Due to the long residence time in reservoir of storage dam, rainwater and river water stored in such a reservoir become colder, more turbid, and eutrophic, potentially causing damage to agricultural crops that are irrigated using reservoir water. By using turbidity data measured at an A Dam in Miyazaki prefecture, the generation and distribution of turbid water in the dam reservoir are investigated. The results show that after periods of no rainfall, even light rainfall events trigger high turbidity, and that after a period of intermittent rainfall, even heavy rainfall events usually fail to trigger high turbidity.
