Impact of rising sea levels on the Ebro Delta in Spain
If seas rise as little as one metre this century, as forecast
in some scientific models, this will have a dramatic impact upon the Ebro Delta
in Spain.
A sea level rise of one metre will lead to the almost total
loss of the Ebro delta. Half of the Delta has already sunk to the height of sea
level, shown by the blue dotted areas in the first of the maps below.
The Delta loses five millimetres in height each year, (three
millimetres due to compaction and two by the rise of the level of the sea
through recent global warming). The consequence is the immediate entrance of
salt water through the subsoil by the hydrostatic pressure exerted by sea water.
In addition, salt water will penetrate further up the river beyond Tortosa, with
increasing salinisation of the subsoil leading to reduced crop yields. When the
wedge of marine water in the river estuary remains a long time, the water of the
river rots. Salt water, that is located in the lower level, does not mix with
the better oxygenated fresh water above and the accumulation of organic matter
that this causes leads to the consumption of oxygen and that the water ends up
rotting. The lower the volume of the river, the greater the phenomenon of rotten
water. In the past, there was a thriving fishing industry in the river estuary.
Today, however, it is fished very little, because most of the water lacks
oxygen.
Half of the Ebro Delta has sunk to the
height of sea level, shown by the blue dotted areas above
Ebro Delta Satellite Image 2007
Ebro Delta with simulated 1 metre rise
in sea level
