The hydrological year, which began on October 1, 2020, will end this Thursday, September 30, and it does so in the Canary Islands with less rainfall usual.
Specifically, the Canary Islands do not reach the 75 percent of rainfall that would fit with a normal year, according to data from the State Meteorological Agency (AEMET).
Within the islands, the rains have not been evenly distributed and islands such as Fuerteventura do not reach half of the normal rains.
In the country as a whole, the decrease is only 4 percent compared to usual, which makes it a “normal” exercise as a whole, but with rainfall equally distributed irregularly and with several basins in a situation of hydrological drought.
In the absence of definitive results, in this hydrological year until September 26 an average of 606 liters per square meter has rained in the whole of Spain, which represents 4 percent below normal for the reference period, As reported to Europa Press, the AEMET spokesperson, Rubén el Campo.
However, despite being a normal year, the reservoirs are just over 40 percent of their total capacity (40.3%). In fact, the considerable rains that fell in Spain last week have not prevented the accumulated water in the Spanish reservoirs from decreasing again for another week, since the hydraulic reserve lost 109 cubic hectometres in the last week.
At this time, the reservoirs store 22,537 cubic hectometres of water, which is 12.87 percent less than on the same dates a year ago and 23.42 percent less than the average of the last ten years. You have to go back to 2017 to find a lower situation in the reservoirs this week, when they were at 39.40 percent, according to historical data provided to Europa Press by the Ministry for Ecological Transition.
“In the absence of data from the last days, this hydrological year will end within normality, with just 4 percent percent below the average,” confirmed Del Campo, who recalls that the previous rainy year, 2019-2020 it had a humid character, with 664 liters per square meter, 4 percent more than normal, which is 591 liters per square meter.
Previously, he has stated that the year 2018-2019 was 12 percent drier than normal; in 2017-2018 there was a surplus of approximately 12 percent; compared to a hydrological year 2016-2017 “very dry”, with 14 percent less rainfall than the normal average and which was preceded by a normal 2015-2016 exercise, around the average.
“We have had everything in the last five years, which have been very variable,” said the spokesman, who added that, as of August 31 – we will have to wait for the new data from the end of September – five basins were in a situation drought. Specifically, the Ebro basin entered a drought just last August, while Júcar and Segura – who are also in this situation – have been improving their situation and “could leave” that state in September, ” a rainy month “.
With the SPI meteorological drought index, an accumulation basin – which is roughly equivalent to hydrographic basins – enters drought when this reference is below -1, and does not leave that situation until it exceeds +1. “If the meteorological drought is prolonged, it is capable of promoting hydrological droughts,” says the spokesman.
Specifically, it specifies that Júcar and Segura entered a drought situation in September 2020; Eastern Pyrenees in February 2021; Ebro in August 2021 and the South basin in October 2020. “It is the basins of the southern third, the east and the northeast that present this situation,” he commented.
Another characteristic of this hydrological year is the “irregular” distribution of rainfall since in the east it rained more than normal while in the west it remained below the usual values.
In this fiscal year, it rained the most was in the west of the province of La Coruña and in the interior of Pontevedra, which have accumulated up to 2,500 liters per square meter in front of the island of Fuerteventura where they have not been collected in the 12 months ” nor 50 liters per square meter “and in the southeast of the peninsula, as in the province of Almería and the west of the Murcia region, which register a rainfall that has not reached between 150 and 200 liters per square meter throughout the year.
“It has been a year of extremes. In the extreme northwest it has been where it rained the most and in the extreme southeast where the least,” he says.
By areas, they have accumulated a rainfall surplus of between 25 and 50 percent of normal in the northern half of the Valencian Community, southern Teruel province, eastern Castilla-La Mancha, the Iberian system and Zaragoza.
On the contrary, it has not rained even three-quarters of normal (25 percent deficit) in the eastern end of Catalonia, east of Gerona, province of Barcelona and north of Tarragona, as well as in an area of Andalusia, in Córdoba and Jaén, as well as in an area that covers the south of Seville, the northeast of Cádiz and the west of Malaga.
However, the reservoirs in the areas that are in a situation of meteorological drought are above half their capacity in the case of the Júcar, at 51 percent and the Ebro, at 51.6 percent; while the Segura is full to 38.2 percent of its capacity.
Del Campo states that there could be a meteorological reason that explains “the feeling that it has rained a lot while the reservoirs are going down” and that it may be motivated by torrential rains, as is the case in recent days.
The spokesperson indicates that when we see episodes of very intense rain, we tend to think that the reservoirs fill up, something that does not necessarily have to be this way and that may be due to a meteorological reason.
He explains then that the DANAS leave abundant rainfall but in a specific area that “does not have to” be an area where the waters go to reservoirs and, on the other hand, adds that when it rains in a torrential way in a very short time, the runoff is “very high” and, instead of seeping and recharging the aquifers, it goes away quickly, especially if it is a littoral zone.