Wednesday, November 2, 2011

Poor start to spring

Spring is when the rain should fall in Canberra, although in recent years the rain has been coming more in the summer months. Thus far this year, we have had below average rainfall for the first two months of the season. Our yearly total has not yet crested 400 mm, which means that in the last eight weeks or so  of the year we need more than 210 mm to reach the annual average.

The 13 months from February 2010 to February 2011 were months of extremely good rain. Since then, however, only around 210 mm have fallen, leaving the ground parched even though the dams are still full.  The megalitres per mm rate has dropped from a high of 120 early in the year (still low) to a low of 101. And in the past three months we have had less than 7,000 megalitres of runoff.

While I do not think that permanent drought will come upon Canberra in the next decade, which is what I was predicting previously, I think that we are heading in that direction. Large rainfall every few years may make us relatively secure, especially with the new dam. But I am still very concerned.

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