Next Issue
Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Water, Volume 9, Issue 11 (November 2017)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Cover Story (view full-size image) Univariate, bivariate statistical methods and fractal analysis were applied to assess piezometric [...] Read more.
View options order results:
result details:
Displaying articles 1-92
Export citation of selected articles as:
Open AccessArticle Pollution Removal Performance of Laboratory Simulations of Sydney’s Street Stormwater Biofilters
Water 2017, 9(11), 907; https://doi.org/10.3390/w9110907
Received: 13 September 2017 / Revised: 17 November 2017 / Accepted: 17 November 2017 / Published: 22 November 2017
PDF Full-text (2405 KB) | HTML Full-text | XML Full-text
Abstract
The City of Sydney is constructing more than 21,000 square metres of street biofilter units (raingardens) in terms of their Decentralised Water Master Plan (DWMP), for improving the quality of stormwater runoff to Port Jackson, the Cooks River, and the historical Botany Bay.
[...] Read more.
The City of Sydney is constructing more than 21,000 square metres of street biofilter units (raingardens) in terms of their Decentralised Water Master Plan (DWMP), for improving the quality of stormwater runoff to Port Jackson, the Cooks River, and the historical Botany Bay. Recharge of the Botany Sand Beds aquifer, currently undergoing remediation by extraction of industrial chlorinated hydrocarbon pollutants, is also envisaged. To anticipate the pollution removal efficiency of field biofilter designs, laboratory soil-column simulations were developed by Western Sydney University partnered with the City. Synthetic stormwater containing stoichiometric amounts of high-solubility pollutant salts in deionised water was passed through 104 mm columns that were layered to simulate monophasic and biphasic field designs. Both designs met the City’s improvement targets for total nitrogen (TN) and total phosphorus (TP), with >65% median removal efficiency. Prolonged release of total suspended solids (SS) on startup emphasised the need for specifications and testing of proprietary fills. Median removal efficiency for selected heavy metal ecotoxicants was >75%. The researchers suggested that Zinc be added to the targets as proxy for metals, polycyclic aromatic hydrocarbons (PAH) and oils/greases co-generated during road use. Simulation results suggested that field units will play an important role in meeting regional stormwater improvement targets. Full article
(This article belongs to the Special Issue Urban Water Cycle Modelling and Management)
Figures

Figure 1

Open AccessArticle Impact of Combined Sewer Overflow on Wastewater Treatment and Microbiological Quality of Rivers for Recreation
Water 2017, 9(11), 906; https://doi.org/10.3390/w9110906
Received: 20 October 2017 / Revised: 15 November 2017 / Accepted: 16 November 2017 / Published: 22 November 2017
PDF Full-text (635 KB) | HTML Full-text | XML Full-text
Abstract
Within the framework of a one-year study the treatment capacity of a municipal wastewater treatment plant (WWTP) was evaluated, with regard to fecal indicator bacteria (FIB) and to their influence on the recipient. The logarithmic reduction rates for fecal coliforms (FC), Escherichia coli
[...] Read more.
Within the framework of a one-year study the treatment capacity of a municipal wastewater treatment plant (WWTP) was evaluated, with regard to fecal indicator bacteria (FIB) and to their influence on the recipient. The logarithmic reduction rates for fecal coliforms (FC), Escherichia coli (EC) and intestinal enterococci (IE) were 2.84, 2.90 and 2.93. In the investigated period of time, the tested treatment plant released 4.3% of the total annual load flow volume as combined sewer overflow (CSO), that is, when the influent into the combined sewer exceeds the capacity of the treatment plant and coarsely cleaned wastewater arrives at the recipient. This CSO discharge increased the number of FIB significantly by 1.2 × 102 MPN/100 mL for EC, and by 1.8 × 101 MPN/100 mL for IE. For the Styrian part of the Mur River (1.6 million inhabitants), a calculation of FIB of all sewage treatment plants estimating the same ratio of CSO (4.3%) and a given mean flow rate (QM) results in a significant increase of the FIB load in the recipient: 3.8 × 103 MPN/100 mL for EC and 5.8 × 102 MPN/100 mL for IE. On the basis of these values the standards of water quality for recreational purposes cannot be met. Full article
(This article belongs to the Special Issue Recent Advances in Water Management: Saving, Treatment and Reuse)
Figures

Graphical abstract

Open AccessArticle The Biomass and Physiological Responses of Vallisneria natans (Lour.) Hara to Epiphytic Algae and Different Nitrate-N Concentrations in the Water Column
Water 2017, 9(11), 863; https://doi.org/10.3390/w9110863
Received: 4 September 2017 / Revised: 31 October 2017 / Accepted: 2 November 2017 / Published: 22 November 2017
PDF Full-text (1286 KB) | HTML Full-text | XML Full-text
Abstract
Increasing N concentration and the high density of epiphytic algae are both key factors leading to the decline of submerged macrophytes in many eutrophic lakes. In order to investigate the impacts of increased nitrate-N concentration and the growth of epiphytic algae on the
[...] Read more.
Increasing N concentration and the high density of epiphytic algae are both key factors leading to the decline of submerged macrophytes in many eutrophic lakes. In order to investigate the impacts of increased nitrate-N concentration and the growth of epiphytic algae on the decline of submerged vegetation, we conducted a 2 × 4 factorial experiment with the submerged macrophyte Vallisneria natans (Lour.) Hara by measuring the biomass of plants and some physiological indexes in leaves of V. natans under four nitrate-N concentrations in the water column (0.5, 2.5, 5, and 10 mg/L) and two epiphytic groups (epiphytic algae group and no epiphytic algae group). The results suggested that epiphytic algae could impose adverse effects on the biomass accumulation of V. natans, while the increasing nitrate-N concentration (0.5–10 mg/L) could oppositely promote this process and counteract the adverse effect of epiphytic algae. When nitrate-N concentration was 5 mg/L, the total chlorophyll content in leaves of V. natans in the epiphytic algae group was prominently lower compared with the no epiphytic algae group, while MDA, free proline, and anti-oxidant enzyme (SOD, POD, CAT) activities were significantly higher. Overhigh nitrate-N concentration in the water column also directly imposed adverse effects on the physiology of V. natans. When nitrate-N concentration was over 5 mg/L, the total chlorophyll content and free proline decreased in the no epiphytic algae group, while soluble carbohydrates and soluble proteins decreased when nitrate-N was over 2.5 mg/L. Meanwhile, epiphytic algae and nitrate-N content imposed a synergetic effect on the anti-oxidant enzyme activities of V. natans. When nitrate-N concentration was over 5 mg/L, SOD, POD, and CAT activities kept constant or decreased, which indicated that the oxidation resistance of V. natans was inhibited by stress. Our results indicate that epiphytic algae and increasing nitrate-N concentration in the water column could severally or synergistically impose adverse effects on the physiology of submerged macrophytes and are both key factors leading to the decline of submerged macrophytes. Full article
(This article belongs to the Special Issue Eutrophication of Waterways: An Old Problem with Modern Consequences)
Figures

Figure 1

Open AccessArticle Effects of Climate Change on 2-Methylisoborneol Production in Two Cyanobacterial Species
Water 2017, 9(11), 859; https://doi.org/10.3390/w9110859
Received: 24 September 2017 / Revised: 30 October 2017 / Accepted: 2 November 2017 / Published: 22 November 2017
PDF Full-text (1540 KB) | HTML Full-text | XML Full-text
Abstract
2-Methylisoborneol (2-MIB) is a common off-flavor metabolite, and it has a very low odor threshold value. 2-MIB is produced by a variety of cyanobacteria and heterotrophic bacteria. In this study, Dolichospermum spiroides (Anabaena spiroides, FACHB 498) and Planktothrix sp. (FACHB 1371)
[...] Read more.
2-Methylisoborneol (2-MIB) is a common off-flavor metabolite, and it has a very low odor threshold value. 2-MIB is produced by a variety of cyanobacteria and heterotrophic bacteria. In this study, Dolichospermum spiroides (Anabaena spiroides, FACHB 498) and Planktothrix sp. (FACHB 1371) were investigated. The influence of high temperature (27, 35, and 40 °C) and dissolved inorganic carbon (DIC, 18.4, 27.5, and 36.7 mg/L) on the two 2-MIB-producing cyanobacteria were simulated to study the effect of climate change on 2-MIB production. DIC had an effect on 2-MIB production by Planktothrix sp. The results showed that the highest DIC concentration (36.7 mg/L) led to the fastest algal growth, which increased 2-MIB production by Planktothrix sp. However, 40 °C killed all the cyanobacteria. The higher temperature (35 °C) shortened the lifecycle of the two cyanobacteria because it moved forward their logarithmic phase compared to 27 °C. The 2-MIB-producing potential of Dolichospermum spiroides may increase at 35 °C. The Dolichospermum spiroides results showed that the fluorescence intensity and the concentration of extracellular 2-MIB were highly correlated (r2 ≥ 0.90). At 35 °C, there was a stronger correlation between extracellular dissolved organic matters’ (DOMs, fulvic acid (P3 (r2 = 0.90)), humic acid (P4 (r2 = 0.92)) and the soluble microbial metabolites’ (P5 (r2 = 0.71)) fluorescence peak intensities and 2-MIB concentration. The Dolichospermum sproides 2-MIB-producing potential was affected by extracellular humus. The Planktothrix sp. 2-MIB-producing potential declined in general over the growth period. In addition, temperature had no significant effect on the Planktothrix sp. 2-MIB-producing potential and the extracellular 2-MIB component. Full article
Figures

Figure 1

Open AccessTechnical Note An Improved Coupled Routing and Excess Storage (CREST) Distributed Hydrological Model and Its Verification in Ganjiang River Basin, China
Water 2017, 9(11), 904; https://doi.org/10.3390/w9110904
Received: 30 October 2017 / Revised: 10 November 2017 / Accepted: 16 November 2017 / Published: 21 November 2017
Cited by 1 | PDF Full-text (12711 KB) | HTML Full-text | XML Full-text
Abstract
The coupled routing and excess storage (CREST) distributed hydrological model has been applied regionally and globally for years. With the development of remote sensing, requirements for data assimilation and integration have become new challenges for the CREST model. In this paper, an improved
[...] Read more.
The coupled routing and excess storage (CREST) distributed hydrological model has been applied regionally and globally for years. With the development of remote sensing, requirements for data assimilation and integration have become new challenges for the CREST model. In this paper, an improved CREST model version 3.0 (Tsinghua University and China Institute of Water Resources and Hydropower Research, Beijing, China) is proposed to enable the use of remotely-sensed data and to further improve model performance. Version 3.0 model’s runoff generation, soil moisture, and evapotranspiration based on three soil layers to make the CREST model friendly to remote sensing products such as soil moisture. A free water reservoir-based module which separates three runoff components and a four mechanism-based cell-to-cell routing module are also developed. Traditional CREST and CREST 3.0 are applied in the Ganjiang River basin, China to compare their simulation capability and applicability. Research results indicate that CREST 3.0 outperforms the traditional model and has good application prospects in data assimilation, flood forecasting, and water resources planning and management applications. Full article
Figures

Figure 1

Open AccessArticle Detailed Sponge City Planning Based on Hierarchical Fuzzy Decision-Making: A Case Study on Yangchen Lake
Water 2017, 9(11), 903; https://doi.org/10.3390/w9110903
Received: 16 October 2017 / Revised: 9 November 2017 / Accepted: 17 November 2017 / Published: 20 November 2017
Cited by 1 | PDF Full-text (2096 KB) | HTML Full-text | XML Full-text
Abstract
We proposed a Hierarchical Fuzzy Inference System (HFIS) framework to offer better decision supports with fewer user-defined data (uncertainty). The framework consists two parts: a fuzzified Geographic Information System (GIS) and a HFIS system. The former provides comprehensive information on the criterion unit
[...] Read more.
We proposed a Hierarchical Fuzzy Inference System (HFIS) framework to offer better decision supports with fewer user-defined data (uncertainty). The framework consists two parts: a fuzzified Geographic Information System (GIS) and a HFIS system. The former provides comprehensive information on the criterion unit and the latter helps in making more robust decisions. The HFIS and the traditional Multi-Criteria Decision Making (MCDM) method were applied to a case study and compared. The fuzzified GIS maps maintained a majority of the dominant characteristics of the criterion unit but also revealed some non-significant information according to the surrounding environment. The urban planning map generated by the two methods shares similar strategy choices (6% difference), while the spatial distribution of strategies shares 69.7% in common. The HFIS required fewer subjective decisions than the MCDM (34 user-defined decision rules vs. 141 manual evaluations). Full article
(This article belongs to the Special Issue Sponge Cities: Emerging Approaches, Challenges and Opportunities)
Figures

Figure 1

Open AccessArticle On the Dominant Factor Controlling Seasonal Hydrological Forecast Skill in China
Water 2017, 9(11), 902; https://doi.org/10.3390/w9110902
Received: 11 September 2017 / Revised: 12 November 2017 / Accepted: 16 November 2017 / Published: 20 November 2017
PDF Full-text (9402 KB) | HTML Full-text | XML Full-text
Abstract
Initial conditions (ICs) and climate forecasts (CFs) are the two primary sources of seasonal hydrological forecast skill. However, their relative contribution to predictive skill remains unclear in China. In this study, we investigate the relative roles of ICs and CFs in cumulative runoff
[...] Read more.
Initial conditions (ICs) and climate forecasts (CFs) are the two primary sources of seasonal hydrological forecast skill. However, their relative contribution to predictive skill remains unclear in China. In this study, we investigate the relative roles of ICs and CFs in cumulative runoff (CR) and soil moisture (SM) forecasts using 31-year (1980–2010) ensemble streamflow prediction (ESP) and reverse-ESP (revESP) simulations with the Variable Capacity Infiltration (VIC) hydrologic model. The results show that the relative importance of ICs and CFs largely depends on climate regimes. The influence of ICs is stronger in a dry or wet-to-dry climate regime that covers the northern and western interior regions during the late fall to early summer. In particular, ICs may dominate the forecast skill for up to three months or even six months during late fall and winter months, probably due to the low precipitation value and variability in the dry period. In contrast, CFs become more important for most of southern China or during summer months. The impact of ICs on SM forecasts tends to cover larger domains than on CR forecasts. These findings will greatly benefit future work that will target efforts towards improving current forecast levels for the particular regions and forecast periods. Full article
Figures

Figure 1

Open AccessFeature PaperReview The Zeolite-Anammox Treatment Process for Nitrogen Removal from Wastewater—A Review
Water 2017, 9(11), 901; https://doi.org/10.3390/w9110901
Received: 15 October 2017 / Revised: 8 November 2017 / Accepted: 13 November 2017 / Published: 20 November 2017
Cited by 2 | PDF Full-text (560 KB) | HTML Full-text | XML Full-text
Abstract
Water quality in San Francisco Bay has been adversely affected by nitrogen loading from wastewater treatment plants (WWTPs) discharging around the periphery of the Bay. While there is documented use of zeolites and anammox bacteria in removing ammonia and possibly nitrate during wastewater
[...] Read more.
Water quality in San Francisco Bay has been adversely affected by nitrogen loading from wastewater treatment plants (WWTPs) discharging around the periphery of the Bay. While there is documented use of zeolites and anammox bacteria in removing ammonia and possibly nitrate during wastewater treatment, there is little information available about the combined process. Though relatively large, zeolite beds have a finite ammonium adsorption potential and require periodic re-generation depending on the wastewater nitrogen loading. Use of anammox bacteria reactors for wastewater treatment have shown that ammonium (and to some degree, nitrate) can be successfully removed from the wastewater, but the reactors require careful attention to loading rates and internal redox conditions. Generally, their application has been limited to treatment of high-ammonia strength wastewater at relatively warm temperatures. Moreover, few studies are available describing commercial or full-scale application of these reactors. We briefly review the literature considering use of zeolites or anammox bacteria in wastewater treatment to set the stage for description of an integrated zeolite-anammox process used to remove both ammonium and nitrate without substrate regeneration from mainstream WWTP effluent or anaerobic digester filtrate at ambient temperatures. Full article
(This article belongs to the Special Issue Recent Advances in Water Management: Saving, Treatment and Reuse)
Figures

Figure 1

Open AccessArticle Three-Dimensional Numerical Study of Free-Flow Sediment Flushing to Increase the Flushing Efficiency: A Case-Study Reservoir in Japan
Water 2017, 9(11), 900; https://doi.org/10.3390/w9110900
Received: 12 October 2017 / Revised: 10 November 2017 / Accepted: 14 November 2017 / Published: 19 November 2017
Cited by 1 | PDF Full-text (4701 KB) | HTML Full-text | XML Full-text
Abstract
The catchment of the Dashidaira reservoir located on the Kurobe River has high sediment yield. Because of the sufficient available amount of water in the catchment during flood events, the free-flow sediment flushing operation with full water-level drawdown is employed every year to
[...] Read more.
The catchment of the Dashidaira reservoir located on the Kurobe River has high sediment yield. Because of the sufficient available amount of water in the catchment during flood events, the free-flow sediment flushing operation with full water-level drawdown is employed every year to preserve the effective storage capacity of the Dashidaira reservoir. This paper focuses first on the numerical simulation of a previously conducted free-flow flushing operation in the Dashidaira reservoir using the available in situ obtained data. Afterwards, to improve the flushing efficiency, the effects of water and discharge manipulation and the construction of an auxiliary channel on the total volume of the flushed sediment were studied. A fully 3D numerical model using the finite volume approach in combination with a wetting/drying algorithm was utilized to reproduce the flow velocity field and simulate the movable bed variations. The outcomes revealed that increasing the average free-flow discharge during the free-flow stage by approximately 56%, in the form of multiple discharge pulses, can enhance the flushing efficiency by up to 13%, and the construction of an auxiliary channel in the wide midstream of the reservoir can locally increase the sediment erosion from this area. Full article
(This article belongs to the Special Issue Adaptive Catchment Management and Reservoir Operation)
Figures

Figure 1

Open AccessArticle Winter Snow Level Rise in the Northern Sierra Nevada from 2008 to 2017
Water 2017, 9(11), 899; https://doi.org/10.3390/w9110899
Received: 10 October 2017 / Revised: 14 November 2017 / Accepted: 15 November 2017 / Published: 18 November 2017
Cited by 4 | PDF Full-text (5268 KB) | HTML Full-text | XML Full-text
Abstract
The partitioning of precipitation into frozen and liquid components influences snow-derived water resources and flood hazards in mountain environments. We used a 915-MHz Doppler radar wind profiler upstream of the northern Sierra Nevada to estimate the hourly elevation where snow melts to rain,
[...] Read more.
The partitioning of precipitation into frozen and liquid components influences snow-derived water resources and flood hazards in mountain environments. We used a 915-MHz Doppler radar wind profiler upstream of the northern Sierra Nevada to estimate the hourly elevation where snow melts to rain, or the snow level, during winter (December–February) precipitation events spanning water years (WY) 2008–2017. During this ten-year period, a Mann-Kendall test indicated a significant (p < 0.001) positive trend in snow level with a Thiel-Sen slope of 72 m year−1. We estimated total precipitation falling as snow (snow fraction) between WY1951 and 2017 using nine daily mid-elevation (1200–2000 m) climate stations and two hourly stations spanning WY2008–2017. The climate-station-based snow fraction estimates agreed well with snow-level radar values (R2 = 0.95, p < 0.01), indicating that snow fractions represent a reasonable method to estimate changes in frozen precipitation. Snow fraction significantly (p < 0.001) declined during WY2008–2017 at a rate of 0.035 (3.5%) year−1. Single-point correlations between detrended snow fraction and sea-surface temperatures (SST) suggested that positive SST anomalies along the California coast favor liquid phase precipitation during winter. Reanalysis-derived integrated moisture transported upstream of the northern Sierra Nevada was negatively correlated with snow fraction (R2 = 0.90, p < 0.01), with atmospheric rivers representing the likely circulation mechanism producing low-snow-fraction storms. Full article
Figures

Figure 1

Open AccessArticle Development of a Predictive Tool to Support Environmentally Sustainable Management in Port Basins
Water 2017, 9(11), 898; https://doi.org/10.3390/w9110898
Received: 28 September 2017 / Revised: 10 November 2017 / Accepted: 15 November 2017 / Published: 18 November 2017
PDF Full-text (3020 KB) | HTML Full-text | XML Full-text
Abstract
According to the Water Framework Directive, harbours that are classified as heavily modified water bodies must either reach or maintain good ecological potential. Moreover, following the marine spatial planning principles, the effects of port structure changes on water quality must also be considered.
[...] Read more.
According to the Water Framework Directive, harbours that are classified as heavily modified water bodies must either reach or maintain good ecological potential. Moreover, following the marine spatial planning principles, the effects of port structure changes on water quality must also be considered. To support the sustainable management of harbour waters, we calculated flushing time (FT) through the use of a numerical model within the Civitavecchia port under different scenarios. To assess the effects of the realization of new infrastructure that will significantly alter the port configuration in the coming years, we also developed the flushing efficiency index (FEI). The increase in the harbour basin size due to the embankment extension result in high values of FT, particularly in the inner part of the port, in accordance with the highest values of the enrichment factor of the trace metals found in the sediment. The deterioration of water quality is confirmed by negative FEI values. Otherwise, the index assumes positive values after the realization of a second entrance in the southern part of Civitavecchia port, highlighting a drastic improvement in harbour water renewal. This study provides a low-cost and predictive tool to correctly address environmentally sustainable management of port activities. Full article
Figures

Figure 1

Open AccessArticle Effects of Permafrost Degradation on the Hydrological Regime in the Source Regions of the Yangtze and Yellow Rivers, China
Water 2017, 9(11), 897; https://doi.org/10.3390/w9110897
Received: 22 July 2017 / Revised: 12 October 2017 / Accepted: 10 November 2017 / Published: 16 November 2017
Cited by 3 | PDF Full-text (1326 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Climate warming has intensified permafrost degradation, which could have a variety of implications on the hydrological regime in permafrost regions. In this study, we analyzed the effects of permafrost degradation on the hydrological regime via four hydrological variables for 10 unregulated catchments in
[...] Read more.
Climate warming has intensified permafrost degradation, which could have a variety of implications on the hydrological regime in permafrost regions. In this study, we analyzed the effects of permafrost degradation on the hydrological regime via four hydrological variables for 10 unregulated catchments in the source regions of the Yangtze and Yellow rivers. The results demonstrate that catchments with high permafrost coverage are expected to have an increased winter discharge ratio (proportion of winter discharge contribution to total annual flow), a decreased recession coefficient and a decreased ratio of Qmax/Qmin due to permafrost degradation. However, the great storage effects of lakes and wetlands, which could contribute to more groundwater instead of direct surface discharge, may affect the hydrological effects of permafrost degradation and result in the abnormal performance at catchment scale. The correlation analysis between summer precipitation (July–September) and the following winter discharge (December–February) indicates that permafrost degradation may affect the redistribution of summer precipitation towards the following winter discharge via increasing the soil storage capacity and delaying the release of water into streams in permafrost regions. However, unlike the Arctic and sub-Arctic regions, no significant changes for the hydrological regime (four hydrological variables) are detected over the individual periods of records for each catchment. Decreased precipitation in summer seems to reduce the water infiltration to supply the groundwater, which weakens the effects of permafrost degradation on the hydrological regime. This study implies that the storage effects of lakes and wetlands and the changes of summer precipitation patterns should be considered in future permafrost hydrological simulations, which have suggested that a large increase in groundwater discharge to streams will likely occur in response to permafrost degradation due to the warming climate in the ideal scenario. Full article
Figures

Figure 1

Open AccessFeature PaperArticle Quality of Roof-Harvested Rainwater as a Function of Environmental and Air Pollution Factors in a Coastal Mediterranean City (Haifa, Israel)
Water 2017, 9(11), 896; https://doi.org/10.3390/w9110896
Received: 30 September 2017 / Revised: 6 November 2017 / Accepted: 13 November 2017 / Published: 16 November 2017
PDF Full-text (1314 KB) | HTML Full-text | XML Full-text
Abstract
The quality of roof-harvested rainwater in a Mediterranean climate, which is characterised by dry summers and erratic wet winters, was studied. The effects of environmental factors (rain depth, length of dry period between consecutive rain events, time since the beginning of the rainy
[...] Read more.
The quality of roof-harvested rainwater in a Mediterranean climate, which is characterised by dry summers and erratic wet winters, was studied. The effects of environmental factors (rain depth, length of dry period between consecutive rain events, time since the beginning of the rainy season, roof type, wind speed, and wind direction) and air pollution parameters (O3, SO2, NO2, NO, PM2.5, and PM2.5–10) on roof runoff quality were studied. Three roofs of three common types (concrete, steel sheets, and tiles) were constructed. Roof-generated runoff was collected over two rainy seasons (>50 rain events) and were analysed for presence of metals, chemical and physical constituents, and faecal coliforms (a total of 23 parameters). Rain depth and runoff volume from each roof were recorded for each rain event. Most parameters examined complied with the Israeli potable water regulations. A stepwise multivariate linear regression established a significant effect of roof type on runoff pollutant concentrations, especially for ones generated by the roof material itself (e.g., Ca from the concrete roof and Zn from roof tiles). A significant effect of various air pollutants on the quality of roof-runoff water was found, as explained by rain washing off pollutants that accumulated in the atmosphere during the antecedent dry period. Both O3 and PM2.5–10 affected 17 quality parameters each. Rain depth affected only four out of the 23 water quality variables. In contrast, the length of the dry period between consecutive rain events was an important factor, affecting 12 roof-runoff quality variables. Full article
(This article belongs to the Special Issue Advances on Urban Stormwater Harvesting Strategies)
Figures

Figure 1

Open AccessFeature PaperArticle Effect of Water Quality Sampling Approaches on Nitrate Load Predictions of a Prominent Regression-Based Model
Water 2017, 9(11), 895; https://doi.org/10.3390/w9110895
Received: 5 October 2017 / Revised: 27 October 2017 / Accepted: 6 November 2017 / Published: 16 November 2017
PDF Full-text (3575 KB) | HTML Full-text | XML Full-text
Abstract
High frequency in-situ measurements of nitrate can greatly reduce uncertainty in nitrate flux estimates. Water quality databases maintained by various federal and state agencies often consist of pollutant concentration data obtained from periodic grab samples collected from gauged reaches of a stream. Regression
[...] Read more.
High frequency in-situ measurements of nitrate can greatly reduce uncertainty in nitrate flux estimates. Water quality databases maintained by various federal and state agencies often consist of pollutant concentration data obtained from periodic grab samples collected from gauged reaches of a stream. Regression models, such as the LOAD ESTimator (LOADEST), are frequently used to model variations in concentrations associated with changes in water discharge to provide integrated solute flux measurements. However, uncertainty in the relationships between nutrient concentration and flow may lead to errors in the corresponding flux estimates. In this study, a high frequency, in-situ measurement of nitrate concentration was implemented to ascertain uncertainty in the concentration/discharge relationship caused by nitrate hysteresis. It was found that observed nitrate hysteresis, as influenced by complex storm/watershed interactions, was not readily predictable. Therefore, it can lead to substantial nitrate flux uncertainty, based on periodic grab sample monitoring approaches. Scientists and engineers should take advantage of the proposed findings in future studies to enhance the quality of the associated decision making processes. Full article
Figures

Figure 1

Open AccessArticle Contamination Event Detection Method Using Multi-Stations Temporal-Spatial Information Based on Bayesian Network in Water Distribution Systems
Water 2017, 9(11), 894; https://doi.org/10.3390/w9110894
Received: 13 October 2017 / Revised: 13 November 2017 / Accepted: 14 November 2017 / Published: 16 November 2017
PDF Full-text (2506 KB) | HTML Full-text | XML Full-text
Abstract
As a core part of protecting water quality safety in water distribution systems, contamination event detection requires high accuracy. Previously, temporal analysis-based methods for single sensor stations have shown limited performance as they fail to consider spatial information. Besides, abundant historical data from
[...] Read more.
As a core part of protecting water quality safety in water distribution systems, contamination event detection requires high accuracy. Previously, temporal analysis-based methods for single sensor stations have shown limited performance as they fail to consider spatial information. Besides, abundant historical data from multiple stations are still underexploited in causal relationship modelling. In this paper, a contamination event detection method is proposed, in which both temporal and spatial information from multi-stations in water distribution systems are used. The causal relationship between upstream and downstream stations is modelled by Bayesian Network, using the historical water quality data and hydraulic data. Then, the spatial abnormal probability for one station is obtained by comparing its current causal relationship with the established model. Meanwhile, temporal abnormal probability is obtained by conventional methods, such as an Autoregressive (AR) or threshold model for the same station. The integrated probability that is calculated employed temporal and spatial probabilities using Logistic Regression to determine the final detection result. The proposed method is tested over two networks and its detection performance is evaluated against results obtained from traditional methods using only temporal analysis. Results indicate that the proposed method shows higher accuracy due to its increased information from both temporal and spatial dimensions. Full article
Figures

Figure 1

Back to Top