The neighbours have suffered the greatest flow in the region of Pamplona following the overflow of Arga and Ultzama, which forced a man who was surrounded by water and trapped in the tractor to be rescued by helicopter. In Senpere, Ezpeleta and Azkaine there have also been significant damage to the Urdazubi River, which has been completely burned down. Last January, the overflow of the Ribera reached over 2,000 hectares, a decrease of 4.8 per cent. In October 2012 Navarre was also the most punished community and in November 2011 people living in Fadura de Getxo or Txomin Enea de Donostia and Martutene will still be remembered. The zodiak had to be taken aboard several of the last inhabitants of the area. In many villages that were left without electricity, roads were cut, railway services were suspended, the Elorrabi bridge was torn down in Hernani, and two people were killed by the river: A 76-year-old man died in Irun (Gipuzkoa) and a 66-year-old woman in Derio.

These are just a few isolated examples, and the Azti-Tecnalia research center predicts that rains will increase by 10% in the future, which means that flooding will be more frequent in Euskal Herria, due to climate change. We must not forget that the rains and the floods produced by them are a natural phenomenon. “The river ecosystem has its own dynamics and to maintain its natural balance, periodic floods are indispensable phenomena. The flooding limits the growth of vegetation in the rivers and limits the flow,” says Iratxe Garrido Tejedor, a member of the environmental group Eguzki. The problem is that these ecosystems have been transformed, because we've robbed the river of the areas it needs to overflow, building infrastructures. “Some (bridges, fences…) are aimed at limiting the flow of water and others (reservoirs, dams…) want to store the water – Garrido explains. To this must be added the artificialization of the soil, since the land that can absorb water is increasingly scarce”. In the asphalted margins, in addition, the rain reaches the rivers faster.

The occupation of river margins accelerated in the 1950s, and since then we have been transforming and assimilating more and more flood zones. The abrupt orography of the Basque Country has meant that there are few plains, “the wild building of the last two decades has built it on the floodplains of the rivers,” explains Garrido. Roads, parking lots, bridges, houses in wet areas have been built and works have been carried out that have narrowed the flow of rivers. Moreover, the Cambó Law of the Spanish State promoted the drying and occupation of the marshes, claiming that they were sterile areas. The Director of Planning and Works of the Basque Water Agency, José María Sanz de Galdeano, considers that the authorities have evolved very slowly on this issue because they did not know the importance and risks of these ecosystems, but that in recent years they are changing the perspective from management.

In this regard, Sanz de Galdeano recalled that, at present, the Agency can prevent the urban development of a flood area, a philosophy that maintains the CAPV Hydrological Plan and the Sectoral Territorial Plan for the Protection of River Margins. One of the objectives of URA is to avoid construction in areas where turbulence can occur. However, we can also see examples to the contrary. In Hernani, for example, in the Karabel district, where the river overflows, flood rules have been established, but at the same time new homes are being built. In Ondarroa, in the Alleri neighborhood, it was the platform created by the citizenry that managed to paralyze the project of constructing 500 homes in the wetland: The Supreme Court found that the protected marsh cannot be urban land and that the project the administration wanted to carry out was illegal. Iratxe Garrido considers that these urban plans are often in the hands of municipalities and that economic interests prevail: “The regulations that prohibit building in certain areas are quite new and in many cases governments do not comply with them properly; many of the infrastructures and housing that have just been built are illegal.”

Return of the marshes to the river

The first step is not to build more on the river bank, yes, but what to do in the already built areas? Garrido considers that the most appropriate solution is the total emptying of these spaces, but in most cases the degree of artificialization of these places is so high that “it is already impossible to return to the original natural state. However, in some areas, wetlands can be restored, following strategic plans, since it is not enough to return to the rivers the land that has been taken away for years, it is necessary to understand the dynamics of the ecosystems to deal with the problems that may arise in the near future.”

The Basque Water Agency has 30 priority projects, including the transfer of houses and industrial sites, the improvement of pipelines, the creation of parallel channels (to favor the original channel when a large flow of water arrives), or the construction of protective infrastructures when there are no better alternatives. Similar projects are being carried out in Navarra and Iparralde. Sanz de Galdeano has also underlined the importance of prevention, as the forecast and forecast of rainfall is essential to ensure an adequate response. The agency works in coordination with Civil Protection and the UHATE prediction and early warning system (in particular, the Flood Forecasting and Resolution System) has been tested on departures this year. The failure of the forecasts, however, has led to a lack of resources and avoidable damage in Navarre in the recent floods.

What measures are being taken today to deal with floods? One of the main options is to lift walls or barriers, but often it is not the right choice. In rural areas the installation of barriers to water obstruction and the protection of the surrounding fields is widespread, especially in Álava and Navarre. In the event that the wall overpasses or ruptures, the degree of erosion and flow strength increases, damage increases, and in addition, the water that returns to the stream in a few hours will be maintained for days in the campas, as the wall prevents the return to the river. Even when it fails to overcome the obstacle, the water lowers with higher pressure and velocity pressured by the walls and can overflow more strongly later.

Dredging is not a solution

Dredging is another measure that is often taken by city councils. But Sanz de Galdeano explains that the same rivers purify themselves and dredge them alone, and that if we dredge them, in the next wave the river will return to its previous state, as the new sediments will fill the empty space: “This kind of action is therefore absolutely useless and the elimination of vegetation or dredging of the river flows.” Eguzki has criticized that the project of a million euros presented in February by the City of Vitoria-Gasteiz to broaden and clean the Errekaleor and Santo Tomás rivers is an economic waste. According to Garrido, increasing the depth and width of the road through the elimination of natural sediments does not solve anything, destroys biodiversity and produces side effects such as erosion over the areas where the draga runs, canal sinking and irregularities in the bottom, decrease of the water surface (and consequently drying of irrigation wells), loss of stability of the supports of bridges and tailings, etc.

Nevertheless, Garrido added that most interventions are carried out on the riverbanks and it would be advisable to maintain river basins to minimize the effects of flooding, since “when river basins are artificialized the consequences are the same”. Similarly with springs: if not properly conserved, the elements that provide the living waters of the head will accumulate and later, for example, in urban areas, may cause the overflow of the river.

Reservoirs, beneficial or dangerous?

Reservoirs also have a lot to say in all of this. In the case of very small reservoirs, they do not have the capacity to influence the flow. On the contrary, larger reservoirs, such as the Zadorra and Añarbe reservoirs, can reduce river overflow and partially stop it if efficient management is carried out. The solution would be to cut off the water flow through the dam and allow a lower flow to occur in a controlled manner, as the URA member has clarified. “But if the reservoir has a limit and reaches a level that cannot accumulate more water, it would have to free up all the flow that is entering, so if infrastructures have been built in flood areas under the dam, they can become real traps.” If the reservoirs are not able to withstand the rain, the problem that is created can be very serious, hence the importance of the forecasts, so that before the rain begins the dam will empty enough and make room.

Sanz de Galdeano offers an example of good management: in the rains of January and February last year, in the section running through Vitoria-Gasteiz, the Zadorra reached a maximum flow of 125 cubic meters per second and reached a height of 2.90 meters. To achieve this, the management of the reservoirs was essential, otherwise the Zadorra would have reached 375 cubic meters per second and 5.5 meters high, and the damage would probably be much greater. “There are several administrations and institutions involved in the decisions on the management of reservoirs under the coordination of URA. The experience so far has been very good.” They are more critical of the environmental group Eguzki, who considers that the operation of dams, both private and public, is in the hands of private companies, “they are the ones who decide when to open and close the floodgates and the criterion is based on energy demand”.

Finally, bridges play an important role in waves. Any structure that hinders the flow of water is causing the bridge to be wide and high enough for there to be no discomfort, as Sanz de Galdeano explained. “That’s also what we’ve regulated now, but many of the old bridges that are already built are a real problem and is often a protected heritage, because of its historical value.”

Urumea, Cadagua,
Zadorra, Ebro…

We have a lot of black dots in Euskal Herria. The Ebro has left more than a shudder in Navarre – we must also take into account the Bidasoa and the Arga – and in Gipuzkoa, Urumea and Oria are the rivers with the highest risk, not to mention Deba and Urola; in Álava we must especially look at the Zadorra; in Bizkaia, Ibaizabal, Nerbioi (which also affects Cadálava). In general, Eguzki’s member recalls that any river that does not have a flood plain and has a rainy river basin can overflow. In Euskal Herria, as we know, rain often accompanies us and, if we do not take effective measures, we will be able to have unpleasant surprises in the future.