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Water, Volume 6, Issue 6 (June 2014), Pages 1482-1872

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Open AccessArticle Climatic Characteristics of Reference Evapotranspiration in the Hai River Basin and Their Attribution
Water 2014, 6(6), 1482-1499; doi:10.3390/w6061482
Received: 26 February 2014 / Revised: 16 May 2014 / Accepted: 20 May 2014 / Published: 28 May 2014
Cited by 3 | PDF Full-text (2901 KB) | HTML Full-text | XML Full-text
Abstract
Based on the meteorological data from 46 stations in the Hai River Basin (HRB) from 1961–2010, the annual and seasonal variation of reference evapotranspiration was analyzed. The sensitivity coefficients combined with the detrend method were used to discuss the dominant factor affecting the
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Based on the meteorological data from 46 stations in the Hai River Basin (HRB) from 1961–2010, the annual and seasonal variation of reference evapotranspiration was analyzed. The sensitivity coefficients combined with the detrend method were used to discuss the dominant factor affecting the reference evapotranspiration (ETo). The obtained results indicate that the annual reference evapotranspiration is dominated by the decreasing trends at the confidence level of 95% in the southern and eastern parts of the HRB. The sensitivity order of climatic variables to ETo from strong to weak is: relativity humidity, temperature, shortwave radiation and wind speed, respectively. However, comprehensively considering the sensitivity and its variation strength, the detrend analysis indicates that the decreasing trends of ETo in eastern and southern HRB may be caused mainly by the decreasing wind speed and shortwave radiation. As for the relationship between human activity and the trend of ETo, we found that ETo decreased more significantly on the plains than in the mountains. By contrast, the population density increased more considerably from 2000 to 2010 on the plains than in the mountains. Therefore, in this paper, the correlation of the spatial variation pattern between ETo and population was further analyzed. The spatial correlation coefficient between population and the trend of ETo is −0.132, while the spatial correlation coefficient between the trend of ETo and elevation, temperature, shortwave radiation and wind speed is 0.667, 0.668, 0.749 and 0.416, respectively. This suggests that human activity has a certain influence on the spatial variation of ETo, while natural factors play a decisive role in the spatial variation of reference evapotranspiration in this area. Full article
Open AccessArticle Water Banks: Using Managed Aquifer Recharge to Meet Water Policy Objectives
Water 2014, 6(6), 1500-1514; doi:10.3390/w6061500
Received: 20 February 2014 / Revised: 20 May 2014 / Accepted: 21 May 2014 / Published: 28 May 2014
Cited by 5 | PDF Full-text (1193 KB) | HTML Full-text | XML Full-text
Abstract
Innovation born of necessity to secure water for the U.S. state of Arizona has yielded a model of water banking that serves as an international prototype for effective use of aquifers for drought and emergency supplies. If understood and adapted to local hydrogeological
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Innovation born of necessity to secure water for the U.S. state of Arizona has yielded a model of water banking that serves as an international prototype for effective use of aquifers for drought and emergency supplies. If understood and adapted to local hydrogeological and water supply and demand conditions, this could provide a highly effective solution for water security elsewhere. Arizona is a semi-arid state in the southwestern United States that has growing water demands, significant groundwater overdraft, and surface water supplies with diminishing reliability. In response, Arizona has developed an institutional and regulatory framework that has allowed large-scale implementation of managed aquifer recharge in the state’s deep alluvial groundwater basins. The most ambitious recharge activities involve the storage of Colorado River water that is delivered through the Central Arizona Project (CAP). The CAP system delivers more than 1850 million cubic meters (MCM) per year to Arizona’s two largest metropolitan areas, Phoenix and Tucson, along with agricultural users and sovereign Native American Nations, but the CAP supply has junior priority and is subject to reduction during declared shortages on the Colorado River. In the mid-1980s the State of Arizona established a framework for water storage and recovery; and in 1996 the Arizona Water Banking Authority was created to mitigate the impacts of Colorado River shortages; to create water management benefits; and to allow interstate storage. The Banking Authority has stored more than 4718 MCM of CAP water; including more than 740 MCM for the neighboring state of Nevada. The Nevada storage was made possible through a series of interrelated agreements involving regional water agencies and the federal government. The stored water will be recovered within Arizona; allowing Nevada to divert an equal amount of Colorado River water from Lake Mead; which is upstream of CAP’s point of diversion. This paper describes water banking in Arizona from a policy perspective and identifies reasons for its implementation. It goes on to explore conditions under which water banking could successfully be applied to other parts of the world, specifically including Australia. Full article
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Open AccessArticle Urban Flood Vulnerability and Risk Mapping Using Integrated Multi-Parametric AHP and GIS: Methodological Overview and Case Study Assessment
Water 2014, 6(6), 1515-1545; doi:10.3390/w6061515
Received: 8 February 2014 / Revised: 14 May 2014 / Accepted: 20 May 2014 / Published: 30 May 2014
Cited by 17 | PDF Full-text (4886 KB) | HTML Full-text | XML Full-text
Abstract
This study aims at providing expertise for preparing public-based flood mapping and estimating flood risks in growing urban areas. To model and predict the magnitude of flood risk areas, an integrated Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) analysis techniques are
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This study aims at providing expertise for preparing public-based flood mapping and estimating flood risks in growing urban areas. To model and predict the magnitude of flood risk areas, an integrated Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) analysis techniques are used for the case of Eldoret Municipality in Kenya. The flood risk vulnerability mapping follows a multi-parametric approach and integrates some of the flooding causative factors such as rainfall distribution, elevation and slope, drainage network and density, land-use/land-cover and soil type. From the vulnerability mapping, urban flood risk index (UFRI) for the case study area, which is determined by the degree of vulnerability and exposure is also derived. The results are validated using flood depth measurements, with a minimum average difference of 0.01 m and a maximum average difference of 0.37 m in depth of observed flooding in the different flood prone areas. Similarly with respect to area extents, a maximum error of not more than 8% was observed in the highly vulnerable flood zones. In addition, the Consistency Ratio which shows an acceptable level of 0.09 was calculated and further validated the strength of the proposed approach. Full article
(This article belongs to the Special Issue Advances in Remote Sensing of Flooding)
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Open AccessArticle Analysis of the Possible Use of Solar Photovoltaic Energy in Urban Water Supply Systems
Water 2014, 6(6), 1546-1561; doi:10.3390/w6061546
Received: 28 February 2014 / Revised: 13 May 2014 / Accepted: 21 May 2014 / Published: 30 May 2014
Cited by 3 | PDF Full-text (1085 KB) | HTML Full-text | XML Full-text
Abstract
Because of the importance of water supply for the sustainability of urban areas, and due to the significant consumption of energy with prices increasing every day, an alternative solution for sustainable energy supply should be sought in the field of Renewable Energy Sources
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Because of the importance of water supply for the sustainability of urban areas, and due to the significant consumption of energy with prices increasing every day, an alternative solution for sustainable energy supply should be sought in the field of Renewable Energy Sources (RES). An innovative solution as presented in this paper has until now not been comprehensively analyzed. This work presents the solution with the application of a (Photovoltaic) PV generator. The main technological features, in addition to the designing methodology and case study are presented in this paper. The critical period approach has been used for the first time for system sizing. The application of this sizing method provides a high reliability of the proposed system. The obtained results confirm the assumption that the PV generator is a promising energy sustainable solution for urban water supply systems. The service reservoir, which acts as water and energy storage for the proposed system, provides the basis for a sustainable solution of water and energy supply. In accordance with the proposed, the reliability of such system is high. This concept of energy supply operation does not generate any atmospheric emission of greenhouse gases, which contributes significantly to the reduction of the impacts of climate changes. The proposed solution and designing methodology are widely applicable and in accordance with the characteristics of the water supply system and climate. Full article
Open AccessArticle Future Climate Forcings and Olive Yield in a Mediterranean Orchard
Water 2014, 6(6), 1562-1580; doi:10.3390/w6061562
Received: 11 February 2014 / Revised: 22 May 2014 / Accepted: 26 May 2014 / Published: 30 May 2014
PDF Full-text (722 KB) | HTML Full-text | XML Full-text
Abstract
The olive tree is one of the most characteristic rainfed trees in the Mediterranean region. Observed and forecasted climate modifications in this region, such as the CO2 concentration and temperature increase and the net radiation, rainfall and wind speed decrease, will likely
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The olive tree is one of the most characteristic rainfed trees in the Mediterranean region. Observed and forecasted climate modifications in this region, such as the CO2 concentration and temperature increase and the net radiation, rainfall and wind speed decrease, will likely alter vegetation water stress and modify productivity. In order to simulate how climatic change could alter soil moisture dynamic, biomass growth and fruit productivity, a water-driven crop model has been used in this study. The numerical model, previously calibrated on an olive orchard located in Sicily (Italy) with a satisfactory reproduction of historical olive yield data, has been forced with future climate scenarios generated using a stochastic weather generator and a downscaling procedure of an ensemble of climate model outputs. The stochastic downscaling is carried out using simulations of some General Circulation Models adopted in the fourth Intergovernmental Panel on Climate Change (IPCC) assessment report (4AR) for future scenarios. The outcomes state that climatic forcings driving potential evapotranspiration compensate for each other, resulting in a slight increase of this water demand flux; moreover, the increase of CO2 concentration leads to a potential assimilation increase and, consequently, to an overall productivity increase in spite of the growth of water stress due to the rainfall reduction. Full article
Open AccessArticle Identifying Major Factors Affecting Groundwater Change in the North China Plain with Grey Relational Analysis
Water 2014, 6(6), 1581-1600; doi:10.3390/w6061581
Received: 4 December 2013 / Revised: 9 May 2014 / Accepted: 12 May 2014 / Published: 3 June 2014
Cited by 6 | PDF Full-text (2122 KB) | HTML Full-text | XML Full-text
Abstract
The North China Plain (NCP) is facing a water crisis under the dual impact of natural and anthropogenic factors. Groundwater levels have declined continuously since 1960, causing a series of environmental problems that have restricted sustainable development in the region. In the present
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The North China Plain (NCP) is facing a water crisis under the dual impact of natural and anthropogenic factors. Groundwater levels have declined continuously since 1960, causing a series of environmental problems that have restricted sustainable development in the region. In the present study, we first utilized a previously developed 3D groundwater model to determine changes in groundwater level in the region over the past 50 years (1961–2010). We then applied grey relational analysis (GRA) to identify and ordinate major factors that have contributed to these changes. The results show an overall decreasing trend in groundwater levels in this region over the past 50 years and an increase in the water table depth at a rate of approximately 0.36 m/a. Groundwater exploitation showed the most significant correlation with the groundwater table decline, when compared with other factors including precipitation and river leakage. Therefore, human activities should be considered the primary force driving the groundwater level down. The results of this study have implications for developing criteria that consider changes in both climate and socio-economics. Furthermore, since the NCP is one of the most water-scarce and densely populated regions in the world, the analytical approach used in and the insights gained from this study are of international interest. Full article
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Open AccessArticle Water Relationships in the U.S. Southwest: Characterizing Water Management Networks Using Natural Language Processing
Water 2014, 6(6), 1601-1641; doi:10.3390/w6061601
Received: 17 January 2014 / Revised: 14 May 2014 / Accepted: 15 May 2014 / Published: 3 June 2014
Cited by 3 | PDF Full-text (6139 KB) | HTML Full-text | XML Full-text
Abstract
Natural language processing (NLP) and named entity recognition (NER) techniques are applied to collections of newspaper articles from four cities in the U.S. Southwest. The results are used to generate a network of water management institutions that reflect public perceptions of water management
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Natural language processing (NLP) and named entity recognition (NER) techniques are applied to collections of newspaper articles from four cities in the U.S. Southwest. The results are used to generate a network of water management institutions that reflect public perceptions of water management and the structure of water management in these areas. This structure can be highly centralized or fragmented; in the latter case, multiple peer institutions exist that may cooperate or be in conflict. This is reflected in the public discourse of the water consumers in these areas and can, we contend, impact the potential responses of management agencies to challenges of water supply and quality and, in some cases, limit their effectiveness. Flagstaff, AZ, Tucson, AZ, Las Vegas, NV, and the Grand Valley, CO, are examined, including more than 110,000 articles from 2004–2012. Documents are scored by association with water topics, and phrases likely to be institutions are extracted via custom NLP and NER algorithms; those institutions associated with water-related documents are used to form networks via document co-location. The Grand Valley is shown to have a markedly different structure, which we contend reflects the different historical trajectory of its development and its current state, which includes multiple institutions of roughly equal scope and size. These results demonstrate the utility of using NLP and NER methods to understanding the structure and variation of water management systems. Full article
Open AccessArticle Enhancing the Predicting Accuracy of the Water Stage Using a Physical-Based Model and an Artificial Neural Network-Genetic Algorithm in a River System
Water 2014, 6(6), 1642-1661; doi:10.3390/w6061642
Received: 28 February 2014 / Revised: 14 April 2014 / Accepted: 21 May 2014 / Published: 3 June 2014
Cited by 5 | PDF Full-text (1005 KB) | HTML Full-text | XML Full-text
Abstract
Accurate simulations of river stages during typhoon events are critically important for flood control and are necessary for disaster prevention and water resources management in Taiwan. This study applies two artificial neural network (ANN) models, including the back propagation neural network (BPNN) and
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Accurate simulations of river stages during typhoon events are critically important for flood control and are necessary for disaster prevention and water resources management in Taiwan. This study applies two artificial neural network (ANN) models, including the back propagation neural network (BPNN) and genetic algorithm neural network (GANN) techniques, to improve predictions from a one-dimensional flood routing hydrodynamic model regarding the water stages during typhoon events in the Danshuei River system in northern Taiwan. The hydrodynamic model is driven by freshwater discharges at the upstream boundary conditions and by the water levels at the downstream boundary condition. The model provides a sound physical basis for simulating water stages along the river. The simulated results of the hydrodynamic model show that the model cannot reproduce the water stages at different stations during typhoon events for the model calibration and verification phases. The BPNN and GANN models can improve the simulated water stages compared with the performance of the hydrodynamic model. The GANN model satisfactorily predicts water stages during the training and verification phases and exhibits the lowest values of mean absolute error, root-mean-square error and peak error compared with the simulated results at different stations using the hydrodynamic model and the BPNN model. Comparison of the simulated results shows that the GANN model can be successfully applied to predict the water stages of the Danshuei River system during typhoon events. Full article
Open AccessArticle The Economics of Groundwater Replenishment for Reliable Urban Water Supply
Water 2014, 6(6), 1662-1670; doi:10.3390/w6061662
Received: 11 March 2014 / Revised: 27 May 2014 / Accepted: 29 May 2014 / Published: 10 June 2014
Cited by 9 | PDF Full-text (426 KB) | HTML Full-text | XML Full-text
Abstract
This paper explores the potential economic benefits of water banking in aquifers to meet drought and emergency supplies for cities where the population is growing and changing climate has reduced the availability of water. A simplified case study based on the city of
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This paper explores the potential economic benefits of water banking in aquifers to meet drought and emergency supplies for cities where the population is growing and changing climate has reduced the availability of water. A simplified case study based on the city of Perth, Australia was used to estimate the savings that could be achieved by water banking. Scenarios for investment in seawater desalination plants and groundwater replenishment were considered over a 20 year period of growing demand, using a Monte Carlo analysis that embedded the Markov model. An optimisation algorithm identified the minimum cost solutions that met specified criteria for supply reliability. The impact of depreciation of recharge credits was explored. The results revealed savings of more than A$1B (~US$1B) or 37% to 33% of supply augmentation costs by including water banking in aquifers for 95% and 99.5% reliability of supply respectively. When the hypothetically assumed recharge credit depreciation rate was increased from 1% p.a. to 10% p.a. savings were still 33% to 31% for the same reliabilities. These preliminary results show that water banking in aquifers has potential to offer a highly attractive solution for efficiently increasing the security of urban water supplies where aquifers are suitable. Full article
Open AccessArticle Effect of Hydrograph Separation on Suspended Sediment Concentration Predictions in a Forested Headwater with Thick Soil and Weathered Gneiss Layers
Water 2014, 6(6), 1671-1684; doi:10.3390/w6061671
Received: 26 February 2014 / Revised: 16 April 2014 / Accepted: 20 April 2014 / Published: 11 June 2014
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Abstract
Two-component hydrograph separation using oxygen-18 concentrations was conducted at a sediment runoff observation weir installed in a small subcatchment of a forested gneiss catchment in Japan. The mean soil thickness of this catchment is 7.27 m, which comprises 3.29 m of brown forest
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Two-component hydrograph separation using oxygen-18 concentrations was conducted at a sediment runoff observation weir installed in a small subcatchment of a forested gneiss catchment in Japan. The mean soil thickness of this catchment is 7.27 m, which comprises 3.29 m of brown forest soil (A and B layers) and a 3.98-m layer of heavily weathered gneiss. Data were collected for a storm on 20–21 May 2003, and the percentage of event water separated by the stable isotope ratio in comparison with the total rainfall amount was about 1%. This value is within the ratio of a riparian zone in a drainage area. Temporal variation of suspended sediment concentration exhibited higher correlation with the event water component than with the total runoff or pre-event water component. This shows that the riparian zone causes rainwater to flow out quickly during a rain event, and that this is an important area of sediment production and transportation in a forested headwater with thick soil and weathered gneiss layers. Full article
(This article belongs to the Special Issue Environmental Tracers) Print Edition available
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Open AccessArticle Water Footprint and Impact of Water Consumption for Food, Feed, Fuel Crops Production in Thailand
Water 2014, 6(6), 1698-1718; doi:10.3390/w6061698
Received: 13 February 2014 / Revised: 29 April 2014 / Accepted: 3 June 2014 / Published: 16 June 2014
Cited by 15 | PDF Full-text (1439 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The proliferation of food, feed and biofuels demands promises to increase pressure on water competition and stress, particularly for Thailand, which has a large agricultural base. This study assesses the water footprint of ten staple crops grown in different regions across the country
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The proliferation of food, feed and biofuels demands promises to increase pressure on water competition and stress, particularly for Thailand, which has a large agricultural base. This study assesses the water footprint of ten staple crops grown in different regions across the country and evaluates the impact of crop water use in different regions/watersheds by the water stress index and the indication of water deprivation potential. The ten crops include major rice, second rice, maize, soybean, mungbean, peanut, cassava, sugarcane, pineapple and oil palm. The water stress index of the 25 major watersheds in Thailand has been evaluated. The results show that there are high variations of crop water requirements grown in different regions due to many factors. However, based on the current cropping systems, the Northeastern region has the highest water requirement for both green water (or rain water) and blue water (or irrigation water). Rice (paddy) farming requires the highest amount of irrigation water, i.e., around 10,489 million m3/year followed by the maize, sugarcane, oil palm and cassava. Major rice cultivation induces the highest water deprivation, i.e., 1862 million m3H2Oeq/year; followed by sugarcane, second rice and cassava. The watersheds that have high risk on water competition due to increase in production of the ten crops considered are the Mun, Chi and Chao Phraya watersheds. The main contribution is from the second rice cultivation. Recommendations have been proposed for sustainable crops production in the future. Full article
Open AccessArticle Exposure of Mediterranean Countries to Ocean Acidification
Water 2014, 6(6), 1719-1744; doi:10.3390/w6061719
Received: 28 February 2014 / Revised: 3 June 2014 / Accepted: 3 June 2014 / Published: 16 June 2014
Cited by 7 | PDF Full-text (599 KB) | HTML Full-text | XML Full-text
Abstract
This study examines the potential effects of ocean acidification on countries and fisheries of the Mediterranean Sea. The implications for seafood security and supply are evaluated by examining the sensitivity of the Mediterranean to ocean acidification at chemical, biological, and macro-economic levels. The
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This study examines the potential effects of ocean acidification on countries and fisheries of the Mediterranean Sea. The implications for seafood security and supply are evaluated by examining the sensitivity of the Mediterranean to ocean acidification at chemical, biological, and macro-economic levels. The limited information available on impacts of ocean acidification on harvested (industrial, recreational, and artisanal fishing) and cultured species (aquaculture) prevents any biological impact assessment. However, it appears that non-developed nations around the Mediterranean, particularly those for which fisheries are increasing, yet rely heavily on artisanal fleets, are most greatly exposed to socioeconomic consequences from ocean acidification. Full article
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Open AccessArticle Assessing Climate Change Impacts on Water Resources and Colorado Agriculture Using an Equilibrium Displacement Mathematical Programming Model
Water 2014, 6(6), 1745-1770; doi:10.3390/w6061745
Received: 27 October 2013 / Revised: 7 May 2014 / Accepted: 12 May 2014 / Published: 16 June 2014
Cited by 1 | PDF Full-text (499 KB) | HTML Full-text | XML Full-text
Abstract
This research models selected impacts of climate change on Colorado agriculture several decades in the future, using an Economic Displacement Mathematical Programming model. The agricultural economy in Colorado is dominated by livestock, which accounts for 67% of total receipts. Crops, including feed grains
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This research models selected impacts of climate change on Colorado agriculture several decades in the future, using an Economic Displacement Mathematical Programming model. The agricultural economy in Colorado is dominated by livestock, which accounts for 67% of total receipts. Crops, including feed grains and forages, account for the remainder. Most agriculture is based on irrigated production, which depends on both groundwater, especially from the Ogallala aquifer, and surface water that comes from runoff derived from snowpack in the Rocky Mountains. The analysis is composed of a Base simulation, designed to represent selected features of the agricultural economy several decades in the future, and then three alternative climatic scenarios are run. The Base starts with a reduction in agricultural water by 10.3% from increased municipal and industrial water demand, and assumes a 75% increase in corn extracted-ethanol production. From this, the first simulation (S1) reduces agricultural water availability by a further 14.0%, for a combined decrease of 24.3%, due to climatic factors and related groundwater depletion. The second simulation (S2-WET) describes wet year conditions, which negatively affect yields of irrigated corn and milking cows, but improves yields for important crops such as non-irrigated wheat and forages. In contrast, the third simulation (S3-DRY) describes a drought year, which leads to reduced dairy output and reduced corn and wheat. Consumer and producer surplus losses are approximately $10 million in this simulation. The simulation results also demonstrate the importance of the modeling trade when studying climate change in a small open economy, and of linking crop and livestock activities to quantify overall sector effects. This model has not taken into account farmers’ adaptation strategies, which would reduce the climate impact on yields, nor has it reflected climate-induced shifts in planting decisions and production practices that have environmental impacts or higher costs. It also focuses on a comparative statics approach to the analysis in order to identify several key effects of changes in water availability and yields, without having a large number of perhaps confounding assumptions. Full article
Open AccessArticle Public Perception of Water Consumption and Its Effects on Water Conservation Behavior
Water 2014, 6(6), 1771-1784; doi:10.3390/w6061771
Received: 15 April 2014 / Revised: 7 June 2014 / Accepted: 10 June 2014 / Published: 16 June 2014
Cited by 2 | PDF Full-text (566 KB) | HTML Full-text | XML Full-text
Abstract
The usual perception of consumers regarding water consumption is that their bills do not match their actual water consumption. However, this mismatch has been insufficiently studied; particularly for cases related to specific water-use patterns, water conservation practices, and user socio-demographics. In this study,
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The usual perception of consumers regarding water consumption is that their bills do not match their actual water consumption. However, this mismatch has been insufficiently studied; particularly for cases related to specific water-use patterns, water conservation practices, and user socio-demographics. In this study, a total of 776 households in 16 villages situated in the rural Wei River Basin are investigated to address the gap in the literature. Questionnaires and 3-day water diaries are used for data collection and comparison. Results show that significant relations exist between perceived water consumption and actual water consumption. Participants have different perceptions of specific water-use patterns. Participants tend to underestimate their outdoor and kitchen water consumption and overestimate their indoor water consumption. Females and elder consumers accurately estimate their water consumption, whereas consumers with high education levels and incomes underestimate their actual water consumption. The groups who can accurately estimate water consumption have better water conservation consciousness and water conservation practices than those who underestimate their water consumption. The huge disparities highlighted by the results suggest that community policies and programs to improve public water conservation consciousness or practices must be implemented to enhance consumer understanding of water consumption. Full article
(This article belongs to the Special Issue Water Consumption and Water End-uses in Buildings)
Open AccessArticle Photocatalytic Degradation of Phenol and Phenol Derivatives Using a Nano-TiO2 Catalyst: Integrating Quantitative and Qualitative Factors Using Response Surface Methodology
Water 2014, 6(6), 1785-1806; doi:10.3390/w6061785
Received: 23 April 2014 / Revised: 27 May 2014 / Accepted: 5 June 2014 / Published: 17 June 2014
Cited by 12 | PDF Full-text (570 KB) | HTML Full-text | XML Full-text
Abstract
Due to the toxicity effects and endocrine disrupting properties of phenolic compounds, their removal from water and wastewater has gained widespread global attention. In this study, the photocatalytic degradation of phenolic compounds in the presence of titanium dioxide (TiO2) nano-particles and
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Due to the toxicity effects and endocrine disrupting properties of phenolic compounds, their removal from water and wastewater has gained widespread global attention. In this study, the photocatalytic degradation of phenolic compounds in the presence of titanium dioxide (TiO2) nano-particles and UV light was investigated. A full factorial design consisting of three factors at three levels was used to examine the effect of particle size, temperature and reactant type on the apparent degradation rate constant. The individual effect of TiO2 particle size (5, 10 and 32 nm), temperature (23, 30 and 37 °C) and reactant type (phenol, o-cresol and m-cresol) on the apparent degradation rate constant was determined. A regression model was developed to relate the apparent degradation constant to the various factors. The largest photocatalytic activity was observed at an optimum TiO2 particle size of 10 nm for all reactants. The apparent degradation rate constant trend was as follows: o-cresol > m-cresol > phenol. The ANOVA data indicated no significant interaction between the experimental factors. The lowest activation energy was observed for o-cresol degradation using 5-nm TiO2 particles. A maximum degradation rate constant of 0.0138 min−1 was recorded for o-cresol at 37 °C and a TiO2 particle size of 13 nm at a D-optimality value of approximately 0.98. The response model adequately related the apparent degradation rate constant to the factors within the range of factors under consideration. Full article
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Open AccessArticle Effect of Selected Plant Extracts and D- and L-Lysine on the Cyanobacterium Microcystis aeruginosa
Water 2014, 6(6), 1807-1825; doi:10.3390/w6061807
Received: 26 April 2014 / Revised: 7 June 2014 / Accepted: 10 June 2014 / Published: 17 June 2014
Cited by 2 | PDF Full-text (583 KB) | HTML Full-text | XML Full-text
Abstract
We tested extracts from Fructus mume, Salvia miltiorrhiza and Moringa oleifera as well as L-lysine and D-Lysine as curative measures to rapidly suppress the cyanobacterium Microcystis aeruginosa NIVA-CYA 43. We tested these compounds under similar conditions to facilitate comparisons. We hypothesized that
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We tested extracts from Fructus mume, Salvia miltiorrhiza and Moringa oleifera as well as L-lysine and D-Lysine as curative measures to rapidly suppress the cyanobacterium Microcystis aeruginosa NIVA-CYA 43. We tested these compounds under similar conditions to facilitate comparisons. We hypothesized that for each compound, relatively low concentrations—i.e., 5–50 mg L−1, would reduce M. aeruginosa biomass. At these low concentrations, only L-lysine caused a decline in M. aeruginosa biomass at ≥4.3 mg L−1. F. mume extract was effective to do so at high concentrations, i.e., at ≥240 mg L−1, but the others were virtually non-effective. Low pH caused by organic acids is a probable explanation for the effect of F. mume extract. No complete wipe-outs of the experimental population were achieved as Photosystem II efficiency showed a recovery after six days. L-lysine may be effective at low concentrations—meaning low material costs. However, the effect of L-lysine seems relatively short-lived. Overall, the results of our study did not support the use of the tested plant extracts and amino-acid as promising candidates for curative application in M. aeruginosa bloom control. Full article
Open AccessArticle Investigation of Groundwater Flow Variations near a Recharge Pond with Repeat Deliberate Tracer Experiments
Water 2014, 6(6), 1826-1839; doi:10.3390/w6061826
Received: 25 January 2014 / Revised: 30 May 2014 / Accepted: 3 June 2014 / Published: 17 June 2014
Cited by 4 | PDF Full-text (1263 KB) | HTML Full-text | XML Full-text
Abstract
Determining hydraulic connections and travel times between recharge facilities and production wells has become increasingly important for permitting and operating managed aquifer recharge (MAR) sites, a water supply strategy that transfers surface water into aquifers for storage and later extraction. This knowledge is
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Determining hydraulic connections and travel times between recharge facilities and production wells has become increasingly important for permitting and operating managed aquifer recharge (MAR) sites, a water supply strategy that transfers surface water into aquifers for storage and later extraction. This knowledge is critical for examining water quality changes and assessing the potential for future contamination. Deliberate tracer experiments are the best method for determining travel times and identifying preferential flow paths between recharge sites over the time scales of weeks to a few years. This paper compares the results of two deliberate tracer experiments at Kraemer Basin, Orange County, CA, USA. Results from the first experiment, which was conducted in October 1998, showed that a region of highly transmissive sedimentary material extends down gradient from the basin for more than 3 km [1]. Mean groundwater velocities were determined to be approximately 2 km/year in this region based on the arrival time of the tracer center of mass. A second experiment was initiated in January 2008 to determine if travel times from this basin to monitoring and production wells changed during the past decade in response to new recharge conditions. Results indicate that flow near Kraemer Basin was stable, and travel times to most wells determined during both experiments agree within the experimental uncertainty. Full article
(This article belongs to the Special Issue Environmental Tracers) Print Edition available
Open AccessArticle Species-Specific Variations in the Nutritional Quality of Southern Ocean Phytoplankton in Response to Elevated pCO2
Water 2014, 6(6), 1840-1859; doi:10.3390/w6061840
Received: 6 February 2014 / Revised: 12 May 2014 / Accepted: 4 June 2014 / Published: 17 June 2014
Cited by 9 | PDF Full-text (518 KB) | HTML Full-text | XML Full-text
Abstract
Increased seawater pCO2 has the potential to alter phytoplankton biochemistry, which in turn may negatively affect the nutritional quality of phytoplankton as food for grazers. Our aim was to identify how Antarctic phytoplankton, Pyramimonas gelidicola, Phaeocystis antarctica, and Gymnodinium
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Increased seawater pCO2 has the potential to alter phytoplankton biochemistry, which in turn may negatively affect the nutritional quality of phytoplankton as food for grazers. Our aim was to identify how Antarctic phytoplankton, Pyramimonas gelidicola, Phaeocystis antarctica, and Gymnodinium sp., respond to increased pCO2. Cultures were maintained in a continuous culture setup to ensure stable CO2 concentrations. Cells were subjected to a range of pCO2 from ambient to 993 µatm. We measured phytoplankton response in terms of cell size, cellular carbohydrate content, and elemental, pigment and fatty acid composition and content. We observed few changes in phytoplankton biochemistry with increasing CO2 concentration which were species-specific and predominantly included differences in the fatty acid composition. The C:N ratio was unaffected by CO2 concentration in the three species, while carbohydrate content decreased in Pyramimonas gelidicola, but increased in Phaeocystis antarctica. We found a significant reduction in the content of nutritionally important polyunsaturated fatty acids in Pyramimonas gelidicola cultures under high CO2 treatment, while cellular levels of the polyunsaturated fatty acid 20:5ω3, EPA, in Gymnodinium sp. increased. These changes in fatty acid profile could affect the nutritional quality of phytoplankton as food for grazers, however, further research is needed to identify the mechanisms for the observed species-specific changes and to improve our ability to extrapolate laboratory-based experiments on individual species to natural communities. Full article
Open AccessArticle Development of a Continuous Phytoplankton Culture System for Ocean Acidification Experiments
Water 2014, 6(6), 1860-1872; doi:10.3390/w6061860
Received: 6 February 2014 / Revised: 23 May 2014 / Accepted: 4 June 2014 / Published: 17 June 2014
Cited by 2 | PDF Full-text (404 KB) | HTML Full-text | XML Full-text
Abstract
Around one third of all anthropogenic CO2 emissions have been absorbed by the oceans, causing changes in seawater pH and carbonate chemistry. These changes have the potential to affect phytoplankton, which are critically important for marine food webs and the global carbon
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Around one third of all anthropogenic CO2 emissions have been absorbed by the oceans, causing changes in seawater pH and carbonate chemistry. These changes have the potential to affect phytoplankton, which are critically important for marine food webs and the global carbon cycle. However, our current knowledge of how phytoplankton will respond to these changes is limited to a few laboratory and mesocosm experiments. Long-term experiments are needed to determine the vulnerability of phytoplankton to enhanced pCO2. Maintaining phytoplankton cultures in exponential growth for extended periods of time is logistically difficult and labour intensive. Here we describe a continuous culture system that greatly reduces the time required to maintain phytoplankton cultures, and minimises variation in experimental pCO2 treatments over time. This system is simple, relatively cheap, flexible, and allows long-term experiments to be performed to further our understanding of chronic responses and adaptation by phytoplankton species to future ocean acidification. Full article

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Open AccessTechnical Note Use of Pollutant Load Regression Models with Various Sampling Frequencies for Annual Load Estimation
Water 2014, 6(6), 1685-1697; doi:10.3390/w6061685
Received: 7 April 2014 / Revised: 4 June 2014 / Accepted: 5 June 2014 / Published: 12 June 2014
Cited by 4 | PDF Full-text (771 KB) | HTML Full-text | XML Full-text
Abstract
Water quality data are collected by various sampling frequencies, and the data may not be collected at a high frequency nor over the range of streamflow conditions. Therefore, regression models are used to estimate pollutant data for days on which water quality data
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Water quality data are collected by various sampling frequencies, and the data may not be collected at a high frequency nor over the range of streamflow conditions. Therefore, regression models are used to estimate pollutant data for days on which water quality data were not measured. Pollutant load regression models were evaluated with six sampling frequencies for daily nitrogen, phosphorus, and sediment data. Annual pollutant load estimates exhibited various behaviors by sampling frequency and also by the regression model used. Several distinct sampling frequency features were observed in the study. The first was that more frequent sampling did not necessarily lead to more accurate and precise annual pollutant load estimates. The second was that use of water quality data collected from storm events improved both accuracy and precision in annual pollutant load estimates for all water quality parameters. The third was that the pollutant regression model automatically selected by LOADEST did not necessarily lead to more accurate and precise annual pollutant load estimates. The fourth was that pollutant regression models displayed different behaviors for different water quality parameters in annual pollutant load estimation. Full article

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