Defending the Mountain Water Towers of Spain’s Sierra Nevada

Defending the Mountain Water Towers of Spain’s Sierra Nevada

All through human historical past, the waterscape has reworked us, and in flip, we’ve altered it. The Mediterranean options a few of the oldest humanized landscapes on the earth. There, farming communities took form in areas similar to Spain’s Sierra Nevada (“snowy mountains” in English). In these areas, scarce rainfall at low elevations supplemented by water flowing from “mountain water towers” (snowmelt and rainfall reserves saved in mountain ranges) supported a mixture of farming and pastoral life. Arguably, this working societal contract with water ultimately subtle to societies internationally [Boccaletti, 2021].

Immediately, a number of stressors are endangering this ecocultural contract with water. Such stressors, together with rural exodus, urbanization, altering land use, and intensifying local weather swings, make the waterscape essentially the most altered of all of Earth’s main biogeochemical cycles.

All over the world, freshwater sources, and the myriad of ecosystem providers they supply, have gotten more and more important underneath the mixed assault of anthropogenic and local weather change impacts. Such impacts are most seen for mountain water sources which can be the supply of a lot of the world’s streams, lakes, wetlands, and main rivers—the pure “water towers” of the world [Viviroli et al., 2007; Immerzeel et al., 2020].

Right here we spotlight the plight of Sierra Nevada water sources in Spain, together with schooling and conservation steps being taken to guard this important peninsular useful resource.

The World’s Water Towers

About half of humanity depends upon mountain water towers (MWTs) for on a regular basis family consumption, farming, business, and high quality of life. Nonetheless, as a result of MWTs are notably delicate to intensifying anthropogenic impacts and ongoing local weather change—high-altitude ecosystems are warming quicker than the worldwide common, for instance [Intergovernmental Panel on Climate Change (IPCC), 2021]—each mountain ecosystems and downstream communities face growing water-related uncertainties.

Mountains cowl some 27% of Earth’s floor and supply greater than 50% of the world’s freshwater sources.

Mountains, which cowl some 27% of Earth’s floor, present greater than 50% of the world’s freshwater sources. MWTs play an important position due to their worldwide distribution, coupled with an immense capability for intercepting, capturing, and storing precipitation and distributing it to lowlands. Mountains which can be glaciated and periglaciated (having subterranean ice reserves) may even out moist and dry durations by holding water in reserve in winter and releasing it throughout subsequent dry and sizzling summer season months [Huss and Hock, 2018; Immerzeel et al., 2020].

Water from MWTs is much more important in dry areas such because the Mediterranean [Viviroli et al., 2007; Food and Agricultural Organization of the United Nations (FAO), 2012]. Mountain lakes, streams, and rivers additionally maintain quite a few fragile ecosystems similar to riparian forests and biodiverse wetlands of their watersheds [FAO, 2012]. Nonetheless, each the amount and high quality of mountain waters, the ecosystems they maintain, and the providers they supply are more and more threatened by local weather change (e.g., warming; excessive droughts and floods; decreased rain, snow, and ice or their growing loss), unsustainable land use and water extraction, and ongoing air pollution. All these components endanger the attainment of the U.N. Sustainable Growth Purpose of Clear Water and Sanitation [United Nations, 2021], which goals to supply common and equitable entry to protected and inexpensive consuming water, sanitation, and hygiene by 2030.

Sierra Nevada Mountain Water Sources

The Sierra Nevada is Europe’s southernmost glacial mountain vary (Determine 1), with 15 peaks increased than 3,000 meters (the very best being 3,479 meters). It stretches throughout some 2,273 sq. kilometers in southern Spain, and its watershed encompasses a number of Mediterranean bioclimates alongside its altitudinal and latitudinal extent. The Sierra Nevada incorporates 74 glacial lakes, and it’s the supply of a whole lot of streams and a number of other main rivers. For instance, the watersheds of the Río Genil and Río Poqueira finish within the Atlantic Ocean and Mediterranean Sea basins, respectively.

Fig. 1. The Sierra Nevada, Europe’s southernmost glacial mountain vary, are situated simply east of Granada in southern Spain. Credit score: Base map: Google, map information ©2022 Inst. Geogr. Nacional

Immediately, components of the Sierra Nevada are included within the Sierra Nevada Nationwide Park system, and your entire vary is a U.N. Academic, Scientific and Cultural Group biosphere reserve. These mountains, situated throughout the Mediterranean Sea from the African continent, expertise pronounced interannual variability in local weather, together with average winter situations and frequent, extreme droughts. Though the final everlasting glaciers of the Sierra Nevada melted away on the flip of twentieth century, ice and snow cowl nonetheless happen within the highest reaches for a lot of the 12 months, and substantial reserves of periglacial ice persist, enabling the Sierra Nevada to maintain a various array of ecosystems [Zamora and Oliva, 2022].

The mid-March 2022 occasion turned the skies over Europe pink, components of southern Spain had been drenched in mud rain, and the snow on the Sierra Nevada turned brown.

The Sierra Nevada vary receives Saharan mud on an everyday in addition to episodic foundation. The mud fertilizes the water and soil of this Mediterranean ecosystem with key vitamins similar to iron, calcium, and phosphorus. Some transcontinental mud occasions could be huge: The mid-March 2022 occasion turned the skies over Europe pink, components of southern Spain had been drenched in mud rain, and the snow on the Sierra Nevada turned brown.

Simply as mountains intercept rain clouds from transferring air lots, they disproportionately intercept mud circulating within the free troposphere, relative to flatlands within the panorama. (The free troposphere is above the planetary boundary layer, about 1,700 ± 500 meters above sea stage.) Additional, mud lowers the albedo of snow, ice, and water. This variation in albedo warms snow and ice and enhances its melting, which impacts the water cycle of the Sierra Nevada and its watershed [Zamora and Oliva, 2022].

Although totally different mountain ranges of the world expertise local weather change and anthropogenic impacts in a different way, there are frequent ongoing results, similar to depleting MWTs and degrading mountain and downstream ecosystems. We now have noticed long-term (decadal) tendencies in altering situations (lowering annual precipitation, growing warming, snow loss, air pollution, and so on.) in time collection observations from the Sierra Nevada World Change Observatory.

On 12 July 2018 (left), the water within the 150-meter-wide Laguna La Caldera, a mountain lake close to Mulhacén peak in Spain’s Sierra Nevada, appeared clear and blue amid situations of common snowfall and low mud deposition. Nonetheless, on 31 Might 2022, the lake appeared muddy and brown following lower-than-average snowfall and intensive mud deposition. Areas across the lake underwent an unusually early spring thaw in 2022 after huge mud deposition occasions in late winter decreased the albedo of accrued snow and ice and quickly warmed the panorama. Credit score: Mani Villar-Argaiz

These tendencies are in keeping with growing ice loss in lakes throughout the Northern Hemisphere and decreased winter ice that results in elevated interannual variability in water movement. In recent times, southern Spain has been experiencing more and more milder winters, hotter springs, and summers that embody warmth waves.

Moreover, water high quality within the Sierra Nevada watershed has deteriorated over the previous few a long time, in sync with elevated human appropriation of water and recurring drought occasions. Many of those watershed observations, made on the mountains and in downstream areas, usually mimic these happening in mountain ecosystems globally (the Andes, Rockies, Himalayas, and so on.). Concurrent lack of glacial and periglacial ice is a looming downside internationally, and it impacts water availability, water high quality, and biodiversity [IPCC, 2021].

Schooling and Conservation within the Sierra Nevada

At the moment, researchers on the College of Granada coordinate two modern tasks masking excessive mountain lakes, streams, and rivers in Spain’s Sierra Nevada watershed. These tasks, which contain college students and neighborhood members, broaden youth participation and inform the general public in regards to the intrinsic worth of water of their on a regular basis lives and the necessity for its safety and conservation [Zamora and Oliva, 2022].

In a single program, Ríos de Vida (Rivers of Life), highschool college students who stay in numerous components of the Río Genil basin work in partnership with the college. The scholars chronicle modifications within the ecology and well being within the stretches of the river closest to them because it runs from the mountains by way of Granada, a metropolis of 300,000 folks, and different communities on its approach towards the ocean. On the finish of the college 12 months, all of them collect for a convention to share information and focus on their observations.

Highschool college students collaborating within the Ríos de Vida mission pattern aquatic macroinvertebrates within the Río Genil throughout an outing in February 2022. The mission engages college students as neighborhood scientists in hands-on monitoring, analyses, and interpretation of the well being of mountain rivers in an effort to strengthen watershed science, enhance water administration, and form water coverage. Credit score: Mani Villar-Argaiz

On the entire, there are 13 energetic river renaturalization tasks underway in Spain that goal to revive biodiversity and pure hydraulic flows within the watershed. Nonetheless, these efforts are principally targeted on downstream and concrete stretches of the rivers, the place sturdy environmental consciousness prevails amongst city communities.

The mission focuses on extending environmental protections and restoration practices to the mountain headwater ecosystems, which have obtained much less consideration than areas farther downstream.

The opposite mission coordinated by way of the College of Granada, 74 Excessive Mountain Glacial-Lake Oases, focuses on the headwater areas of the Sierra Nevada’s rivers. This neighborhood science marketing campaign has made an excellent begin by involving all segments of the general public and stakeholders. The mission focuses on extending environmental protections and restoration practices to the mountain headwater ecosystems, which have obtained much less consideration than areas farther downstream.

The headwaters are the place the water towers primarily recharge and maintain delicate mountain biodiversity (high-altitude wetlands and different wildlife endemic to mountain ecosystems) and supply quite a few downstream ecosystem providers. Challenge contributors—everybody from hikers and scientists to farmers and metropolis managers—hold their eyes on the 74 glacial lakes of the Sierra Nevada by sharing pictures of and notes in regards to the lakes.

As a result of the ways in which folks use and misuse water are intently tied to how they worth it, such neighborhood science tasks can spur wider engagement and implementation of sustainable water insurance policies. This engagement is changing into more and more necessary as a result of many components of the world with Mediterranean climates, together with California, Chile, southern Africa, and southern Australia, are experiencing important water shortages and deterioration of water high quality. These issues are attributed to a succession of episodic and intensifying droughts and exponentially rising water calls for, together with the ensuing focus of present pollution. The state of affairs is especially important within the southwestern United States and Chile (areas present process megadroughts) and within the Spanish Sierra Nevada area, which is experiencing its worst drought on report.

The Way forward for Mountain Water Towers

The world’s MWTs are not often valued as strategic water reserves, although they assist to make sure regular annual flows of water that have an effect on practically half of humanity. These water reserves even out modifications in water provides by capturing and freezing huge portions of water through the winter months and releasing them throughout hotter summer season months.

College students and instructors within the Ríos de Vida mission focus on their observations of and samples collected from the Río Genil to find out water high quality in February 2022. Credit score: Mani Villar-Argaiz

Periglacial water represents one necessary hole in our data. The mixed motion of glacial and periglacial water is key to the supply of water to streams, rivers, and water tables within the watershed. Information of periglacial water swimming pools and fluxes is essential to adapting to a world the place all continental glaciers are quick disappearing. We hope that the lately operational Gravity Restoration and Local weather Experiment Comply with-On (GRACE-FO) satellite tv for pc, which makes delicate measurements of belowground gravity anomalies, will make clear the scale and turnover of this hidden part of the world’s MWTs.

As groundwater depletion continues unabated all over the world, the worth of mountain water towers to the water steadiness of downstream societies and ecosystems can solely improve.

As groundwater depletion continues unabated all over the world, the worth of MWTs to the water steadiness of downstream societies and ecosystems can solely improve. It’s time that MWTs obtain their due safety at each the watershed and international scales. On this context, there’s encouraging information that the Spanish authorities is making ready to increase safety to 41 aquifers within the Iberian Peninsula, with 7 of them situated within the province of Granada, which incorporates the 74 glacial lakes of the Sierra Nevada. Preserving mountain water towers is our greatest insurance coverage coverage for making certain a steadier water provide and damping the rising tendency for floods and droughts because the local weather more and more warms and the water cycle wobbles ever extra.


This work was supported by a Fulbright Fellowship on the College of Granada to B.B. and LifeWatch mission “Sensible EcoMountains” (LifeWatch-2019-10-832 UGR-01) and Ministerio de Ciencia e Innovación mission “REMOLADOX” (PID2020-118872RB-I00) to M.V.-A. and J.M.-S. We’re grateful to the contributors (college students, lecturers, volunteers, and colleagues) concerned within the two neighborhood science tasks.


Boccaletti, G. (2021), Water: A Biography, Pantheon Books, New York.

Meals and Agriculture Group of the United Nations (FAO) (2012), Worldwide Mountain Day,

Huss, M., and R. Hock (2018), World scale hydrological response to future glacial mass loss, Nat. Clim. Change, 8, 135–140,

Immerzeel, W. W., et al. (2020), Significance and the vulnerability of world’s water towers, Nature, 577, 364–369,

Intergovernmental Panel on Local weather Change (IPCC) (2021), Local weather Change 2021: The Bodily Science Foundation. Working Group I Contribution to the IPCC Sixth Evaluation Report, Cambridge Univ. Press, Cambridge, U.Ok.,

United Nations (2021), The sustainable growth targets report,

Viviroli, D., et al. (2007), Mountains of the world, water towers for humanity: Typology, mapping and international significance, Water Resour. Res., 43, W07447,

Zamora, R., and M. Oliva (2022), The Panorama of the Sierra Nevada: A Distinctive Laboratory of World Processes in Spain, Springer, Cham, Switzerland,

Creator Data

Bopaiah A. Biddanda ([email protected]), Annis Water Sources Institute, Grand Valley State College, Allendale, Mich.; and Manuel Villar-Argaiz and Juan Manuel Medina-Sánchez, Instituto del Agua and Departamento de Ecología, College of Granada, Andalucía, Spain

Quotation: Biddanda, B. A., M. Villar-Argaiz, and J. M. Medina-Sánchez (2022), Defending the mountain water towers of Spain’s Sierra Nevada, Eos, 103, Printed on 16 September 2022.
This text doesn’t signify the opinion of AGU, Eos, or any of its associates. It’s solely the opinion of the writer.
Textual content © 2022. The authors. CC BY-NC-ND 3.0
Besides the place in any other case famous, pictures are topic to copyright. Any reuse with out categorical permission from the copyright proprietor is prohibited.

Leave a Reply