scholarly journals Spatio-Temporal Variations in Water Quality of the Chao Phraya River, Thailand, between 1991 and 2008

2012 ◽  
Vol 04 (09) ◽  
pp. 725-732 ◽  
Author(s):  
Piyathap Avakul ◽  
Tuantong Jutagate
Keyword(s):  
Water Quality ◽  
Temporal Variations ◽  
Spatio Temporal ◽  
Chao Phraya River

scholarly journals Temporal Variation of Chlorophyll-a Concentrations in Highly Dynamic Waters from Unattended Sensors and Remote Sensing Observations

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2699 ◽  
Author(s):  
Jian Li ◽  
Liqiao Tian ◽  
Qingjun Song ◽  
Zhaohua Sun ◽  
Hongjing Yu ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Quality ◽  
Chlorophyll Fluorescence ◽  
Chlorophyll A ◽  
Temporal Variations ◽  
Lake Area ◽  
Short Term ◽  
Chl A ◽  
Spatio Temporal

Monitoring of water quality changes in highly dynamic inland lakes is frequently impeded by insufficient spatial and temporal coverage, for both field surveys and remote sensing methods. To track short-term variations of chlorophyll fluorescence and chlorophyll-a concentrations in Poyang Lake, the largest freshwater lake in China, high-frequency, in-situ, measurements were collected from two fixed stations. The K-mean clustering method was also applied to identify clusters with similar spatio-temporal variations, using remote sensing Chl-a data products from the MERIS satellite, taken from 2003 to 2012. Four lake area classes were obtained with distinct spatio-temporal patterns, two of which were selected for in situ measurement. Distinct daily periodic variations were observed, with peaks at approximately 3:00 PM and troughs at night or early morning. Short-term variations of chlorophyll fluorescence and Chl-a levels were revealed, with a maximum intra-diurnal ratio of 5.1 and inter-diurnal ratio of 7.4, respectively. Using geostatistical analysis, the temporal range of chlorophyll fluorescence and corresponding Chl-a variations was determined to be 9.6 h, which indicates that there is a temporal discrepancy between Chl-a variations and the sampling frequency of current satellite missions. An analysis of the optimal sampling strategies demonstrated that the influence of the sampling time on the mean Chl-a concentrations observed was higher than 25%, and the uncertainty of any single Terra/MODIS or Aqua/MODIS observation was approximately 15%. Therefore, sampling twice a day is essential to resolve Chl-a variations with a bias level of 10% or less. The results highlight short-term variations of critical water quality parameters in freshwater, and they help identify specific design requirements for geostationary earth observation missions, so that they can better address the challenges of monitoring complex coastal and inland environments around the world.

scholarly journals Spatio-Temporal Variations of Hydrochemical and Microbial Characteristics in Karst Water in Samcheok, South Korea

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3407
Author(s):  
Han-Sun Ryu ◽  
Heejung Kim ◽  
Jin-Yong Lee ◽  
Jiwook Jang ◽  
Sangwook Park
Keyword(s):  
Water Quality ◽  
Rainy Season ◽  
Temporal Variations ◽  
Dry Season ◽  
Quality Analysis ◽  
Dominant Factor ◽  
Karst Water ◽  
Seasonal Characteristics ◽  
Microbial Characteristics ◽  
Spatio Temporal

This study analyzed the hydrochemical characteristics and microbial communities of karst water in Samcheok, Korea, and compared water quality results to identify the seasonal characteristics and hydrogeological connectivity of the study areas of Hamaengbang-ri, Gyogok-ri, Yeosam-ri, and the downtown area of Samcheok. Field survey and water quality analysis were performed in July 2019, February 2020, and April 2020. Hydrochemical analysis of karst water (groundwater and surface water) showed that most samples were comprised of Ca-HCO3 and that water–rock interactions were a dominant factor compared to precipitation and evaporation (crystallization). For seasonal characteristics, water–rock interactions appeared more active in the dry season than in the rainy season. Calcite weathering was dominant in the dry season, whereas dolomite weathering dominated the rainy season. Moreover, the saturation indexes for the dry and rainy seasons were less than and greater than 0, respectively, corresponding to an unsaturation (oversaturation) state; thus, white precipitate distributed in the study areas was deposited in the rainy season. Finally, as a result of analyzing the hydraulic characteristics between regions, hydrogeological similarities were identified between Hamaengbang-ri and Yeosam-ri, and between Gyogok-ri and downtown Samcheok, which suggested hydrogeological connectivity between each of the pairs.

scholarly journals Survey of Water Quality of the Chao Phraya River Flood in Thailand in 2011 Focusing on Flow and Status of Floodwater

2012 ◽  
Vol 35 (11) ◽  
pp. 187-195
Author(s):  
Asako NISHIJIMA ◽  
Shinichirou NAKAMURA ◽  
Daisuke KOMORI ◽  
Masashi KIGUCHI ◽  
Jeanne FERNANDEZ ◽  
...  
Keyword(s):  
Water Quality ◽  
River Flood ◽  
Chao Phraya River
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