The characteristics of Lake Tonle Sap in Cambodia based on changes in conductivity

金沢大学環日本海域環境研究センターエコテクノロジー研究部門Lake Tonle Sap in Cambodia is the largest freshwater lake in Southeast Asia, covering an area of about 2,500 km2 in the dry season and 12,500 km2 in the monsoon season. Due to such a unique seasonal change in hydrological phenomena related to the Mekong River system, the lake\u27s water quality must change dramatically. As there is a lack of basic data on the water quality and hydrological phenomena of Lake Tonle Sap, we launched a limnological research survey. This paper deals with the characteristics of the lake based on conductivity changes. Between the monsoon dry seasons, conductivity and water depth in the lake shore changed dramatically. Both were low in the dry season when the water depth was 0.5 m and the conductivity was 40 μS cm-1, and they were both high in the monsoon season, at 8 m and 120 μS cm-1, respectively. However, the conductivity offshore was high at an approximately constant rate throughout the year at around 100 ∼ 120 μS cm-1. This is because the waters that flow back from the Mekong River in the monsoon season remain in the offshore area. Conductivity decreases in the lake shore area in the dry season, which causes a low level of conductivity water to flow in from surrounding regions of the lake. It is the influence of the water flowing back from the Mekong River that increases the conductivity in the lake shore region during the monsoon season