Characteristics of the Annual Maximum and Minimum Water Temperatures in Tonle Sap Lake, Cambodia from 2000 to 2019

The aim of this paper is to study diurnal fluctuations of the water level in streams draining headwaters and to identify the controlling factors. The fieldwork was carried out in the Gryżynka River catchment, western Poland. The water levels of three streams draining into the headwaters via a group of springs were monitored in the years 2011–2014. Changes in the water pressure and water temperature were recorded by automatic sensors – Schlumberger MiniDiver type. Simultaneously, Barodiver type sensors were used to record air temperature and atmospheric pressure, as it was necessary to adjust the data collected by the MiniDivers calculate the water level. The results showed that diurnal fluctuations in water level of the streams ranged from 2 to 4 cm (approximately 10% of total water depth) and were well correlated with the changes in evapotranspiration as well as air temperature. The observed water level fluctuations likely have resulted from processes occurring in the headwaters. Good correlation with atmospheric conditions indicates control by daily variations of the local climate. However, the relationship with water temperature suggests that fluctuations are also caused by changes in the temperature-dependent water viscosity and, consequently, by diurnal changes in the hydraulic conductivity of the hyporheic zone.

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Do the regular annual extreme water level changes affect the seasonal appearance of Anabaena in Poyang Lake?

10.7287/peerj.preprints.27388v1 ◽

2018 ◽

Author(s):

Kuimei Qian ◽

Martin Dokulil ◽

Yuwei Chen

Keyword(s):

Water Temperature ◽

Water Level ◽

Poyang Lake ◽

Environmental Parameters ◽

High Water ◽

Water Level Change ◽

Extreme Water Level ◽

Level Change ◽

Heterocyst Frequency ◽

Water Level Changes

Background. Poyang Lake is an exceptional system exhibiting a water level change of up to 14 m every year. In the years 2013 and 2014 water level changes were 8.03 m and 11.22m respectively. The biomass of Anabaena and heterocyst frequency increased in the summers of recent years. Methods. A weekly or bi-weekly monitoring period from June to November 2013 and 2014 was set up to explain the reason for this phenomenon. Results. Anabaena was observed throughout the year. The average relative biomass of Anabaena in the study period was over 40%, being most abundant in summer. The average heterocyst frequency was 0.226% in 2013 and 0.760% in 2014. The SPSS analysis indicated a positive correlation of Anabaena biomass with water temperature and water level and negative one with TN, which is the reason for the increase of heterocyst frequency from 2013 to 2014. It also indicated that heterocyst frequency of Anabaena was positively correlated with water temperature, water level and PO4-P, and negatively with DIN/DIP, NO3-N and TN. At the same time, water temperature and DIN/DIP were significantly correlated with water level, which means that water level changes have a direct effect on Anabaena and its heterocyst formation in Poyang Lake. Conclusions. The results of the study support the hypothesis that increasing biomass and heterocyst formation of Anabaena were primarily caused by changes in the environmental parameters, such as high water temperature and suitable nutrients in summer and autumn, driven by the regular annual extreme water level change of Poyang Lake. The results can provide a theoretical basis for the management and utilization of Lake Poyang.

Download Full-text

Do the regular annual extreme water level changes affect the seasonal appearance of Anabaena in Poyang Lake?

10.7287/peerj.preprints.27388 ◽

2018 ◽

Author(s):

Kuimei Qian ◽

Martin Dokulil ◽

Yuwei Chen

Keyword(s):

Water Temperature ◽

Water Level ◽

Poyang Lake ◽

Environmental Parameters ◽

High Water ◽

Water Level Change ◽

Extreme Water Level ◽

Level Change ◽

Heterocyst Frequency ◽

Water Level Changes

Background. Poyang Lake is an exceptional system exhibiting a water level change of up to 14 m every year. In the years 2013 and 2014 water level changes were 8.03 m and 11.22m respectively. The biomass of Anabaena and heterocyst frequency increased in the summers of recent years. Methods. A weekly or bi-weekly monitoring period from June to November 2013 and 2014 was set up to explain the reason for this phenomenon. Results. Anabaena was observed throughout the year. The average relative biomass of Anabaena in the study period was over 40%, being most abundant in summer. The average heterocyst frequency was 0.226% in 2013 and 0.760% in 2014. The SPSS analysis indicated a positive correlation of Anabaena biomass with water temperature and water level and negative one with TN, which is the reason for the increase of heterocyst frequency from 2013 to 2014. It also indicated that heterocyst frequency of Anabaena was positively correlated with water temperature, water level and PO4-P, and negatively with DIN/DIP, NO3-N and TN. At the same time, water temperature and DIN/DIP were significantly correlated with water level, which means that water level changes have a direct effect on Anabaena and its heterocyst formation in Poyang Lake. Conclusions. The results of the study support the hypothesis that increasing biomass and heterocyst formation of Anabaena were primarily caused by changes in the environmental parameters, such as high water temperature and suitable nutrients in summer and autumn, driven by the regular annual extreme water level change of Poyang Lake. The results can provide a theoretical basis for the management and utilization of Lake Poyang.

Download Full-text