Katherine floods, January 1998

Some of the heaviest rainfall and worst flooding over northern Australia occurs when a tropical cyclone crosses the coast and moves inland. Deprived of the energy it derives from warm tropical waters, the cyclone weakens and eventually dissipates - but as it weakens, the storm can drop prodigious quantities of water.

Early on 24 January 1998, Tropical Cyclone “Les” developed over the Gulf of Carpentaria, then moved westward, accompanied by winds gusting to 170km/h. As it made landfall, it weakened into a rain depression, which drifted west towards Katherine on 25-26 January. Rain began to fall in Katherine on the afternoon of the 25th, settled into a steady and heavy downpour, and continued virtually without a break until the early afternoon of the 27th. In three days (up to the 28th), about 400-500mm of rain drenched significant areas of the Katherine, Roper and Daly River catchments.

Such rainfall amounts falling over catchments already saturated from heavy rain earlier in the month had a dramatic impact. By the 27th the Katherine River had risen to more than 20 metres - the largest flood in Katherine’s history, eclipsing the previous record (set in 1957) by 0.7 metres. Two metres of muddy water covered the main street, and the whole central business district was inundated. Some 2,000 people had to abandon their homes and most of their possessions to the swirling waters; many lost everything. In many cases, evacuations were a “last minute” exercise - partly due to complacency but, in at least some cases, people put off leaving for fear of looters. Electronic communications were badly disrupted, and the Katherine telephone exchange was only saved through sandbagging by the military. Damage to roads and other transport links was extensive, and took many days to repair. Three bodies were recovered from the muddy wreckage.

Flooding in the streets of Katherine, N.T. due to torrential rains caused by ex-cyclone “Les”, 28 January 1998 (photo courtesy of the Northern Territory News)

Katherine was by no means the only place to suffer. Downstream, the entire community of Daly River - more than 400 people - was evacuated, and every building inundated. Local rain first flooded properties and communities on 28 January; two days later, floodwaters from the Fergusson River arrived; and finally the Katherine River flood peak struck on 3 February. Various other communities in the Roper and Moyle River catchments were severely affected, involving hundreds of evacuations in some cases.

The Katherine flood was but one of a number of exceptionally heavy rain events in the Australian tropics during the 1997/98 Wet season. The 1990s were exceptionally wet over the northwestern Australian tropics: in this time, Darwin endured four of its five wettest Wet seasons (October to April) for the Century.