Some primary characteristics of water quality in a closed water body in Sasaguri, Fukuoka prefecture, Japan

In closed water bodies such as lakes and reservoirs, due to the poor exchange rate with external water sources, many problems with their water quality easily occur such as thermal stratification, lack of dissolved oxygen in the bottom layers, and other water quality problems. Thermal stratification which is dependent greatly on meteorological conditions, is one of important features, which has great impact on water quality in the closed water bodies. To examine the variation of their water quality in response to the change in environmental factors such as meteorological conditions, Tabiishidani reservoir, which is located in Sasaguri town, Fukuoka prefecture, Japan was chosen as a case of study. Field observations on meteorological conditions (solar radiation, relative humidity, wind speed, wind direction, air temperature) were made by a system of meteorological sensors, while the measurement of the water quality was performed in site by using the multi-probe (W-23XD series, Horiba, Ltd., Kyoto-Japan). The results of this research have shown many valuable information on water quality in Tabiishidani reservoir under different meteorological patterns. Besides, the results would play an important part as inputs for simulating the wind-induced circulation and water quality in the reservoir, which would be studied in further researches.