Fluctuations In Water Quality Research Articles

Effect of water quality variation on fish assemblages in an anthropogenically impacted tropical estuary, Colombian Pacific

In tropical estuaries, fish diversity varies spatially and temporally due to behavioral processes such as reproductive migrations, predator avoidance, and foraging, which are affected by water quality. Eutrophication is one of the main factors affecting water quality in estuaries. The objective of this study was to determine variation in fish assemblage explained by fluctuating water quality in the Buenaventura Bay. Fish were captured using artisanal trawl nets during the wet, dry, and transitional seasons at four sampling sites. Additionally, alkalinity; phosphate, nitrite, and nitrate concentrations; dissolved oxygen; pH; temperature; and suspended solids were measured. Multivariate analysis was used to assess the effect of water quality on fish assemblage. In Buenaventura Bay, the assemblage composition of Pseudupeneus grandisquamis, Daector dowi, and Citharichthys gilberti was affected by nitrate concentration. Moreover, large fish biomasses were associated with high nitrite concentration, intermediate salinity, and low dissolved oxygen, suggesting that these estuaries are dominated by species tolerant to poor water quality. Species richness was associated with low nitrate and phosphate concentrations, more suitable water quality indicators, and intermediate temperatures. These results suggest that the deteriorating water quality of estuaries as a result of the anthropogenic impact could increase dominance and decrease richness, resulting in structural changes of fish assemblages.

Effects of silver(I) toxicity on microstructure, biochemical activities, and genic material of Lemna minor L. with special reference to application of bioindicator.

In this research, several biochemical variations in plant of Lemna minor L. were investigated to reflect Ag+ toxicity. Lemna minor L. changed colorless AgNO3 to colloidal brown at doses equal to and greater than 1mgL-1. Optical and fluorescence microscopy revealed the presence of bright spots in roots of tested plant related to Ag/Ag2O-NPs. Photosynthetic pigment contents of Lemna minor L. declined upon exposure to Ag+ with an evidently higher decrease in chlorophyll a than in chlorophyll b. Similarly, Ag+ treatment caused an evident reduction in the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). The reduction in antioxidase activity was significantly higher in POD than in SOD and CAT. Ag+ treatment resulted in a significant increment in the level of malondialdehyde (MDA) content as the judging criteria of cellular injury which showed sign of dose-related. The alterations occurred in RAPD profiles of treated samples following Ag+ toxicity containing loss of normal bands, appearance of new bands, and variation in band intensities compared with the normal plants. In addition, morphological character and biomass of Lemna minor L. subjected to increasing Ag+ concentrations were evaluated to reveal Ag+ toxicity. Our study demonstrated that Lemna minor L. have a high sensitivity to indicate fluctuation of water quality. It would be beneficial that modulating the genotype of Lemna minor L. to bear high proportion of contaminates.

Cilamaya estuary zonation based on sea surface salinity with 2 Sentinel-2A satellite imagery

Estuaries act as transitional areas on the coastal zone that connect highly saline ocean environments with fresh river systems. This dynamic aquatic ecosystem is created by deep fluctuations in water quality and salinity levels. Cilamaya estuary supports a highly diverse marine ecosystem that is underutilized due to knowledge deficiencies of its variable rates of salinity. The aim of this study is to show the difference zone of estuary based on the sea surface salinity in the different time, so that Cilamaya Estuary areas can be utilized optimally for resource management. Sea surface salinity is obtained using algorithmic calculations based on the Sentinel-2A imagery. Salinity levels are studied based on the rainy and dry seasons. The higher salinity occur on the dry seasons, while on the rainy seasons have a lower salinity. Estuary areas experience 0.5-30 %o salinity placing it within the three zoning classes of the Venice System; Mexo-oligohaline; Mexo-mesohaline and Mexo-polyhaline.

Guest Editorial: Permian Shale Water Management: The Hidden Costs

Guest editorial Water management in shale plays is an extremely competitive business. Every cent counts. This is most evident in the Permian Basin where companies work tirelessly to minimize operating costs in order to contract new capacities and fill their capital-rich infrastructure. These players are under enormous pressure to evaluate every component of costs and wring out excesses. While traditional operating expenses (OPEX) are heavily scrutinized, a full picture of profitability in water management is gained only after comprehensively examining the unique aspects of their overall business model. Traditional OPEX components in produced water management include labor, chemicals, consumables, infrastructure maintenance, transportation, disposal, solids handling, and power and other utilities. Capital expenses (CAPEX) must also be considered in light of tradeoffs between CAPEX and OPEX. Water CAPEX is generally composed of infrastructure, including pipelines, disposal wells, ponds/storage treatment facilities, and associated utilities infrastructure; equipment; engineering, project management, and permitting costs; and land. While all companies focus on these key expenses, another very significant cost driver emerges when the business model is more closely examined. Midstream companies’ revenues originate from three primary sources: Handling fees. Operators pay companies to collect and dispose of their produced water/flowback on a volume basis, and disposal is usually to a saltwater disposal (SWD) well. Gathering fees are charged for pipeline collection and disposal fees are charged for volumes disposed into SWDs. Commodity-based margins. Companies separate skim oil from disposed volumes and sell oil. In some cases, ownership of the skim oil remains with the operator. Royalties and accounting costs must be considered as a component of the profitability of skim oil sales. Treatment fees. Instead of disposing to a SWD, companies can treat produced water/flowback and sell recycled water to operators on a volume basis. The fact that recycling in the Permian is gaining in popularity due to local water scarcity, transportation costs, environmental stewardship, and/or SWD limitations creates additional opportunities for generating new revenue by increasing the volumes of water treated and associated water disposal/delivery fees. Revenue Bottlenecks As recycling is more readily adopted, revenues are becoming constricted by a number of factors including: pipeline capacity, treatment facility capacity, water quality fluctuations that cause upsets in facility operations, and transportation distances/location to fracturing sites.

Analysis of Water Quality Fluctuations in Upstream Namhan River Watershed Using Long-term Statistical Analysis

Analysis of Water Quality Fluctuations in Upstream Namhan River Watershed Using Long-term Statistical Analysis

Water Quality Assessment of Hebbal Lake in Bangalore City

Bangalore city consists of many artificial lakes which was constructed for domestic water supply, industrial, agricultural and also for recreational purposes. Due to huge population growth, pollution and urbanization the lakes of Bangalore is depleting day by day. Hebbal lake is one among the oldest lake in Bangalore, with its source being rainwater. Hence there is a need to study, restore and protect this lake. The present study deals with studying and analyzing the physico-chemical parameters of Hebbal Lake at its different sampling points. The following parameters were analyzed in laboratory using different analytical methods i.e Temperature, Dissolved oxygen, Biochemical oxygen demand (BOD), Chemical oxygen demand (COD), Electrical conductivity, Total hardness, Total dissolved solids (TDS), and chloride. All other parameters were well within the permissible limits. The BOD exceeded the maximum limit as per the standards 6mg/lit prescribed by BIS. Water quality index was plotted to know its water quality fluctuations at different sampling points. The obtained results revealed the importance of lake restoration and management of the hebbal lake. It was concluded that the lake water could be used for domestic purpose, irrigation, and also for drinking purpose with proper filtration. This paper presents the qualitative assessment of hebbal lake and its remedial measures for water crisis in Bangalore city.

Coupled benthic–hyporheic responses of macroinvertebrates to surface water pollution in a gravel-bed river

Interactions between the hyporheic and benthic zones play a vital role in maintaining the integrity of river ecosystems, but simultaneous assessments of hyporheic and benthic macroinvertebrate responses to surface water pollution are limited. We examined how hyporheic (50 cm below surface) and benthic (surface) invertebrates responded to water pollution that originated from a point source (wastewater treatment plant) in a gravel-bed river in Hokkaido, Japan. Dissolved nutrient levels and algal biomass were significantly higher at sample sites down- than upstream of the point source. Furthermore, nitrate concentrations increased gradually from up- to downstream sites, which suggest the presence of diffuse pollution sources in the surrounding areas. Closely synchronized fluctuations of water temperature and similar water quality in the surface and hyporheic zones indicated that the hyporheic zone was highly hydrologically interactive with the surface water. Chloroperlidae (mostly Alloperla ishikariana) had a disproportionately high abundance in the hyporheic zone relative to the benthic zone, regardless of the surface water quality. Numerically dominant invertebrate taxa increased in abundance below the point source of pollution in both the benthic and hyporheic habitats. High N stable isotope ratios (SIR) of the invertebrates in both habitat types indicated that invertebrates assimilated anthropogenic N via the ingestion of pollution-contaminated food resources. End-member mixing analyses based on C SIR demonstrated that assimilation of anthropogenic N occurred because of the increase in available food resources originating from the biofilm. The trophic structure of invertebrates changed less markedly in the hyporheic zone than in the benthic zone, suggesting that the hyporheic assemblage was less sensitive than the benthic assemblage to the changes in surface water quality. Overall, our findings showed that the numeric responses of the invertebrate assemblage to anthropogenic changes in surface water quality were similar and coupled between the benthic and hyporheic zones.

The combined effects of salinity, hypoxia, and oil exposure on survival and gene expression in developing sheepshead minnows, Cyprinodon variegatus

The 2010 Deepwater Horizon oil spill released approximately 780 million liters of crude oil contaminating coastal habitats from Texas to Florida which are important habitats for many fish species during early life stages. These diverse habitats are also prone to rapid fluctuations in water quality, such as dissolved oxygen concentration and salinity. The consequence of combined exposure to crude oil and suboptimal environmental conditions during early life stage development of fish is still largely unknown. The objective of this project was to investigate the impacts of exposure to crude oil in combination with varying environmental stressors on developing Cyprinodon variegatus survival, growth, and gene expression. Three life stages (embryonic, post-hatch, and post-larval) were exposed to four nominal concentrations (6.25%, 12.5%, 50% and 100% with actual polycyclic aromatic hydrocarbon (PAH) concentrations ranging from 0 to 512 μg/L) of high energy water accommodated fractions (HEWAF) under different oxic (2.0 or >5.0 mg/L) and salinity (10 or 30 ppt) regimes at 30 °C for 48 h. We found that the post-larval developmental stage was the most sensitive to oil toxicity. Median lethal concentrations during the post-larval exposures followed a treatment-dependent pattern with the highest mortality observed under hypoxic-high salinity conditions (64.55 μg/L). Real-time PCR analysis identified down regulation of target genes, encoding cytochrome P450-1α (cyp1a1), erythropoietin (epo), and the aryl hydrocarbon receptor nuclear translocator (arnt1) only when oil exposure occurred under hypoxic-high salinity conditions in treatments with PAH concentrations greater than 226 μg/L. The target genes measured in this experiment are involved in the aryl hydrocarbon receptor signaling pathway which modulates metabolism of PAHs (a major component of crude oil), and the hypoxia inducible 1-α signaling pathway which is responsible for resilience to hypoxic stress, and it is known that disruption of these pathways can lead to an array of acute and chronic effects. Our results indicated that sheepshead minnow are most sensitive to oil exposure during the post-larval developmental stage. Survival data from this age-stage also indicate that oil toxicity response is exacerbated in hypoxic and high salinity environments. The increased mortality observed during the post-larval developmental stage might be attributed to the suppression of the aryl hydrocarbon receptor signaling and the hypoxia inducible 1-α signaling pathways which is evident in by the down-regulated expression of cyp1a1, epo, and arnt1. These findings provide more information about interactions between oil and abiotic factors which enable us to make better assumptions of the ecological impacts of DWH on coastal estuaries.

Study on the treatment of organic wastewater from soil thermal desorption by Fenton method

Fenton’s reagent has been widely used as a high-grade oxidation technology in the treatment of refractory, high-concentration, toxic and harmful organic wastewater, and has achieved remarkable results. The organic wastewater generated by thermal desorption of soil has the characteristics of high pollutant content, complex composition and large fluctuation of water quality. Generally, the organic wastewater components produced by thermal desorption of soil mainly include polycyclic aromatic hydrocarbons, polychlorinated biphenyls, chlorobenzene and the like.

Composite Control of Post-Chlorine Dosage During Drinking Water Treatment

Chlorination is an effective disinfection method of drinking water treatment. Optimizing this process poses certain challenges, as the objectives of reaching the required disinfection effect and limiting the formation of disinfection by-products must be met simultaneously. These need adjusting the chlorine dosage in real time to cope with fluctuations in water quality and maintaining a free chlorine residual at the clear-water reservoir outlet that does not exceed regulatory limits. This paper proposes a composite control scheme that combines disturbance observer (DOB) and model predictive control (MPC) to meet the aforementioned objectives. MPC is employed for the feedback control of post-chlorine dosage, and DOB is adapted to monitor fluctuations in influent water quality. The estimated value from the DOB is applied in the feed-forward control of post-chlorine dosage. Both simulation and experimental results demonstrate that the proposed DOB-MPC composite control scheme provides a better disturbance rejection effect against fluctuations in influent water quality than MPC-only and PID-only control schemes, and it can effectively stabilize the quality of treated water.

基于时空分析的生态保护与修复试点工程实施效果评估——以赣州市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于时空分析的生态保护与修复试点工程实施效果评估——以赣州市为例 DOI: 10.5846/stxb201905291126 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 自然资源部国土整治中心课题（20191603） Evaluation on the implementation effect of the pilot project for ecological protection and restoration of multi ecological elements based on spatio-temporal analysis: A case study of Ganzhou Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以“山水林田湖草生命共同体”为中心思想，从生态系统的格局和质量两个方面，对赣州市山水林田湖生态保护与修复试点工程实施效果进行了综合评估。结果如下：（1）从生态系统格局来看，2015到2018年，赣州市森林、农田和城镇生态系统面积明显增加，超过40%的草地生态系统转变为森林生态系统，且近45%的城镇生态系统面积增量由草地生态系统贡献。此外，多数自然生态系统的斑块破碎化加剧，森林生态系统破碎化现象最为明显，最大斑块指数从54.36降低到37.41，而半自然生态系统最大斑块指数增大。（2）从生态系统质量来看，赣州市归一化植被指数稳定在0.7以上并呈增长趋势，水土流失综合治理面积从16543.8 km2增长到18550.4 km2，重点流域水质基本稳定在Ⅱ、Ⅲ级，城镇生态系统受土壤重金属污染的风险较小，但部分县区农田生态系统受一种或多种土壤重金属污染的风险较大。整体而言，赣州市山水林田湖生态保护与修复试点工程取得了显著成效，较好的完成了实施方案中的规划目标。在进一步的生态保护与修复工作中，应重视赣州市自然生态系统斑块破碎化严重地区、水质出现波动较大的河流断面以及农田生态系统受土壤重金属污染威胁较大的县区。 Abstract:From the perspective of the ecosystem pattern and quality, the effectiveness of the pilot project for ecological protection and restoration of multi ecological elements in Ganzhou was comprehensively evaluated based on the central idea of mountains-rivers-forests-farmlands-lakes-grasslands system as a community of life. The results are as follows:(1) For ecosystem pattern, the area of forest, farm and urban ecosystems in Ganzhou increased significantly. More than 40% of grassland ecosystems were converted to forest ecosystems, and nearly 45% of urban ecosystem area increment were contributed by grassland ecosystems. In addition, landscape fragmentation in most natural ecosystems was intensified, and the largest patch index (LPI) of forest ecosystems were decreased from 54.36 to 37.41, while the LPI in semi-natural ecosystems were increased. (2) Regarding ecosystem quality, the normalized difference vegetation index (NDVI) of Ganzhou was stable above 0.7 and showed an increasing trend. The comprehensive control area of soil erosion increased from 16543.8 km2 to 18550.4 km2, and the water quality in key river basins was basically stable at Grade II and III. For the quality of soil environment, urban ecosystems were less threatened by the risk of soil heavy metal pollution. But the soil of farm ecosystems in some areas were at higher risk of being contaminated by one or more heavy metals. Overall, the ecological protection and restoration project in Ganzhou has achieved remarkable effectiveness, and the planning objectives in the implementation plan have been well completed. In the further ecological restoration work, there are three problems should be taken seriously, including the natural ecosystems with severe landscape fragmentation, the rivers with large fluctuations in water quality, and the farm ecosystems with high risk of heavy metal pollution. 参考文献 相似文献 引证文献

Water insecurity, illness and other factors of everyday life: A case study from Choma District, Southern Province, Zambia

Recent reports from the UN find that 2.6 billion people have gained access to improved drinking water sources since 1990, but 663 million people still live without. Other recent work demonstrates that 4 billion people annually face severe water scarcity as a result of seasonal fluctuations in water availability and quality. How is it that, despite the significant development in water resource availability documented by the UN, literally billions of people are regularly experiencing water insecurity? To begin to understand how a lack of access to reliable water resources affects everyday life, I focus on a specific outcome of water insecurity: waterborne illness. Given the difficulty in linking illness to a particular source, this research focuses on perceptions of water safety. I ask participants about illness they perceive coming from their drinking water, conducting face-to-face surveys (N = 224) spatially distributed around Choma town, Southern Province, Zambia. In particular, I investigate how these perceptions affect everyday life and what intersecting factors are likely to increase or decrease the probability of a person perceiving drinking water as the source of their illness. Our findings demonstrate that individual perceptions of waterborne illness are tightly coupled with perceptions of water needs being met or not, water flexibility (water storage capacity and water resource type and number available), total water use, food security and distance to various services. My work identifies and qualifies intersecting relationships that are critical to the design of any policy or other means of intervention intended to reduce experienced and perceived waterborne illness and other everyday needs of subsistence farmers facing the challenges presented by climate change and other forms of environmental change.

Application of High Efficacy Clarification Tank and Rotary Filter in Advanced Treatment Process of Northern WWTP

In order to improve the effluent quality, the advanced treatment process mainly including the combination technology of highly efficient clarification tank and rotary filter was used for Chuanhu Wastewater Treatment Plant in Changchun city. This paper introduces the advanced wastewater treatment process, design parameters of main structures and corresponding equipment. The actual operation results show that advanced treatment process can achieve good effluent quality in spite of high contaminant concentration and big fluctuation of water quality of raw water. Effluent quality can steadily meet the requirement of grade A of pollutant discharge standard of urban sewage treatment plant (GB 18918-2002).

Impacts of natural conditions and anthropogenic activities on groundwater quality in Tebessa plain, Algeria

Abstract The “Merdja” is the shallow aquifer of Tebessa plain, located in the northeast of Algeria. The climate is typical of semi-arid steppes, where extensive agro-pastoral activities are dominating. It is still the main water resource used by major sectors. Due to its proximity to the City, it is vulnerable to pollution. According to earlier studies, this aquifer undergoes seasonal water quality fluctuations (between wet and dry seasons), induced mainly through anthropogenic activities. The study is utmost important, as it tracks the groundwater quality and aims to gain an understanding of how the local and natural conditions influence this resource at temporal (interannual) and spatial scales, by following up the evolution trend of hydrochemical parameters of the “Merdja” aquifer. Seventy-one groundwater samples were collected and analyzed from drinking/irrigation wells, through four field measurement campaigns (2001, 2006, 2009, and 2010). The results obtained confirm the fact of water pollution. Point-sources of pollution with nitrate and salinity are revealed on the respective maps of these parameters, especially downstream at the nearby areas of Tebessa City. Non-point sources of groundwater pollution are also manifested. The Piper diagram reveals a relative stability of water type and that rainfall plays a role in the natural remediation, by taking part in the aquifer recharge. The ionic ratios and the principal components analysis highlight that the temporal change of groundwater quality results respectively from: (i) ionic exchange process and the dissolution of evaporites; (ii) the sources of nitrate in groundwater remain the excess application of inorganic nitrogenous fertilizers, organic manures, and wastewater effluents.

Biodesulfurization of sulfide wastewater for elemental sulfur recovery by isolated Halothiobacillus neapolitanus in an internal airlift loop reactor

The biodesulfurization of sulfide wastewater for elemental sulfur recovery by isolated Halothiobacillus neapolitanus in an internal airlift loop reactor (IALR) was investigated. The flocculant producer Pseudomonas sp. strain N1-2 was used to deposit the produced elemental sulfur during biodesulfurization. The functional group analysis indicated that biofloculation was closely associated with NH and CO. The biodesulfurization system performed well under moderate water quality fluctuations (1.29–3.88 kg·m−3·d−1 COD; 1.54–3.08 kg·m−3·d−1·S2−) as it maintained stable S2− removal and sulfur flocculation rates. Meanwhile, the qRT-PCR analysis indicated that the transcriptional level of cbbL decreased in the presence of organic carbon, while the expressions of sqr, sat, and cytochrome C3 increased under higher sulfide stress. Moreover, the relative proportions of Halothiobacillus was strengthened via microbial intervention of the LJN1-3 strain. The S2− removal efficiency and elemental sulfur production was further improved by 32.5% and 28.2%, respectively, in an IALR.

The effects of water quality on back-reef sponge survival and distribution in the Florida Keys, Florida (USA)

For decades, water quality in Florida Bay and the shallow, back-reef areas of large portions of the Florida Keys (Florida, USA) have varied dramatically as a consequence of climatic conditions and water management strategies in the adjacent freshwater marshes of the Everglades. The resulting fluctuations in water quality have led to die-offs of seagrass and sponges in hard-bottom habitats, transforming the ecosystem. In this study, we examined the implications of water quality on sponge community structure in two ways. First, in laboratory experiments we tested the tolerance of five prominent sponge species to salinities ranging from 15 psu to 45 psu at typical summer and winter temperatures. We then compared sponge distributions at 32 sites in the Florida Keys with regional patterns in water quality. Our experiments showed that during the summer the loggerhead sponge (Speciospongia vesparium) and glove sponge (Spongia cheiris) were the most tolerant of sustained changes in salinity, but most species died at higher rates at salinities other than 35 psu. Salinity-associated mortality declined in the winter, but was again higher at salinities <35 psu. A pulsed change in salinity at summer temperatures yielded idiosyncratic results depending on the species. Analysis of the field data showed that some species such as Ircinia variablis and Cinachyrella alloclada grow in most environments, whereas the occurrence of most species declines when salinity is variable and at high nutrient concentrations. These results provide a more detailed picture of the species-specific environmental tolerance of several shallow-water Caribbean sponges, and suggest that changes in environmental conditions are likely to significantly impact their distribution and species composition with potentially drastic impacts on ecosystem function.

The Fluctuation of Water Quality of Ci Lutung flow areas in Majalengka and Sumedang.

The river is the main source of water in Indonesia, which at the moment, this quality tends to get worse and is no longer worth consuming for various needs. The cause of the pollution is the entry of pollutants both point source (industrial waste) and non-point source (residential and agricultural land). Rainfall can be a non-point source pollutant agent from a watershed to a water body. The impact of rainfall on increasing concentrations of pollutants is very significant, especially the high intensity rainfall that falls after the long dry season. In this study, water quality data is obtained from river outlets located in Damkamun taken every 30 minutes during the rainfall event so that fluctuation in water quality can be seen. Water quality indicators studied in this research are TDS, DHLNitrate, Phosphate and Ph. The author, in analyzing, using rainfall Himawari 8 which is obtained every 10 minutes. The result shows that rainfall is directly related to the water flow and the fluctuation of the discharge affects the water quality. From the calculations, the chemical quality of water is also influenced by the use of land in the watershed. Nitrate value increases when the occurrence of rain occurs in land use while phosphate experiences a high value during the event.

Revisiting Hydrology of Lake Ngami in Botswana

Lake Ngami, an integral part of the Okavango Delta in Botswana, is a seasonal shallow lake that depends mostly on spills deriving from Boro River and rarely from Thamalakane River. In essence, the lake water is critical to the local population supporting the fishing industry, farming, livestock and tourism. This work attempts to revisit and to understand the hydrological conditions of the lake, which are of paramount importance for planning and development processes in the lake area. By referring to earlier historical publications and analyzing annual inflow of Okavango River at Mohembo in Botswana from 1932 to 2016, and annual outflow of Lake River to the lake at Mogapelwa from 1974 to 2016, three flooding regimes have been identified for the Lake Ngami namely wet, seasonal and dry. The hydrological data analysis has shown that the Okavango inflow directly influences the Lake River outflow which in turn determines the lake’s three regimes. The findings show that the longest wet phase for the lake was from 1959 to 1972 and that the longest dry phase was from 1980 to 2003. Water depths measured at six accessible cross-sectional points along a distance of 39.3 km at higher water levels in September 2012 showed that the average depth of water in the lake was 3.508 m. Historical observations on the lake dimensions with water are varied. However, in September 2012 the volume of water determined for the lake was 974 Mm3 occupying 277.7 km2. Outflow volumes to the lake via Lake River and water levels in the lake from 1974 to 2016 provide further evidence to explain the lake regimes. Water quality fluctuations in a given year are varied but can be improved through simple treatments such as boiling or chlorination. This study contributes to the understanding of the lake flow regimes and possible water allocations to the users.

Evaluating statistical model performance in water quality prediction

Exposure to contaminated water while swimming or boating or participating in other recreational activities can cause gastrointestinal and respiratory disease. It is not uncommon for water bodies to experience rapid fluctuations in water quality, and it is therefore vital to be able to predict them accurately and in time so as to minimise population's exposure to pathogenic organisms. E. coli is commonly used as an indicator to measure water quality in freshwater, and higher counts of E. coli are associated with increased risk to illness. In this case study, we compare the performance of a wide range of statistical models in prediction of water quality via E. coli levels for the weekly data collected over the summer months from 2006 to 2014 at the recreational site on the Oreti river in Wallacetown, New Zealand. The models include naive model, multiple linear regression, dynamic regression, regression tree, Markov chain, classification tree, random forests, multinomial logistic regression, discriminant analysis and Bayesian network. The results show that Bayesian network was superior to all the other models. Overall, it had a leave-one-out and k-fold cross validation error rate of 21%, while predicting the majority of instances of E. coli levels classified as unsafe by the Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas 2003, New Zealand. Because Bayesian networks are also flexible in handling missing data and outliers and allow for continuous updating in real time, we have found them to be a promising tool, and in the future, plan to extend the analysis beyond the current case study site.

The reliability evaluation of reclaimed water reused in power plant project

The reuse of reclaimed water has become one of the important measures to solve the shortage of water resources in many cities, But there is no unified way to evaluate the engineering. Concerning this issue, it took Wanneng power plant project in Huai city as a example, analyzed the reliability of wastewater reuse from the aspects of quality in reclaimed water, water quality of sewage plant, the present sewage quantity in the city and forecast of reclaimed water yield, in particular, it was necessary to make a correction to the actual operation flow rate of the sewage plant. the results showed that on the context of the fluctuation of inlet water quality, the outlet water quality of sewage treatment plants is basically stable, and it can meet the requirement of circulating cooling water, but suspended solids(SS) and total hardness in boiler water exceed the limit, and some advanced treatment should be carried out. In addition, the total sewage discharge will reach 13.91×104m3/d and 14.21×104m3/d respectively in the two planning level years of the project. They are greater than the normal collection capacity of the sewage system which is 12.0×104 m3/d, and the reclaimed water yield can reach 10.74×104m3/d, which is greater than the actual needed quantity 8.25×104m3/d of the power plant, so the wastewater reuse of this sewage plant are feasible and reliable to the power plant in view of engineering.