The scientists studied Pelus River in Malaysia to understand how rainfall affects the river's water level and flow. They found a strong connection between rainfall and the water level, showing that heavy rain leads to more water in the river. The researchers also discovered that the river's shape and size change during different seasons, particularly during high-flow periods when more sediment is carried downstream. Their main goal was to investigate these changes to help plan for possible developments, like hydroelectric plants, in the area. The study aims to find ways to manage the river effectively for the benefit of local communities and the environment.