Human Water Demand Research Articles

Multi-source water characterisation for water supply and management strategies on a small Mediterranean island

The small islands in the Mediterranean Sea suffer water shortages, aggravated by pressure from tourism during the dry season. Many are affected by the intense and increasing human water demand and the harsh climatic and geographic nature of the island terrain. The present study, carried out on the island of Favignana, Egadi Archipelago (southern Italy), evaluates the regime of recharge to the subsurface, and hypothesizes a solution for identifying the areas where groundwater is most abundant, as well as the best management options for human use. By means of hydrological measurements and chemical analyses, a specific location has been identified in the eastern sector of the island where groundwater has optimal quality and the water table is at a depth of only a few metres. In other areas of the island the groundwater is more saline, due to seawater intrusion, and it is present only at greater depths. The residents of the island have in the past lived harmoniously with the climatic and hydrological regime of the island, and have shown good ability to manage the groundwater resources, fed by the limited precipitation that comes in winter, using it as a supplement to the drinking water supply that comes from Trapani (mainland Sicily) by a submarine pipeline and by tanker. Optimized management of the groundwater resources could reduce the volume of freshwater transferred from the mainland.

Coupled reservoir-river systems: Lessons from an integrated aquatic ecosystem assessment

Sustainable reservoir-river management requires balancing complex trade-offs and decision-making to support both human water demands and ecological function. Current numerical simulation and optimization algorithms can guide reservoir-river operations for optimal hydropower production, irrigation, nutrient management, and municipal consumption, yet much less is known about optimization of associated ecosystems. This ten-year study demonstrates an ecosystem assessment approach that links the environmental processes to an ecosystem response in order to evaluate the impact of climatic forcing and reservoir operations on the aquatic ecosystems of a coupled headwater reservoir-river system. The approach uses a series of numerical, statistical, and empirical models to explore reservoir operational flexibility aimed at improving the environmental processes that support aquatic ecosystem function. The results illustrate that understanding the seasonal biogeochemical changes in reservoirs is critical for determining environmental flow releases and the ecological trajectory of both the reservoir and river systems. The coupled models show that reservoir management can improve the ecological function of complex aquatic ecosystems under certain climatic conditions. During dry hydrologic years, the high post-irrigation release can increase the downstream primary and macroinvertebrate production by 99% and 45% respectively. However, this flow release would reduce total fish biomass in the reservoir by 16%, providing management tradeoffs to the different ecosystems. Additionally, low post-irrigation flows during the winter season supports water temperature that can maintain ice cover in the downstream river for improved ecosystem function. The ecosystem assessment approach provides operational flexibility for large infrastructure, supports transparent decision-making by management agencies, and facilitates framing of environmental legislation.

The water-scarcity footprint of Australian adult diets – evidence from a large population health survey

AbstractThe food system is responsible for around 70% of global freshwater use. Pathways toward responsible consumption and production of food are therefore critically needed to ensure the planetary boundary for freshwater use is not transgressed. There is also an uneven spatial distribution of freshwater resources and human water demands, meaning that water-scarcity is acute in some regions but a lesser concern in others. Quantifying the water-scarcity impacts associated with food consumption is therefore a complex challenge due to the diversity of individual eating patterns, the very large number of individual food products available, and the many different regions where food is grown or processed. To our knowledge, this is the first study to calculate water footprints for a large number of self-selected diets. Life cycle assessment was used to model the water-scarcity footprints of 9,341 individual Australian adult diets obtained through 24-hour recall as part of the most recent Australian Health Survey. Three water-scarcity indicators were used, including the AWARE model recently developed by a project group working under the auspices of the United Nations Environment Programme (UNEP) / Society of Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative (www.lifecycleinitiative.org). In addition, a diet quality score was calculated for each of these diets. Our objective was to identify pathways toward healthier diets with lower water-scarcity impacts. Dietary water-scarcity footprints averaged 362 L-eq person-1 day-1 and were highly variable (sd. 218 L-eq person-1 day-1), reflecting the diversity of eating habits in the general community. The largest water-scarcity impacts were related to the excessive consumption of discretionary foods (alcoholic beverages, processed meat products, dairy desserts, cream, butter, muesli bars, confectionery, chocolate, biscuits, cakes, waffles, fried potato and extruded snacks, etc.). The potential to reduce dietary water-scarcity impacts is large, although the opportunity to intervene through amended dietary guidelines is not straightforward due to the large variations in water-scarcity footprint intensity between individual foods within a food group, and the inability of consumers to identify lower water-scarcity footprint products without food labeling. Reductions in the water-scarcity footprint of Australian food consumption are likely best achieved through reductions in food waste, technological change to improve water-use efficiency in food production, as well as the implementation of product reformulation and procurement strategies in the food manufacturing sector to avoid higher water-scarcity footprint intensity ingredients.

Declining Soil Moisture Threatens Water Availability in the U.S. Great Plains

HighlightsFuture water security in the U.S. Great Plains is threated by a drying trend in average annual soil moisture.Agricultural management will become increasingly challenging due to declines in surface water storage.Alternative management strategies are needed to meet future environmental and anthropogenic surface water demand.Abstract. Spatiotemporal trends in soil moisture are of considerable importance within the food-energy-water nexus. Soil moisture dictates the productivity of ecosystems, plays a major role in land-atmosphere interactions, influences climate change projections, and shapes future water security. Monitoring of long-term soil moisture trends has proven useful for managing water resource allocation and developing solutions to global water security challenges. Thus, we examine annual trends in surface soil moisture throughout the U.S. Great Plains region from 1987 to 2016 using data from NASA’s observation-driven SPoRT-LIS land surface model at 3 km resolution. Results reveal a drying trend in soil moisture for a majority of the U.S. Great Plains, although wetter conditions have been realized in the northernmost region of the Missouri River basin. These results, when coupled with climate change-driven increases in temperature and evapotranspiration, will inevitably drive baseline soil moisture to drier conditions in the future. Under drying soil moisture conditions, future agricultural production and water resource management in the U.S. Great Plains will become increasingly complicated, thereby threatening future food and water security. However, these results can be applied to inform and improve climate change adaptation strategies in order to ensure adequate volumes of freshwater to meet future human and environmental water demand. Keywords: Climate change, SPoRT-LIS, Trend analysis, Water security.

Water and radiation use efficiencies in maize: Breeding effects on single-cross Argentine hybrids released between 1980 and 2012

Water deficit has been signaled as an important determinant of grain yield (GY) gaps between potential and actual GYs. Breeding for improved water as well as solar radiation productivities is a sustainable means to reduce this gap. The aim of this study was to evaluate breeding effects on GY and its physiological determinants, including water (WUE) and radiation (RUE) use efficiencies, of temperate maize hybrids grown under a wide range of environmental conditions in Argentina. We hypothesized that breeding focused on GY performance and broad adaptation produced an increase in crop biomass linked to an increased tolerance to adverse growing conditions, a trend associated with an increase in WUE and/or RUE. For this purpose, hybrids were grown under three stand densities and eight environmental conditions in the main target environment for the production of temperate hybrids in Argentina. Analyzed traits were GY, total shoot biomass (BT) production, harvest index (HI = GY/BT), crop evapotranspiration (ETC), crop radiation interception (IPARC: cumulative amount of intercepted incident photosynthetically active radiation), radiation use efficiency (RUE = BT/IPARC), water use efficiency (WUE) for biomass production (WUEB,ETc= BT/ETC) and WUE for GY production (WUEGY,ETc= GY/ETC). No breeding effect was registered on ETC and IPARC, whereas significant breeding effects (P < 0.05) were detected on GY (0.5 % YOR−1 from 1980 onwards). The latter were due to the improvement of BT (from 1993 onwards) as well as of HI (between 1980 and 1993), with gains of 0.5 % YOR−1 in both cases. Mentioned trends were associated with a significant increase in RUE (0.7 % YOR−1 from 1993 onwards) and consequently in WUEB,ETc (0.6 % YOR−1 from 1993 onwards) and WUEGY,ETc (0.5 % YOR−1 from 1980 onwards). Results demonstrated that breeding efforts, which have been driven almost exclusively by GY improvement, had no evident effect on the crop water use but had clear effects on crop biomass production and its partitioning. These unintended positive effects of breeding on RUE and WUEs are welcome on a global scale, considering that predicted trends of increasing human demand for water will require increased water productivity rather than increased water use by crops.

A new species of the live-bearing fish genus Poeciliopsis from northern Mexico (Cyprinodontiformes, Poeciliidae).

Poeciliopsis jackschultzisp. nov., is described based on seven specimens (17.9–26.7 mm SL) from the Río Concepción (also known as Río Magdalena), Sonora, Mexico. The new species belongs to the Leptorhaphis species group and can be distinguished from other members of this group by features of the skeleton and colouration. The new species is sympatric with P. occidentalis, a hybridogenetic all-female biotype P. monacha-occidentalis, and hybrids between P. monacha-occidentalis females and P. jackschultzi males. The distribution of P. jackschultzi is highly restricted, and the main habitat, spring-fed marshy streams and pools, is susceptible to loss and degradation in a desert environment with increasing human water demand.

Integrated Solutions for the Water-Energy-Land Nexus: Are Global Models Rising to the Challenge?

Increasing human demands for water, energy, food and materials, are expected to accentuate resource supply challenges over the coming decades. Experience suggests that long-term strategies for a single sector could yield both trade-offs and synergies for other sectors. Thus, long-term transition pathways for linked resource systems should be informed using nexus approaches. Global integrated assessment models can represent the synergies and trade-offs inherent in the exploitation of water, energy and land (WEL) resources, including the impacts of international trade and climate policies. In this study, we review the current state-of-the-science in global integrated assessment modeling with an emphasis on how models have incorporated integrated WEL solutions. A large-scale assessment of the relevant literature was performed using online databases and structured keyword search queries. The results point to the following main opportunities for future research and model development: (1) improving the temporal and spatial resolution of economic models for the energy and water sectors; (2) balancing energy and land requirements across sectors; (3) integrated representation of the role of distribution infrastructure in alleviating resource challenges; (4) modeling of solution impacts on downstream environmental quality; (5) improved representation of the implementation challenges stemming from regional financial and institutional capacity; (6) enabling dynamic multi-sectoral vulnerability and adaptation needs assessment; and (7) the development of fully-coupled assessment frameworks based on consistent, scalable, and regionally-transferable platforms. Improved database management and computational power are needed to address many of these modeling challenges at a global-scale.

Drought-Induced, Punctuated Loss of Freshwater Mussels Alters Ecosystem Function Across Temporal Scales

Punctuated, mass mortality events are increasing for many animal taxa and are often related to climatic extremes such as drought. Freshwater mussels are experiencing increased mass mortality events linked to hydrologic drought. Because mussels play important functional roles in rivers it is important to understand the ecosystem effects of these die-offs. Here, we address how mass mortality events of mussels caused by drought may impact stream ecosystem function. We first present a conceptual model, based on the literature, of how mussel mass mortality should affect different ecosystem functions across various ecological time scales, from hours to decades. Next, we highlight two case studies of drought-linked, mussel-mass mortality events from rivers in the southern U.S. We then present the results of an experiment we performed quantifying the ecosystem effects of a punctuated mussel die-off. Finally, we combine our experimental results with field data from a recent mussel die-off to predict how mussel losses will influence ecosystem function. Based on the presented case studies, our mesocosm experiment, and our extrapolated nutrient pulse due to a mussel die-off, we conclude that stream ecosystems are extensively altered following mussel mass mortality events. Mussel loss is governed by drought severity, location within the river network, and species-specific drought tolerances. In the short term, decomposing carrion from mussel die-offs releases a large pulse of nutrients into the water which stimulates food web productivity. In the long term, the overall loss of mussel biomass, and the loss of functional traits as more sensitive species decline, leads to decreases in ecosystem function which may take decades to recover. Drought and human demand for water will make mussel die-offs more likely in the future and it is unlikely that drought sensitive species will recover without changes in water management and restoration of populations through mussel propagation. Our research provides an example of how the loss of an abundant, long-lived organism has cascading and long-term impacts on ecosystems.

Groundwater management in an agro-industrial school in Argentina

Introduction: water management is of paramount importance in productive activities, such as agriculture, livestock and industry, due to its direct impact on both the quality and the availability of this valuable resource. However, groundwater management is usually addressed under a non-integrated approach which originates a high risk of pollution as well as water shortage for food and animal production in the agro-industrial systems. Objective: to analyze water quality for human consumption, hydrogeological features, water demand, and discharge of liquid effluents on soil and surface water. Methods: we carried out a diagnostics of water management in an agro-industrial school located in Buenos Aires province, Argentina. The production system includes a bovine dairy farm; calf, pork and rabbit breeding; beekeeping; poultry farming; dairy and cheese factory; agriculture and fodder area; processing of meat, and orchard. To perform the analysis, we calculated water requirements for six productive activities and evaluated the hydrological features of the area through water table measurements considering the groundwater flow sense. We analyzed the groundwater quality seasonally during a period of a year through five water samples. We considered microbiological and physicochemical parameters and they were compared with recommended level by law, and we carried out the monitoring of residual chlorine during a week. Also, we evaluated the generation and disposal of effluents. Results: water was suitable for human consumption, although we detected variations in its quality indicators. We determined that the main issues hindering an integrated water management were the diversified production developed with high volumes of water demanded, the water quality deterioration by the agro-industrial productions carried out, and the hydrogeological features of the area. In addition, we measured a high water demand which is in conflict with groundwater shortage and the complex hydrological conditions of extraction in the studied area. Conclusion: this study demonstrated the usefulness of applying effective strategies to act on environmental-priority subjects and to develop good practices regarding water management from an integrated approach.

The modelling of rainfall interception in growing and dormant seasons for a pine plantation and a black locust plantation in semi-arid Northwest China

Interception loss can remove a significant portion of rainwater from forested ecosystems. Therefore, the quantification and modelling of interception loss are of significant importance if human and ecosystem water demands are to be balanced under a future changing climate. This is particularly true for semi-arid/arid regions, where afforestation has become an important ecological restoration measure to tackle desertification, poverty and climate change. However, quantification and modelling of interception loss of plantations in these regions have rarely been reported. In the present study, rainfall interception loss was quantified and modelled over a one-year period (January-December 2016) for a deciduous broad-leafed R. pseudoacacia plantation and an evergreen needle-leaf P. tabuliformis plantation (common afforestation tree species) situated in the semi-arid Loess Plateau of China. The stand age, density, canopy cover and leaf area index of R. pseudoacacia during the study period were 15 years, 2000 tree ha−1, 0.48 and 1.41 m2 m−2, respectively. The corresponding values for Pinus tabuliformis were 17 years, 1200 tree ha−1, 0.62 and 2.53 m2 m−2. The measured throughfall, stemflow and derived estimates of interception loss for R. pseudoacacia were 81.1%, 1.3% and 17.6%, respectively. The corresponding values for P. tabuliformis were 75.4%, 0.7% and 23.9%. Given that the weather conditions experienced by the two forest stands were similar, the observed higher interception loss for P. tabuliformis can be explained by the higher canopy storage capacity and wet canopy evaporation rate of this species. The revised Gash analytical model of rainfall interception was well calibrated and validated against field measurements and was able to simulate the cumulative interception loss at two forest stands accurately, and it also effectively captured the seasonal variation (leafed growing and leafless dormant seasons), provided that the optimized wet-canopy evaporation rates were used. The revised model was highly sensitive to the canopy storage capacity and changes in the ratio of mean wet canopy evaporation to mean rainfall intensity and less sensitive to canopy cover, but it was found to be fairly insensitive to the trunk storage capacity.

Soil Functions: Connecting Earth's Critical Zone

Soil is the central interface of Earth's critical zone—the planetary surface layer extending from unaltered bedrock to the vegetation canopy—and is under intense pressure from human demand for biomass, water, and food resources. Soil functions are flows and transformations of mass, energy, and genetic information that connect soil to the wider critical zone, transmitting the impacts of human activity at the land surface and providing a control point for beneficial human intervention. Soil functions are manifest during bedrock weathering and, in fully developed soil profiles, correlate with the porosity architecture of soil structure and arise from the development of soil aggregates as fundamental ecological units. Advances in knowledge on the mechanistic processes of soil functions, their connection throughout the critical zone, and their quantitative representation in mathematical and computational models define research frontiers that address the major global challenges of critical zone resource provisioning for human benefit. ▪ Connecting the mechanisms of soil functions with critical zone processes defines integrating science to tackle challenges of climate change and food and water supply. ▪ Soil functions, which develop through formation of soil aggregates as fundamental eco-logical units, are manifest at the earliest stages of critical zone evolution. ▪ Global degradation of soil functions during the Anthropocene is reversible through positive human intervention in soil as a central control point in Earth's critical zone. ▪ Measurement and mathematical translation of soil functions and critical zone processes offer new computational approaches for basic and applied geosciences research.

Predicting hydrologic disturbance of streams using species occurrence data

Aquatic organisms have adapted over evolutionary time-scales to hydrologic variability represented by the natural flow regime of rivers and streams in their unimpaired state. Rapid landscape change coupled with growing human demand for water have altered natural flow regimes of many rivers and streams on a global scale. Climate non-stationarity is expected to further intensify hydrologic variability, placing increased pressure on aquatic communities. Using a machine learning approach and georeferenced species occurrence data, we modeled and mapped spatial patterns of hydrologic disturbance for streams in Arkansas, Missouri, and eastern Oklahoma. Random forest (RF) models trained on fish community data, hydrologic, and landscape metrics for gaged streams in the National Hydrography (NHDPlusV2) database were used to predict a hydrologic disturbance index (HDI) for ungaged streams. The HDI is part of the USGS Geospatial Attributes of Gages for Evaluating Streamflow (GAGESII) database and is a composite index of watershed-scale disturbance from anthropogenic stressors. Fish presence/absence data had similar overall model prediction accuracy (77%; 95% CI: 0.74, 0.80) as flow variables (76%; CI: 0.73, 0.80). Including topographic variables increased the RF prediction accuracy of both the fish (90%; CI: 0.88, 0.92) and flow models (86%; CI: 0.84, 0.89). Spatial patterns of hydrologic disturbance suggest distinct ecohydrological regions exist where conservation actions may be focused. Streams with low HDI were predominately located in the Ozark Highlands, Boston Mountains, and Ouachita Mountains. Correlation analysis of HDI by flow regime showed groundwater stable streams had the lowest disturbance frequency, with over 50% of stream reaches with low HDI located in forested land cover. HDI was highest for big rivers, intermittent runoff streams and streams in areas of agricultural land use. Our results show long-term georeferenced biological data can provide a valuable resource for predictive modeling of hydrologic disturbance for ungaged rivers and streams.

A nature-based reservoir optimization model for resolving the conflict in human water demand and riverine ecosystem protection

Although construction of reservoirs and dams is one of the most common approaches to satisfy water demand and alleviate water scarcity, this approach severely affects river ecosystems. The most direct impact of human activities on rivers, for instance, regulating river can lead to degraded riverine ecosystems as part of the hydrological alteration. This paper determines the available ratio of water resource of natural or semi-natural rivers for ecological feasible regions using a method that transcends the traditional perspective of designed environmental flow. Our framework involves a modified percent of flow approach to identify the ecological feasible region of water resources utilization, which sequentially acts as a constraint for a reservoir optimization model based on the Cuckoo Search algorithm to obtain an optimal diversion process. Indicators of the hydrological alteration statistical method and the histogram matching approach are used to examine the framework's performance. The Han to Wei inter-basin water transfer project of China is selected as a case study. Results indicate that: (1) the allowable diversion rate with this modified percent of flow approach is more effective for reducing interference of diversion on the ecosystems than the conventional planned diversion rule; water demand, however, cannot be satisfied by the allowable diversion rate; (2) ecological feasible region is an accessible constraint for reservoir operation model, and the optimal diversion rate of such model is a trade-off output between the human water demand and the riverine ecosystems protection; and (3) increased allowable diversion rates alter flow indicators including the February flow, 30-day minimum flow, and low pulse count more appreciably than does the optimal diversion rate. This study provides key insights on how to achieve a trade-off between human water demand and riverine ecosystems protection, therefore contributing to the local sustainable development of social economy and ecological environment.

Pedotechnique applications in large-scale farming: Economic value, soil ecosystems services and soil security

Since ancient times Humans and Soil have experienced interwoven links. Nowadays soil scientists continue to stress such links highlighting the importance of soil in: i) satisfying the ever growing Human demand for food, water and energy, and ii) providing ecosystem services that mitigate climate changes, influence human health and improve biodiversity.Pedotechniques are recently used to generate soils suitable for table grape cultivation in order to increase productivity and grape quality, thus to get substantial financial returns. We show one emblematic study case of pedotechniques applied in Sicily (Italy). Aims of the investigation were: i) stressing threats to soil security derived by the generation of anthropogenic soils, ii) assessing the economic sustainability of pedotechniques and table grape production, taking into consideration only the internal factors and excluding the external economic contributions that are allocated to social sustainability and iii) stressing the role of soil science to focus on “economic value” to the soil ecosystem services and degradation processes.Results highlight that soil transformations allow for considerable investment costs. The highest productivity and the consequent higher profitability of the cultivation amortize the start-up costs. From the other side transformations could trigger considerable deterioration of both soil ecosystem services and environmental quality. In order to stress this last aspect and to define the relationships between pedotechnique application and soil security we have considered the five soil security dimensions (i.e. capability, condition, capital, connectivity and codification).

Lipid Production From Waste Materials in Seawater-Based Medium by the Yeast Yarrowia lipolytica.

The global limitation of fossil fuels impels scientists to search for new energy sources. A good alternative is biodiesel produced from crop plants. However, its production requires huge quantities of farmland, fertilizers and fresh water, which is in conflict with the human demand for water for consumption and land for food production. Thus, production of single cell oil (SCO) by oleaginous microorganisms remains the best solution for the coming years. Whereas most microorganisms require fresh water for proper cell metabolism, in this study we demonstrate that the unconventional yeast Yarrowia lipolytica is able to produce huge quantities of fatty acid in seawater-based medium. Here we shown that Y. lipolytica is able to produce fatty acids in medium based on seawater and crude glycerol as the main carbon source, which allows for low-cost production of SCO, is beneficial for industrial application and is ecologically friendly.

Toward a better understanding of freshwater fish responses to an increasingly drought-stricken world

Drought is a constant and important consequence of natural climatic processes and most freshwater fishes have adaptations to counter its effects. However, a changing global climate coupled with increasing human demand for water is reducing the availability of fresh water to fishes and contributing to more frequent and intense drought around the globe. A clear understanding of how fishes, fish habitat, and fisheries are affected by extended drought is needed to help resolve conflicts over water. We therefore identify key questions and research themes to promote the conservation of freshwater fishes as drought increases in length, frequency and severity. (1) How does drought affect fish habitat? (2) What is drought tolerance in fishes? (3) What are drought refuges for fishes? (4) What kills fish during drought? (5) What is the nature of species succession in drought-stricken waters? (6) What are the long-term consequences of drought to fishes? (7) How does climate change affect drought-fish interactions? (8) How does drought influence fisheries? Our limited ability to provide answers to these questions indicates that fish diversity and abundance worldwide is threatened by drought. Planning, including collection of long-term data, is necessary so that conservation and water re-allocation strategies can be implemented in a timely manner to maintain habitats necessary to support biodiversity during drought periods. Without increased understanding of physiological and behavioural factors that determine the tolerance of fishes to drought, it will not be possible to establish realistic targets for management and restoration of populations and species confronting increasing drought frequency and severity.

Modelling environmental impacts of treated municipal wastewater reuse for tree crops irrigation in the Mediterranean coastal region

Wastewater reuse provides valuable solutions to solve the societal challenges of decreasing availability and limiting access to secure water resources. The present study quantifies the environmental performance of nectarine orchards irrigation using treated municipal wastewater (TMW) and surface water using a unique dataset based on field experimental data. Climate change, toxicity (for human and freshwater), eutrophication (marine and freshwater) and acidification impacts were analysed using the impact assessment method suggested by the International Reference Life Cycle Data System (ILCD). The water footprint associated to the life cycles of each system has been estimated using the Available WAter REmaining (AWARE) method. Monte Carlo simulation was used to assess data uncertainty. The irrigation of nectarine orchards using TMW performs better than the irrigation using surface water for eutrophication impact categories. Compared with surface water resources, the potential impacts of TMW reuse in agriculture on climate change and toxicity are affected by the wastewater treatment phase (WWT). Only eutrophication and acidification burdens are generated by in-field substitution of surface water with TMW. Considering human and ecosystem water demand, the irrigation with TMW increases water consumption of 19.12 m3 per kg of nectarine produced. Whereas, it shows a positive contribution to water stress (−0.19 m3) if only human water demand is considered. This study provides important results that allow for a better understanding of the potential environmental consequences of TMW reuse in agriculture. It suggests that embracing the type of WWTs, the replacement of fertilizers, the effects on water scarcity and ecosystem quality might be useful to redefine water reuse regulations and increase public acceptance for the reuse of TMW in agriculture. Moreover, this study reveals the need for developing consensus and standardized guidance for life cycle analysis of water reuse applications.

Assessing the Effect of Incorporating Environmental Water Requirement in the Water Stress Index for Thailand

Human and environmental demands for water are both important; therefore, two approaches are proposed for assessing water scarcity using the water stress index. In one of them, the human demand for water explicitly includes environmental water as one of the components (WSIe1), whereas in the other, environmental water is explicitly reserved by subtracting it from the water availability (WSIe2). The results obtained from using the two approaches in the case of Bang Pakong watershed correspondingly contribute to the explanation of the existing stress situation, especially in the dry season. The stressful results were noticed during December to February for both approaches as a result of less available water and higher environmental water requirement. The assessment of environmental water requirement (EWR) in this study was quantified according to low and high flow periods. The two approaches perform well for assessing water scarcity in the Bang Pakong watershed; however, the result interpretation using the WSIe1 approach is more serious than the WSIe2 approach in terms of water scarcity potential beyond the critical threshold. In conclusion, priority of water allocation is the key consideration for selecting the approach. Higher priority for the environment favors the use of WSIe2 for policy making whereas for a lower priority, the use of WSIe1. In case of Thailand, the WSIe2 approach would be recommended in order to put the EWR as the first priority. Then, water allocation priorities can be rearranged only for human demands for water while the EWR is already safeguarded by setting it aside.

Effects of a Surfactant Seed Coating on Alkali Bulrush Germination and Biomass

Great Salt Lake (GSL) wetlands provide vital ecosystem services, including habitat for migratory birds. Alkali bulrush (Bolboschoenus maritimus) plays an important role in providing these services, but invasion by Phragmites australis has reduced the extent of alkali bulrush stands in GSL wetlands. Restoring alkali bulrush is a primary goal for GSL managers following Phragmites removal. However, rising temperatures and changing precipitation patterns with climate change, as well increasing human water demands upstream, may alter the hydropattern of GSL wetlands, thus lowering soil moisture availability and potentially inhibiting alkali bulrush germination and seedling establishment. Surfactant seed coatings have been effective in aiding the germination of seeds in upland restoration sites by reducing soil water repellency, but have not been tested in wetlands. We tested whether the addition of a surfactant seed coating to alkali bulrush seeds improved germination at four water levels in a greenhouse. Water level and seed coating were significantly associated with improved germination. In a second experiment, we tested the effect of the seed coating at a low and high dose and staggered water level drawdowns on seedling height and biomass over six weeks. Seed coating and time of water level drop were not significantly associated with differences in seedling height. The water level decrease may not have been extreme enough to negatively affect seedlings. More research is needed to determine if a surfactant seed coating enhances alkali bulrush germination and growth under less favorable water availability conditions.

The Life Cycle of Water Used in Flotation: a Review

Since human daily demands for fresh water have been increased significantly, the supply of fresh water for the mining industry, especially froth flotation, should be considerably reduced. In addition, stricter environmental standards have been implemented in many countries to reduce the risks due to the disposal of wastewater, many flotation operators have to seek more efficient ways to utilize the limited fresh water sources. Recycling water with high concentrations of impurities is a normal strategy for most of the mineral processing plants; however, water quality should be carefully considered to guarantee a smooth flotation process. Recently, the application of seawater in flotation has attracted much attention due to its availability and abundance rather than fresh water. However, the influencing mechanisms due to the application of seawater in flotation have not been fully understood especially the reactions between mineral particles and bubbles in the presence of high concentrations of cations and anions. This would impede the application of alternatives to fresh water in the flotation. Therefore, this paper reviews the current water sources and the technologies for water recycling in the flotation process. Specifically, the life cycle of water in flotation was proposed. In addition, the strategies including high pulp density flotation as well as the most promising alternatives to fresh water have been discussed in details, with the related mechanisms being demonstrated.