Riverbed eyesore has its days numbered
Black plastic sheeting used to ' protect' river Gorgos is now polluting it
The black plastic sheeting used to ' protect' river Gorgos and which has eventually polluted it, is being removed.
MANY people have commented on the ugly black plastic sheeting on the sides and bed of the Gorgos and Girona rivers in the Marina Alta area. Apart from being an eyesore, lately they were disintegrating and beginning to look like part of a problem ( pollution), instead of the solution to the giant canes that invade the area.
These giant canes ( Arundo donax) are classified amongst the 100 most harmful invasive plant species in the world, although their seeds are sterile, they spread rapidly through their underground rhizomes. They thrive on riverbeds and banks and become hazardous when there is heavy rainfall. During the floods of October 2007, the River Girona uprooted an enormous quantity of reeds that made it difficult for the water to flow freely under bridges and exacerbated the destructive effect of the torrential rains.
The reeds are also a fire risk as they burn very easily, but are tough and resistant so that fires do not kill them off, as their underground rhizomes are unaffected, allowing them to grow back stronger than before.
The science behind the plastic
The Confederación Hidrográfica del Júcar ( CHJ) river authority was receiving almost daily requests from Marina Alta town councils to clear the vast amount of canes that invade the area’s rivers and ravines; hence, they decided to try to destroy the canes’ rhizomes using the power of the sun. This technique, called solarisation, consists of putting down black plastic during the warmest months.
Therefore, in 2018 the CHJ cut down the reeds in the River Gorgos riverbed between Benigembla and Alcalali and then covered the area with synthetic geotextile black matting held in place by giant staples.
Workers with machinery laboured for weeks to put the matting in place. As black intensifies heat, temperatures under the plastic during a hot summer day easily reached up to 70 º C killing off the rhizomes completely.
The idea being to replant the area later with native plant species from river environments, such as poplars, tamarisks, elms, hackberries and willows.
This method was also used on a section of the River Girona between Beniarbeig and Ondara, near the Santonja reservoir.
he only drawback to this was thought to be cosmetic with the black plastic being rather an eyesore, but as Costa Blanca News reader, Zoë Coadwell pointed out last week, the plastic weaving was deteriorating.
Zoë had also contacted the mayor of Benigembla to complain that plastic threads from the material placed in the stretch of the river between Benigembla and Alcalalí were now all over the place, mainly due to Storm Gloria and would be washed into the sea in the next heavy rainfall. The mayor replied that his hands were tied, as anything to do with the river and its banks falls under the responsibility of the CHJ.
CHJ reply
On drawing a blank with the mayor, Zoë contacted the Costa Blanca News and gave an explanation of the problem, accompanied by photos, asking if there was anything we could do. Last Friday CBN contacted the CHJ head office in Alicante and raised the subject of the solarisation process; asking when the plastic was to be removed and if they were going to reforest the area. We were pleasantly surprised to receive a prompt reply on Monday which read as follows:
“Good afternoon and thank you very much for contacting us. The action which you refer to, in your email, we carry out in conjunction with the forest fire prevention service and the wildlife service of the department of agriculture, environment, climate change and rural development, with the aim of restoring riverside vegetation in certain sectors with a high density of Arundo donax, an invasive non- native plant, which we selected for its uniqueness in its capability to increase the probability, intensity, and spread of fires in areas of the Natura 2000 Network.
With the restoration of these sectors, the masses of giant canes will no longer be connected to forestland thus reducing the risk of spreading a possible fire through the riverbed, which could then lead to a larger forest wildfire.
Likewise, eliminating the canes will also contribute to the improvement of the drainage capacity of the riverbed and to achieve the environmental objectives in accordance with the
EU Water Framework Directive.
In these interventions, the forest fire prevention service selects the area; the CHJ, that is us, we place and remove ( after a certain period of time) the geotextile material, and the wildlife service brigades carry out the replanting as well as their maintenance.
The plastic covering is removed when the wildlife service carry out an evaluation and deem that it has met the efficiency criteria of the methodology.
he intervention began in 2018 with the implantation of the geotextile, and its removal is scheduled for next week.
And in answer to your second question, to inform you that, indeed, a replanting with native riverside vegetation will be taking place, in this case, carried out by the brigades of the wildlife service, dependent on the aforementioned ministry, as indicated above .
Greetings, and thanks for your collaboration.”
So, in the weeks to come, workers will be removing the plastic and its debris, new native species will be planted and hopefully entice wildlife to the area, which will now have a reduced risk of forest fires.
Thank you to the CHJ for taking the time to look into the matter and provide an answer and thank you to Zoë Coadwell for caring.