That the drought is mercilessly hitting Catalonia is clear: so far this hydrological year (from October 1, 2022 until now), in the eastern half, the most affected by the rainfall deficit, it has rained between 60 % and 70% less than usual. "The situation is catastrophic," says Vicent Altava, an expert in droughts and a technician in applied research and modeling at the Servei Meteorològic de Catalunya (SMC). And the worst: it is impossible to know what will happen in the coming months.
So far in the hydrological year 2022-2023, there are areas where 300 milliliters (ml) less than the usual average has precipitated. "It's outrageous," emphasizes Altava, who recalls that the figure covers a temporary space of just over six months (from October 2022 to April 14 of this year).
Where has this severe deficit occurred? In almost all of Ripollès, Garrotxa, the north of Alt Empordà, almost all of Selva, Vallès Oriental, Moianès, the area of Begues, the massif of Sant Llorenç del Munt and the area between Alt and Baix Penedès. "In terms of percentages, in these areas it has rained between 60% and 70% less than usual".
These figures, according to the SMC technician, are "very significant" because they include usually rainy seasons: autumn (in this case, 2022) and part of this spring (until April 14). In the Pla de Lleida, 100 ml less than what should have fallen has fallen. "As we approach the north and east of Catalonia, the deficit grows."
Within the eastern half of Catalonia (the most affected) there is a zero zone, where the lack of precipitation is still more pronounced. They are the counties of Berguedà, Bages, Osona and part of Vallès Oriental.
To this worrying precipitation deficit that we have been dragging on since October 1, 2022, we must add the year and a half of more that Catalonia accumulates of lack of rain: the SMC places the start of the drought in March 2021. If we accumulate rain –Altava argues- the fall from April 2021 to April 2023 shows that “it has only rained above average in the Ports de Beseit area and on the north face of the Pyrenees”. In the rest of Catalonia, it has done below average. "Where less, in the middle is again."
If we do the same comparative exercise but looking at the last year, "nowhere in Catalonia has precipitation been above the average: not nine months, not six, not four, not two... The drought is global".
In the first months of 2023, it has continued to expand. Altava asserts that the month of March has been "very dry" and that April "will surely break a record." The areas that have registered a greater rainfall deficit are Solsonés, Berguedà, a part of Osona, north of Bages and La Noguera.
And the worst: we do not know what is going to happen. “From a scientific point of view, seasonal forecasts in Catalonia (and not only here, in all mid-latitudes) do not work. Because? Because they don't have predictive ability." Altava explains that the atmosphere is "so chaotic" that you cannot go beyond 15 days.
“As you increase the days of prediction, the errors, the uncertainties, accumulate. So we don't know what will happen. It is very hard to say, but it is so, ”she says.
Where the models do get it right - he continues - is in the intertropical zones. "Why? Because the atmosphere near the equator is much more predictable."
In Spain, the two communities most affected by the drought are Catalonia and Andalusia. In the rest they are better. According to Aemet data, the global precipitation figure (so far this hydrological year) is 22% below the usual average value.
