Impacts of Summer Monsoons on flood characteristics in the Lancang-Mekong River Basin

•The impacts of monsoon on flood characteristics were assessed at local and spatial scales.•Flood start date advances, Q10 and flood volume increase during the strong monsoon years.•Monsoon impact on flood is regionally distributed with impact in tributary larger than mainstream.•The trade-off of water from different areas can disturb the tendency of monsoon impact on flood.