11 September 2010
The floods in Pakistan may have faded from the headlines in Europe, but unfortunately the impact continues, even though the rainfall events that caused them occurred more than a month ago. The most dramatic illustration of this is a set of satellite images collected by NASA using the MODIS instrument.
This is an image of the area around Sukkur taken on 7th July, before the rainfall event that initiated the disaster:
By way of comparison, this image was taken on 7th September, showing the same area:
Two things to note. First the extensive flooding along the line of the main part of the Indus remains. This may well be an indication that water is draining very slowly from behind the broken levees, which are now serving to keep water in despite their failure to keep the water out in the initial event. Such problems with broken levees are common. Second, note the parallel course of the Indus that has been created, where the flooding is much more intense. I assume that this is the river occupying one of its old drainage paths. The problem here may be that the downstream end of this huge (check out the scale bar on the imagery) new watercourse is Mancchar Lake. This is an artificial lake, created in the 1930s, with a range of existing environmental problems. The lake appears to be connected to the main Indus River by just two small canals (see Google Earth image below):
This limited drainage path is may cause the floods to drain very slowly, prolonging the agony for those affected. The flood waters must now be highly polluted, increasing the potential for health problems for the affected population.