Values Of Water Quality Parameters Research Articles

Application of Landsat 5 and Landsat 7 images data for water quality mapping in Mosul Dam Lake, Northern Iraq

Mosul Dam Lake is the main reservoir in Iraq, supporting the water demand of Mosul, Baghdad, and other cities. The aim of this study is to derive simple and accurate algorithms for the retrieval of water quality parameters for Mosul Dam Lake from Landsat 5 and Landsat 7 reflectance data. The water quality measurements were performed in situ during March and July 2011. These measurements included temperature, turbidity, Secchi disk, chlorophyll-a, nitrate, nitrite, phosphate, total inorganic carbon, dissolved organic carbon, total dissolved solids, and pH. In order to properly use the values of reflectance bands, images enhancement techniques have been used. The field measurements were compared with reflectance values of Landsat 5 and Landsat 7 bands using different band combination of empirical algorithms. Generally, the results of analysis showed significant correlation between these models and water quality parameters with R2 > 0.7 and p 0.9 and p 0.9, and values of the root mean square error ranged from 0.9 to 0.001. ArcGIS 10 was used to simulate the distribution values of water quality parameters calculated from spectral values of TM5 and ETM+ bands. The results of spatial analysis demonstrate that it is possible to use the TM5 and ETM+ images to evaluate the water quality for Mosul Dam Lake.

Use of EO-1 Advanced Land Imager (ALI) multispectral image data and real-time field sampling for water quality mapping in the Hirfanlı Dam Lake, Turkey

This paper focuses on the evaluation of water quality variations in Hirfanlı Water Reservoir, which is one of the most important water resources in Turkey, through EO-1 (Earth Observing-1) Advanced Land Imager (ALI) multispectral data and real-time field sampling. The study was materialized in 20 different sampling points during the overpass of the EO-1 ALI sensor over the study area. A multi-linear regression technique was used to explore the relationships between radiometrically corrected EO-1 ALI image data and water quality parameters: chlorophyll a, turbidity, and suspended solids. The retrieved and verified results show that the measured and estimated values of water quality parameters are in good agreement (R (2) >0.93). The resulting thematic maps derived from EO-1 multispectral data for chlorophyll a, turbidity, and suspended solids show the spatial distribution of the water quality parameters. The results indicate that the reservoir has average nutrient values. Furthermore, chlorophyll a, turbidity, and suspended solids values increased at the upstream reservoir and shallow coast of the Hirfanlı Water Reservoir.

Assessment of Water Quality and Eutrophication of Lakes

In this study, water quality and eutrophication aspects of Mansar, Surinsar, Tsokar, Tsomoriri and Renuka lakes have been discussed. The water quality parameters were compared with BIS standards for drinking purposes. The values of physico-chemical water quality parameters for Mansar and Surinsar lakes (Jammu Division) were found within the desirable limits except low DO in hypolimnion. Whereas, the values of physico-chemical parameters for Tsomoriri and Tsokar lakes (Ladakh region) were found beyond limits having much higher concentration of pH, total dissolved solids, total hardness, chloride, calcium, magnesium. The water quality of Renuka lake shown higher concentration of magnesium, iron, manganese, lead, total coliform, faecal coliform and low DO in hypolimnion. The eutrophication status assessed on the basis of phosphate concentration show eutrophic condition of Mansar, Surinsar, Tsomoriri and hyper-eutrophic condition of Tsokar and Renuka lake. The results indicate that efforts are required to lower the existing eutrophication levels by adopting conservation measures for the lakes.

GODAVARI RIVER POLLUTION & USE OF COCONUT SHELL AS FILTER MEDIA FOR DESIGN OF DUAL MEDIA FILTERS.

The research and developmental activities for generating new water quality models provide a valuable source of knowledge in the fields of water resources and environmental engineering. Due to limited water quality data and high cost of water quality monitoring, the data based modeling approaches are being extensively used. This paper presents the forecasted monthly values of water quality parameters viz., pH, Water Temperature and Dissolved Oxygen of River Godavari especially in Ramkund region. As the puja materials such as coconut are extensively used in this region, we will analyze the efficiency of coconut shells as filter media, as it is in large quantity in this area. As a solution, a Water Quality Index (WQI) integrate the intricate analytical data and generates a single number stating the quality of a given water body. WQI is found out for the specific purpose of ‘irrigation’.The Ramkund Region and its surrounding region are subjected to high river pollution due to large bathing and other activites.Also the wastes of all the activities such as puja is generated .Peoples throw large amount of materials such as flowers and coconut shells etc which are also responsible for pollution of river water. The wastes such as coconut are in abundant quantity,which is the main problem regarding pollution.One of the remedial measure regarding this is use of these shells as a filter media and design the dual media filters.The papers also deals with the effectiveness of dual media filter using coconut shell as filter media.

Time Series Forecasting Of Water Quality Of River Godavari

The research and developmental activities for generating new water quality models provide a valuable source of knowledge in the fields of water resources and environmental engineering. Due to limited water quality data and high cost of water quality monitoring, the data based modeling approaches are being extensively used. This paper presents the forecasted monthly values of water quality parameters viz., pH, Water Temperature and Dissolved Oxygen of River Godavari at Rajahmundry water quality monitoring station, Andhra Pradesh, India. Time series methods of forecasting were used for the predictions of parameter values. The predicted values are compared with actual measured observations using statistical performance tests. The results indicated that the proposed models were performing well. The MAE, RMSE and MAPE values, for pH 0.249, 0.359and 3.228; for Water Temperature 0.94, 1.18 and 3.24 and for Dissolved Oxygen 0.56, 0.67 and 7.52, respectively. The forecasted water quality parameter observations for the study period (2009-2012) and the future period (2012-2015) showed seasonal trend pattern which indicated quality of water is greatly influenced by the seasonal inflows. The time series forecasting methods with allowable error limits can be used to assess the future water quality and for taking protection measure for conservation of the river.

Water quality assessment: surface water sources used for drinking and irrigation in Zaria, Nigeria are a public health hazard

We assessed the quality and pollution status of source surface waters in Zaria, Nigeria by monitoring the nature, cause and extent of pollution in Samaru stream, Kubanni River and Kubanni dam over a period of 10 months, between March and December 2002. A total of 228 water samples was collected from 12 sites and analysed for a total of ten physicochemical and one bacteriological quality indicators, using standard methods. Aesthetic water quality impairment parameters were also observed. The mean values of most water quality parameters were significantly higher (P < 0.05) in both the stream and river than in the dam. There was no significant correlation between faecal coliform counts (FCC) and water temperature (in the range 15-33°C); pH (5.77-7.32); and turbidity (1.4-567 NTU). The high FCC ranged from 2.0 × 10(1) to 1.6 × 10(6) MPN/100 ml and exceeded the WHO standards for drinking water and water used for fresh-produce irrigation, and correlated positively (P < 0.05) with conductivity (in the range 68-1,029 μS/cm); TDS (10.0-70.0 mg/l); TSS (10.0-70.0 mg/l); Cl (7.5-181 mg/l); PO(4)(-) P (0.01-0.41 mg/l); NO(3)(-) N (0.6-3.8 mg/l) and BOD(5) (0.1-14.9 mg/l). The main pollution sources were municipal wastewater, stormwater runoffs, the ABU sewage treatment plant, abattoir effluents and irrigation farms treated with chemical fertilisers. We conclude that these water bodies are potentially hazardous to public health and that proper sewage treatment and river quality monitoring are needed to warn against hazards to public health.

Roadway Runoff Water Quality from Milled and Unaltered Surfaces during Convective Storms

Time series of total suspended solids, and total and dissolved copper, zinc, and lead concentrations were compared between milled hot-mix asphalt (HMA) roadway sections (n=6) and unaltered HMA roadway sections (n=6). Milled and unaltered road surface runoff water quality parameter values were within the ranges reported previously for unaltered rural and urban roadways. Event mean concentrations of suspended solids and lead were greater for milled roadway surfaces than for unaltered surfaces. No differences in copper and zinc concentrations were observed between road treatments. Contaminant mobilization was flow-driven, with incomplete wash-off of roadway constituents during the short-duration convective storm events. Storm precipitation intensity was not an indicator of storm-water quality. The presence of lead in runoff from milled roadway sections in this study indicated a road side soil source of the solids resulting from overland flow from adjacent land surfaces onto the roadway. Future milling operat...

Remote sensing of water quality in an Australian tropical freshwater impoundment using matrix inversion and MERIS images

The purpose of this study was to investigate how semi-analytical inversion techniques developed for the remote sensing of water quality parameters (chlorophyll a, tripton and coloured dissolved organic matter (CDOM)) in inland waters could be adapted or improved for application to Australian tropical and sub-tropical water bodies. The Matrix Inversion Method (MIM) with a semi-analytic model of the anisotropy of the in-water light field was applied to MERIS images of Burdekin Falls Dam, Australia, a tropical freshwater impoundment. Specific attention was required to improve the atmospheric correction of the MERIS data. The performance of the conventional three band exact solution of the MIM was compared to that of over-determined solutions that used constant and differential weighting for each sensor band. The results of the application of the MIM algorithm showed that the best weighting scheme had a mean chlorophyll a retrieval difference of 1.0 μgl − 1 , the three band direct matrix inversion scheme had a mean difference of 4.2 μgl − 1 and the constant weight scheme had a mean difference of 5.5 μgl − 1 . For tripton, the best performed weighting scheme had a mean difference of 1.2 mgl − 1 , the three band scheme had a mean difference of 3.4 mgl − 1 and the constant weight scheme had a mean difference of 1.8 mgl − 1 . For the CDOM retrieval, the mean difference was found to be 0.12 m − 1 for the best performed weighting scheme, 0.25 m − 1 for the three band scheme and 0.52 m − 1 for the constant weight scheme. It was found that significant improvements in the accuracy and precision of retrieved water quality parameter values can be obtained by using differentially weighted, over-determined systems of equations, rather than exact solutions. These more reliable estimates of water quality parameters will allow water resource managers to improve their monitoring regimes.

Suitability assessment of shallow and deep groundwaters for drinking and irrigation use in the El Khairat aquifer (Enfidha, Tunisian Sahel)

The El Khairat aquifer is an important groundwater aquiferous system, which is considered a major source for drinking and irrigation water in Enfidha in Tunisian Sahel. The analysis of groundwater chemical characteristics provides much important information useful in water resources management. Assessing the water quality status for special use is the main objective of any water monitoring studies. An attempt has been made for the first time in this region to appreciate the quality and/or the suitability of shallow and deep groundwater for drinking and irrigation. In order to attend this objective, a total of 35 representative water samples were collected during February 2007 from both boreholes (17) and wells (18); and analyzed for the major cations (sodium, calcium, magnesium and potassium) and anions (chloride, sulphate, bicarbonate, and nitrate) along with various physical and chemical parameters (temperature, pH, total dissolved salts, and electrical conductivity). Based on the physico-chemical analyses, irrigation quality parameters like sodium absorption ratio (SAR), residual sodium carbonate (RSC), percentage of sodium (Na%), and permeability index (PI) were calculated. In addition to this, iso-concentration maps were constructed using the geographic information system to delineate spatial variation of qualitative parameters of groundwater samples. The correlation of the analytical data has been attempted by plotting different graphical representations such as Piper, Wilcox, and US Salinity Laboratory for the classification of water. The suitability of the water from the groundwater sources for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with World Health Organization guideline values for drinking water. A preliminary hydrochemical characterization shows that most of the groundwater samples fall in the field of calcium–magnesium–chloride–sulphate type of water. Majority of the samples are not suitable for drinking purposes and far from drinking water standards. The high EC value and the percentage of Na in most of the groundwater render it unsuitable for irrigation. Wilcox classification suggested that around 50% of both deep and shallow groundwater samples are unsuitable for irrigation. According to the US Salinity Classification, most of the groundwater is unsuitable for irrigation unless special measures are adopted.

Hydro-Chemical Analysis of the Ground Water of the Basaltic Catchments: Upper Bhatsai Region, Maharastra

Water being an excellent solvent tends to dissolve the minerals in the geological system. The chemical nature of the ground water is influenced by several factors such as chemical weathering of the country rocks and interaction with the country rocks. The importance of the hydrochemical analysis underlies the fact that the chemistry of the ground water can directly be rated with the source of water, climate, and geology of the region. In this paper chemical analysis of the ground water has been carried out for upper Bhatsai region in Maharastra. There are eight water quality variables (SO4 2- , Na ++ , K + , Mg 2+ , Ca 2+ , NO 3- , TH, and pH) and the specific Conductance and Total Dissolved Solids were selected for this analysis. In this paper a) The values of water quality parameters were analyzed using statistical methods, b) the existence of trends and the evaluation of the best-fitted models were performed in order to classify the quality of the ground water. The geochemical analysis of the water samples has shown that it is free from certain anomalies and the water is suitable for human and cattle consumption. However, the presence of certain degree of anions indicates that the ground water in the study area is facing stress which could change the quality of the water in the near future. The quality of water resources is a subject of ongoing concern. The assessment of long-term water quality changes is also a challenging problem. During the last decades, water quality of many rivers in India has been done using standard measurements techniques. In the present study, water sam- ples were collected from cased wells during post-monsoon (December) period in order to determine their physical and chemical properties. The location of the samples is given in Fig. (1). Chemical analysis were carried out based on the procedures stipulated by APHA (1995, 1989) (1, 2); and Hem (1959) (3) and the chemical analysis data is given in Table 1. Concentration of total dissolved solids (TDS), total hardness (TH), total carbon oxide (CO2) and chloride (Cl - ) were determined by using the standard methods (4-7). 2. STUDY AREA The study area is situated in upper Bhatsai basin of Ma- harastra and falling under the latitudes 19°30.9´ and 19°13.18´ and longitudes 73°14.55´ and 73°21.43´, covering an area of approximately 59.5208 km 2 . The study area falls in the survey of India topological map numbered 47E/7. This is located in the northern part of the Thane district of Ma- harashtra that includes area around Shahpur and adjacent areas. The location of the study area is shown in Fig. (2) and the location map of the water samples is given in Fig. (1).

Potability Assessment of Selected Brands of Bottled Water in Abeokuta, Nigeria

This study was carried out to determine the potability of selected brands of bottled water in Abeokuta metropolis. Water quality parameters such as physical (Color, turbidity, total suspended solids (TSS), total dissolved solids (TDS), total solids (TS)), chemical (pH, total hardness, alkalinity, chloride (Cl-), free chlorine, sulphate (SO42-), nitrate (NO3 -) and iron (Fe2+) and microbiological (total coliform) were determined using standard procedures. The results obtained were subjected to statistical analysis for analysis of variance using SPSS 15.0. Mean values of water quality parameters were compared to World Health Organization (WHO) standards in drinking water. Results showed that water parameters like colour (< 7.0 Pt. Co.), TDS (

Decision support for the planning of integrated wastewater reuse projects in South Africa

Wastewater reuse is an attractive option for supplementing available water supplies. Benefits of reuse include pollution abatement due to the reduction of effluent discharge to surface water bodies, the decrease in the use of freshwaters from sensitive ecosystems, replenishment of soil nutrients in agriculture, enhancement of groundwater recharge and delay in the future expansion of water supply infrastructure. This paper presents ongoing research in developing and testing of a decision support system (DSS) for assessing the feasibility of implementing wastewater reuse projects in South Africa. The DSS employs multi-criteria qualitative assessment across technical, environmental, social, institution and water resources. The database of the DSS contains 33 wastewater treatment unit processes with known information on performance, costs and qualitative criteria obtained from literature. The knowledge base on the other hand, consists of a set of rules for combining the treatment units to form treatment trains and contains information on maximum allowable values for different water quality parameters for five end users. The weighted average method was used to aggregate scores obtained from the assessment of the different criteria to generate an indicative value that could form the basis for decision making. Testing of the DSS was applied to the Parow wastewater treatment plant in Cape Town. Results of the analysis shows that only the water resources evaluation score (1.0) is considered excellent for reuse implementation while the institutional evaluation score is weak (0.35) in guaranteeing success. Social evaluation and treatment train technical/environmental have qualitative evaluation scores of 0.76. The desirable score for all the criteria is 1.0 in order to facilitate the successful implementation of any reuse project. The quality of treated effluent from the proposed treatment trains meets the quality requirement in most of the pollutant determined except total phosphorus (2.88). The value is acceptable if the use of the effluent is limited to irrigation. If decision makers give adequate attention to the criteria highlighted in this model, success of a reuse project in South Africa can be better enhanced.

An Application of Landsat-5TM Image Data for Water Quality Mapping in Lake Beysehir, Turkey

The main goal of this study was to investigate spatial patterns in water quality in Lake Beysehir, which is the largest freshwater reservoir in Turkey, by using Landsat-5TM (Thematic Mapper) data and ground surveys. Suspended sediment (SS), turbidity, Secchi disk depth (SDD), and chlorophyll-a (chl-a) data were collected from 40 sampling stations in August, 2006. Spatial patterns in these parameters were estimated using bivariate and multiple regression (MR) techniques based on Landsat-5TM multispectral data and water quality sampling data. Single TM bands, band ratios, and combinations of TM bands were estimated and correlated with the measured water quality parameters. The best regression models showed that the measured and estimated values of water quality parameters were in good agreement (0.60 < R 2 < 0.71). TM3 provided a significant relationship (R 2 = 0.67, p < 0.0001) with SS concentration. MR between chl-a and various combinations of TM bands showed that TM1, TM2, and TM4 are strongly correlated with measured chl-a concentrations (R 2 = 0.60, p < 0.0001). MR of turbidity showed that TM1, TM2, and TM3 explain 60% (p < 0.0001) of the variance in turbidity. MR of SDD showed a strong relationship with measured SDD, with R 2 = 0.71 (p < 0.0001) for the ratio TM1/TM3 and TM1 band combinations. The spatial distribution maps present apparent spatial variations of selected parameters for the study area covering the largest freshwater lake and drinking water reservoir in Turkey. Interpretation of thematic water quality maps indicated similar spatial distributions for SS, turbidity, and SDD. A large area in the middle portion of the lake showed very low chl-a concentrations as it is far from point and nonpoint sources of incoming nutrients. The trophic state index values were calculated from chl-a and SDD measurements. Lake Beysehir was classified as a mesotrophic or eutrophic lake according to chl-a or SDD parameters, respectively.

Acute toxicity of potassium permanganate to fingerlings of the African catfish, Clarias gariepinus (Burchell, 1822)

Laboratory static bioassays were conducted to determine the 96-h LC50 and the lethal levels of concentrations of the aquaculture therapeutant, potassium permanganate (KMnO4) on fingerlings (mean weight, 6.24 ± 0.15 g and mean length, 4.25 ± 0.07 cm) of the African catfish, Clarias gariepinus. A total number of one hundred and eighty (180) fingerlings of mixed sex and brood stock were used for the toxicity bioassay. The 96-h median lethal concentration (LC50) value obtained for treatment of the fingerlings of the catfish C. gariepinus with potassium permanganate was 3.02 mg/L KMnO4 with lower and upper 95% confidence limits of 0.40 and 3.73 mg/L KMnO4, respectively. There was very strong and positive correlation between the variables (r = 0.96) with 93% (r2) association. Toxicity curve revealed 11.20 mg/L KMnO4 at 8.20 h as the threshold value for the 96 h assay of potassium permanganate on fingerlings of C. gariepinus. The 96 h LT50for 10, 8 and 6 mg/L KMnO4 to the test fish were also determined to be 10.40, 11.30 and 17.80 h, respectively. Varying behavioural patterns were observed in the fish, which included erratic swimming, loss of reflexes, total loss of equilibrium, paleness of skin and gasping for air. The value of water quality parameters monitored during the exposure period did not differ significantly (P>0.05) within the various concentrations of the therapeutant (KMnO4) as well as with the control. However, pH and total alkalinity tended to increase with increasing concentration of the toxicant. Key words: Potassium permanganate, acute toxicity, LC50, LT50, behaviour,Clarias gariepinus, Nigeria.

Acute toxicity of potassium permanganate to fingerlings of the African catfish, Clarias gariepinus (Burchell, 1822)

Laboratory static bioassays were conducted to determine the 96-h LC50 and the lethal levels of concentrations of the aquaculture therapeutant, potassium permanganate (KMnO4) on fingerlings (mean weight, 6.24 ± 0.15 g and mean length, 4.25 ± 0.07 cm) of the African catfish, Clarias gariepinus. A total number of one hundred and eighty (180) fingerlings of mixed sex and brood stock were used for the toxicity bioassay. The 96-h median lethal concentration (LC50) value obtained for treatment of the fingerlings of the catfish C. gariepinus with potassium permanganate was 3.02 mg/L KMnO4 with lower and upper 95% confidence limits of 0.40 and 3.73 mg/L KMnO4, respectively. There was very strong and positive correlation between the variables (r = 0.96) with 93% (r2) association. Toxicity curve revealed 11.20 mg/L KMnO4 at 8.20 h as the threshold value for the 96 h assay of potassium permanganate on fingerlings of C. gariepinus. The 96 h LT50 for 10, 8 and 6 mg/L KMnO4 to the test fish were also determined to be 10.40, 11.30 and 17.80 h, respectively. Varying behavioural patterns were observed in the fish, which included erratic swimming, loss of reflexes, total loss of equilibrium, paleness of skin and gasping for air. The value of water quality parameters monitored during the exposure period did not differ significantly (P>0.05) within the various concentrations of the therapeutant (KMnO4) as well as with the control. However, pH and total alkalinity tended to increase with increasing concentration of the toxicant.

Water quality trend analysis for the Karoon River in Iran

The Karoon River basin, with a basin area of 67,000 km(2), is located in the southern part of Iran. Monthly measurements of the discharge and the water quality variables have been monitored at the Gatvand and Khorramshahr stations of the Karoon River on a monthly basis for the period 1967-2005 and 1969-2005 for Gatvand and Khorramshahr stations, respectively. In this paper the time series of monthly values of water quality parameters and the discharge were analyzed using statistical methods and the existence of trends and the evaluation of the best fitted models were performed. The Kolmogorov-Smirnov test was used to select the theoretical distribution which best fitted the data. Simple regression was used to examine the concentration-time relationships. The concentration-time relationships showed better correlation in Khorramshahr station than that of Gatvand station. The exponential model expresses better concentration - time relationships in Khorramshahr station, but in Gatvand station the logarithmic model is more fitted. The correlation coefficients are positive for all of the variables in Khorramshahr station also in Gatvand station all of the variables are positive except magnesium (Mg2+), bicarbonates (HCO3-) and temporary hardness which shows a decreasing relationship. The logarithmic and the exponential models describe better the concentration-time relationships for two stations.

Water Quality Retrievals from High Resolution Ikonos Multispectral Imagery: A Case Study in Istanbul, Turkey

This paper presents an application of high resolution satellite remote sensing data for mapping water quality in the Goldon Horn, Istanbul. It is an applied research emphasizing the present water quality conditions in this region for water quality parameters; secchi disc depth (SDD), chlorophyl-a (chl-a) and total suspended sediment (TSS) concentration. The study also examines the retrievals of these parameters through high resolution IKONOS multispectral data supported by in situ measurements. Image processing procedure involving radiometric correction is carried out for conversion from digital numbers (DNs) to spectral radiance to correlate water quality parameters and satellite data by using multiple regression technique. The retrieved and verified results show that the measured and estimated values of water quality parameters in good agreement (R 2 > 0.97). The spatial distribution maps are developed by using multiple regression algorithm belonging to water quality parameters. These maps present apparent spatial variations of selected parameters and inform the decision makers of water quality variations in a large water region in the Istanbul metropolitan area.

Environmental, financial and quality assessment of drinking water processes at Waternet

Waternet (formerly Amsterdam Water Supply) has been seeking a sustainable scenario for producing drinking water and offering services that fulfill the requirements of clients and regulations, and, at the same time, maintains a sound environmental performance while keeping costs as low as possible. Presently, the company is in the process of evaluating alternatives for the treatment of water that cause the least financial and environmental impacts. The quantification of these impacts, for the current conditions, was carried out in earlier investigations. However, until now, the water quality aspect was not yet considered. In order to include this water quality aspect into the financial and environmental assessment, a quality function was constructed created by comparing water quality parameter values for a current and an alternative treatment process. Four qualifications were assigned to the sum of these scores: “Worse”, “Same”, “Better” and “Much better”. The qualifications allowed the comparison of the water quality and the financial and environmental impacts of the selected alternatives using a graphical representation of them. The method was applied focusing on the environmental and financial assessment of six alternative processes for the Loenderveen–Weesperkarspel treatment line, and including the quality aspect, as a third parameter for comparison.

Cascade Correlation Artificial Neural Networks for Estimating Missing Monthly Values of Water Quality Parameters in Rivers

Three layer cascade correlation artificial neural network (CCANN) models have been developed for the prediction of monthly values of some water quality parameters in rivers by using monthly values of other existing water quality parameters as input variables. The monthly data of some water quality parameters and discharge, for the time period 1980–1994, of Axios river, at a station near the Greek – FYROM borders and for the time period 1980–1990, of Strymon river, at a station near the Greek – Bulgarian borders, were selected for this study. The training of CCANN models was achieved by the cascade correlation algorithm which is a feed-forward and supervised algorithm. Kalman's learning rule was used to modify the artificial neural network weights. The choice of the input variables introduced to the input layer was based on the stepwise approach. The number of nodes in the hidden layer was determined based on the maximum value of the correlation coefficient. The final network arhitecture and geometry were tested to avoid over-fitting. The selected CCANN models gave very good results for both rivers and seem promising to be applicable for the estimation of missing monthly values of water quality parameters in rivers.

Water Quality Classification of Lakes Using 250-m MODIS Data

The traditional method used in the water quality classification of Finnish lakes includes the collection of water samples from lakes and their analysis in laboratory conditions. The classification is based on statistical analysis of water quality parameter values and on expert opinion. It is possible to acquire similar information by using radiance values measured with the Earth Observing System Terra/Aqua Moderate Resolution Imaging Spectroradiometer (MODIS). In this letter, the classification accuracy with MODIS data is about 80%. Only about 0.2% of the 20 391 pixels were misclassified by two or more classes, as a four-class classification system is used.