Javier Davara (Santa Cruz de Tenerife, 1970) is a Mining Engineer, passionate about his profession and a history lover. His professional career has been linked to the water sector for 28 years, first in the private sector and then in the public sphere. Since 2016, he has been the manager of the Insular Water Council of Tenerife (CIATF), where he succeeded José Fernández Bethencourt, who retired after nearly 25 years in office.
[–>[–>
Are drought declaration processes continuing despite the recent rainfall?
[–>
If it had rained normally in the past two years within the normal rainfall levels, we would not be in this situation of declaring an emergency due to drought. The rainfall recorded in recent weeks has not had a significant impact on the island’s water situation. One of the main indicators is the filling level of the Balten reservoirs and it has only increased by 6% during March compared to February. Furthermore, if we compare April 1, 2023, with 67.4%, and April 1, 2024, when the storage was at 46.7%, it is likely that the water situation in the agricultural sector this year will be repeated with greater severity than the previous year. To mitigate the adverse effects, the measures being considered to include in the emergency declaration approved at the Council meeting are crucial. We have gathered information from all municipalities, owners of desalination plants with possible surpluses, agricultural sector administrations, as well as internal work carried out specifically at CIATF on increasing groundwater use. Based on this, the indicators and measures that will govern the declaration will be determined, which will be presented to the public for subsequent final approval.
Is the groundwater supply model (wells and galleries) a thing of the past?
[–>
Not at all; in fact, it continues to exist as it represents almost 75% of the water supply and will continue to play a fundamental role in it in the coming years, although this percentage will decrease. CIATF has a groundwater hydrology model that has predicted the behavior of the island’s multi-aquifer for almost two decades. Time has proven the accuracy of this diagnosis as the aquifer levels are very close to those anticipated about 20 years ago. The volume of groundwater storage from rainfall is gradually decreasing, which will inevitably affect the flow rates of well and gallery yields. At an estimated magnitude of 1.5 million cubic meters per year or its equivalent, 4,000 cubic meters per day. Some galleries, especially those fed by the Las Cañadas sub-aquifer, may increase or maintain flow rates, which will be welcome; however, this water usually has high mineralization levels, with high levels of sodium, fluorine, and saline conductivity coming from the volcanic activity around Teide. Before being used for human or agricultural consumption, it will be necessary to desalinate them as is being done today.
Is the future key in desalinated and regenerated water?
[–>
The Tenerife Hydrological Plan established 30 years ago that the decrease in groundwater supply and the increase in demand should be met with industrial water production; that is, desalination of seawater or regeneration of wastewater. Fortunately, this strategy has been maintained. Regarding desalination, an industrial activity with more than two decades of experience in Tenerife, it depends solely on energy. In the case of CIATF, it will come from more than 50% from renewables produced on the island in 2024; in 2025 and subsequent years, it will be 100%. In recent years, except for the energy crisis due to the war in Ukraine, the cost of desalinated seawater produced by CIATF has been below the average cost of groundwater. As for the controversial brine discharged into the sea, after 20 years of monitoring and control programs in the dilution conduits to the environment, we have not been aware of any breaches of environmental regulations. Regarding regenerated water, the reasons for its adoption are even clearer and more compelling. The technology implemented, through the construction or expansion of ten treatment plants, allows and will allow treated wastewater discharged into the sea to be safely reused with guaranteed agronomic quality at half the cost of desalinated or groundwater production. This approach, supported by over 30 years of proven experience by the Council, the University of La Laguna, and CIATF, has provided new water resources for irrigation, while also ceasing seawater discharges in two years in Tacoronte-Tegueste-La Laguna and in the important tourist area of Adeje-Arona, achievements that will soon be seen in Granadilla, Guía de Isora, Santiago del Teide, Las Galletas, and Santa Cruz, and in the medium term in Puerto de La Cruz. These economic and environmental milestones are solid indicators that Tenerife is moving in the right direction in water management.
What is the current status of the Balten reservoir network?
[–>
The data as of April 1 indicate a storage volume of 2.2 cubic hectometers compared to 1.8 on March 1. This increase, due to last month’s rainfall, is well below the storage level on April 1, 2023, mentioned earlier. We have less stored volume to face an expected hot summer. This is the most important justification for the water emergency declaration being processed. The south is perhaps a bit better off with a storage level of 60% while in the north it is 40%. Balten has had to address in recent years the resealing of the reservoirs, some built over 30 years ago, and that is also a negative factor. The Tenerife reservoir plan was an excellent and innovative initiative of the Council in the 1980s that came to cover
Challenges of Large Dams on the Island due to Geological Structure and Topography
The deficit of large dams on the Island is conditioned by its lithological structure and topography. It was possible to store surplus from winter galleries or runoff. These reservoirs are the perfect complement for retaining purified and regenerated water without pouring it into the sea.
Can Water Losses in Municipal Networks be Eliminated?
It is highly complicated for a water supply network to have zero physical losses. Especially in an Island like Tenerife, whose municipalities have very dispersed urban areas and therefore very long supply networks. These networks are also subjected to high pressure as a result of the island’s topography. However, it is possible to achieve very acceptable levels that, according to experience in the sector, can be around 10%. In fact, larger municipalities have very high hydraulic efficiencies – the ratio between the water supplied by the system divided by the amount billed to the subscriber. Not many years ago, a 75% efficiency was considered good, and with new leak detection technologies and pressure control, some municipalities now reach 90%. However, there are also areas on the Island with room for improvement. The good news is that they know exactly what needs to be done. In fact, about four years ago, the CIATF developed an economic and technical plan to address leaks, and there are many specialized professionals in control of these supply networks. Some of these municipalities have also applied for European aid and are working towards improvement. An achievable goal is to recover around 13,000 m3 daily within three years, which could supply a population of 50,000 inhabitants. Unfortunately, today a significant amount is lost both underground and due to fraud.
Can the Irrigation System in Tenerife’s Fields be Optimized?
Globally, agricultural sector consumption has not changed in the last ten years, according to 2020 water balance data. It remains at around 87 Hm3 per year, which accounts for 43% of the total consumption, well below the Spanish average of 80%. This difference is striking and partially due to the cost of water, which has traditionally been much higher in the Canary Islands. The economic principle applies in this sector that the higher the cost of a good, the more its consumption is optimized. In other words, people usually don’t take care of what is free.
Does the Tourism Sector Consumption Influence the Current Drought?
According to the hydraulic balance, the tourism sector consumes around 21 Hm3 per year, which is 10% of the total consumption of the Island, much lower than urban consumption, which accounts for 35%. Most of this water comes from desalination plants managed by the CIATF in Adeje-Arona, Fonsalía, and Granadilla. Such as the desalination plants in Adeje like La Caleta de Adeje or the twenty desalination plants that some hotels have authorized for self-consumption. With these data, it can be argued that tourism does not deplete resources from other sectors since they make use of facilities specifically designed to supply the tourism sector. Moreover, the wastewater generated by tourism in the largest area of the Island, Adeje-Arona, is treated and reused 100% for irrigation. The same will soon be seen in the coastal areas of Santiago del Teide, Guía de Isora, and Granadilla. An example was seen during the pandemic when the absence of visitors significantly reduced the production of wastewater in tourist centers, restricting the availability of regenerated water for irrigation.
Public (municipalities), private (indirect), or mixed model in the integral water cycle management?
The debate that caused so much controversy years ago is now a thing of the past. Municipalities (18) with indirect management, meaning through a specialized operator, have water losses that do not exceed 20%, while those with direct systems (13) exceed 40%. Additionally, municipalities with indirect management usually maintain a balance between income and expenses, whereas the others need to cover the economic imbalance with municipal funds; in other words, water is subsidized, which does not contribute to saving. There are exceptions with a combination of municipal resources supported by occasional private professional help where good work is being done. Like almost everything in life, problems should be entrusted to professionals. What the administration should not give up is control supported by regulations to prevent abuses in such a strategic sector; from there, whatever a private entity can do better and cheaper, let them do it. From drafting hydraulic engineering projects to plumbing works. An example of public-private collaboration.
Are Water Supply Cuts Expected Next Summer?
Anticipating a summer with 5 or 6 heatwaves similar to what happened in 2023, very specific incidents are foreseen in some areas, as was the case last year with a decrease in water supply pressure. However, a generalized scarcity is by no means expected.
