“In Valencia they differ two types of reeds: the wild, with a thick and overflowing appearance, which acquires large dimensions at the edge of riversand the domestic one, which the farmer plants to establish a margin and defend his land from erosion, to mark the limits, cut the winds from the sea and protect himself from frost”, cited the Ministry of the Environment of era, romanticallyin its Spanish Inventory of Traditional Knowledge Related to Biodiversity. Explained in this way, and so as not to be noticed in a small box in the publication, the Arundo Donax, the cane, it would not pass for being, as it really is, a voracious speciesas is mandatory when dealing with an invasive plant.
“When the canes stop being cut, after 4 to 5 years, new branches grow from the axillary buds, thus generating a big tangle“and by varying his physiognomy,” continues the publication. The truth is that at the end of the last decade, when the inventory was published, the farmer had long stopped using wild reeds to fence fields or as tomato plant guides. This is why the cane, uncontrollable, became a real problem in river basins like the Júcar or the Turia. Today, the images of the devastation after DANA have left many images of the remains of the flood, full of remains of reeds which, together with the water, helped to destroy everything. Especially because of the flooding caused by the overflowing of the Barranco del Poyo.
Among the reasons for its eradication, there is not only the fact that it is invasive and that it prevents the growth of native flora of river banks, consuming more water. The Generalitat emphasizes that “its abundance of plant matter, due to its stems and leaves, makes it In the event of a river flood, the reeds block the flow of water making the flooding even more serious. Images of the eyes of bridges over rivers blocked by thousands of reeds carried by the current are common.
In 2021, the Arundo Donax invaded, according to data from the Department of the Environment of the Valencian Generalitat, 56% of the Valencian river network. About seven thousand kilometers, according to data provided at the time by the regional government. A species already cataloged as one of the 100 most harmful invasive alien species in the world, by the International Union for Conservation of Nature and also, since 2013, included in the Spanish catalog of invasive alien species. There are therefore many programs to eradicate them from waterways…and the bottom of ravines, like Poyo.
Do the housework a kilometer of Arundo Donax it costs a million eurosaccording to consulted sources of any solvency, also confirmed by the money invested, throughout these years, by entities like the Hydrographic Confederation of Júcar or the Ministry of the Environment itself, which, just in 2021 , invested 4.7 million euros for the elimination of reeds. and the regeneration of river banks in the Turia Natural Park.
Image of the remains of the flood in the Albufera of Valencia.
EFE
CHJ sources detail to EL ESPAÑOL that the treatment is so expensive because “the aerial part of the cane is first cleared and crushed then, once the land is suitable, a geotextile cover is installed in polypropylene which will allow the rhizome – the underground stem – of the cane to be exhausted. The tarpaulins will remain on the ground. at least 18 monthsthe estimated time necessary for the plant not to grow back. “DANA also devastated all the banks that were in recovery thanks to the many actions that were taken.
In 2023, the Hydrographic Confederation of Júcar itself awarded more than 8 million euros of investments to maintain, recover and preserve river channels falling within its jurisdiction. A significant part of this work has been devoted to the “recovery of riparian forests from river beds occupied by invasive alien species, mainly “Arundo Donax.” At that time, the CHJ was in progress 54 river restoration actions distributed on a total of 32 channels in the Valencian Community.
Concerning the field of competence, local administrations are responsible for the maintenance of the sections which cross their municipal limits. In 2022, the Confederation “granted a total of 226 authorizations carry out this type of maintenance and conservation actions in the demarcation”, specify the same sources.
Bad or good?
Even the Ministry of Ecological Transition, in collaboration with the Foundation for Biodiversity and coordinated by the Consorci de Ribera, finances a program, “Canne à canne”, to eradicate the Arundo in the lower Júcar basin. It is endowed with nearly 4 million euros, to be invested between 2022 and 2025. “The main objective of the project is reduce the impact of high probability flooding in the municipalities of the lower basin of the Júcar River,” explains the ministry’s website.
However, and contrary to the arguments of the Ministry and the Ministry and “widespread belief, the damage caused by flooding does not occur as a consequence of the state of the canals, especially if they are in their natural state, but rather due to the occupation of the territory carried out in flood zones“, they explain to EL ESPAÑOL from the Hydrographic Confederation of Júcar.
Floodwater damage “depends on two factors: the speed and depth of the water.” Thus, they emphasize, “the cleaner and clearer a canal is, the more the water gains speed and draft (since there is no lamination) as the flood advances, considerably increasing the damage caused downstream. In other words, according to the Confederation, The greater the cleanliness, the greater the danger..
On the contrary, “the existence of vegetation, whether common reed or native specieshas two main functions in relation to the avenues, one is to support the banks of the canals and the other is to laminate the flows, “from the vegetation”increases the roughness of the channel”, and as a result, “the speed of the water decreases, the depth increases and overflows occur in the lands bordering the banks, fulfilling this rolling function, as stipulated in Article 6 of the Regulations of the Public Hydraulics. Domain”. Therefore, “keep clean channels are a measure contrary to their own nature and only aggravates the damage caused by flooding.
The powers
Regarding the field of competence, the CHJ emphasizes that Law 10/2001 of July 5 of the National Hydrological Plan establishes, in its article 28.4, that actions in public canals located in urban areas will correspond to the competent administrations “in matters of territorial planning and town planning, that is to say, in the present case, to the Valencian Generalitat or the respective local entities. In other words, it is the local entities or the Valencian Generalitat itself that must carry out actions on public canals when they circulate in urban areas, as is the case with ravines.
To do this, the entities “must request the corresponding authorization from the basin organization, because these are actions in an area of the public hydraulic domain. Additionally, depending on environmental restrictions that may exist near the action area, this may be necessary. environmental body reportsince, in the event of elimination of invasive alien species Arundo donax The use of heavy machinery is sometimes necessary.
A man walks in a devastated street in Paiporta, with remains of reeds washed away by the flood.
EFE
The regulations, however, allow the possibility of concluding agreements between the Ministry of Ecological Transition and the Demographic Challenge and regional and local administrations for the financing of these actions. “In the Hydrographic Confederation of Júcar, in these cases of reed removal, priority is given to actions for which there is a commitment by the regional or local administration for its subsequent maintenance”.
Thus, “the powers of eradication of invasive species, such as the common reed, and the powers of sanitation of solid waste They mainly come from the Valencian Generalitat. Furthermore, when it comes to urban areas of the river, the competence also belongs to them, shared with local entities”.
Thus, the CHJ assures that “it only acts to eliminate the common reed when it must be replaced by native riparian vegetation”. Indeed, he assures, because the objective of the Ministry of Ecological Transition and the Demographic Challenge is to “to achieve the good condition of rivers and not, on the other hand, the elimination of reeds or the prevention of fires”. Sometimes, and following a series of technical criteria established by the Water Framework Directive, “the presence of reeds and the absence of native species represent a hydromorphological deterioration of the river. It is on these occasions that the Hydrographic Confederation of Júcar acts.
However, as this newspaper has already reported, the current General Flood Risk Plan, from the Ministry of Ecological Transition, published in 2023, specifies that the “canalization, adaptation and drainage” of the Poyo ravine“competence” of the CHJ, was pending, since “the environmental feasibility, economic and social viability studies have not been carried out nor approved”. Specifically, actions such as “adaptation and channeling in the urban area of Aldaia and drainage of flows towards the Poyo ravine”.
