In brackish water areas, where sea water and fresh water co-exist, accurately identifying
the behavior of salt water is important for the fishing industry, and for studying environmental problems.
Laying an optical fiber temperature sensor along the bottom of a river or lake can provide continuous, wide-ranging detection
of the boundaries between salt water and fresh water, based on temperature differences.
Combination with conventional salt meters and sonic probes allows extremely precise analysis of brackish water areas. The
data gained helps to analyze sea level rises due to global warming and the impact of river construction works.