3 August 2010

Update on the flood wave in Pakistan, plus an update on the monsoon in India and on typhoon activity in the NW Pacific

Posted by Dave Petley

The true magnitude of the disaster in Pakistan is now becoming clear – this appears to be the country’s equivalent of Hurricane Katrina.  It has to be hoped that lessons are learnt both within the country and by the international community in terms of disaster risk reduction there.

In 2007 the World Health Organisation produced a flood potential map for Pakistan, which I reproduce below:

The flood wave is travelling down the Indus River at present, concentrated initially on the most westerly of the three main tributaries shown above.  The latest PakMet hydrographs show that the flood has now peaked at Taunsa and is rising downstream at Guddu.  Unfortunately the graphs are incomplete on the PakMet site (it appears they have a software issue) – I’ll try to put this right later once they have corrected the error.  For locations see the Google Earth map I produced yesterday.

The flood routing model suggests that the peak should reach Guddu in about three days from the peak at Taunsa, and then take a further day to get to Sukkur and finally three days or so to reach the sea.  Hopefully there is sufficient warning to relocate people away from the water, but the potential for damage is high. The government (i.e. the NDMA) in Pakistan is once again coming under severe criticism for its response – this letter, written about Taunsa, gives a flavour of the concerns.  Whilst it is easy to criticise NDMA, the core issue probably remains a lack of investment and capacity building in this agency.  This needs to be corrected.  Unfortunately, the assassination of an MP in Karachi yesterday has also led to severe civil unrest in that city, which is only serving to magnify the range of problems facing Pakistan.

Meanwhile the emergency in Northwest Pakistan continues, but the operation is being hampered by further rain.  Reports now suggest that the loss of life is in the order of 1,400, but note that it is not unusual for estimates a few days into an emergency to be too high, with a further 3 million people reported to have been directly affected.  Stories about the event are truly heartbreaking – it is hard to imagine what it must be like to lose your children, house, belongings and livelihood to a single event.  The impact of the flood in mountain communities is well illustrated by this image, showing the loss of roads and bridges, and extensive riverbank erosion that has triggered house collapses:

 Meanwhile, across a large swathe of northern and western India rainfall activity in this monsoon remains low:

And typhoon activity in the Pacific is also unusually quiet – indeed global tropical cyclone activity is at its lowest level for the 30 year period for which reliable measurements are available (see image below from Ryan Maue’s excellent site).  ACE is a measure of the energy expended by tropical cyclones.  Given that tropical cyclones are a major trigger of landslides, this is keeping the overall occurrence lower than might have been expected.