scholarly journals Water quality trend analysis of Cheurfas II dam, Algeria

2021 ◽  
Author(s):  
Salima Rezak ◽  
Farid Rahal ◽  
Abdellah Bahmani
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Surface Waters ◽  
Temporal Evolution ◽  
Kendall Test ◽  
Organic Pollution ◽  
Water Volume ◽  
Northwestern Part ◽  
Different Origins ◽  
Increasing Trends

The northwestern part of Algeria is characterized by a semi-arid climate which has created semi-permanent rivers and dams with low filling rates. It is important to preserve the water resource, which is becoming increasingly scarce. Additionally, it is worth indicating that the mobilized surface waters are continually under threat of significant organic pollution. Indeed, the dam of Cheurfas II, in the northwestern part of the country, is indicative of this situation. In order to establish a diagnosis of the state of the temporal evolution of water quality, time series of 11 variables indicating the presence of organic pollution in this dam were thus analyzed. The data collected were analyzed using the Mann-Kendall test to look for significant trends and the Webel-Ollech test to detect the presence of seasonality. The results obtained showed increasing trends in dry residues, organic matter, phosphates and dissolved oxygen. However, variables like BOD5, COD and NO-3 showed decreasing trends. As for the variables NH+4, NO-2 and pH, they presented no trend. Finally, the water volume of the dam exhibited a significant increase. In addition, no seasonality was detected in the variables studied, with the exception of the PO43- time series and water volume. These findings indicate that the watershed of the dam received pollutants from different origins, in particular industrial pollutants. This makes water biodegradability difficult to achieve.

scholarly journals A Comprehensive Study of Spatiotemporal Variations in Temperature Extremes across China during 1960–2018

2021 ◽  
Vol 13 (7) ◽  
pp. 3807
Author(s):  
Na Zhao ◽  
Mingxing Chen
Keyword(s):  
Spatial Heterogeneity ◽  
Mainland China ◽  
Kendall Test ◽  
Northern China ◽  
Central China ◽  
Maximum Temperature ◽  
Temperature Extremes ◽  
Northwestern Part ◽  
Spatiotemporal Variations ◽  
Increasing Trends

Understanding the changing patterns of extreme temperatures is important for taking measures to reduce their associated negative impacts. Based on daily temperature data derived from 2272 meteorological stations in China, the spatiotemporal variations in temperature extremes were examined with respect to covariates by means of the Mann–Kendall test and a spatiotemporal model during 1960–2018. The results indicated that the temporal changes in cold extremes showed decreasing trends and warm extremes experienced increasing trends across almost all of China, with mean change rates of −3.9 days, −1.8 days, 3.7 days and 2.3 days per decade for TN10p, TX10p, TN90p and TX90p, respectively. Nighttime warming/cooling was higher than daytime warming/cooling, which indicated that trends in minimum temperature extremes are more rapid than trends in maximum temperature extremes. In addition, the temporal effect on the temperature extremes varied throughout the year, with significant increasing trends in the temporal heterogeneity of warm extremes occurring during 1992–2018. The areas with strong spatial heterogeneity of cool nights mainly included northeastern and central China, and the spatial variation on cool days was more prominent in northern China. For warm nights, the areas showing high spatial heterogeneity were mainly located in the northwestern part of China, while areas for warm days were distributed in northern China. Our results provide meaningful information for a deeper understanding of the spatiotemporal variations in temperature extremes across mainland China.

scholarly journals Study on the Assessment of the Oxygen Regime and the Nutrients Content of Some Water Streams in Gorj County

2020 ◽  
Vol 71 (2) ◽  
pp. 315-323
Author(s):  
Daniela Cirtina ◽  
Maria Nicoleta Mihut
Keyword(s):  
Water Quality ◽  
Surface Waters ◽  
Oxygen Demand ◽  
Organic Pollution ◽  
Environmental Legislation ◽  
Oxygen Regime ◽  
Ammonium N ◽  
Nitrite Content ◽  
Hydrographic Network

The study aims to characterize the quality of some representative surface waters of Gorj county�s hydrographic network by assessing the oxygen regime, namely the dissolved oxygen content (DO), the chemical oxygen demand (COD-Cr), the biochemical consumption of oxygen BOD5) and nutrients measured by ammonium (N-NH4+), nitrites (N-NO2-), nitrates (N-NO3-), total nitrogen, soluble orthophosphates (P-PO43-) and total phosphorus during 2016-2018. In order to carry out the study, representative sections of the Jiu, Motru and Jilt rivers were monitored in areas considered vulnerable to nutrient and organic pollution. The results regarding water quality from the monitored natural receptors generally showed an evolution within the limits allowed by the environmental legislation, except for the nitrite content that was exceeded for all three monitored rivers. Also, the values of the COD-Cr and BOD5 indicators have been exceeded in some Jiu and Jilt river monitoring sections. Consequently, there is a need to monitor the mentioned parameters.

DEVELOPMENT OF STREAMFLOW DROUGHT INDICES IN THE MORAVA RIVER BASIN

2020 ◽  
Author(s):  
Ondrej Ledvinka ◽  
◽  
Pavel Coufal ◽  
Keyword(s):  
Time Series ◽  
Kendall Test ◽  
Drought Indices ◽  
Drought Period ◽  
Left Hand ◽  
Low Flows ◽  
Current Period ◽  
Catchment Size ◽  
Morava River ◽  
The Stability

The territory of Czechia currently suffers from a long-lasting drought period which has been a subject of many studies, including the hydrological ones. Previous works indicated that the basin of the Morava River, a left-hand tributary of the Danube, is very prone to the occurrence of dry spells. It also applies to the development of various hydrological time series that often show decreases in the amount of available water. The purpose of this contribution is to extend the results of studies performed earlier and, using the most updated daily time series of discharge, to look at the situation of the so-called streamflow drought within the basin. 46 water-gauging stations representing the rivers of diverse catchment size were selected where no or a very weak anthropogenic influences are expected and the stability and sensitivity of profiles allow for the proper measurement of low flows. The selected series had to cover the most current period 1981-2018 but they could be much longer, which was considered beneficial for the next determination of the development direction. Various series of drought indices were derived from the original discharge series. Specifically, 7-, 15- and 30-day low flows together with deficit volumes and their durations were tested for trends using the modifications of the Mann– Kendall test that account for short-term and long-term persistence. In order to better reflect the drivers of streamflow drought, the indices were considered for summer and winter seasons separately as well. The places with the situation critical to the future water resources management were highlighted where substantial changes in river regime occur probably due to climate factors. Finally, the current drought episode that started in 2014 was put into a wider context, making use of the information obtained by the analyses.

Long Term Monitoring of the Macrobenthos of the Upper Clyde Estuary

1984 ◽  
Vol 16 (5-7) ◽  
pp. 359-373 ◽  
Author(s):  
Anne R Henderson
Keyword(s):  
Water Quality ◽  
Seasonal Variation ◽  
Organic Pollution ◽  
Long Term Changes ◽  
Pollution Loading ◽  
Faunal Density ◽  
History Of ◽  
Long Term Monitoring ◽  
Term Monitoring

The sublittoral macrobenthic invertebrate populations of the Upper Clyde Estuary are described. The estuary has a long history of organic pollution. The long term changes in species composition, faunal density and dominance patterns between 1974 and 1980 are presented. The fauna is dominated by brackish, pollution tolerant oligochaetes and polychaetes. Fluctuations in populations can be related to both seasonal variation in environmental conditions and long term improvements in water quality through a reduction in pollution loading to the estuary.

Algae Migration Characteristics in Fresh Water Red Tide

1993 ◽  
Vol 28 (7) ◽  
pp. 197-201 ◽  
Author(s):  
Dunchun Wang ◽  
Isao Somiya ◽  
Shigeo Fujii
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Fresh Water ◽  
Field Data ◽  
Field Survey ◽  
Red Tide ◽  
Bottom Layer ◽  
Total Biomass ◽  
Quality Indices ◽  
Vertical Distributions

To understand the algae migration characteristics in the fresh water red tide, we performed a field survey in the Shorenji Reservoir located in Nabari City, Japan. From the analysis of the field data, it is found that the patterns of vertical distributions of the indices representing biomass are very different in the morning and the afternoon. Since some water quality indices have reverse fluctuations between the surface and the bottom layer in respect of the time series changes and the total biomass of the vertical water column is relatively constant, it is concluded that vertical and daily biomass variation of red tide alga is caused by its daily migration, that is the movement from the bottom layer to the surface in the morning and the reverse movement in the afternoon.

scholarly journals The RiBaTox web tool: selecting methods to assess and manage the diverse problem of chemical pollution in surface waters

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Kees J. M. Kramer ◽  
Frank Sleeuwaert ◽  
Guy Engelen ◽  
Christin Müller ◽  
Werner Brack ◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Waters ◽  
Complex Problem ◽  
End Users ◽  
Water Bodies ◽  
Chemical Pollution ◽  
The Novel ◽  
Web Tool ◽  
Novel Approaches ◽  
Local Water

Abstract Chemical pollution of water bodies is a complex problem around the globe. When described by the extremes of the range of problem definitions, water bodies can be chemically polluted by a single compound that is emitted from a point source or an incidental spill, or by chronic diffuse emissions from local and upstream land uses. The resulting mixture exposures can vary in space and time, e.g. due to the use of pesticides in the crop growing season. The environmental management objectives are commonly to protect and restore surface waters against human influences. Currently, chemical pollution is globally judged for a selected set of compounds, by judging each of these individually in comparison with protective environmental quality standards. Research has provided a novel assessment paradigm (solution-focused risk assessment) and novel data, measurement methods and models to improve on current practices. Their adoption and application require establishing novel linkages between the diverse problem definitions and the novel approaches. That would assist water quality professionals to select the most effective option or options to protect and restore water quality. The present paper introduces the RiBaTox (River Basin Specific Toxicants assessment and management) web tool. It consists of short descriptions of the novel approaches (made available as Additional file 1) and a decision tree for end-users to select those. The overview of novel approaches collated in RiBaTox is relevant for end-users ranging from local water quality experts up till strategic policy developers. Although RiBaTox was developed in the context of European water quality problems, the methods provided by RiBaTox are relevant for users from (inter)national to local scales. This paper is part of a series of Policy Briefs from the EU-FP7 project SOLUTIONS (http://www.solutions-project.eu), which provide backgrounds on chemical pollution of surface waters and policy practices and proposed improvements.

scholarly journals Assessment of Automatically Monitored Water Levels and Water Quality Indicators in Rivers with Different Hydromorphological Conditions and Pollution Levels in Greece

Hydrology ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 86
Author(s):  
Angeliki Mentzafou ◽  
George Varlas ◽  
Anastasios Papadopoulos ◽  
Georgios Poulis ◽  
Elias Dimitriou
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Quality Indicators ◽  
High Frequency ◽  
Automatic Monitoring ◽  
Water Levels ◽  
High Temporal Resolution ◽  
Water Quality Indicators ◽  
Pollution Levels ◽  
Riverine Ecosystems

Water resources, especially riverine ecosystems, are globally under qualitative and quantitative degradation due to human-imposed pressures. High-temporal-resolution data obtained from automatic stations can provide insights into the processes that link catchment hydrology and streamwater chemistry. The scope of this paper was to investigate the statistical behavior of high-frequency measurements at sites with known hydromorphological and pollution pressures. For this purpose, hourly time series of water levels and key water quality indicators (temperature, electric conductivity, and dissolved oxygen concentrations) collected from four automatic monitoring stations under different hydromorphological conditions and pollution pressures were statistically elaborated. Based on the results, the hydromorphological conditions and pollution pressures of each station were confirmed to be reflected in the results of the statistical analysis performed. It was proven that the comparative use of the statistics and patterns of the water level and quality high-frequency time series could be used in the interpretation of the current site status as well as allowing the detection of possible changes. This approach can be used as a tool for the definition of thresholds, and will contribute to the design of management and restoration measures for the most impacted areas.

scholarly journals Diatom Algae-Indicators of Water Quality in the Lower Zarafshan River, Uzbekistan

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 358
Author(s):  
Sophia Barinova ◽  
Karomat Mamanazarova
Keyword(s):  
Water Quality ◽  
Organic Pollution ◽  
Middle Part ◽  
Pollution Indices ◽  
Distribution Analysis ◽  
State Monitoring ◽  
Ecological Mapping ◽  
Semi Arid Region ◽  
Species Richness And Abundance ◽  
Toxicity Indices

This work is the first, the purpose of which was a comprehensive assessment of the ecological state of the lower reaches of the Zarafshan River using bioindication of water quality by diatoms based on species’ ecological preferences, pollution indices, statistics, and ecological mapping. A total of 198 species and subspecies of diatoms were first identified from 195 samples collected four times a year at six sites in the lower reaches of the Zarafshan River in 2009–2015. The richest species were Cymbella, Navicula, and Nitzschia. Pleurosira laevis, resistant to salinity, was first found in aquatic habitats in Uzbekistan. Bioindicators of nine environmental variables make up 91% of the list. Distribution analysis of variables, pollution indices (SLA—SládečDek index of saprobity), and toxicity indices (WESI—Water Ecosystem State Index) show increases in salinity, turbidity, and decreases in organic pollution downstream. The source of acidification can be the Navoi region. We found an increase in the ability to self-purify with an increase in species richness and abundance of diatoms in the lower part of Zarafshan. Thus, the ecosystem of the studied part of the river successfully copes with the incoming pollution from the middle part of Zarafshan and demonstrates some stability and successful self-purification with a water quality class of 2–3. The first studied lower reaches of the ecosystem of the Zarafshan River using bioindicators, statistics, and ecological mapping show that the problem of aridization in Central Asia does not necessarily lead to degradation of the river ecosystem and an increase in pollution, but with rational water use can improve water quality and self-purification processes. Hence, diatoms can be good indicators of river water quality in a semi-arid region and reflect the climate and anthropogenic load change. We recommend that attention be paid to nutrient and turbidity management and to expand state monitoring points to the lower part of the river up to the Karakul region.

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