GUADIANA BASIN Water quality and the development of the Alqueva region

64 Pages·2009·3.86 MB·English

GUADIANA BASIN
Water quality and the development
of the Alqueva region

Report of the NeWater project - New Approaches to Adaptive
Water Management under Uncertainty

www.newater.info
Title
Purpose Inventory and analysis of the pollution sources in
the Guadiana basin as a tool for the future
development of the Alqueva region.
Filename Guadiana Basin water quality
Authors Marco Estrela, Eduardo Silva
Document history
Current version. Final
Changes to previous version.
Date 19 January 2009
Status Final
Target readership
General readership
Correct reference

Marco Estrela, editor
Instituto de Soldadura e Qualidade

January 2009

Prepared under contract from the European Commission

Contract no 511179 (GOCE)
Integrated Project in
PRIORITY 6.3 Global Change and Ecosystems
in the 6th EU framework programme

Deliverable title: Report on Water quality and the development of
the Alqueva region

Actual submission date: 10.01.2009
Start of the project: 01.01.2005
Duration: 4 years
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Table of contents

1 Guadiana basin..........................................................................................................................1
1.1 Water quality under the scope of international basins.....................................1
2 Water quality issues................................................................................................................3
3 Inventory of Pollution Sources............................................................................................9
3.1 Point Sources.....................................................................................................................9
3.2 Diffuse sources...............................................................................................................33
4 Water Quality Analysis.........................................................................................................45
5 Conclusion.................................................................................................................................56
6 List of references....................................................................................................................58
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1 Guadiana basin

The Guadiana river is an international basin with a total area of 66 860 km2,
having it is headwaters in Spain with a basin of 55 260 km2. The national area
has 11 600 km2 and a big dam was built, Alqueva, creating a reservoir with 250
km2 and a storage capacity of 4150 hm3. The main tributaries in the Portuguese
part are the Caia, Degebe, Cobre, Vascão and Odeleite rivers, all located in the
right margin, and Ardila and Chança rivers located in the left margin.

The Guadiana River has an important role in the south of Portugal, a region with
drought problems.
1.1 Water quality under the scope of international basins
Raising awareness that the protection and use of transboundary water streams
are important and urgent tasks that can only be successfully be carried out with
the cooperation of the involved countries originated several actions and
promotion of studies to reach those objectives.
The quantity and quality of water reaching the border will be determinant to
assure the quality objectives that will allow current and future water uses.
Therefore it is necessary to implement bilateral studies that allow characterizing
international basins as a whole, namely regarding the different pollution sources,
existing water uses and the ecosystems specificities in order to achieve a
diagnostic of the current situation and to define the needed measures that allow
reaching the defined quality objectives.
The quality objectives to be set on the transboundary basins water are a result
of those that were set regarding the border stretches and from the knowledge
that exists regarding the most common uses and most characteristic fish
species.
Figure 1 shows a map with a proposal for water quality objectives in the
Guadiana basin.

Although the poor water quality that reaches the border, the Portuguese basin
also has some important pollution sources. These can be distributed as 35 per
cent urban discharges, 39 per cent animal feedlots sector and 18 per cent food
production. Many of these discharges do not have any treatment which causes a
large amount of nutrients exportation to the water and soil. On the other hand,
agricultural activities and animal production have a great impact in this basin as
non-point pollution sources. During the last years, algae bloom occurred in
several reservoirs that are spread all over the watershed, and in even in the
Guadiana river, showing that this basin has already eutrophication problems.

According to Article 5 and Annex II of the Water Framework Directive (WFD) is
required that Member States identify significant anthropogenic pressures on river
basins and also assess the potential impact of these pressures on the water
bodies. The following areas have to be identified: point and diffuse sources
pollution, the water abstraction, the water flow regulation, the morphological
alterations and land use patterns.

1
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GGoooodd --BBaatthhiinngg wwaatteerr
AA22 ––pprroodduuccttiioonn ooff ddrriinnkkiinngg wwaatteerr
GGoooodd -- FFiisshh wwaatteerrss --ccyypprriinniiddss

Figure 1: Water quality proposal (source: )

For a correct basin management, it is necessary to minimize these impacts, with
action plans and monitoring programmes, to improve water quality and achieve
the environmental objectives.

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2 Water quality issues
The Guadiana River and its affluent are characterized by a flow regime with
strong inter-annual variation and strong seasonal character, with long periods of
reduced flow.
These flow characteristics associated with conditions of high temperatures and
significant pollutant discharges gave origin to a system with “strong” pollution
and signs of eutrophication, where severe algae blooms frequently occur and
subsequent death of aquatic fauna.
This aspect is particularly evidenced at the end of Summer/beginning of the
raining season, which run-off causes leaching of the soil and transport of
sediments accumulated during the dry season, at the bottom of the tributaries
bed, added to the agro-industry wastewater, inevitably causes the fast increase
of the pollutant load.
It is important to understand the schematic representation of the Guadiana River
and its tributaries, which is represented in Figure 2. We should then analyse the
evolution of the water quality along the Guadiana River as well as estimate the
origin of the main factors leading to its degradability.
It is known that the Guadiana River when entering the Portuguese territory
already presents a considerable pollution level. Note that 83% of the Guadiana
River Basin is on Spanish territory and that the demographic, industrial and
agricultural occupation is substantially higher then the one in Portuguese
territory.
A significant set of polluting units although of small/medium size and connected
to farming, cattle and mining activities also exist in the Portuguese part of the
basin. This fact is worsened by the hydrological deficit registered during summer
season, during which the water lines where no dam is built have very low flows
or no water.
Several studies have been made during the years to identify and inventory the
pollution sources at the basin. All of them point out as the main pollution sources
a pulp and paper plant at Mourão, the mining of minerals, the agricultural and
cattle breeding activities, wastewater, and use of fertilizers.
For and easier interpretation of the data in this study the Guadiana basin was
divided in physiographic units, considered as homogeneous areas having as a
basis the hydrographical limits of the basins and the geological, hydrogeological,
geomorphological, and environmental characteristics. Data will be then
presented having these physiographic units into account being them:
• Zone A, corresponding to the Portuguese area of the Guadiana basin
north of the Degebe and Ardila river basins;
• Zone B, corresponding to the Degebe and Ardila river basins;
• Zone C, corresponding to the Guadiana basin between those two basins
and the limit of the Guadiana basin defined by the Pulo do Lobo section;
• Zone D, corresponding to the remaining Portuguese part of the
Guadiana basin, from Pulo do Lobo section until the estuary.

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Guadiana (Spain)

Xévora

1 Reservoir
Caia Water quality stations
1
Caia 1- Caia 8- Monte Clérigo
Mures and Monte da
2- Lucefécit 9- Boavista
Asseca Vinha
3- Vigia 10- Oeiras
Lucefécit 2 4- Monte Novo
Lucefécit 5- Alqueva 11- Guadiana (Chança)
Azeval e
Alamo
Vigia Alcarrache
Vale Vasco
3
Azenha de
Cerieiros
Degebe 5
4
Ardila
Monte Novo 6
Vale da
Serra
Pias
Marmelar, Odearça
e Amoreira
7 Enxoé
Terges
Limas
8
Cardeira e
9
Cobres
Oeiras 10 Rocha da Galé
Rocha da Nora
Carreiras Chanza
11
Vascão e
Alcoutim
Cais de
Foupana
Alcoutim
12
Odeleite
13
Beliche
Estuary
Figure 2: Schematic Representation of Guadiana River and its tributaries
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Each of these large areas were sub-divided in smaller areas, having as a basis
the limits of hydrographical sub-basins defined by the sections of water lines
selected according to the following criteria:
• Confluence between main water lines;
• Location of main dams;
• Location of hydrometrical stations;
• Location of main wastewater discharge points.

Following these principles, 52 physiographical units were established,
numbered from North to South as follows:

• Zone A – 9 physiographical units, from A1 to A9;
• Zone B – 16 physiographical units, from B1 to B16;
• Zone C – 14 physiographical units, from C1 to C14;
• Zone D – 13 physiographical units, from D1 to D13.
For a better understanding of this division please see Figure 3.
In this analysis of the water quality of the Guadiana and its tributaries we also
took into account the sensible areas of the basin. These are determined
according the Decree-law n. 152/97, of 19 June, that transposes the Council
Directive 91/271/CEE, that establishes the general conditions regarding
collection, treatment and discharge of urban wastewaters into the aquatic
medium.
This Decree-law also defines the deadlines for the operation of drainage systems
e for the installation of adequate treatment, population dimensions to which it
applies and procedures of analytical control for the discharges made in those
zones.
Therefore a certain water extension will be identified as Sensible Zone if it
belongs to one of the following categories:
• Natural freshwater lakes, other freshwater extensions, estuaries and
coastal waters that are eutrophic or are prone to become eutrophic in
the near future if protection measures are not taken;
• Surface water for abstraction of potable water, which nitrates content
may exceed the nitrates concentration established in the 75/440/CEE
Directive of 16 July, regarding the quality of surface water for
production of potable water if protection measures are not taken;
• Areas where other treatments beyond that foreseen in article 5 are
needed in order to comply with the requirements of Council Directive.
An extension or zone of sea water may be identified as a Less Sensible Zone if
the discharge of wastewaters does not deteriorates the environment due to the
morphology, hydrology or specific hydraulic conditions from that zone. When
identifying those zones, the risk of transferring the discharged load to the
adjacent zones where they may be harmful to the environment. The following
aspects should also be considered: open bays, estuaries and other coastal
waters with a good renovation and that are subject neither to eutrophication
neither to oxygen impoverishment or which eutrophication or oxygen
impoverishment as a sequence of urban wastewater discharges is considered to
be improbable.
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Figure 3: Guadiana basin (Portuguese part) divided in Physiographic Units

Six Sensible Areas were identified in the Guadiana basin:

Nr. Name Identification
Section of Guadiana river from the confluence with
29 Guadiana
Caia river to the confluence with Chança river.
30 Vigia Reservoir
31 Monte Novo Reservoir
32 Múrtega Múrtega creek
33 Caia Reservoir
Sapal de Castro All Castro Marim marshland area and respective
38
Marim hydrographical basin
Table 1- Sensible Areas in the Guadiana Basin

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