PROJECT ALERT NOTICE (HI) Moderate flooding in Guam

Date: Tue, 10 Oct 2023 18:00:42 EDT

Summary: Typhoon Bolaven brought heavy rainfall across the Island of Guam resulting in moderate flooding over the last 24 hours.

Typhoon Bolaven passed just north of the Island of Guam Tuesday evening (GMT+10hr) bringing 4 to 7 inches of rain during a 24-hr period that caused moderate flash flooding in most streams. PIWSC operates a network of 6 stream gages, 1 stage-only reservoir, and 8 rain gages in Guam and all gages remained operational throughout the storm. Streamflow was below the peak of record at all gages, and some gages recorded discharge peaks similar in magnitude to levels reached during Super Typhoon Mawar in May of this year. Streamflow levels have already receded to near baseflow conditions.

PIWSC had one technician in Guam during the storm performing routine fieldwork who flew back this morning. We are evaluating the need to send a crew back to Guam to collect high water marks and conduct indirect surveys.