In The content of this essay highlights

In this essay
I will be focussing on the socionatural impacts caused by the intensification
of economic activities, water demand and urbanisation along the Tagus River,
which runs through both Spain and Portugal before discharging into the Atlantic
Ocean. It has a total length of 1060km, with a catchment area of 80,500km ². The river has been an importance to
the modern economic development of the area by catering for water demands from
urban settlements, such as Madrid and Lisbon, providing water to additional
regions outside of the catchment area that are in water deficit, and being used
for industrial processes (Burgen 2017). It also has more than 60 dams along its
course, with an installed power capacity of more than 1,200,000 kilowatts.
Erik Swyngedouw has argued that nature and society should be analysed without
abstraction from one another, as both the ‘social’ and the ‘natural’ are always
intertwined (Swyngedouw 1999). The content of this essay highlights the
dualistic qualities between nature and society, by drawing upon the
anthropogenic environmental stresses on the aquatic and riparian communities of
the Tagus River catchment, and how these connect with the ‘human’ impacts, both
caused by such economic developments. Rivers are of great significance to
humans and the environment, and therefore the socionatural impacts caused by
human development are important to examine. Rivers provide humans with critical
resources including drinking water, irrigation water, fish and hydroelectric
power, and ecologically, rivers “are central constituents of fresh water
ecosystems” (Conca 2006, p.73). River catchments provide habitats for a diverse
variety of species, are a means of cycling water and nutrients and bring about
vital interactions between aquatic and terrestrial ecosystems. The negative
impacts on the ecology of the river, in turn harms the human uses of the river,
so these are intertwined.

The Tagus is located in the Mediterranean basin, which
experiences dry summers dominated by subtropical high-pressures,
making rainfall unlikely.
For regions such as this, that experience seasonal water scarcity, dams and
reservoirs are “key infrastructure for water and hydropower generation”
(Lopez-Moreno et al 2009).
Approximately 9 million people live within the Tagus basin, each with domestic
and drinking water supply requirements. For the populations needs to be met, it
is essential that the water scarcity is overcome to provide people with
sufficient quantities of water. Dams such as the Alcantara Dam have been
constructed on the Tagus to tackle the issue of unreliable water supplies. A
dam’s main purpose is to release stored water in order to maintain ecological
flow, as well as to meet basic water requirements during periods of drought or
reduced water flow. The Alcantara reservoir is the second largest in Europe,
“and because of its large capacity, the reservoir has a large potential to
modify the river regime downstream in Portugal, where the water is mostly used
for agriculture, industry, and domestic supply” (Lopez-Moreno et al 2013). Diverting water from its
natural course and ensuring that instead it meets these human requirements,
prioritises the human needs for the river water over the environmental demands.
This belief is illustrated by Maria Soledad Gallego, an
environmental lawyer who said that “Spain’s water management has been
driven by economics, not environmental considerations” (Burgen 2017). Damming
is a form of manipulating rivers, which can lead to destructive effects on
freshwater biodiversity by altering a watersheds critical ecosystem. Conca
(2006) states that freshwater ecosystems, such as rivers, are home to most of
the world’s endangered species of fish and that “dams…and other forms of river
manipulation are the chief culprit in their precarious state”. Lopez-Moreno et al present that the dam has indeed
altered the Tagus’ river ecosystem through increasing the magnitude of droughts
(2013), which are major hydroclimatic hazards, leading to many economic, social
and environmental problems caused by water demand (from both the environment
and people), exceeding water supply. The impact of prolonged and intensified
droughts effects both the environment and the ‘human world’ simultaneously,
displaying how the consequences of development along the Tagus demonstrates
Swyngedouw’s neologism of socionature.  For
dams to be able to store water, reservoirs are created. The Alcantara Dam forms
the largest artificial lake in Western Europe. To create the reservoir,
extensive areas of land must be flooded, causing destruction to diverse
ecological systems, furthering the alteration to natural ecosystems.

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As described by Pittock et al (2009), another practice of
managing water demands that is performed in the Tagus basin, is through water
transfer, from the Tagus to other nearby regions lacking water supplies.
Operational since 1978, the Tagus-Segura IBT is a 286km pipeline that connects
the Tagus river flow to the Júcar, Segura and Guadiana river basins, which
belong to regions with high water demands due to their large agriculture and
tourism industries.  The main objective
of the pipeline is to provide water to provinces with water deficits, by
carrying 1km³ of water a year into the Segura River
Basin, which is the most water scarce basin in Spain. The Segura region is also
one of the most productive agricultural regions in Spain, so the water transfer
is of great economic importance to the receiving region. However, the designers
of the project based their calculations on a particularly high river flow that
is not representative of the Tagus’ typical state, so estimated that 1.3km³
would be available to be transferred from the Tagus annually (Pittock et al 2009). “Climate and land use
changes in the upper Tagus basin have resulted in a reduction of 47% in average
streamflow over the past 40 years” (Estevan et al. 2007) c. (Pittock et al 2009). This caused an
overestimation of water available for transfer each year.  Pittock et
al (2009) state that during 30 years of water transfer from the Tagus, over
70% of the headwater flows have been transported to the Segura basin, creating social,
economic and environmental consequences in the Tagus.  This reduces flows in the Tagus river and
consequently water availability within the basin, which as a result, negatively
impacts riparian vegetation. The lowered water levels in the Tagus also result
in pollution from towns and cities, such as Madrid, and from industry to be
more concentrated in the river water. Management rules of the water transfer
have not been altered since the beginning of the operations to fit the much
different hydrological conditions of the Tagus, further straining the demands
for water in the Tagus River basin. Hernandez-Mora and Del Moral (2015) express
concerns over the scheme, due to there being no surplus water in the Tagus for
economic expansion or to maintain a good ecological status of the river, whilst
the Segura is receiving enough water to meet demands and for economic
development. While water transfer improves productivity in Segura, it causes
environmental and economic damage in the donor basin (Cabo et al 2014), thus being a major catalyst for conflicts between the
two basins.

It is not
only through water management schemes that socionatural impacts of development
along the Tagus occur however. Water pollution is another major source of
stress on the Tagus River. Problems include the discharge of waste from nuclear
power plants and also from large urban centres, such as Madrid. The Almaraz
Nuclear Power Plant is cooled with water from the Tagus, and after use,
releases this water back into the Torrejón reservoir on the river. The released
water contains levels of tritium (3H), a radioactive isotope in the
aqueous form of HTO, which is more radiotoxic than the gaseous form, HT (ICRP
1978) c. Baeza et al (2001).
Eyrolle-Boyer et al (2014) present
that in fact, “HTO is 25 000 times more radiotoxic to human beings than HT,
mainly due to its longer residence time in biota tissues and abiotic components
(e.g., soils and rivers) (ASN 2011)”. HTO is extremely mobile in the environment and in biological
systems, so can be quickly integrated into cycles. Therefore, it can be
extremely dangerous due to numerous studies indicating that in living animals
it can produce cancer, cause developmental abnormalities and cell death (Dobson
1979). Water containing tritium is thus dangerous for human consumption and may
cause damage to organisms living in or interacting with the Tagus River. The
powerplant consists of two pressurised water reactors that produce over 750 000
MWh of energy each month. Nuclear energy is comparable with renewable energy
when considering greenhouse gas emissions (Sims et al 2003), so is an effective greenhouse gas mitigation option. Even
though this process of forming energy may have negative impacts on the local
area, it could be seen as better for the planet as a whole in the long term,
due to not releasing GHGs into the atmosphere. The Tagus also receives
radioactive pollution from two additional power plants upstream, alongside from
hospitals and laboratories in large cities.

Madrid is a major Spanish city of over 3.1 million people that depends
on the Tagus for its water supply. Carr (2016) reported for the Guardian that a
spokesman for Defence for the Tagus, Miguel Ángel Sánchez, voiced that one of
the main three factors causing the river to collapse, is due to the waste
Madrid produces. The degradation of the Tagus due to pollution has substantial
socionatural impacts at many different scales. A study carried out by Nevado et al between 2002 and 2004 reveals that
Madrid does indeed contribute heavily to polluting the Tagus River, by
observing that downstream to the Jarama River input (Madrid’s input), there was
a higher degree of pollution and degradation compared to 160km upstream from
the Jarama input, where there are few anthropogenic contributors (2008). For
example, high levels of organic pollution reach the Tagus through the Jarama
input, which cause decreased oxygen (DO) levels. DO levels above 6 mg/L promote
the growth of aquatic organisms (Miller 1994) c. Nevado et al (2008), however DO levels were found to be only 2.31 mg/L in
the Jarama River, where Madrid’s waste ends up. Through the Jarama waters
flowing into the Tagus, DO levels are therefore decreased from levels of 9.2
and 10.3 mg/L, as observed in upper stations. 
Dissolved oxygen is vital for many fresh water organisms such as fish,
bacteria and plants to survive. Microbes recycle nutrients through microbial
decomposition, which DO is vital for (EPA 2013). Although, the pollution caused
by Madrid into the Tagus River does not only negatively impact the environment.
Nevado et al (2008) also observed that there was a
significant increase in chloride downstream from the Jarama River confluence.
Both sewage waters and industrial effluents are found be high in chloride,
indicating to pollution emerging from Madrid. This study therefore displays
that the increased levels of pollution in the Tagus, results from the waste
water input from the city of Madrid. It is not only urban centres, which
largely cause the pollution, that are negatively impacted by the reduced water
quality however. It also impacts those from rural surrounding areas, as they
have reduced drinking and irrigation water quality. This could therefore be
seen as unfair on these people, as they have not largely contributed to the
degradation of the water supply. Through damaging the rivers ecology with
anthropogenic pollution, the water quality is reduced, impacting both the
environment and human uses of the river, thus showing the interconnectivity
between the environmental and social impacts.


transfer and management, nuclear electricity production and the waste produced
by large cities, each create socionatural change along the Tagus River and in
its catchment area. These human influences are in some cases seen as necessary
by many, for example the transfer of water from the Tagus to areas that without
it, would not meet basic water requirements. However, the Mediterranean Basin
is one of Earth’s biodiversity hotspots, and without protection, could be spoilt
by such human interventions. Approximately 9 million people live within the
Tagus Basin, and their needs must be met despite causing negative environmental
impacts, that in turn impact humans negatively. However, these impacts should
be weighed up against the many positive reasons for these human interventions,
such as managing water so that it is available in times of water stress or for
places that receive little water, the production of non-greenhouse gas emitting
electricity and through people settling in large urban settlements, increasing
social and economic gains in many instances. However, alternative methods of
human activity should be thought about in order to lessen the negative socionatural