scholarly journals Monitoring water quality parameters of Lake Koronia by means of long time-series multispectral satellite images

2017 ◽  
Vol 52 (2) ◽  
pp. 176-188
Author(s):  
Triantafyllia-Maria Perivolioti ◽  
Antonios Mouratidis ◽  
Dimitra Bobori ◽  
Georgia Doxani ◽  
Dimitrios Terzopoulos
1994 ◽  
Vol 29 (3) ◽  
pp. 69-76 ◽  
Author(s):  
Hubert Hellmann

The period between 1955 and 1988 was the time of reconstruction in the destroyed Federal Republic of Germany, marked by booming industrial development and - with some delay -by the rise and spread of ecological awareness and the idea of water conservation. This is the background against which the analysis of water quality and of pollution load trends should be seen. The study of a long-term load trend presupposes the following requirements:–sufficiently large number of measured data;–reliable, reproducible analytical methods which produce comparable results over long time series; and–hydrological interpretation and evaluation of results. The continuous efforts to improve analytical methods and the elimination of distorting substances and matrix effects led to the situation that long time series of data are not directly comparable. In some cases, summative analyses (aggregate parameters) have been replaced by newly developed substance-specific methods so that the continuity of records has been broken. Furthermore, there is a general underestimation of the necessity to consider and evaluate analytical data in a space-time continuum. However, on the whole, we are able to give a satisfying interpretation of trends for the classical parameters. In the case of the trace substances detected by modem methods, this is possible only for the past two decades and with some reservations.


Author(s):  
R. A. Shuchman ◽  
K. R. Bosse ◽  
M. J. Sayers ◽  
G. L. Fahnenstiel ◽  
G. Leshkevich

Long time series of ocean and land color satellite data can be used to measure Laurentian Great Lakes water quality parameters including chlorophyll, suspended minerals, harmful algal blooms (HABs), photic zone and primary productivity on weekly, monthly and annual observational intervals. The observed changes in these water quality parameters over time are a direct result of the introduction of invasive species such as the <i>Dreissena</i> mussels as well as anthropogenic forcing and climate change. Time series of the above mentioned water quality parameters have been generated based on a range of satellite sensors, starting with Landsat in the 1970s and continuing to the present with MODIS and VIIRS. These time series have documented the effect the mussels have had on increased water clarity by decreasing the chlorophyll concentrations. Primary productivity has declined in the lakes due to the decrease in algae. The increased water clarity due to the mussels has also led to an increase in submerged aquatic vegetation. Comparing water quality metrics in Lake Superior to the lower lakes is insightful because Lake Superior is the largest and most northern of the five Great Lakes and to date has not been affected by the invasive mussels and can thus be considered a control. In contrast, Lake Erie, the most southern and shallow of the Laurentian Great Lakes, is heavily influenced by agricultural practices (i.e., nutrient runoff) and climate change, which directly influence the annual extent of HABs in the Western Basin of that lake.


2018 ◽  
Vol 4 (1) ◽  
pp. 188 ◽  
Author(s):  
Ehsan Jafari Nodoushan

This study investigates the efficiency of Bayesian network (BN) and also artificial neural network models for predicting water quality parameters in Honolulu, Pacific Ocean. Monthly forecasting of three important characteristics of water body including water temperature, salinity and dissolved oxygen have been taken under consideration. Two separate strategies were applied in which the first strategy was related to prediction of the water quality parameters based on previous time series of the same variable. In the second strategy, an attempt was made to forecast DO using different affecting parameters such as temperature, salinity, previous time series of DO, and amount of chlorophyll. The efficiency of the models were assessed by using error measures. Results revealed that the BN models are superior over the ANN models in case of temperature and DO forecasting. Also, it was found that the first strategy is more efficient than the second strategy for predicting DO concentration. The best BN models for temperature, salinity and DO were achieved when time series of the same parameter up to 3, 2, and 3 previous months applied as input variables respectively. Overall, it can be concluded that BN and ANN models can be successfully applied for water quality modelling and forecasting in coastal waters. Moreover, the current study demonstrated that the BN models have a great ability dealing with time series including incomplete or missing data.


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