149 research outputs found
Application of environmetric methods to investigate control factors on water quality
No full textIn the study, environmetric methods were successfully performed a) to explore natural and anthropogenic controls on reservoir water quality, b) to investigate spatial and temporal differences in quality, and c) to determine quality variables discriminating three reservoirs in Izmir, Turkey. Results showed that overall water quality was mainly governed by “natural factors” in the whole region. A parameter that was the most important in contributing to water quality variation for one reservoir was not important for another. Between summer and winter periods, difference in arsenic concentrations were statistically significant in the Tahtalı, Ürkmez and iron concentrations were in the Balçova reservoirs. Observation of high/low levels in two seasons was explained by different processes as for instance, dilution from runoff at times of high flow seeped through soil and entered the river along with the rainwater run-off and adsorption. Three variables “boron, arsenic and sulphate” discriminated quality among Balçova & Tahtalı, Balçova & Ürkmez and two variables “zinc and arsenic” among the Tahtalı & Ürkmez reservoirs. The results illustrated the usefulness of multivariate statistical techniques to fingerprint pollution sources and investigate temporal/spatial variations in water quality
Water pollution sources assessment by multivariate statistical methods in the Tahtali Basin, Turkey
No full textIn this study, multivariate statistical methods including factor, principal component and cluster analysis were applied to surface water quality data sets obtained from the Tahtali River Basin, Turkey. Factor and principal components analysis results revealed that surface water quality was mainly controlled by agricultural uses and domestic discharges. Cluster analysis generated two clusters. Based on the locations of the sites consisted by each cluster and variable concentrations at these stations, it was concluded that agricultural discharges strongly affected north and northeast part of the region. These methods are believed to assist water managers to understand complex nature of water quality issues and determine priorities to improve water quality. © 2007 Springer-Verlag
Heavy metal fingerprinting in surface water using chemometrics
No full textIn this study, chemometric methods were applied to fingerprint heavy metals in surface water in Tahtali Basin, Turkey, and were found to assist water managers in determining drinking water quality. Principal component analysis (PCA) was used to determine pollutant sources governing water quality, and Multidimensional Scaling (MDS) was used to identify spatial differences in the basin. Results showed that the level of heavy metals found in surface water was predominantly influenced by urban runoff (mainly in residential areas) and agricultural runoff. However, heavy metal concentrations were found to be lower than the threshold values set by European drinking water standards. Therefore, heavy metal levels in surface water were "acceptable" for a drinking water supply. This study showed that chemometric methods can assist water managers fingerprinting surface water quality
Utilization of statistics based classification approach to investigate water supply profile of Turkey
No full textIn the paper water supply profile of Turkey was examined. In this scope, the questionnaire survey conducted by Turkish Statistical Institute in 2004 to investigate annual amount of water abstracted to drinking water networks by type of resources in 81 provinces was evaluated. In the questionnaire, sources were grouped under five categories as spring, (artificial) lake, river, reservoir and well. Due to the complex and multivariate characteristics of the data sets, to replace a large collection of variables with a smaller number of factors the statistical method "factor analysis" was performed. Results revealed that, water supply systems in the country were mainly governed by groundwater sources (well and/or spring). However, in the northeastern part of the country, rivers were allocated for drinking water supply. On the other hand, reservoir dependent cities were densely located in Marmara, Central Anatolia and Southeast Anatolia Regions. This study showed that statistics based classification methods assist decision makers to extract information from multidimensional complex data sets representing environmental conditions
Surface water quality assessment by environmetric methods
No full textThis environmetric study deals with the interpretation of river water monitoring data from the basin of the Buyuk Menderes River and its tributaries in Turkey. Eleven variables were measured to estimate water quality at 17 sampling sites. Factor analysis was applied to explain the correlations between the observations in terms of underlying factors. Results revealed that, water quality was strongly affected from agricultural uses. Cluster analysis was used to classify stations with similar properties and results distinguished three groups of stations. Water quality at downstream of the river was quite different from the other part. It is recommended to involve the environmetric data treatment as a substantial procedure in assessment of water quality data
Investigation of temporal trends in hydrochemical quality of surface water in western Turkey
No full textThis study comprises application of non-parametric trend analysis (Mann-Kendall test and Sen's Slope estimator techniques) and multidimensional scaling method to water quality data sets. Water samples analyzed (for chloride, nitrate-nitrogen, sodium, sulfate and total dissolved solid parameters) semi-monthly at seven river monitoring stations in Tahtali Basin, Turkey for 6 years were evaluated. The results revealed that agricultural discharges caused spatial differences in terms of water quality in the basin. Moreover, variable concentrations generally decreased or did not change over time. This study showed that, trend detection and data grouping methods help decision makers to judge effectiveness of management programs. © 2008 Springer Science+Business Media, LLC
Ecological water quality index associated with factor analysis to classify surface waters
No full textThe object of this study was the development of a new water quality index called the Ecological Water Quality Index (EWQI) which is flexible enough to represent the ecological status of surface waters by assessing chemical quality based on supranational legislation. Eleven variables including nutrients, salts and total parameters were selected as index components. Threshold values were assigned to seven water-quality classes as defined by the legislation and were used to develop mathematical equations to convert observed values to index scores. Depending on the ecological importance of the parameters, weights were assigned to each variable and then a weighted sum method was performed to aggregate sub-indices. The applicability of the method was demonstrated in two basins located in Turkey. Factor analysis was applied to optimize the index component selection process. Several alternatives were tested to comprise at least one variable from each defined factor class (e.g. salinity content) to calculate an index score representing ecological status. Results showed that there were slight differences between index scores of the various tested alternatives. These differences did not cause misclassification of surface waters. The study showed that the EWQI method combined with factor analysis could be a practical and efficient way to represent the ecological status of surface waters. © 2020 IWA Publishing. All rights reserved
New approach to domestic grey water footprinting: country-scale accounting using statistical methods in Türkiye
No full textABSTRACT This study aimed to develop an approach for country-scale domestic grey water footprint (GWFdomestic) accounting and examine spatio-temporal differences using statistical methods. In this scope, the GWFdomestic was calculated as the amount of water required to reduce the total nitrogen concentrations of domestic wastewater released into receiving media from 81 cities in Türkiye. GWFdomestic values were estimated based on the data on wastewater amount and applied wastewater treatment process. GWFdomestic was calculated by dividing the pollutant load of discharged water by the critical concentration in the surface water. The empirical results showed that (a) the produced wastewater amount increased up to 125 m3/year in some cities. (b) GWFdomestic values showed a difference between 330 and 1,900 depending on the level of treatment, and the average value was about 750 m3/ca.year. (c) A total of 81 cities were grouped under four categories, and applied water treatment technology was the main characteristic of this classification. (f) GWFdomestic has not statistically significantly changed over time in a large part of the country. It can be concluded that country-scale GWFdomestic accounting can assist water managers in developing prevention measures by analyzing spatio-temporal differences in the water footprint of domestic discharges.</jats:p
IMPUTING MISSING DATA IN A SWAT WATER QUALITY MODELLING STUDY USING STATISTICAL METHODS
No full textLarge water -quality databases are useful in modeling studies to identify optimal measures for pollution mitigation and management of water basins. The objective of the study was to conduct statistical methods to impute missing data in the water quality simulation study in the K & uuml;& ccedil;& uuml;k Menderes River Basin, T & uuml;rkiye, where missing data caused by a lack of periodic sampling is an important challenge. In the study, the Soil Water Assessment Tool (SWAT) was used to simulate nitrate -nitrogen concentrations (NO 3 -N). Water -quality data collected between 2001 and 2012 from the outlet of the basin was subjected to regression analysis -based imputation methods. In this scope, simple regression models were developed to estimate missing water quality data. Hence, a continuous data set was created, and then the SWAT water quality model was calibrated and validated. Since the calculated Nash- Sutcliffe model efficiency coefficient values were above 0.65, model simulations were judged good. Furthermore, the MannWhitney U test was applied to test model performance by comparing continuous data generated by the SWAT model with the limited observed water quality data. It can be concluded that a simple regression model and non -parametric Mann -Whitney U tests can be performed to impute missing data and evaluate model performance in modeling studies of data shortage basins.Programme of the Scientific and Technological Research Council of Turkiye (TUBITAK) [116Y423]This research was supported by the 1003 Programme of the Scientific and Technological Research Council of Turkiye (TUBITAK) under Grant Agreement No 116Y423. We thank the project team members who provided insight and expertise that greatly assisted the research
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