Tropical cyclone-Induced heavy rainfall and flow in Colima, Western Mexico

Tropical cyclone (TC) landfall is often accompanied by storm surges, strong winds, and heavy rain that cause destructive flash floods, especially in mountainous regions. However, there is limited understanding of the contribution of TCs to major flood events, especially in Western Mexico. In this study, we assess the contribution of TCs to the annual rainfall, extreme rainfall and stream flow in the mountainous region of Colima, one of the most TC-exposed areas in Western Mexico. The top 1% of daily rainfall and stream flow, annual maximum rainfall and the highest 20 stream flow events from 1970 to 2015 are examined for their association to TCs. Results indicate that the relative contribution of TCs to the average annual rainfall can exceed 25% in the coastal area of Colima. Over 25-35% of heavy daily rainfall (top 1% rainfall) recorded in the coastal rain gauges is found to be associated with TCs. In terms of high flow, approximately 20-24% of the top 1% flow events and 28-35% (similar to 7 events) of the top 20 flow events are driven by TCs. The heaviest precipitation and high flow events occur typically in the late TC season (September and October). Our results provide insights on the role of TCs in inducing rainfall and stream flow relevant for water and flood risk management.