Tuesday, January 04, 2011

To know a flood.....

I have been reluctant to write about the floods.

Two reasons. The first is that we're physically out of danger, our house on a ridge which, even though it runs down to the lagoon, is still probably 20 meters above it. & while there are people whose houses are surrounded by water, who have been forced to relocate, it seems a bit vicarious, a bit like playing the tourist, to be talking about it.

The second thing is that it all seems quite bizarre, that we're living in a disjointed landscape. Go down to the river & you can hear it roar, as megaliters of water rush down to the sea at probably 30 or 40 kilometers an hour. Move away from it, & the flood seeps in silence, spreads almost imperceptibly, creating a topography at times that somehow resists logic. Some of the water dispersement is obvious: the river flowing across a road, then following natural channels with the water backing up once the channels are filled. But there are parts where there is no water for a block or two, & then it suddenly appears. Perhaps, & most probably, it has found its way into a stormwater drain which has then overflowed somewhere else in its route.

You can't see the disruption to lives because that part of town is beyond the road closed barriers. Like the rest of the world, we see it only on television. But the roads along the hilly ridge that separates the city from the flood plain allow a view of just how much water there is around, & how much land it covers in all directions. The airport is closed, the highway & railway south—the direction the bulk of supplies for the city comes from—is closed, the highway west is cut, the highway north is possibly going to be cut this afternoon, & the Yeppen Flood Plain has just been declared a maritime exclusion zone by the Gladstone Harbor Master who's in charge of such things, hereabouts. (Though the majesty of the proclamation somewhat spoilt for the pedant in me by the continued use of the term "Flood Plane.")

The rugby fields across the road—50 meters away, maybe 20 meters below us—have now been covered by water coming up from the lagoon. Where yesterday there were ibis digging for grubs in the soggy ground, today there are ducks swimming around, & the ibis have taken to the grassy knoll normally occupied by spectators when the rugby is on. & the State Emergency Services are now using the bottom of the street as a landing port for their boats as they bring in people whose homes have been swamped.

Sure, there's been recent rain in Rockhampton. Half the half meter of rain that fell during 2010 fell in the four days over Christmas. That filled up the lagoons. But the water we're seeing now had its origins hundreds of kilometers away, & a couple of weeks ago.

The Fitzroy has the largest catchment area—somewhere around 140,000 square kilometers—of any Australian river system on the east coast, & the second largest in Australia, behind the Murray. Within the catchment area are a number of large river systems, each with their headwaters in a different area but then combining with another, & then those combinations combine, & then they join with the Fitzroy for the last 200 kilometers to the sea.

There has been heavy rain throughout the catchment area for the past few months, but it was the first incursion of this season's monsoon trough that pushed the rivers beyond capacity. There has been record flooding through much of Queensland: within the catchment area, one river totally flooded the town of Theodore, another river flooded 80% of the town of Emerald; both rivers feed the Fitzroy.

One of my first discoveries when we arrived in Rockhampton was the flood height gauge, with indicators showing various flood heights, in the river beside Quay Street. At that point in time, the river was its normal height of maybe two to three meters, & about seven meters below road level. The indicator for the 1918 flood was roughly at eye level, 10.11 meters. Freaky, I thought. There were a couple of lesser floods noted, both over nine meters. I didn't pay it much serious attention.

Over the next few years, the measuring gauge remained a curiosity. Then, in January of 2008, we experienced our first flood here, & the gauge became a point of call for the duration. That flood only reached about 7.75 meters, started dropping, rose up again a month later when the monsoon trough hit. But you could see the measurements changing significantly day by day.

This time around, there's now a shallow layer of water edging across the carpark where we used to park. The road has barricades blocking it off & you have to walk the last half of a kilometer. The river height barely seems to shift—that possibly five centimeters a day is obscured by the eddies & choppiness on the water's surface—but it has now reached 9.15 meters. The amount of water flowing hasn't decreased: it's just that it now spreads across a far wider area & for each of those few centimeters of rise, the area the flood reaches probably increases by hundreds of meters. The river itself is now part of the huge lake this region has become, identifiable from a vantage point by the difference in color, a wide ribbon of gray in the midst of an even wider muddy-brown ocean.


Blogger AlexG said...

thx for the report. I was worried but then felt -- no it wasn't that near him.

1:20 PM  
Blogger Tom Beckett said...

Good to know you're safe and dry.

8:43 AM  
Blogger pb said...

Hi Mark,
Lucky your house is up on that ridge. Glad to hear you're ok.
Hope the waters are gradually receding.

4:47 PM  

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