noted. Planetary-scale conditions for sustainability of the global water circulation system are discussed in terms of a recently proposed Planetary Freshwater Boundary, and the consumptive water use reserve left to be shared between water requirements for global food production, fuelwood production and carbon sequestration is discussed. Finally, the importance of a paradigm shift in the further conceptual development of water security is stressed, so that adequate attention is paid to water's fundamental role in both natural and socio-economic systems.

A Changing Framework for Urban Water Systems

Abstract: Urban water infrastructure and the institutions responsible for its management have gradually evolved over the past two centuries. Today, they are under increasing stress as water scarcity and a gr...

Making the distinction between water scarcity and drought using an observation‐modeling framework

Abstract: [1] Drought and water scarcity are keywords for river basin management in water-stressed regions. “Drought” is a natural hazard, caused by large-scale climatic variability, and cannot be prevented by local water management. “Water scarcity” refers to the long-term unsustainable use of water resources, which water managers can influence. Making the distinction between drought and water scarcity is not trivial, because they often occur simultaneously. In this paper, we propose an observation-modeling framework to separate natural (drought) and human (water scarcity) effects on the hydrological system. The basis of the framework is simulation of the situation that would have occurred without human influence, the “naturalized” situation, using a hydrological model. The resulting time series of naturalized state variables and fluxes are then compared to observed time series. As second, more important and novel step, anomalies (i.e., deviations from a threshold) are determined from both time series and compared. We demonstrate the use of the proposed observation-modeling framework in the Upper-Guadiana catchment in Spain. Application of the framework to the period 1980–2000 shows that the impact of groundwater abstraction on the hydrological system was, on average, four times as high as the impact of drought. Water scarcity resulted in disappearance of the winter high-flow period, even in relatively wet years, and a nonlinear response of groundwater. The proposed observation-modeling framework helps water managers in water-stressed regions to quantify the relative impact of drought and water scarcity on a transient basis and, consequently, to make decisions regarding adaptation to drought and combating water scarcity.

A global water scarcity assessment under Shared Socio-economic Pathways – Part 1: Water use

Abstract: . A novel global water scarcity assessment for the 21st century is presented in a two-part paper. In this first paper, water use scenarios are presented for the latest global hydrological models. The scenarios are compatible with the socio-economic scenarios of the Shared Socio-economic Pathways (SSPs), which are a part of the latest set of scenarios on global change developed by the integrated assessment, the IAV (climate change impact, adaptation, and vulnerability assessment), and the climate modeling community. The SSPs depict five global situations based on substantially different socio-economic conditions during the 21st century. Water use scenarios were developed to reflect not only quantitative socio-economic factors, such as population and electricity production, but also key qualitative concepts such as the degree of technological change and overall environmental consciousness. Each scenario consists of five factors: irrigated area, crop intensity, irrigation efficiency, and withdrawal-based potential industrial and municipal water demands. The first three factors are used to estimate the potential irrigation water demand. All factors were developed using simple models based on a literature review and analysis of historical records. The factors are grid-based at a spatial resolution of 0.5° × 0.5° and cover the whole 21st century in five-year intervals. Each factor shows wide variation among the different global situations depicted: the irrigated area in 2085 varies between 2.7 × 106 and 4.5 × 106 km2, withdrawal-based potential industrial water demand between 246 and 1714 km3 yr−1, and municipal water between 573 and 1280 km3 yr−1. The water use scenarios can be used for global water scarcity assessments that identify the regions vulnerable to water scarcity and analyze the timing and magnitude of scarcity conditions.

Methodological Challenges in Volumetric and Impact‐Oriented Water Footprints

Abstract: Summary This work identifies shortcomings in water footprinting and discusses whether the water footprint should be a volumetric or impact-oriented index A key challenge is the current definition of water consumption according to which evaporated water is regarded as lost for the originating watershed per se Continental evaporation recycling rates of up to 100% within short time and length scales show that this definition is not generally valid Also, the inclusion of land use effects on the hydrological balance is questionable, as land transformation often leads to higher water availability due to locally increased runoff Unless potentially negative consequences, such as flooding or waterlogging, and adverse effects on the global water cycle are considered, water credits from land transformation seem unjustified Most impact assessment methods use ratios of annual withdrawal or consumption to renewability rates to denote local water scarcity As these ratios are influenced by two metrics—withdrawal and availability—arid regions can be regarded as uncritical if only small fractions of the limited renewable supplies are used Besides neglecting sensitivities to additional water uses, such indicators consider neither ground nor surface water stocks, which can buffer water shortages temporally Authors favoring volumetric indicators claim that global freshwater appropriation is more important than local impacts, easier to determine, and less error prone than putting complex ecological interaction into mathematical models As shown in an example, volumetric water footprints can be misleading without additional interpretation because numerically smaller footprints can cause higher impacts

The Indus Basin of Pakistan: The Impacts of Climate Risks on Water and Agriculture

Abstract: This study, Indus basin of Pakistan: the impacts of climate risks on water and agriculture was undertaken at a pivotal time in the region. The weak summer monsoon in 2009 created drought conditions throughout the country. This followed an already tenuous situation for many rural households faced with high fuel and fertilizer costs and the impacts of rising global food prices. Then catastrophic monsoon flooding in 2010 affected over 20 million people, devastating their housing, infrastructure, and crops. Damages from this single flood event were estimated at US dollar 10 billion, half of which were losses in the agriculture sector. Notwithstanding the debate as to whether these observed extremes are evidence of climate change, an investigation is needed regarding the extent to which the country is resilient to these shocks. It is thus timely, if not critical, to focus on climate risks for water, agriculture, and food security in the Indus basin of Pakistan.

'Glocal' water governance: a multi-level challenge in the

Abstract: The water crisis is a crisis of governance. A literature reviewreveals that this crisis concerns definitional issues, issues ofownership and access, boundary issues, the multiple uses ofwater, and the levels at which water should be managed.Paradigms for managing water have evolved from integratedwater resource management through more experimental andlearning based adaptive governance to understanding thatwater is not a sector but a cross-cutting issue and shouldperhaps be dealt with through the ‘nexus’ approach. Theliterature reveals a toolbox of policy instruments,infrastructures and institutions for managing water butconcludes that solutions need to be crafted in a contextrelevant manner taking the relevant drivers of water use andmisuse into account.

Water Accounting Plus (WA+) - a water accounting procedure for complex river basins based on satellite measurements

Abstract: Coping with water scarcity and growing competition for water among different sectors requires proper water management strategies and decision processes. A pre-requisite is a clear understanding of the basin hydrological processes, manageable and unmanageable water flows, the interaction with land use and opportunities to mitigate the negative effects and increase the benefits of water depletion on society. Currently, water professionals do not have a common framework that links depletion to user groups of water and their benefits. The absence of a standard hydrological and water management summary is causing confusion and wrong decisions. The non-availability of water flow data is one of the underpinning reasons for not having operational water accounting systems for river basins in place. In this paper, we introduce Water Accounting Plus (WA+), which is a new framework designed to provide explicit spatial information on water depletion and net withdrawal processes in complex river basins. The influence of land use and landscape evapotranspiration on the water cycle is described explicitly by defining land use groups with common characteristics. WA+ presents four sheets including (i) a resource base sheet, (ii) an evapotranspiration sheet, (iii) a productivity sheet, and (iv) a withdrawal sheet. Every sheet encompasses a set of indicators that summarise the overall water resources situation. The impact of external (e.g., climate change) and internal influences (e.g., infrastructure building) can be estimated by studying the changes in these WA+ indicators. Satellite measurements can be used to acquire a vast amount of required data but is not a precondition for implementing WA+ framework. Data from hydrological models and water allocation models can also be used as inputs to WA+.

A Dynamic Model for Vulnerability Assessment of Regional Water Resources in Arid Areas: A Case Study of Bayingolin, China

Abstract: Water scarcity is a common problem in many countries, especially those located in arid zones. The vulnerability of water resources due to climate change is an imperative research focus in the field of water resources management. In this study, a System Dynamics (SD) model was developed to simulate the water supply-and-demand process in Bayingolin, a prefecture in China, and to evaluate water resources vulnerability currently as well as in the future. The model was calibrated and validated using historical data. Three alternative scenarios were designed by changing parameters to test the vulnerability of water resources: i) increase the Wastewater Treatment Rate by 50 %; ii) decrease the Irrigation Water Demand per Hectare by 20 %; iii) increase Total Water Supply by 5 %. Results show that the baseline vulnerability of study region is high. The agricultural irrigation is the largest water use, and the water demand structure will change in future. Decreasing the irrigation water demand is the most suitable intervention to relatively reduce the vulnerability. Results also demonstrated that SD is a suitable method to explore management options for a complex water supply and demand system.

Actual state of European wetlands and their possible future in the context of global climate change

Abstract: The present area of European wetlands is only a fraction of their area before the start of large-scale human colonization of Europe. Many European wetlands have been exploited and managed for various purposes. Large wetland areas have been drained and reclaimed mainly for agriculture and establishment of human settlements. These threats to European wetlands persist. The main responses of European wetlands to ongoing climate change will vary according to wetland type and geographical location. Sea level rise will probably be the decisive factor affecting coastal wetlands, especially along the Atlantic coast. In the boreal part of Europe, increased temperatures will probably lead to increased annual evapotranspiration and lower organic matter accumulation in soil. The role of vast boreal wetlands as carbon sinks may thus be suppressed. In central and western Europe, the risk of floods may support the political will for ecosystem-unfriendly flood defence measures, which may threaten the hydrology of existing wetlands. Southern Europe will probably suffer most from water shortage, which may strengthen the competition for water resources between agriculture, industry and settlements on the one hand and nature conservancy, including wetland conservation, on the other.

A global and spatially explicit assessment of climate change impacts on crop production and consumptive water use.

Abstract: Food security and water scarcity have become two major concerns for future human's sustainable development, particularly in the context of climate change. Here we present a comprehensive assessment of climate change impacts on the production and water use of major cereal crops on a global scale with a spatial resolution of 30 arc-minutes for the 2030s (short term) and the 2090s (long term), respectively. Our findings show that impact uncertainties are higher on larger spatial scales (e.g., global and continental) but lower on smaller spatial scales (e.g., national and grid cell). Such patterns allow decision makers and investors to take adaptive measures without being puzzled by a highly uncertain future at the global level. Short-term gains in crop production from climate change are projected for many regions, particularly in African countries, but the gains will mostly vanish and turn to losses in the long run. Irrigation dependence in crop production is projected to increase in general. However, several water poor regions will rely less heavily on irrigation, conducive to alleviating regional water scarcity. The heterogeneity of spatial patterns and the non-linearity of temporal changes of the impacts call for site-specific adaptive measures with perspectives of reducing short- and long-term risks of future food and water security.

Risk-based principles for defining and managing water security

Abstract: The concept of water security implies concern about potentially harmful states of coupled human and natural water systems. Those harmful states may be associated with water scarcity (for humans and/or the environment), floods or harmful water quality. The theories and practices of risk analysis and risk management have been developed and elaborated to deal with the uncertain occurrence of harmful events. Yet despite their widespread application in public policy, theories and practices of risk management have well-known limitations, particularly in the context of severe uncertainties and contested values. Here, we seek to explore the boundaries of applicability of risk-based principles as a means of formalizing discussion of water security. Not only do risk concepts have normative appeal, but they also provide an explicit means of addressing the variability that is intrinsic to hydrological, ecological and socio-economic systems. We illustrate the nature of these interconnections with a simulation study, which demonstrates how water resources planning could take more explicit account of epistemic uncertainties, tolerability of risk and the trade-offs in risk among different actors.