1/ All what you see here used to be land until yesterday. Most of the Ebro Delta has been erased by storm #Gloria, which leaves 9 dead, 4 missing in Spain.
We'll see what the environmental impact is, but this delta's ironic history deserves a thread ⬇️⬇️
We'll see what the environmental impact is, but this delta's ironic history deserves a thread ⬇️⬇️
2/ I took this picture back in 2013. The Delta has been loosing area in the last decades. The sediment eroded from the Pyrenees and other areas does not reach the mouth anymore because of the dams built since the 50s, upstream the Ebro River. 
3/ what happened yesterday to the lighthouse in the video above (which looked like this two days ago)...
4/ ...has happened to other lighthouses in the delta during the last decades. Here is Faro de Buda (aka Faro del Cabo Tortosa) since 1864 until recently.
5/ There is (there was?) a salt pan in the southern tip of that delta.
6/ The rest is (was?) mostly rice crops with some limited areas protected as a natural reserve used by lots of migrating bird species.
7/ The Sentinel-1 radar by @CopernicusEU (no visible imaging available since it is still cloudy here in the region) shows this before and after. The emerged area left in the center is were the lucky Deltebre town lays.
8/ Now, the irony of all this is that the Ebro delta was not formed really naturally. These cartoons are based on historical cartography and soil studies. When the Romans arrived to the Iberian Peninsula, they described a tiny plain near the mouth of the Ebro.
9/ In fact, the Ebro delta is about 10 million years old, and it accumulates several kilometers of thickness of sediment excavated and transported from the Ebro Basin (NE Spain)
10/ For most of this long history, the delta was submarine only, invisible to humans.
While it is still disputed what triggered the delta to emerge and expand, the theories I know include deglaciation, agriculture revolution and, most popular, deforestation.
While it is still disputed what triggered the delta to emerge and expand, the theories I know include deglaciation, agriculture revolution and, most popular, deforestation.
11/ All of this could a priori explain the increase of the loss of soil in the continent and the higher sedimentation rates in the delta, outpacing subsidence & sea level changes.
But only deforestation starting at the Roman period seems to fit the historical expansion.
But only deforestation starting at the Roman period seems to fit the historical expansion.
12/ But that anthropogenic effect was reverted when dams were built, leading to the present retreat of the delta. The animation in earthEngine shows very nicely these dynamics:
earthengine.google.com/timelapse#v=40…
earthengine.google.com/timelapse#v=40…
And 13/ In short: the Ebro delta was a submarine one for 10 million years until human land uses changed and facilitated soil erosion. Only during the XXth century, dams reverted this expansion.
Whether storm #Gloria will be the final kick, we'll see in the coming days. 🤞
Whether storm #Gloria will be the final kick, we'll see in the coming days. 🤞
this picture about the human land uses...
A link with more details about the historical Ebro Delta evolution and a diagram showing delta classification. The Ebro Delta turned from River- to Wave-dominated upon dam construction
earthobservatory.nasa.gov/images/91832/t…
earthobservatory.nasa.gov/images/91832/t…
15) Epilogue:
Waters are receding and it seems that morphologically the changes will be moderate. Apart from the rice crops & real state, the news have reported high looses in shellfish farms.
Waters are receding and it seems that morphologically the changes will be moderate. Apart from the rice crops & real state, the news have reported high looses in shellfish farms.
