The researchers studied how tides and river flow interact in a tropical estuary over a year. They used different methods to analyze water levels and found that the river's seasonal changes affect the tides. The estuary was divided into three zones, each with its own response to the tides and river flow. The tides were weaker near the river's mouth compared to further upstream, where the river's influence was stronger. The researchers discovered that the river's flow affects how tides move in the estuary, slowing them down and changing their patterns.