Report: TR 2002/10

Author: Adam Munro

Abstract

This report examines the key aspects of the “Weather Bomb Event, June 21 2002”, which resulted in two Civil Defence emergencies being declared for the Thames Coromandel and South Waikato Districts. It has been produced as part of Waikato Regional Council’s internal reporting requirements.

The purpose of the report is to provide a comprehensive overview of the storm event that brought torrential rain and strong winds to many parts of the region, particularly the Thames Coromandel (TCDC) and South Waikato (SWDC) Districts. As a result, both districts declared states of civil defence emergencies. TCDC declared at 2.30am on Friday June 21 due to a significant number of homes being flooded (forcing evacuations), widespread power cuts, and water treatment issues. SWDC declared at 8am on the same morning due to public health concerns, public safety issues, and unknown extent of damage.

The event produced rainfall intensities in the order of 100mm in one hour registering return periods of 100 years and creating river levels ranging from 5 year to 100 year return interval events. Trickling hillside streams became raging torrents in just a few minutes, carrying fallen trees, boulders, and many thousand tonnes of mud through homes, properties and roads.

The report also discusses how the event was managed, what lessons were learnt, recommendations for operational improvements, and the drawing together of general event information to ensure responses to future emergencies are carried out to the best extent possible.

The weather bomb, 21 June 2002 : final technical report [PDF, 1.4 MB]