ecological assessment of guadalete river, spain 2012

Assessment of the ecological state of the

Guadalete River, Andalucía, Spain

Description of the ecological state of the Guadalete River and advice

about sustainable usage of the river’s services

By

STUDENTS BACHELOR OF WATER MANAGEMENT – YEAR 4

Vlissingen, 15-11-2012

Edisonweg 4, 4382 NW, Vlissingen, Netherlands

Justification

Title : Assessment of the ecological state of the Guadalete River, Andalucía, Spain

Subtitle : Description of the ecological state of the Guadalete River and advice about

sustainable usage of the river’s services

Date : 15-11-2012

Place : Vlissingen

Country : Netherlands

Written by : Students Bachelor of Water Management – Year 4

Version : Version 1

Contact : Jasper Verhaar (student no: 00047279)

Edisonweg 4

4382 NW Vlissingen

Postbus 364

4380 AJ Vlissingen

T +31 65 206 76 74

[email protected]

Institution : HZ University of Applied Sciences

Department : Delta Academy

Degree : Bachelor of Water Management

Course : CU05026 River Basin Management

Assignment : Field Study Week 2012

Delivered to : Henk Massink

Joao Salvador de Paiva

Jouke Heringa

Michiel Michels

Tony van der Hiele

i

Preface

The HZ University of Applied Sciences (HZ) class of graduation students of Bachelor of Water

Management has been participating in a Field Study Week (FSW) as part of the course River Basin

Management. Gaining knowledge about how to investigate a water system including topics such as

selecting the correct variables, planning of activities, cooperating, presenting results and so on has

been the intention of this FSW. The water system, which has been investigated during this year’s

FSW from September 28th till October 5th 2012 (week 39/40), is the Guadalete River in the south of

Spain.

For the field week, we have formed four different groups. Each group was focusing on a different

aspect of the river basin, namely Human Activity, Hydrology, Chemistry, and Biology. Each of our

groups has prepared its own activities in weeks 36 till 39 and has been responsible for its field of

expertise. The group leaders of each group have been communicating with each other in order to

coordinate the investigation. This assessment report is a product of these four groups, formed during

the FSW and contains an introduction about the research, applied (field) methods, achieved results,

discussion, conclusion and recommendations.

We would like to thank various people for their contribution to the Field Study Week of 2012; our

supervisors Henk Massink, Joao Salvador de Paiva, Jouke Heringa, Michiel Michels and Tony van der

Hiele for their patience in guiding us and the assistance they gave during our research. As the HZ

University of Applied Sciences is taking part in the RAAK project “Het Zoute Goud” (The Salty Gold) it

was made financially possible to undertake this field week. We would like to extend our thanks to the

‘Stichting Innovatie Alliantie’ (SIA) for this support.

Also we would like to thank our international partners at the University of Cadiz and IFAPA for letting

us become acquainted with the developments of aquaculture in Spain. Special thanks should be

given to Juan Miguel Mancera Romero and Erik-Jan Malta from the University of Cadiz and IFAPA for

their support. The willingness of all the researchers at the research center of ‘Centro el Toruño’ as a

part of IFAPA to give their time for explaining their work has also been very much appreciated.

Special thanks are given to ‘Campus el Sabio’ and Marcos for making our stay in Spain as pleasant as

it could get.

Have a good time reading!

Vlissingen, October 2012

Students Bachelor of Water Management – Year 4 (2012-2013)

Wouter Bareman, Kay Bouts, Marta Canto Lopez, João da Cunha Pinheiro Naves Gomes, Marianni de

Aragao Nogare, Bart de Clerck, Pieter-Bas Dijkman, Hanneke Ebbeng, Thalitha Ferreira Arruda, Frank

Herrewijn, Frauke Hünnekes, Samara Hutting, Daniel Ivanov, João Jacobus, Jan Janse, Benjamin

Klemm, Maxim Marcenco, Daan Pijnenburg, Anna Roman, Bart Roothans, Koen Schippers, Friso

Snijder, Juliana Spohr Pereira, Xiaodong Tang, Kristiaan van Rooijen, Tim van Roon, Mitra Vaskoska,

Jasper Verhaar, Ariany Viana Gomes, Peter Vollaard and Wendy Wösten.

ii

Summary

The fourth year students of Bachelor of Water Management from the HZ University of Applied

Sciences in Vlissingen have conducted an investigation on the Guadalete River in the Province of

Andalucía, Spain in October 2012 by means of a field study.

The purpose of this field study was to identify the relationship between the ecological state of the

Guadalete River and its relation to human activity in the catchment area. A descriptive report about

the state has been written including recommendations for more sustainable usage of the river’s

ecosystem services by its users.

The outcome of this investigation indicates a poor water quality based on biological, chemical and

hydrological measurement. Often the oxygen concentrations were below the standard of 5 mg/L and

the presence of nutrients such as nitrate and phosphate was clearly measurable. Disruptive

structures made by humans (such as dams and in this case wastewater treatment plants) have been

pointed out as main causes of these problems.

Overexploitation of water from the Guadalete River is believed to be problematic in the sense of

lowering of the discharge and therefore the availability and diversity of natural habitat for local flora

and fauna. Although it has been said that the Spanish government applies water saving measures,

still a lot of water is used for irrigation of crops (mainly cotton) and golf courses. In the past, a weir

was constructed relatively far inland to prevent salt water entering upstream zones of the river. This

weir, together with large dams may form obstacles for migrating aquatic animals such as fish and

crayfish.

Challenges for the local government of the region of the Guadalete River lie in providing better

treatment of waste- and runoff water by constructing wetlands for the elimination of polluting

substances, solving the problem of stratification in the reservoirs during dry periods, building a fish

passage at the weir, and keeping the river beds clean of waste and litter that derives from urban

areas.

Table of Contents

Preface ......................................................................................................................................................................i

Summary .................................................................................................................................................................. ii

1. Introduction ........................................................................................................................................................ 1

1.1 Background ................................................................................................................................................... 1

1.2 Assignment ................................................................................................................................................... 2

1.2.1 Aim ........................................................................................................................................................ 2

1.2.2 Research question ................................................................................................................................. 2

1.3 Chaptering .................................................................................................................................................... 3

2. Research Design .................................................................................................................................................. 4

2.1 Area ............................................................................................................................................................... 4

2.2 Planning ........................................................................................................................................................ 4

2.3 Fields of Interest ........................................................................................................................................... 5

2.3.1 Human Activity ...................................................................................................................................... 5

2.3.2 Biology ................................................................................................................................................... 5

2.3.3 Hydrology .............................................................................................................................................. 6

2.3.4 Chemistry .............................................................................................................................................. 6

3. Human Activity .................................................................................................................................................... 8

3.1 Methods ........................................................................................................................................................ 8

3.1.1 Stakeholder Interviews .......................................................................................................................... 8

3.1.2 Literature Research ............................................................................................................................... 9

3.2 Results ........................................................................................................................................................... 9

3.2.1 Policy and Legislation ............................................................................................................................ 9

3.2.2 Water Users ........................................................................................................................................... 9

3.2.3 Wastewater Treatment ....................................................................................................................... 13

3.3 Discussion ................................................................................................................................................... 15

3.4 Conclusion................................................................................................................................................... 15

4. Hydrology .......................................................................................................................................................... 17

4.1 Method and Materials ................................................................................................................................ 17

4.1.1 Discharge of the River ......................................................................................................................... 17

4.1.2 Tidal Influence ..................................................................................................................................... 18

4.1.3 Total Suspended Solids ........................................................................................................................ 19

4.1.4 Erosion ................................................................................................................................................. 19

4.2 Results ......................................................................................................................................................... 21

4.2.1 Discharge of the River ......................................................................................................................... 21

4.2.2 Tidal Influence ..................................................................................................................................... 21

4.2.3 Total Suspended Solids and Erosion .................................................................................................... 22

4.3 Discussion ................................................................................................................................................... 23

4.4 Conclusion................................................................................................................................................... 24

5. Chemistry .......................................................................................................................................................... 26


5.1.1 Field Measurements ............................................................................................................................ 26

5.1.2 Laboratory Measurements .................................................................................................................. 27

5.2 Results ......................................................................................................................................................... 27

5.2.1 Field Measurements ............................................................................................................................ 27

5.2.2 Laboratory Measurements .................................................................................................................. 30

5.3 Discussion ................................................................................................................................................... 34

5.4 Conclusion................................................................................................................................................... 34

6. Biology ............................................................................................................................................................... 36


6.1.1 Macrofauna Sampling ......................................................................................................................... 36

6.1.2 Macrophyte Sampling ......................................................................................................................... 38

6.1.3 Biotic Index .......................................................................................................................................... 38

6.1.4 Ecological Quality Ratio ....................................................................................................................... 39

6.2 Results ......................................................................................................................................................... 40

6.2.1 Biotic Index .......................................................................................................................................... 40

6.2.2 Ecological Quality Ratio ....................................................................................................................... 41

6.2.3 Macrophytes........................................................................................................................................ 41

6.3 Discussion ................................................................................................................................................... 43

6.4 Conclusion................................................................................................................................................... 43

7. Comprehensive Discussion ................................................................................................................................ 46

8. Comprehensive Conclusion ............................................................................................................................... 47

9. Recommendations ............................................................................................................................................ 49

9.1 Sufficient treatment of wastewater/irrigation water ................................................................................. 49

9.2 Oxygen level ................................................................................................................................................ 52

9.3 Concrete weir ............................................................................................................................................. 53

9.4 Waste/litter in and around the river .......................................................................................................... 54

9.5 Research ..................................................................................................................................................... 54

10. Literature ......................................................................................................................................................... 55

Appendix I: Example of erosion calculation .......................................................................................................... 58

Appendix II: Cross-sections and hydraulics ........................................................................................................... 59

Appendix III: Flow velocity .................................................................................................................................... 64

Appendix IV: Time lapse pictures of water level fluctuation at weir .................................................................... 65

Appendix V: Field and laboratory data chemistry ................................................................................................. 66

Appendix VI: Result tables macrofauna ................................................................................................................ 68

Appendix VII: Result tables macrophytes ............................................................................................................. 71

1

Assessment of the ecological state of the Guadalete River, Andalucía, Spain

1. Introduction

1.1 Background

The Guadalete River is a river in the Spanish region Andalucía and originates from ‘Sierra de la

Grazalema’ at a height of 1000 meters above sea level. The river has a total length of 172 km and

meets the Atlantic Ocean at the Bay of Cadiz via El Puerto de Santa Maria south of Cadiz (see figure

1.1) (Rutas Rurales en Cadiz). On its way the Guadalete River receives water from the Majaceite River

as one of its major tributaries (El Rio Guadalete).

The Guadalete River is part of the Guadalete and Barbate river basin (see figure 1.2). The relatively

high average temperature of 16.8°C and long periods of drought in the region of the Guadalete River

result in high uptake of water for multiple purposes. During short periods of heavy rainfall the dry

soil can easily be flushed away with runoff water into the surface water. This may result in high

concentrations of nitrogen from soil fertilizers and the presence of toxins from pesticides

(Deputacion de Grenada 2010).

Figure 1.1 Location of Guadalete River (source: FSW manual and Google Earth)

Since the construction of a number of dams in the Guadalete River itself and in its major tributary the

Majaceite River, the character of the river system is no longer hundred percent natural. Dams were

built to create reservoirs which are man-made lakes serving in water supply for drinking water,

irrigation and flood protection. Between 1900 and 1950 the number of reservoirs in Spain had a

growth rate of more than four per year and reached a number of 741 by 1975. Today, there are 1172

large dams. The effect of dams on the natural character of a river can be enormous; the hydrological

cycle will change and subsequently affect the ecological state. In particular fish will have major

problems migrating up and down a river that is dammed (European Environment Agency).

2


Figure 1.2 River basin ‘Guadalete and Barbate’

1.2 Assignment

Graduation students of Bachelor of Water Management of the HZ University of Applied Sciences are

assigned to describe the aquatic system of the Guadalete River by means of planning an

investigation, conducting measurements on the river, and writing an informative/advisory report.

The students should learn about the functioning of the river by measuring hydrological, chemical and

biological variables. Moreover, the assignment functions as an opportunity for the students to apply

theoretical and practical knowledge about water management – gained during their study at the HZ –

to a real case scenario.

1.2.1 Aim

The aim of this investigation is to analyse the relationship between human activity along the

Guadalete river (in terms of policy & legislation, water usage, and wastewater treatment) and

ecological functioning of the Guadalete river (in terms of hydrology, chemistry and biology) in order

to advice local authorities about sustainable use of the river’s services.

1.2.2 Research question

The main question which should be answered during this investigation can be described as follows:

How can the relationship between human activity along

and ecological functioning of the Guadalete River be

described, and how can this be transformed into an advice

about sustainable usage of the river’s services?

3


1.3 Chaptering

This report is structured according to four disciplines; Human activities, Hydrology, Chemistry and

Biology respectively presented in chapters 3, 4, 5 and 6. Prior to this, in chapter 2, the design of the

research is given in which the research area, planning and theory of the disciplines are described. In

chapter 7 and chapter 8 comprehensive discussion and comprehensive conclusion of the results are

given respectively. The main section of this report is rounded off in the form of recommendations in

chapter 9 in which the conclusions of this study are transformed into an integrated advice.

4


2. Research Design

2.1 Area

The area of the Guadalete river that is investigated in this study stretches from the dam of the

reservoir located at the city of Arcos de la Frontera (50 km northeast from Cadiz as the crow flies) to

the mouth of the river at the city of El Puerto de Santa Maria were it enters the Bay of Cadiz. The

length this stretch is approximately 170 km.

Figure 2.1 Location and water related features of the Guadalete River in Spain

The upstream area of the stretch lies in an area which is characterized by hills and steep slopes

combined with small urban areas and agricultural rural areas of Arcos de la Frontera. Further

downstream it gradually changes into a more flattened landscape consisting of mainly agricultural

parcels and small cities and villages near the river. Closer to the river mouth the Guadalete passes

the south side of the relatively large city of Jerez de la Frontera. Finally, the Guadalete river enters

the Bay of Cadiz just after passing by the city center of El Puerto de Santa Maria (see figure 2.1).

2.2 Planning

The Guadalete River is investigated by a team of student engineers during the first and second day of

October, 2012 and half of the subsequently day of field study. During this period of time

standardized research methods were used to extract data which can even be understood by people

with little to no knowledge about water management.

The team of student engineers (Bachelor of Water Management) consists of twenty-nine persons of

whom seven are exchange student with a background of Civil Engineering in Brazil and Biology in

Spain. The regular (twenty-three) student engineers are enrolled in the fourth year of the Bachelor of

Water Management program and are expected to graduate in the summer of 2013. Their

background knowledge consists of an integration of biological, hydrological, chemical, and social

aspects of fresh and saline (global and local) water system management.

5


Although it would be logical to use the European Water Framework Directive (EWFD) as a guideline

for this investigation, it has only partly been adopted here. Moreover, instead of Spanish assessment

methods, Dutch assessment methods have been applied. The main reason for this is that the Spanish

Government does not (yet) applies this directive to their water systems. This makes it not possible to

use specific Spanish standards. Moreover, due to a limited period of field study time (2.5 days) and

preference for a maximized number of sampling points it would be more beneficial to investigate

only the basic characteristics of the river system instead of a wide arrange of parameters.

2.3 Fields of Interest

The Guadalete river is investigated according to four different disciplines (or fields of interest),

namely: Human Activity, Hydrology, Chemistry and Biology. The following paragraphs introduce the

disciplines in terms of aim and motivation. Methods, results, discussion and conclusion of each

discipline can be found in the subsequent chapters 3, 4, 5 and 6.

2.3.1 Human Activity

This discipline describes the impact of human activity along the river, taking into account: policy &

legislation, water users (aquaculture, agriculture, industries, and recreation), and wastewater

treatment. By means of interviews with stakeholders and literature research important information

is gathered which can be connected to the other fields of interest in this research.

It is important to know how the activities of human that live near the Guadalete River influence the

ecological state of the river in terms of biology, hydrology and chemistry. Straight forward we could

say that there is some kind of influence anyway since humans are part of the ecosystem for

thousands of years. However, the population of the Cadiz region has not always been as high as it is

today, while the Guadalete River and its catchment area and water regime (based on climate) did not

change in such a high rate. Most likely this results in a growing pressure on the ecological functioning

of the river system. Under the discipline of ‘human activity’ as part of this study, we aim on

identifying the human activities that are expected to have a major influence on the ecological state

of the Guadalete River.

2.3.2 Biology

This discipline describes the biological aspects of the Guadalete River and surroundings. The

emphasis of the Biology discipline lies on the identification of macrofauna and macrophytes living in

and near the water. Based on the species that are found an estimation of biological quality of the

river system can be made and connection to the other disciplines can be laid.

In order to perform a multi-habitat measurement sampling of the macrofauna, all the present

habitats at the location should be sampled. Furthermore it is very important to take samples in the

right (optimal) time of year, to get a good representation of the present macrofauna. The ideal

conditions for collecting macrofauna samples in freshwater habitat is once or twice a year. The

samples can be collected from March till October (in order to apply the EWFD). Samples are to be

collected in such a way that the samples represent the water body. Manmade constructions should

be avoided, for they might disturb the sampling and the results from it. A multi-habitat sampling

method should be applied from the riparian zone till the deeper water.

6


2.3.3 Hydrology

This discipline describes the hydraulic and hydrological elements of the river system in terms of

qualitative and quantitative aspect. Important aspects to this area of research are: flow velocity, flow

rate (discharge), tidal influence, and erosion/sedimentation.

Basic information about flow rate (based on flow velocity and cross-sectional area) is collected for

the Guadalete River and its tributaries. Such information can be important to resolve question not

only related to hydrology, but also to the other fields of interests of this study.

The Guadalete River ends in the bay of Bay of Cádiz, therefore we assume there is at least a part of

the river which is influenced by the tide. It is important to know how far this tidal influence reaches

upstream. Probably this will be till the weir south of El Portal (see figure 2.2). To test this hypothesis

a measurement of the water level right after the weir (downstream) is performed. The water level is

measured every thirty minutes for a couple of hours. In this way, if there is indeed tidal influence, the

water level will rise or decline. The hypothetical water level rise or decline will be connected to a rise

or decline of the tide in the Bay of Cádiz.

Figure 2.2 Weir located south of El Portal

Sediments play an important role in the elemental cycling in aquatic environments. Most sediment in

surface waters originates from surface erosion. For the purposes of aquatic monitoring, sediments

can be classified as deposited or suspended. Deposited sediment is that found on the bed of a river

or lake. Suspended sediment is that found in the water column where it is being transported by

water movements. Many suspended sediments means there is a low visibility. And a low visibility will

influence the algae growth and biological activity in and around the river. Therefore a measurement

to determine the total suspended solids (TSS) is conducted.

2.3.4 Chemistry

This discipline describes the chemical aspects of the river system, taking into account: oxygen

concentration, pH, salinity, temperature and nutrient concentration. Combined, this discipline can

present the water quality and the transport of different substances in the Guadalete River obtained

by field measurements (see figure 2.3) and laboratory analyses.

7


Oxygen is necessary for life in water. If the value is lower than 5 mg/L, there is an increased risk of

oxygen deficiency for heterotrophic organisms. The pH is a very important indicator for the condition

of the water system. The pH also indicates the presence of carbon dioxide in the water as in most

water systems carbon dioxide and carbonates have a large impact on the pH. The salinity is

important because the influence of the tide could be determined based on this.

Ammonium (NH4+-N), nitrite (NO2-N), and nitrate (NO3-N), taken together as dissolved inorganic

nitrogen (DIN) are important nutrients in the nitrogen cycle. The nitrogen cycle consists of different

important processes like nitrogen fixation, mineralization, nitrification and denitrification. The

measured parameters are key elements in these processes so they can give a good insight about the

nitrogen conversion into various chemical forms in the aquatic system of the Guadalete River.

Ortho-phosphate (PO43—P) is an important nutrient because it is often responsible for eutrophication

in ecosystems. Eutrophication means that there are too many nutrients in the water. This could lead

to an algae bloom and eventually to oxygen deficit. It is also a key element in most fertilizers so it can

give a relationship between human activity and ortho-phosphate concentrations found in the

Guadalete River.

Figure 2.3 Field measurements to determine chemical water quality of the Guadalete River

8


3. Human Activity

Human activities which are believed to have a significant effect on the ecological state of the

Guadalete River have been investigated during this study. In this chapter the influences of human

activity, namely policy & legislation, water users, and wastewater treatment, are described in terms

of methods, results, discussion, and conclusion.

3.1 Methods

3.1.1 Stakeholder Interviews

Interviews with stakeholders of the Guadalete River were conducted during the two field days in

Spain (see figure 3.1). Via internet sources and literature a select list of different types of

stakeholders was created including municipalities, crop- and fish farmers, recreational facilities, and

waste water treatment plants. For each type of stakeholder a specified list of questions was

prepared. By e-mail and telephone the stakeholders were contacted and appointments for face-to-

face interviews were made possible.

Figure 3.1 Interview with staff members of municipality of El Puerto de Santa Maria. From left to right: Ceferino Delgado

Gómez (legal advisor municipality), Juan Carlos Neva Delgado (biologist municipality), Juliana Spohr (student HZ

University), Joao Jacobus (student HZ University), and Joao Salvador de Paiva (supervisor HZ University)

9


3.1.2 Literature Research

Literature research was performed before, during and after the field days in order to find supportive

data for the findings in the field. Scientific articles, webpages, textbooks and journals have been

studied to find background information about the selected aspects of human activity along the

Guadalete River.

3.2 Results

3.2.1 Policy and Legislation

For a better understanding of the Spanish legislation and in order to clarify the mechanisms of

administration of water from the Guadalete River, an interview was conducted with the environment

department of the city of El Puerto de Santa Maria. The biologist responsible for environmental

planning Juan Carlos Neva Delgado and Ceferino Delgado Gómez (legal advisor) reported that from

the year 1979 each province is recognized as an autonomous community with its own normative. In

the case of Guadalete River, managed by the province of Andalucía, it is worth remembering that the

river lies within a single province. For this reason the administration is responsibility of Andalucía.

However, in cases where the rivers cut more than one province administration responsibility is for

the federal government.

Each province is provided with its own wastewater treatment, but, in the case of Guadalete province,

many of them have only a primary treatment with no chemical treatment. Nevertheless, the province

classifies the quality of the Guadalete River as ‘Excellent’. The biologist Juan Carlos emphasized the

return of many native species that had disappeared from the river and now, after 30 years, are

returning to their habitat. Even with the return of biodiversity, other species such as lobster and

corvina that used to be benefited by the incoming salt water and going up the river to reproduce,

today cannot overcome the small weir built at the entrance of the river, restricting their

reproduction area. This weir was installed to reduce salt water intrusion during high tide. In addition

native fish species disappear due to illegal introduction of ‘sport fish’ (invasive) species. However, the

government does provide licenses for fishing on these species.

3.2.2 Water Users

Aquaculture

In Andalusia and near the Guadalete River, aquaculture is the one industry that can be seen most

often. Because of the tidal influences of the area the investment in onshore aquaculture business

soon became profitable. Extensive culture of fish, mollusks and crustaceans are most common in old

salt marshes or “Salinas” that were used for the production of salt. These Salinas were turned into

aquaculture facilities which are called “Esteros”. In 2001, the Ministry of Agriculture and Fisheries

was founded and the development of aquaculture plants and business has grown a lot. Now, in the

province of Cadiz, there are 35 land based marine aquaculture and 3 sea based sites. The marine

aquaculture is the best feasible option because of the big influence of the Atlantic Ocean at the

aquaculture zone. The province of Andalucía is known for its production of dorada or sea bream (see

figure 3.2), which take up 64% of the total production of almost 7.500 tons. Still this total production

is increasing every year as there are a lot of experiments done on types of aquaculture (Rivero et al,

2004).

10


Figure 3.2 Example of land-based sea bream cultivation in Andalucía, here at research center IFAPA ‘Centro el Toruño’

The effect of an aquaculture business on the river system is completely depending on the types of

culture and the techniques that are used. Sea bream and sea bass are the most exploited species in

the province of Cadiz, where they mostly combine these farms with the production of salt. When

looking at the usage of water in these plants you see that there are low numbers of net water losses.

Most of the combined and extensive aquaculture plants use sea-water and little water from the

Guadalete River. The water is not pretreated and also after usage it is not treated most of the times.

However, because of the natural character of these extensive plants the water is not much polluted

at all. Fish are mostly fed trough enriching the water with phyto- or zooplankton, or when there are

enough living organisms in the water no enhancing takes place at all. In this way there is not much

pollution of the river nor of the sea. There is also no control on the effluent water though, which can

be necessary to check if water treatment is needed.

Agriculture

For many centuries, Andalusia’s society was mainly agriculture. Even today, 45% of the Andalusia

territory is cultivated. However, looking at the Guadalete – Barbate river basin (see figure 3.3) a total

irrigation area of about 60,498.9 ha is used for agricultural purposes. The by far biggest irrigated area

is cultivated with cotton crops, which occupies an area of about 14,250 hectares, followed by winter

crops with about 10.3 ha. The third largest group is made up by sunflowers and outdoor horticultural

crops 12.4% (7,510 ha) and 11.8% (7,165 ha) of the surface area, respectively. High usage of water

consumption for agriculture use comes from large irrigation schemes such as the Guadalcacín area or

the Northwest Coast of Guadalete – Barbate river basin. These areas require a total volume of 199.3

11


hm3 of gross water demand (62% of total volume), where 58% is used for irrigation of the crop fields,

namely 34.9 ha.

Figure 3.3 Guadelete-Barbate river basin with irrigation water sources (source: Junta de Andalucía)

The water used in the Guadalcacin area for irrigation comes mainly from surface water, namely the

Guadalete River and other surface waters, which make with 272,80 hm3, 85% of the irrigation water,

followed by underground water (39.02 hm3), which is extracted from dwells in the area (see figure

3.4).

Figure 3.4 Sources of water used for irrigation in the Guadalete-Barbate river basin (source: Junta de Andalucía)

12


Industries

In Spain, Jerez de la Frontera is the main capital for production, procession and distribution of sugar.

The sugar beet production is part of a crop cycle where settling ponds store and recycle water. These

water reserves attract in many times different types of amphibians, reptiles and mammals. Also, in

Spain, the wetlands created by the company of Azucarera combine the ponds for an industrial use of

water with the development of wildlife. Populations of Flamenco birds flourish in the ponds of

Azucarera (International Confederation of European Beet Growers & Comité Européen de Fabricant

de Sucer, 2012)

The market leader in Spain “Azucarera” produces around 90.000 tonnes of sugar per year. Because of

the size of the company it provides thousands of jobs at the Port of Cadiz. For the growth of the

sugar beets the company is highly dependent on the water provision from the area. Therefore the

water reservoirs in the upstream part of the river Guadalete River are of big importance for

Azucarera and the growth of the sugar beets. For providing a higher level of sustainability within the

production of sugar the company invested in a fermentation tank, a central distributor for southern

Ibiria and increased the production of sugar from imported sugar canes (F.C. Aleu, 2012).

To improve the usage of water at the beginning of the chain, where the sugar beets are being

produced, research is being done to get a better grip on the water management of the farmer. The

price of water can change in Spain due to possible drought. Therefore different optimizations can be

made to save water and energy during the growing period of the sugar beets. Here you can think of

the water price but also the energy required raising the water to a certain height for irrigation, the

cost for maintenance of the water pumps, irrigation equipment and so on. There has been done a lot

of research to find an optimum in the use of water, but there is still more research needed to make

an integrated approach (Velicia, H., 1996).

Recreation

Spain is known as one of the most popular holiday countries in the world. Especially in summer –

when the climate is hot and dry – hotels and residential villas are highly occupied. However, during

the yearly holiday season a lot of water is used by tourist. For example, an average Spanish citizen

uses approximately 250 liter of water per day, while the average tourist uses 440 liters. This number

can even get doubled if the tourist uses swimming pools and golf courses as well (WWF 2001).

Overall, the tourist water consumption has increased since 1994 by about 80% (Stefano 2004).

Cities and villages near the Guadalete River facilitate many tourists each year. Arcos de la Frontera

for example is famous for its scenic white houses and steep cliffs on which they are built on.

Furthermore, El Puerto de Santa Maria and Cadiz, positioned at the Bay of Cadiz, attract many

tourists for their historic city centers and many beaches. It is expected that like the general trend in

Spain tourists near the Guadalete River use a lot of water too.

In the province of Cadiz five golf clubs with a total of nearly 330 ha of grass fields are located

relatively close to the Guadalete River. Although the water consumption of a golf course depends on

many factors such as size, weather conditions and soil characteristics an estimated volume of 2,500

m3 per day can be used on a hot day. On average a standard 18 hole golf course (with an irrigated

surface of 54 ha) might consume around 0.3 Hm3 per year (Salgot 2012).

13


Golf club ‘Sherry Golf Jerez’ in Jerez de la Frontera says to use mainly rain water to irrigate their

fields. The rain water is collected from land uphill during the rainy periods of the years and stored in

the ponds on the golf course (see figure 3.5). By reusing its own irrigation water it sporadically

happens that there is a shortage (according to personal communication with a representative from

‘Sherry Golf Jerez’). When there is a shortage in extremely dry seasons, the golf club says to buy

water from a local supplier (reused water) and does not extract water directly from the Guadalete

River nor aquifer by themselves.

Figure 3.5 Northern part of 'Sherry Golf Jerez' with its many ponds (dark green areas) which are used for (re)capturing of

water

3.2.3 Wastewater Treatment

Facilities

The wastewater treatment plant (WWTP) of Jerez de La Frontera, better known as EDAR Guadalete

(see figure 3.6), treats an average volume of 70,000 m³ wastewater per day. This amount of

wastewater is mainly from the urban area of Jerez de La Frontera itself, Guadalcacin, Los Albarizones,

La Corta, El Portal and Estella. That way, the main two cities that contribute for the amount of

wastewater are Jerez and Estella, with nearly 211,000 habitants and 14,000 habitants respectively,

according to the city hall websites. All the other areas are part of Jerez or too small to be considered

(for an example, the Los Albarizones, being part of Jerez, and with only 420 habitants). The total

amount of habitants who use the services of the EDAR Guadalete are around 225,000, but the facility

has a capacity to treat water from 250,000 habitants.

14


Figure 3.6 Wastewater treatment plant of Jerez de la Frontera with effluent discharge in the Guadalete River (bottom)

According to the company which provides the service of wastewater treatment of Jerez de La

Frontera, Aguas de Jerez, the plant has three phases of treatment. The wastewater first passes

through a pre-treatment that removes the grease and sand from the wastewater. After that, the

actual treatment starts, first with a decantation, that produces the first sludge, and then with a

biochemical reactor with recirculation, which produces more sludge. Finally, the water passes

through two banks of mercury lamps, consisting of ultra-violet disinfection. The whole process is

considered to be a full tertiary wastewater treatment system.

The executive company Aguas de Jerez states that the wastewater treatment plant’s effluent has

such good quality that it is usable for reutilization for some municipalities’ services, such as watering

green public places or some private services such as watering the golf courses. Unfortunately is not

possible the reutilization for residences, mainly because of the concentration of E. coli (between 0

and 200 UFC/100mL) and suspended solids (between 10 and 20 mg/L).

Policy of waste water

There are many laws concerning water spill and wastewater in Spain. In this maze of legislation and

organizations, we could find some of the most important regulations and directives for the effluent

from a wastewater treatment plant, and who is responsible for monitoring this effluent.

First of all, the “Organismos de Cuenca” (Basin Organizations in free translation) is responsible for the

monitoring of the wastewater (according to “Art. 21 of the Ley de Aguas of 08/08/1985” in Spain’s

Water Law). With that in mind, the “Confederación Hidrográfica de Guadalquivir” is the responsible

for the planning, management and controlling of the Guadalete Basin. Even though this organization

system seems straight forward, there are many other laws and organizations responsible for parts of

the river basin system control. Because of this, the policies in Spain are sometimes like a web that

merges with the European legislation, making a confusing background to what should be a simple

and important law.

15


3.3 Discussion

The information we have collected during the stakeholder interviews and literature research is

valuable in the sense of confirming our predictions about the influence of human activity on the

ecological state of the Guadalete River. We are now able to give an indication whether the selected

activities performed by the selected stakeholders of the river have significant effects or not.

However, the quality of the collected data should be very well discussed here. Stakeholder interviews

did not provide us the amount of information that we were expected to get. It turned out that many

of our selected contacts were not available for questions for a variety of reasons. Much of the

information given in this chapter is therefore coming from a small amount of sources; mainly

literature which might be old dated and even revised by now. Due to the limited amount of

information from interviews it was difficult or not possible to compare opinions of stakeholders

active in the same branches. Such information would have been highly valuable since it gives

different points of views which would have made our results less subjective.

Regarding the results of the different types of human activities presented in this report we can say

that all but one type complies with our prediction of influencing the ecological state of the Guadalete

River. That one type turns out to be the aquacultural activities in the region of the river since not

many companies use fresh water in their systems. The reason for this ‘false’ prediction probably lies

in the preparation of our research. More intensive research would have shown beforehand that

these companies do not use fresh water from the Guadalete River.

The types of human activity that do comply with our predictions – having significant influence on the

river’s ecological state – do not interfere with the widely accepted views on such topics. It is

generally known that a wastewater treatment plant has a major effect on the environment (positive

or negative according to its functioning) for instance. And that domestic and industrial use of river

water is influencing the water regime of a river is already known.

Nevertheless, the confirmation of human activities being present in the region of the Guadalete River

and the (limited) data will be anyway useful for answering the question of the other fields of interest

and for answering the main question of this investigation.

3.4 Conclusion

The aim of investigating the human activities of the Guadalete River was to test whether the selected

activities (policy & legislation, water usage, and wastewater treatment) actually have a significant

impact on the river’s ecosystem. We have tested this by interviewing stakeholder whom perform

such activities and by studying literature. The expectation was that the three types of activities had a

significant impact.

Policy & Legislation

The management of the Guadalete River falls under the responsibility of the Province of Andalucía

since this is the only province in which the river is located. In cases of rivers which cross multiple

provinces another policy is applied, namely that the responsibility is for the federal government. We

presume that the management of a river which falls under the responsibility of a province (such as

the Guadalete River) is better managed compared to a governmental-managed river. Most likely a

province has much more (historic) knowledge about a river than that a large institution would have.

Still, we have identified some contradictions in the qualification of the Guadalete River by the

16


managing province; according to our sources the river is qualified as ‘Excellent’ by the province, while

municipal experts agree on the need of improvement of migration routes of certain organisms.

Moreover, we have found out that release of exotic species of fish into the Guadalete River is

forbidden while the permits handed out for sport fishing are based on the presence of such species.

Water Usage

The extraction and discharge of water by aquaculture companies does not seem to have a significant

effect on the ecological state of the Guadalete River. The majority of aquaculture companies

cultivates saline species and therefore uses salt water from the Bay of Cadiz. Feed that is used in

these companies are mostly cultivated by the companies themselves.

Agriculture in the region of the Guadalete River makes up a very large part of the total water use of

the river. Cotton is the type of crop that is cultivated most in this area and therefore consumes the

majority of water. 85% percent of the total volume of water used for irrigation derives from surface

waters such as the reservoirs of the Guadalete River.

According to our results industries near the Guadalete River make use of river water. They do not

extract the water from the river directly but indirectly they use it by buying water from the reservoirs

in the Guadalete and Majaceite River. The extraction of water from these reservoirs must have an

impact on the ecological function of the river since less water is left for organisms to inhabit the area

and habitat is expected to be less diverse. However, businesses like the sugar factory discussed

earlier in this chapter do benefit from water saving measures in times of scarcity.

We can make the same statement for recreational activities along the Guadalete River; the more

activities take place in forms of tourist attraction, the more water is used from the reservoirs. An

increase in number of tourist in the region of Cadiz is expected and therefore a higher pressure on

the water availability for the river itself.

Wastewater Treatment

If, according to information found on the website of “Aguas de Jerez” (managing company of the

wastewater treatment plant in Jerez de la Frontera), the process of tertiary wastewater treatment

functions as it should, the effect of this activity should be positive for the Guadalete River’s

ecosystem. The plant’s capacity is said to be higher than the number of people served at the moment

so no problems are expected. However, the local newspaper reported a strike of the employees from

“Aguas de Jerez”, they were complaining about the inefficiency of the water treatment, in addition

reported that some liters of sewer were thrown into the river without any treatment. This story can

be confirmed by many surrounding dwellers who also complain about the water quality of the

Guadalete River.

Even though all those problems without the presence of this wastewater treatment facility (and the

other smaller ones in the region) the state of the river would have been much worse. Nevertheless,

proper wastewater treatment is a standard for today’s society and therefore it should be logical that

every modern household is connected to the sewage system. It turned out not be the case in the old

city centers of Jerez de la Frontera and El Puerto de Santa Maria, resulting in the discharge of

untreated wastewater into the Guadalete River.

17


4. Hydrology

The hydraulic and hydrological elements of the river were investigated in a stretch of approximately

110 km running from the point where the Majaceite river meets the Guadalete river till the mouth of

the river in the Bay of Cadiz (see figure 4.1). In this chapter the analysis of the influences of the

hydrology in terms of qualitative and quantitative aspects of the river is described in terms of

methods, results, discussion and conclusion.

Sampling point code: 10 20 30 40 50 60 100 110 120 130 140 150 160 170 180

Distance from starting point (km): 0 6 23 24 34 39 56 67 73 75 84 86 92 99 107

Figure 4.1 Map of Guadalete River with sampling points for hydrological measurements

4.1 Method and Materials

4.1.1 Discharge of the River

To determine the discharge (Q in m3/s), two different parameters should be known: (1) the velocity

(v in m/s) and (2) the surface area (A in m2) of the cross section of the river. By using equation (E4.1)

the discharge can be calculated.

� = � ∗ A (E4.1)

The cross-sectional area is determined by stretching a tape across the river channel (L total (in m)) and

measuring the depth of the water level at different points (D1, D2, etc. (in m)) along this tape (see

figure 4.2). By doing this, different sub-segments are created with a specific area which can be

calculated by using equation (E4.2) (see figure 4.3).

�2 × 0,5� �� × ��ℎ (E4.2)

18


Figure 4.2 Measuring the river’s depth with a scaled pole

The area for the segment can be calculated by using the 2 depths (D1 and D2) and the trapezium

formula (E4.3). At the same place as the depth measurements (D1, D2 etc.) the velocity is measured

with a digital water velocity meter (V1, V2 etc. in m/s). The sub segment 2 velocity is calculated by

taking an average of V1 and V2, which should give you the velocity in the middle (4.3, green line) of

the segment (E4.4). Then the discharge of the different sub-segments is calculated with equation

E4.1. The total discharge is calculated with E4.5. See figure 4.3 for additional information.

Asg2 = (Lsg2*(D1 + D2))/2 ` (E4.3)

Vsg2 = (V1 +V2) /2 (E4.4)

Qtotal = Qsg1 + Qsg2 + Qsg3 +Qsg4 etc. (E4.5)

Figure 4.3 Diagram of method to determine cross-sectional area (blue line indicates the water level)

4.1.2 Tidal Influence

To determine whether there is tidal influence up to the weir near El Portal, a distance of 16km from

the mouth of the river, fluctuation of the water level right after (downstream) the weir is

19


determined. During a period of three hours the water level is measured every thirty minutes. In this

way, if there is indeed tidal influence, the water level will rise or decline. The hypothetical water level

rise or decline will be connected to a rise or decline of the tide in the Bay of Cádiz.

4.1.3 Total Suspended Solids

At different sample locations a plastic bottle is filled with river water. This is done as far away from

the riverbank. This river water is filtered through filter paper to determine the dry weight of the

suspended sediment. The value of total suspended solids (TSS in mg/l) is calculated by using equation

(E4.6).

�� = �� !"�# �� $%#&'�

(E4.6)

4.1.4 Erosion

Different samples of the river soil is taken and compared with a ‘sand standard rural’ (or sand ruler)

(see figure 4.4) to determine D50 and D90.

Figure 4.4 ‘Sand standard rural’ with soil sample (centered) and different

comparative samples to determine D50 and D90

When the D50 and the D90 is found, equation (E4.7) is used to determine the critical velocity (a = 0.28

for sand, a = 0.12 for clay). This means when the river at this specific point has a higher velocity than

the critical velocity erosion (sediment transport) will occur. Equations (E4.8) and (E4.9) are used to

calculate Ck. See appendix I for an example calculation.

� = ( × )* × +,-. (E4.7)

V = critical velocity at which the material starts moving (m/s)

a = factor depending on the density of the material

Ck = Chezy’s coefficient (m½/s)

d90= “maximum” grain size, 90% (m)

)* = 18log 456789

(E4.8)

R = hydraulic radius (m)

20


: = ;<

(E4.9)

A = cross sectional flow area (m2)

O = wetted perimeter

With the help of the Hulström diagram (see figure 4.5) it can be determined under which

circumstances (relation between flow velocity and grain size) erosion, deposition or transport of

sediment occurs.

Figure 4.5 Hulström diagram indicating erosion, transport or deposition of sediment according to flow velocity and grain

size

21


4.2 Results

4.2.1 Discharge of the River

In figure 4.6 the results of discharge calculations are presented in a graph. Detailed data of cross-

sectional area and flow velocity needed to calculate the discharge can be found in appendix II and

appendix III.

Figure 4.6 Discharge of the Guadalete River in m

3/s as a function of the distance along the river in kilometers. The x-axis

starts at the most upstream sampling point (20), indicated by zero. It ends at the most downstream point at the weir

(150). Besides the weir, two other points are indicated in the graph; the addition of water from a side river (Majaceite)

and the water from the WWTP of Jerez de la Frontera. The arrow indicates at which point it is located along the

Guadalete (it is not a separate measuring point). The polynomial line gives an indication of the trend of the discharge

along the river.

4.2.2 Tidal Influence

The measurement to determine the fluctuations in the water level right after (or at) the weir is

shown in figure 5.7 where the water level at the weir (red line) between 15:45 PM and 18:45 PM and

the water level in the Bay of Cádiz (blue line) on 3 October 2012 are presented. Note that the y-axe

corresponds with the water level in the Bay of Cádiz but not with the water level at the weir. For the

water level at the weir only a fluctuation is shown. However, time lap photographs shown in

appendix IV may give an acceptable impression of the fluctuation over time. Measurements right

before (upstream) the weir did not show any fluctuation in water level over a time period of seven

hours on 2nd October 2012.

0

0,5

1

1,5

2

2,5

0 20 40 60 80 100 120

Dis

cha

rge

(m

3/s

)

Upstream Guadalete distance (km) Downsteam

Side river

+ 0,3 m3/s

WWTP

+ 0,8 m3/s

Weir

22


Figure 4.7 Water levels under tidal influence in the Guadalete River (red line) and at the bay of Cádiz (blue line) as a

function of time in hours taken on 3 October 2012. This chart shows the possible difference in time between high/low

tide at the weir and at the mouth of the river. NOTE: the blue line corresponds with the y-axis, but the red line is only an

indication of the tidal difference. The actual height of the tide compared to the one at Cádiz is not known. Do not

compare the water levels of the two different lines, only compare the trend.

4.2.3 Total Suspended Solids and Erosion

Table 4.1 and the graph in figure 4.8 show the results of the erosion and TSS measurements in the

Guadalete River. With the parameters shown in the table it can be determined if there is erosion or

not (based on Hulström diagram, refer to figure 4.5). The TSS is also shown in the table, but it has no

direct relation to the other parameters.

Table 4.1 Overview of results of analyzed parameters that are needed to determine erosion

Location Grain size

(m)

D50

(m)

D90

(m)

a R Ck Vm

(m/s)

V

(m/s)

Erosion

TSS

(mg/l)

20 0,000315 0,000151 0,0002714 0,28 0,57 79,2 0,272 0,007 No 0,1002

35 0,000004 0,000002 0,0000036 0,12 0,26 106,9 0,018 0,060 Yes 0,2572

30 0,000004 0,000002 0,0000036 0,12 0,50 112,0 0,019 0,178 Yes 0,2572

40 0,000004 0,000002 0,0000036 0,12 0,68 114,4 0,019 0,081 Yes 0,2572

60 0,000004 0,000002 0,0000036 0,12 0,95 117,0 0,020 0,074 Yes 0,5535

100 0,000004 0,000002 0,0000036 0,12 0,68 114,4 0,019 0,166 Yes 0,5815

110 0,000004 0,000002 0,0000036 0,12 0,38 109,8 0,019 0,144 Yes 0,5930

120 0,000004 0,000002 0,0000036 0,12 0,94 116,9 0,020 0,017 No 0,7675

160 0,000004 0,000002 0,0000036 0,12

145 0,000004 0,000002 0,0000036 0,12

150 0,000004 0,000002 0,0000036 0,12 1,24 119,1 0,020 0,007 No 0,5650

0

50

100

150

200

250

300

350

0:00 4:48 9:36 14:24 19:12 0:00

Wa

terl

ev

el

(cm

)

Time of the day (hours)

Waterlevel

at Cadiz

Waterlevel

at weir

23


Figure 4.8 Total suspended solids (TSS) in the Guadalete River in mg/L as a function of the distance along the river in

kilometers. The x-axis starts at the most upstream sampling point (20), indicated by zero. It ends at the most

downstream point at the weir (150). Besides the weir, two other points are indicated in the graph; the addition of water

from a side river (Majaceite) and the water of the WWTP of Jerez de la Frontera. The arrow indicates at which point it is

located along the Guadalete (it is not a separate sampling point). The polynomial line gives an indication of the trend of

the total suspended solids along the river.

4.3 Discussion

Cross-section and discharge

Because of heavy rainfall (approximately 200 mm) during the week prior to the field days there was

more water in the river due to runoff and groundwater extrusion, this may have led to a higher

discharge than normal1. As we expected the discharge increased while we followed the river

downstream. The measurements that have been done to construct a cross-section have not been the

most accurate because of the fine sediment on the bottom of the river. By measuring the depth of

the river by a measuring stick or lead line it was found to be difficult to feel when it touched the

upper layer of the bottom. It would have been better to have an application at the end of the

measuring stick or on the bottom of the lead line in order to increase the surface so that the stick or

the lead would not sink into the bottom. It is estimated that the difference in measured water depth

and actual water depth ranges from 0 to 15 centimeter. Since river depth ranges mostly from 0 to 2

meters deep, it is estimated that the error percentage is anywhere up to 7.5%. This estimation is

done by looking at the amount of mud on the measuring stick and/or lead thus indicating how deep

the stick/lead sunk into the sediment before coming to a stop. According to this, the actual water

depth will mostly be lower than then measured water depth.

The width of the river is measured fairly accurate. The only factor that might influence this is the

slight arch the measuring tape makes when measuring from one bank to another. The accuracy is

estimated at 1%, a 10 centimeter possible difference over a 10 meter wide river. It is difficult to

estimate the accuracy of the water velocity meter. This is influenced by the moving of the boat (on

1 Heavy rainfall observed by professor Javier Gracia from University of Cadiz

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

0 20 40 60 80 100 120

TS

S (

mg

/l)


Side river

WWTP

24


which the measuring is done) and possible irregular, or really low water velocities. The accuracy is

estimated at 5%. The percentage is this high because of the really low velocities that were measured.

The measuring device sometimes wasn’t accurate enough to measure the exact velocity.

All of these factors combined give a possible error of 7.5% + 5% + 1% = 13.5%. These percentages are

added because the factors are multiplied by each other. This percentage is rather large. However,

results show that measurements were fairly accurate. An example of this is the measurements done

at two side rivers flowing into one main river. The discharge of the two side rivers combined should

be the discharge of the main river. The difference between the measured discharge and the

calculated discharge is only 0.6%.

Tidal influence

As shown in this report the influence of the tide is only reaching to the weir. During the field days the

difference in water height at the mouth of the river was approximately 2.65 meter. As results show,

there was no change in salinity measured just downstream of the weir during the four hour

measurement. A point of discussion is that those samples were taken at the surface of the water.

Because the density of salt water is higher than the density of fresh water it is more obviously to find

any changes in salinity at the bottom of the river. It would have been better to use a ‘waterhapper’

so it is possible to take water samples from the bottom of the river as well.

Total suspended solids and erosion

There were several limitations during the course of the work on determining the erosion and

suspended solids condition. First of all we were prepared to measure sand particles by means of

“sand standard rural”, but it turned out that most of the sampling locations had clay soil for which

the our measuring method was useless. Therefore, we assumed the clay particle size from the

literature sources. Secondly, the number of the sampling locations in our opinion was not enough for

a holistic overview on the erosion situation on the river, nonetheless we determined no erosion

downstream opposed to the upstream where the clay particles were small enough to get suspended

in the water column. The method of determining the total suspended solids amount also needs

mentioning due to a slight inaccuracy in the method. Due to the absence of the needed materials, as

such – the drying oven, some adjustments were implemented. The wet weight was not used in for

the formula, instead the filters with samples were dried for 24 hours and then measured.

4.4 Conclusion

Regarding the quantitative aspects of the river this study has shown that the water that flows from

the Guadalete River into the Bay of Cadiz is built up of the discharge from the reservoir near Arcos de

la Frontera (0.36 m3/s), the discharge from the Majaceite River tributary (0.37 m3/s), the effluent

from the relatively large waste water treatment plant of Jerez de la Frontera (variable discharge), and

additionally surface runoff water and groundwater (related to precipitation). This adds up to a

discharge of 2.0 m3/s that enters the Bay of Cadiz near El Puerto de Santa Maria.

A significant influence on the hydrological aspects of the Guadalete River is formed by the weir,

located south of El Portal. Fluctuations in water levels due to high and low tides in the Bay of Cadiz

have been observed only downstream of this weir. Upstream of the weir no fluctuations in water

levels due to tidal influences have been observed. This weir was constructed to prevent salt water

intrusion in agricultural fields upstream and based on our observations salt water does not intrude

25


the upstream parts of the Guadalete River indeed. The weir seems to function according to its

purpose.

Due to surface runoff in rural and urban areas during rainy periods the amount of TSS in the river

seems to increase (built up) towards the mouth of the river. The tributary Majaceite River brings

water with a lower amount of TSS into the Guadalete River, It is also clear that the waste water

treatment plant of Jerez de la Frontera delivers water with a lower amount of TSS to the river.

The water quality of the Guadalete River is expected to be influenced by suspended solids. A high

amount of TSS means higher turbidity which again leads to less photosynthetic activity by aquatic

plants and algae and therefore less production of oxygen. Our results show an increase of TSS

towards the mouth of the river, while looking at the results of oxygen measurements (see chapter 6)

we see a corresponding decrease of dissolved oxygen concentration. This suggests there is a solid link

between the TSS, turbidity, and photosynthetic activity.

In the upper part of the river the velocity was higher than in the lower part of the river as expected in

a normal river system. However, the velocity in the lower part of the river – influenced by the weir –

was relatively low. According to the Hulström diagram this would mean that sedimentation is taking

place in this area. Erosion of sediments, therefore, takes place in the upper part of the river where

the velocity is higher.

26


5. Chemistry

The chemical aspects of the river were investigated in a stretch of approximately 170 km running

from the dam of the reservoir near Arcos de la Frontera till the mouth of the river in the Bay of Cadiz

(see figure 5.1). In this chapter the chemical aspects of the influences from the waste water

treatment plant of Jerez de la Frontera, agriculture, tributaries, and tidal influences are described in

terms of methods, results, discussion and conclusion.



Figure 5.1 Map of Guadalete River with sampling points for chemical measurements


5.1.1 Field Measurements

The parameters in the field were measured just below the surface of the water. When it was not

possible to measure directly in the water, samples were taken with a bucket. Dissolved oxygen

concentration, oxygen saturation level, pH, salinity, and temperature were measured in the field.

Salinity, conductivity and temperature

Salinity and conductivity were measured with a digital conductivity-meter (type: WTW LF 330). The

conductivity-meter measures the amount of salt in the water in g/L or conductivity in µS/cm. The

temperature (in °C) was also measured with this meter.

Oxygen

Dissolved oxygen concentration and oxygen saturation level were measured with a digital oxygen-

meter (type: WTW Oxi 330). The oxygen meter measures the concentration of dissolved oxygen in

the water in mg/L and the oxygen saturation level in percentage of saturation.

27


pH

The pH was measured with digital pH-meter (type: WTW 340). The pH-meter measures the acidity

and the amount of free hydrogen ions in the water.

5.1.2 Laboratory Measurements

At each sampling point a water sample from just below the water surface was collected. These

samples were analyzed in a temporary field laboratory. Concentrations of the following chemical

substances in the water samples were determined with a photo-spectrometer or Lasa 20 and the

Hach-kit (Hach/Dr 2400, see figure 5.2):

• Ammonium (NH4

+

- N)

• Nitrite (NO2

-

- N)

• Nitrate (NO3

-

- N)

• Phosphate (PO4

3-

- P)

• Dissolved Inorganic Nitrogen (DIN)

Analyses of chemical substances were performed according to the ‘Hach Company – manual’

Figure 5.2 The Hach-kit used by measuring the chemical parameters

5.2 Results

In this paragraph the results of the field- and laboratory measurements are presented in the form of

graphs which visualize the value of each parameter over the course of the river from the starting

point near Arcos de la Frontera towards the mouth of the river near El Puerto de Santa Maria. Raw

data of all measurements can be found in appendix V.

5.2.1 Field Measurements

Salinity

In the distance between 0 and 120 kilometres from Arcos de la Frontera no significant dissolved salt

content was observed (see figure 5.3). This can be explained by the presence of a weir (refer to

chapter 4) at around 120 kilometres which blocks saline water. Downstream of the weir the salinity

28


increases due to the tidal influence.

Figure 5.3 Salinity (g/L) measured in the Guadalete River

Temperature

The temperature in over the course of the Guadalete River (see figure 5.4) is relatively constant. At

the starting point the temperature is slightly higher. The temperature also rises a little in the lower

reaches, presumably due to mixing with sea water that has a higher temperature.

Figure 5.4 Temperature (°C) measured in the Guadalete River

Oxygen

The red line at 5 mg/l in the graph of dissolved oxygen concentration in figure 5.5 represents a

standard for the minimum dissolved oxygen concentration that is required for healthy water.

0

5

10

15

20

25

30

0 20 40 60 80 100 120 140

Sa

lin

ity

(g

/l)

Distance (km)

Salinity

Salinity

0

5

10

15

20

25

30

0 20 40 60 80 100 120 140

Tem

pe

ratu

re (

°C)

Distance (km)

Temperature

temperature

29


At the beginning of the measured stretch of the Guadalete River (starting at 0 km) a very low

concentration of dissolved oxygen was observed. Presumably this is caused by the water that was

measured derived from the hypolimnion of the reservoir near Arcos de la Frontera. The hypolimnion

is that part of the water column that is isolated from surface wind and usually receives insufficient

irradiance (light) for photosynthesis to occur as a result of stratification.

Figure 5.5 Dissolved oxygen concentration (mg/L) measured in the Guadalete River

Further downstream (at 22.5 km) the oxygen concentration is above 5 mg/L. Most likely this is

caused by the current, rock and small waterfalls present in this part of the river causing more oxygen

to dissolve from the atmosphere into the water. The concentration decreases at around 90

kilometres from the Arcos de la Frontera and even further at 100 kilometres. At these points a small

stream deriving from the suburban and rural areas and the effluent of the waste water treatment

plant enters the Guadalete River respectively. Both point sources are suspect to discharge nutrient

rich water (see also upcoming results of DIN, nitrate and phosphate) in the river which results in an

increase in oxygen demand by bacteria that decompose these nutrients.

pH

The graph of the pH (see figure 5.6) confirms the dissolved oxygen concentration in figure 5.5. At first

the pH is low because the water comes from the hypolimnion part of the reservoir near Arcos de la

Frontera. However, it changes in the course of the Guadalete River. Between the distance of 90 and

100 km from the starting point there is a drop of in the pH. The water becomes more acidic due to

the low oxygen concentrations as shown in figure 5.5. The carbon dioxide rises at those two points.

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100 120 140

Ox

yg

en

(m

g/l

)

Distance (km)

Oxygen

Oxygen

Standard

30


Figure 5.6 PH measured in the Guadalete River

When the amount of carbon dioxide (CO2) in the water increases, the pH decreases. Carbon dioxide

dissolves slightly in water to form a weak acid called carbonic acid (H2CO3) according to the following

reaction:

CO2 + H2O � H2CO3

After that, carbonic acid reacts slightly and reversibly in water to form a hydronium cation, H3O+, and

the bicarbonate ion, HCO3-, according to the following reaction:

H2CO3 + H2O � HCO3- + H3O

+

5.2.2 Laboratory Measurements

Ammonium

The graph in figure 5.7 shows two clear peaks of ammonium concentration in the Guadalete River.

Keeping in mind the earlier explanation of dissolved oxygen concentration (figure 5.5) the peak of

ammonium concentration near the reservoir of Arcos de la Frontera can be explained by

stratification as well. The hypolimnion has a low oxygen concentration, and therefore there is no or

very few oxygen available for the nitrification process that normally converts ammonium into nitrate

via nitrite.

6,8

7

7,2

7,4

7,6

7,8

8

8,2

8,4

0 20 40 60 80 100 120 140

pH

Distance (km)

pH

pH

31


Figure 5.7 Ammonium (mg/l) measured in the Guadalete River

At around a distance of 100 kilometres the waste water treatment plant of Jerez de la Frontera

causes a second peak of ammonium in the investigated stretch of the Guadalete River. Apparently

the effluent of the waste water treatment plant contains a high concentration of ammonium that is

further downstream rapidly converted into nitrate via nitrite.

Nitrite

A peak in nitrite concentration (see figure 5.8) was observed at a short distance (5 km) from the

reservoir near Arcos de la Frontera. The concentration of nitrite is expected to increase in accordance

to a decrease of ammonium. Both results comply with this theory based on the process of

nitrification; ammonium is converted into nitrite. Moreover, this theory is reinforced by the drop of

concentration of dissolved oxygen in this part of the river; oxygen is required in the nitrification

process.

At a distance of about 102 km there is a little drop in nitrite concentration. This can be explained by

the high concentration of ammonium (figure 5.7) due to discharge of effluent from the waste water

treatment plant of Jerez de la Frontera. The concentration of ammonium is higher; therefore the

oxygen concentration is lower which results in a lower concentration of nitrite.

0

1

2

3

4

5

6

7

8

0 20 40 60 80 100 120 140

NH

4+-N

(m

g/l

)

Distance (km)

NH4+-N

NH4+-N

32


Figure 5.8 Nitrite (mg/L) measured in the Guadalete River

Nitrate

The next step in the nitrification process is the conversion of nitrite into nitrate. The results of the

measurements on nitrate (see figure 5.9) are comparable to the results of nitrite (figure 5.8). The

increase at 83 km is not clear, but this can probably explained by the influence of agriculture on the

water quality.

Figure 5.9 Nitrate (mg/L) measured in the Guadalete River

Phosphate

The red line at 0.15 mg/l in the graph of the concentration of ortho-phosphate as P in figure 5.10

represents a standard for the maximum concentration of Ptot that is allowed for healthy water.

At the distance were the waste water treatment plant of Jerez de la Frontera is located the

concentration of ortho-phosphate was extremely high compared to the other sampling points and

the maximum allowable concentration. The reason for the high value at the beginning of the stretch

is most likely due to the high phosphate concentration in the hypolimnion of the reservoir as well.

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0 20 40 60 80 100 120 140

NO

2--N

(m

g/l

)

Distance (km)

NO2- N

NO2- N

0

0,5

1

1,5

2

2,5

3

0 20 40 60 80 100 120 140

NO

3--N

(m

g/l

)

Distance (km)

NO3- -N

NO3- -N

33


Figure 5.10 Ortho-phosphate as P (mg/L) measured in the Guadalete River

Dissolved Inorganic Nitrogen (DIN)

The red line at 2.2 mg/l in the graph of the concentration of DIN in figure 5.11 represents a standard

for the maximum concentration of Ntot that is allowed for healthy water.

Ammonium (NH4+), nitrite (NO2

–) and nitrate (NO3–) are the most common ionic (reactive) forms of

dissolved inorganic nitrogen in aquatic ecosystems. These ions can be present naturally as a result of

atmospheric deposition, surface and groundwater runoff. Between 89 km and 91 km there is a side

stream with many nutrients coming in from Jerez de la Frontera. Before 102 km there is a

wastewater treatment plant; the concentration is very high after this plant.

Figure 5.11 Dissolved inorganic nitrogen (DIN) (mg/L) measured in the Guadalete River

The high concentration of DIN could have major environmental problems to aquatic ecosystems:

0,000

0,200

0,400

0,600

0,800

1,000

1,200

1,400

1,600

1,800

0 20 40 60 80 100 120 140

PO

43

--P

[m

g/l

]

Distance (km)

PO43- -P

Ortho phosphate as P

P total standard

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

8,00

9,00

0 20 40 60 80 100 120 140

Dis

solv

ed

in

org

an

ix n

itro

ge

n [

mg

/l]

distance (km)

Dissolved inorganic nitrogen

DIN

N total standard

34


1. It can increase the concentration of hydrogen ions in fresh water ecosystems without much

acid-neutralizing capacity, resulting in acidification of those ecological systems;

2. It can stimulate or enhance the development, maintenance and proliferation of primary

producers, resulting in eutrophication of estuarine, and coastal marine ecosystems. In some

cases, in organic nitrogen pollution can also induce the occurrence of toxic algae;

3. It can impair the ability of aquatic animals to survive, grow and reproduce as a result of direct

toxicity of ammonia, nitrite and nitrate. In addition, inorganic nitrogen pollution of ground

and surface water could induce adverse effects on human health.2

5.3 Discussion

It should be clear that the results as shown in this chapter are based on measurements that were

conducted in only two field days, meaning that it is just a ‘snapshot’ of what the real situation over a

longer period of time would be.

The significantly high concentrations of nutrients near the dam of Arcos de la Frontera could be

explained by the fact that when the water rushes from the dam sediments with a high abundance of

nutrients will be mixed with the river’s water. Therefore, the concentrations of nitrogen and

phosphorus containing substances may be high. However, nitrogen concentrations are believed not

be high enough to form a direct threat to the survival of aquatic organisms.

As stated in the results, stratification in the reservoir near Arcos de la Frontera most likely has played

an important role in the chemical state of the river. However, this phenomenon has not been

measured during this study. For future research measuring the stratification in this reservoir would

be highly recommended in order to reinforce theories about the chemical state of the Guadalete

River.

5.4 Conclusion

WWTP effluent

The results of the chemical analysis of the Guadalete River show that the waste water treatment

plant of Jerez de la Frontera most likely has a big impact on the chemical state. This is especially

noticeable when looking at the oxygen concentration before and after the point where effluent of

the plant is discharged; right after this point a clear oxygen sag curve is shown and the oxygen

concentration decreases even below 3 mg/L, while the standard for oxygen is 5 mg/L. Also the pH is

decreasing at the point where the effluent is discharged. Concentrations of nutrients (e.g. DIN,

ammonium, and phosphate) show a peak right after the waste water treatment plant. We assume

that these nutrients – and corresponding effects on oxygen concentration and acidity – derived from

the effluent of the waste water treatment plant of Jerez de la Frontera.

Agriculture

Presumably agriculture in the region of the Guadalete River has little impact on the chemical state of

the river. When looking at the results of oxygen measurements, a small decrease in the

concentration is shown between the junction of the Guadalete River and the Majaceite River, and at

the location right before the discharge point of the waste water treatment plant. Therefore,

2 http://www.eoearth.org/article/Inorganic_nitrogen_pollution_in_aquatic_ecosystems:_causes_and_consequences

35


agriculture has relatively low impact on the chemical state and in particular on the oxygen

concentration of the Guadalete River. Although, it is unknown what the influence of the usage of

fertilizers is on the nutrient concentration in the river.

Tributaries

Our results indicate that there is in general not much influence of (natural) tributaries on the

Guadalete River.

Tidal influence

Clear results of measurements of salinity indicate that the tide has no influence on the Guadalete

River that lies upstream of the weir (104 km downstream of the reservoir near Arcos de la Frontera).

The downstream part of the river, after the weir, is highly influenced by the salt water from the Bay

of Cadiz.

Overall chemical water quality

The chemical water quality is not good. But the measured parameters vary significantly at the

different parts of the river. At the first 5 km from the dam the water quality is bad, due to the bad

quality of the inflowing water from the hypolimnion of the reservoir at Arcos de la Frontera (caused

by stratification in the reservoir). But the quality improves rapidly, probably due to vegetation and

less pollution in the water. Until 20 km from the dam, the water quality has reached its peak and is

slowly decreasing. This is probably due the surrounding agriculture and its leaking groundwater into

the river. 80 km downstream a polluted stream from Jerez de la Frontera is flowing into the river.

This is causing a faster decrease in the water quality than the agriculture did. But the most rapid

decrease in the river appears when the effluent of the WWTP flows into the river. An oxygen sag

curve is shown in figure 5.5. This indicates a very bad water quality right after the WWTP effluent

entered the river. After the weir the water quality is slowly improving, but stays under the European

standard. So, overall the chemical water quality of the river the Guadalete is mediocre to poor.

36


6. Biology

The biological aspects of the river were investigated in a stretch of approximately 170 km running

from the dam of the reservoir near Arcos de la Frontera till the mouth of the river in the Bay of Cadiz

(see figure 6.1). In this chapter the biological aspects of the influences from the waste water

treatment plant of Jerez de la Frontera, tributaries, and tidal influences are described in terms of

methods, results, discussion and conclusion.



Figure 6.1 Map of Guadalete River with sampling points for measuring the biological water quality


6.1.1 Macrofauna Sampling

Preconditions measuring area

The measuring are was indicated in advance of the actual sampling itself. The first step was to look

for background information regarding the measuring points, to get a good impression of the

locations. The measuring points were chosen in such a way, that they represent the larger water

body and its habitats. Sampling points where human intervention had recently taken place were

avoided, unless the human interventions represented the total water basin. The measuring area

chosen had an approximate length of 100 meters, with all the measuring points located in this

stretch. It was of the utmost importance to try and find sampling points which were submerged for

the previous two months, this was checked by looking for algae and snails on any possible available

stones (see figure 6.2).

37


Habitat localization

It was of great importance to distinct all the relevant habitats within the measuring area, for the

macrofauna. In order to look for the different habitats, special attention was paid on the following

things:

Table 6.1 Habitats and characteristics

Substrate Consistency, structure and general state

Vegetation Structure and biodiversity

Shore Shape and vegetation

Discharge Fluctuation in discharges

Positioning of the watercourse Positioning of the sun, wind, shade and water-depth

Once the habitats were located and determined, the habitat type and the correlated endeavor were

determined. If the habitat seemed low in biodiversity, the sampling endeavor was great, to make

sure all the possible species would be sampled. There was looked for signs of the quantity of species,

and the endeavor of sampling was adjusted according to it. The more heterogeneous the habitat was

the more endeavor was required, the more homogeneous the habitat was, the less endeavor was

required. In general the required sample length made with the macrofauna net was around 5 meters,

but could be increased to 10 meters once the habitat was determined to be very heterogeneous.

Figure 6.2 Example of sampling area with a variation of habitats as shown here in a tributary of the Guadalete River

Sampling technique

Before starting sampling, the net was checked for possible damages. The net was checked for if it

was clean before applying to a new habitat, in order to make sure no organisms from a previous

38


habitat were left behind. Sampling from the shore is preferred above sampling from the shore

(Werkvoorschrift 12A Bemonstering van macrofauna). Once approaching the actual sampling point,

great attention was paid in order to prevent disturbance of the habitat, by approaching towards the

sun, in order to prevent shadow casting. The net was moved through the water, soil and vegetation

in a jerky way. This was done with a speed which made it impossible for macrofauna to escape from

the net. Once in flowing water, the movement direction was made opposite of the flow, in stagnant

water, a movement was made first and directly after that, another movement opposite of the first,

to trap any potential remainders. The net was checked regularly and emptied, to prevent clogging

and losing of macrofauna. This technique was applied to the soil, water column, submerged

vegetation and emerged vegetation. Once this technique was applied to the soil, the kicking

technique was implemented as well, to stir up soil and the macrofauna inside it

Sample sorting and preservation

Once the samples were taken according to the above mentioned techniques, they were placed in

white photo-trays and sorted and identified at site. Sorting and identifying was done at site to

prevent killing of macrofauna between one another, and guarantee the preservation of macrofauna

which was rare. Fragile animals and predators were placed in separate jars. The jars were next

labeled according to the measurement point. Ethanol of 96% was added to the samples to kill the

macrofauna immediately. For the used literature see ‘Biology’ in Chapter 10 Literature.

6.1.2 Macrophyte Sampling

Only vegetation which was at least partially in the water or influenced by the water was taken into

account. The locations where measurements were taken were determined by accessibility. All the

possible parts of the river with different characteristics were sampled. At the different locations a

section of a hundred meters was chosen from where species were sampled. These sections had to be

a least ten meters from disturbing factors like bridges, weirs and dams. The species which were

recognized at site were to be filled in on the field sheet. Species which were not known, samples

were taken back to the lab. If possible, the whole plant was taken (including leafs, stems, flowers and

roots) back to the lab. Found species were described with (Latin) names, percentage of the total

vegetation and as a percentage of which past was (partially) submerged and which part grew at the

shore.

6.1.3 Biotic Index

The Biotic Index (BI) is used in many European countries as a standard method for water quality

assessment of running water (rivers and streams), which uses indicator species to determine the

water quality. If a ‘sensitive’ species is found, it can be said that the water where it was found, has a

good quality. The BI has a range from 1 to 10, meaning that 1 is very bad and 10 is very good. A

quality of 5 to 6 indicates a moderate quality, but also critical state, since a quality of 3 to 4 is already

a bad quality. The value for biotic index is calculated based on the presence of so called indicator

species. An indicator species or biological indicators are used to monitor the health of an ecosystem.

In the field, as much indicator species as possible are collected to make sure the biotic index is

reliable.

In table 6.2 is shown how the Biotic Index can be calculated. In the horizontal row the total taxa are

found. These are subdivided into classes. This is the easiest way to make clear the diversity in the

water. The biotic index is determined by the intersection of the row corresponding to the most

39


sensitive indicator group that is present in a sample of the column corresponding to the total number

of observed taxa of the same steel.

Table 6.2 ‘Scorecard’ for determination of the Biotic Index

Not all macroinvertebrates that can be found are listed in the biotic index. The reason is that the do

not rely on oxygen within the water for survival. For those macroinvertebrates that do rely on oxygen

in the water, some can only live in water that has a lot of oxygen and vice versa. Generally if the

water is more polluted there is less oxygen dissolved in the water. The categories ascribe different

numerical values to the organisms. On a worksheet the value from that category combined with the

amount of individuals of that species found gives a final value which determines the condition of the

water quality.

6.1.4 Ecological Quality Ratio

For a review of the ecological condition of the Guadalete River according to modern European

standards the methodology of the European Water Framework Directive (EWFD) is applied in this

study. The ecological condition of a water body in this method is expressed as the Ecological Quality

Ratio (EQR) and ranges from 0 to 1. Therefore there is a list with characteristic, positive and negative

taxa. The EWFD has yardsticks. By putting the found indicator species for characteristic, negative and

positive taxa in equation (E6.1) the ecological condition of the Guadalete River can be determined.

In this case the Dutch methodology is used. Every European member state has its own assessment

method and equation.

EQR = { 200*(KM%/KMmax) + 2*(100-DN%) + (KM%+DP%) }/500 (E6.1)

0-1 2-5 6-10 11-15 > 16

Pleceoptera > 2 - 7 8 9 10

Heptageniidae 1 5 6 7 8 9

2 Trichoptera > 2 - 6 7 8 9

Ancylidae 1 5 5 6 7 8

Ephemeroptera 1-2 3 4 5 6 7

Aphelocheirus > 1 3 4 5 6 7

Odonata

Gammaridae

Mollusca

Asellidae > 1 2 3 4 5 -

Hirudinea

Sphaeriidae

Hemiptera

Tubificidae > 1 1 2 3 - -

Chironomus thummi-plumosus

7 Syrphidae- Eristalinae > 1 0 1 1 - -

6

5

4

3

1

TaxaClass

frequencyIndicator groups

Tolerance

class

40


Where:

- DN% (abundance): percentage of negative dominant indicators

- KM% (quantity taxa): percentage of characteristic taxa

- KM% + DP % (abundance): percentage of positive dominant indicators

The Guadalete River is compared with a R6 water type; slowly flowing river on sand and or clay.

Sampling point 32 is classified as a R16-type; fast flowing river on sand or clay. The mouth of the

river, sampling point 170, is a C2-type; estuary with a moderate tidal rate. According to the EWFD a

water body should be compared to a reference. ‘REFCOND Guidance 2003’ prescribes that the

reference water and a ‘very good ecological condition’ is set equal to each other.

6.2 Results

In this chapter for each sampling point the status of macrofauna and macrophytes is reviewed. The

sampling points will be compared with the biological index and the Dutch methodology of European

Water Framework Directive (EWFD).

6.2.1 Biotic Index

Based on the found macrofauna taxa (see figure 6.3) the Biotic Index of the different sampling points

has been determined and shown in table 6.3. Sampling points 20, 32 and 40 have a Biotic Index of 6

and 5 and 5 respectively, which indicates a moderate water quality. At sampling points 135 and 150

no indicator species have been found during the research. Points 158 and 170 turned out to be

brackish water and therefore no Biotic Index has been determined since this method only applies to

freshwater systems. Full list of the identified macrofauna organisms at all sampling points can be

found in appendix VI.

Figure 6.3 Macrofauna of the Guadalete (selection): (A) Ephemeroptera; Caenis spec., (B) Odonata; Ophiogomphus

serpentinus, (C) Odonata; Cercion linden, and (D) Trichoptera; Polycentropodidae (Family).

Table 6.3 Overview of found indicator groups and Biotic Index per sampling point

Sampling point Indicator groups Taxa found Biotic Index

20 Ephemeroptera 11 6

32 Odonata 6 5

40 Trichoptera 3 5

135 none - -

150 none - -

158 n/a n/a n/a

170 n/a n/a n/a

41


6.2.2 Ecological Quality Ratio

The Ecological Quality Ratio (EQR), as the indicator of biological water quality according to the

European Water Framework Directive (EWFD), has only been determined for sampling points 20, 32

and 40 with scores of 0.40 and 0.24 and 0.40 respectively. A selection of characteristic species is

shown in figure 6.4 till figure 6.6. At the other sampling points no characteristic, positive or negative

indicator species have been found and therefore no EQR has been determined.

Figure 6.4 Characteristic species at sampling point 20: (A) Aquarius najas, (B) Gomphidae gomp, and (C) Caloptery spec.

Figure 6.5 Characteristic species at sampling point 32: (A) Vivaparus spec., (B) Ancylus fluviatilis, and (C) Gomphaeschna

spec.

Figure 6.5 Characteristic species at sampling point 40: (A) Hydropsychidae (family), (B) Polycentropodidae (family), and

(C) Tubificidae limnodrilus

6.2.3 Macrophytes

Almost all plant species do not have high demands for the quality of their environment. At nearly

every sampling point, the same plant species were found. In figure 6.7 a selection of plants are

shown which were found in in and near the Guadalete River.

The macrophytes are also rated according to the EWFD. It uses two yardsticks to determine the

quality. The first one is the percentage of the abundance of the growth forms, for instance

submersed or emerged. The second one is the species composition. Each found species is looked up

in a table with the corresponding score. If a species has a score, it resembles a good water quality.

42


Since a Dutch species list is used and these species mainly occur in northern Europe, only the first

method is possible in this case. In table 6.4 the growth form abundance score per sampling point is

shown. These score are the lowest found scores, since it is a ‘weakest link counts’ score. In appendix

VII the overview of the scores for each points are shown.

Table 6.4 growth form abundance score for the macrophytes per sampling point

Sampling point Growth form abundance score

20 Bad (0.2)

32 Very good ( 0.8 )

40 Bad (0.2)

135 Bad (0.2)

150 Bad (0.2)

158 Bad (0.2)

Figure 6.7 Selection of common macrophytes of the Guadalete River: (A) Persicaria maculosa, (B) Mentha aquatic (C)

Potamogeton natans D) Cyperus fuscus

43


6.3 Discussion

Sampling was done as careful and accurate as possible. However, it turned out that it was difficult to

perform the measuring of the benthos in a standardized way on all the sampling points. The terrain

differed, resulting that on the different sampling points different quantities of surface area were

sampled. One location could have been sampled on a bigger stretch than another one.

Due to the time limitation, it was only possible to take samples at each sampling point for a certain

period of time which may have resulted in incompleteness of data. If any indicator species were not

found due to this, the resulting biotic index might be less accurate. Furthermore, the biotic index

which is established only takes macrofauna into account.

The number of found indicator species might also be biased due to time of year in which the sampled

were taken. It might be possible that certain species were not present anymore in the late

summer/early autumn. It would have been better if the river system was monitored for a whole year,

making sure all the seasons and the correlating macrofauna and macrophytes were analysed. A year-

round monitoring would have also made sure that all the different weather conditions – and its

correlating chemical and hydrological properties – which occur in this region were taken into

account.

Concluding it can be said that due to the short time span and the year of time in which the data was

gathered, it might very well be possible that a lot of indicator species were not found. The ecological

state of the Guadalete River based on the biological aspects should therefore be seen as more of a

snapshot than of a complete picture of the situation. The EFWD we used for the calculation is made

for Dutch streams. So in most calculations the EFWD is more accurate than the BI, but this time we’re

not sure. The BI can be used for every stream is the world. Next time it would be better to find a

Spanish version of a method like the EWFD.

6.4 Conclusion

Wastewater Treatment Plant

The WWTP seems to have a big influence on the water quality and thus on the ecological state of the

Guadalete River. Based on the results of the analysis of the chemical water quality (chapter 5) a

sudden drop in oxygen concentration and in acidity of the water is believed to have an effect on the

local flora and fauna. Before the WWTP five species of macrophytes were found, whereas just after

the WWTP only one species was found. The results of the Biotic Index (BI) also support this; just after

the WWTP a Biotic Index has a value of 4.

Tidal influence

From the reservoir near Arcos de la Frontera till the weir the Guadalete River is a fresh water aquatic

system, downstream from the weir it turns from brackish to salt. This weir also meant that there was

a clear distinction between a fresh water zone and a salt water zone of the Guadalete regarding the

macrofauna and the macrophytes.

Tributary

At sampling point 20 (south of Arcos de la Frontera, close to the dam) the Guadalete River was found

to have a Biotic Index of 6. It indicates that the water quality is moderate. At sampling point 32,

which is located on the tributary of the Guadalete, the Majaceite River, a Biotic Index of 5 was

44


determined, which is slightly worse than sampling point 20. However this still does not indicate a bad

water quality. At sampling point 40, which is just south of the location where the Majaceite flows

into the Guadalete a Biotic Index of 5 was determined. Regarding these biotic indexes it is difficult to

say if the tributary Majaceite has a major impact on the water quality of the Guadalete. As the data

shows, it most certainly does not cause a higher score in the biotic index. Therefore it can be

concluded that the tributary does not improve the water quality, but it is difficult to say if it causes a

deterioration of the water quality.

Biotic Index

According to the Biotic Index, the biological water quality of the Guadalete varies between 4 and 6.

The best quality was found upstream, close to Arcos de la Frontera (see figure 6.8). One of the

reasons for this is probably because at this point the influence of human activities is still low. Further

downstream it is expected that more untreated or poorly treated waste water enters the river.

Despite of the lower influence upstream, the Biotic Index for this point is 6. This indicates a moderate

quality, moderate pollution and a critical state. This state means that the river is prone to deteriorate

since the ecosystem is already damaged. It is important for this system to stop the deterioration and

to make changes to get the biotic index at least at a good state (>7).

Figure 6.8 Biotic Index values for the Guadalete River

Ecological Quality Ratio

According to the EQR, calculated for the macrofauna, the values are even worse than the BI values.

The difference can be explained by the different factors which have an influence on the values. The

biotic index only focuses on species groups and distributions of those groups found in the system.

The EQR uses specific species which are important for the water quality. So in theory, the EQR is

more accurate. As shown in (figure 6.9), the quality of the system is bad or even very bad.

45


Figure 6.9 Ecological Quality Ratio (EQR) values for the Guadalete River according to the methods of the European Water

Framework Directive (EWFD)

Macrophytes

Figure 6.10 shows the abundance scores per growth form of the macrophytes. Only sampling point

32 gets a good score for this part. The bad scores can be explained, because only the lowest scores

count in this case. The ‘weakest link’ method.

Figure 6.10 EWFD macrophytes abundance score

46


7. Comprehensive Discussion

The information about the ecological functioning of the Guadalete River and its human activities

consists of many valuable data derived from own measurements. Having this data enables us to find

answers to our main question and to make conclusions as well as recommendations.

Nonetheless, it should be made clear first that our data was collected within a relatively short period

of time; nearly three days. Therefore we should be aware of the fact that our results are just a

‘snapshot’ of the actual situation since the Guadalete River is normally exposed to many different

circumstances (weather conditions for instance). On the other hand, because of the great amount of

and diversity of data that we have collected we are able to integrate. Making links and connections

between the different disciplines makes it possible to compare the situation of the Guadalete River

to the ‘normal’ functioning of an ecosystem.

For example, we are now able to connect the nutrient concentration and oxygen concentration in the

water and presume that the presence of certain organism is related to this. Moreover, the

assumption that the reservoir near Arcos de la Frontera is stratified is reinforced by the results of

measurements on chemical substances near this point. Also it is not a rarity that high concentrations

of nutrients are found near the discharge point of effluent from a wastewater treatment plant.

Overall, we have confidence of the reliability of the results of this investigation. Many processes that

occur in ecosystem in situations comparable to the Guadalete River have been found here as well.

47


8. Comprehensive Conclusion

The aim of this study was to analyse the relationship between human activity along the Guadalete

river (in terms of policy & legislation, water usage, and wastewater treatment) and ecological

functioning of the Guadalete River (in terms of biology, hydrology, and chemistry) in order to advice

local authorities about sustainable use of the river’s services. Therefore the following research

question was formulated: “How can the relationship between human activity along and ecological

functioning of the Guadalete River be described, and how can that be transformed into an advice

about sustainable usage of the river’s services?”

Ecological functioning under the influence of human activity

To determine the ecological state of the Guadalete River we have combined the results of the

biological, hydrological and chemical analyses. As we have seen in the results of biological water

quality the river has a moderate to bad state between sampling points 20 and 40 (see figure 8.1).

Also the chemical water quality is not very good at the start of the investigated stretch. The dam near

Arcos de la Frontera discharges oxygen poor and nutrient rich water into the river at this point which

has negative effect on the local flora and fauna. The dam functions as a wall to retain water in the

adjacent reservoir that is used by humans as we have concluded in chapter 3.



Figure 8.1 Oxygen concentrations in the Guadalete River categorized from very good (blue) to very bad (red)

Further downstream (up to the suburban areas south of Jerez de la Frontera) the ecological state of

the Guadalete River seems to improve in terms of oxygen and nutrient concentrations. However, the

presence of indicator species does not seem to react on this and show a gradual decline. An increase

of turbidity could explain this phenomenon. This area is relatively quiet in terms of human activity; it

48


is mostly agriculture that borders the river. It suggests that agricultural activities do not have a

significant effect on the ecological state of the Guadalete River.

However, a rather clear conclusion about the ecological state near the wastewater treatment plant

of Jerez de la Frontera can be made. The oxygen levels drop, nutrients levels increase and the

presence of organisms indicating good water quality lack. The most logical explanation for this to

occur is the discharge of nutrient rich effluent of the wastewater treatment plant. It suggests that the

intensive treatment that is performed in this plant (according to the responsible company itself) does

not remove nitrogen rich substances from the wastewater.

A bit further downstream a weir is found which turns out to function as a salt water blockade. This

man-made structure effect almost every element of the ecological function of the Guadalete since on

the upstream side of the weir the river is a freshwater ecosystem and on the downstream side it is a

brackish to saline ecosystem with corresponding salinity concentrations and organisms typical for

such environments.

Sustainable future

In summary we can say that the Guadalete River including its ecological functioning and human

influences faces a number of major challenges. The biodiversity of the river system is clearly affected

by human interference in terms of hydrological barriers (the dam, the weir and water extraction) and

chemical pollution by wastewater from nearby urbanization. In order for local authorities to make

changes a number of recommendations are proposed to improve the water quality of the Guadalete

River without losing the ability to use the river’s services. These can be found in chapter 9.

49


9. Recommendations

People living near the Guadalete are complaining that the environment of the river and its

surroundings are full of waste and therefore polluted. They think that the water quality of the

Guadalete is too bad to use the water of the river. To develop the environment of the Guadalete the

students of the 4th year had come up with causes, their effects and possible improvements (see

figure 9.1).

Figure 9.1 Cause-Effect diagram and possible improvements for the Guadalete River

9.1 Sufficient treatment of wastewater/irrigation water

Insufficient treatment of wastewater and irrigation water leads to low oxygen levels and an immense

nutrient load. To reduce the negative impact it is advised to employ fertilizers more efficient as well

as the methods of irrigation. The canals that are leading from agriculture and industries into the

Guadalete could be advanced by making those more natural like getting rid of the concrete and using

vegetation rolls for taking up nutrients, acting like biological filters, and avoiding erosions (see figure

9.2).

50


Figure 9.2 Vegetation rolls to improve the water quality

Those vegetation rolls can also be used for Floating Islands (see figure 9.3).

Figure 9.3 Construction of a Floating Island

Floating islands are used in treatment wetland projects for the removal of pollutants in water bodies

such as:

• Nutrients like phosphorus and nitrogen (direct plant uptake from the water through the

plant roots and microbial metabolism);

• Suspended solids (particulate organic matter) by filtration and sedimentation;

• Organic matter (BOD, COD) and volatile organic compounds like MTBE and benzene by

biodegradation and direct plant uptake of contaminants and metabolism within the marsh

plants;

51


• Heavy metals by precipitation as insoluble salts and binding to particulate matter and uptake

by plants and root mat biofilm microbes and following sedimentation processes.

Artificial and natural floating islands are characterized by buoyant dense mats of roots and rhizomes

of marsh plants (helophytes). There are natural self-buoyant floating root mats and artificial ones

growing on rafts.

The plant roots growing in the water take up nutrients and provide large surfaces on their root and

rhizome mats for active biofilms (microbes improving water quality). By shading the water surface

floating root mats suppress the proliferation of algae. Floating rafts provide wildlife habitats for

waterfowl above the water surface and breeding areas for young fishes in the root network below

Figure 9.4 Floating Island to improve the water quality

Natural wetlands, permanently waterlogged areas populated by hydrophytic plants such as reeds,

comprise a variety of sub-surface micro-habitats of differing oxygenation and redox potential, and

support a diversity of microorganisms – bacteria, fungi, actinomycetes, protozoa – which degrade

organic and inorganic substrates entering the system. Constructed wetland systems are increasingly

being employed for treatment of wastewaters, sludge and industrial effluents as a cost-effective, low

energy and robust alternative to traditional engineered biological treatment such as the activated

sludge process.

The construction of such constructed wetlands would also be advised to the farmers and industries

(see figure 9.5). This does not only increase the water quality by acting as a biological filter, but also

by acting as a sediment trap. The helophytes, out of which the wetland will mainly exist, will clean

the water, and by mowing it once or twice a year, the pollutants which get trapped in the plants are

removed from the water system. Furthermore the water between the helophytes will become more

stagnant, giving the sediment a chance to participate, and by this being extracted from the water

column. And this stagnant water between the helophytes will create a new microenvironment for

small animals.

52


Figure 9.5 Constructed wetland for wastewater treatment

9.2 Oxygen level

The Guadalete is fed by the reservoirs. Water from the reservoir that is discharged into the river is

coming from the hypolimnion (see figure 9.6). The hypolimnion has a low oxygen concentration and

therefore it has an impact on the river downstream.

Figure 9.6 Stratification of a lake

To prevent this we recommend aeration in the reservoir, to increase the oxygen concentration and

for mixing the aerobic water from the epilimnion with the lower parts of the reservoir (see figure

9.7). It does not upset its thermal stability and thus avoids the mixing of the deeper layers with the

warmer surface layers. Compressed air is blown into a diffuser at the bottom of the LIMNO and

entrains water up with it. The water is reoxygenated by contact with the air bubbles, and then it

returns to the bottom where it discharges through radial outlets. The excess air is discharged through

the vent pipe.

53


Figure 9.7 LIMNO-hypolimnion aerator

9.3 Concrete weir

The weir can either be removed or has to be improved. For example a fish ladder can be constructed

to give the fish free passage (see figure 9.8). This way fish which migrate from saline water into

freshwater will get the opportunity to do this without problems. When bigger fish return to the river

system, it might even have a social-economic impact, by for instance recreational fishing.

Figure 9.8 Construction of a fish ladder at the weir that separates the salt and fresh water

54


9.4 Waste/litter in and around the river

The overall pollution of the river should be brought back to a minimum. There is a lot of garbage by

the local inhabitants on the shores and in the river itself. This waste disposal does not only increase

the biological oxygen demand of the river, but it also damages the way people look at the river. A

river littered with waste loses the interest of the local inhabitants, creating a vicious circle in which

no one feels responsible and cares for the improvement of the water quality of the Guadalete.

9.5 Research

If further research is to be done on the Guadalete river system, the most important thing which is

advised is to be more thoroughly and take more time to monitor the river system. If a year-round

observation of the river is done of not only the biological aspect, but also for the hydrological and

chemical aspects, a better overall view of the river system will arise.

55


10. Literature

Human Activity

Aleu F.C. (2012). La Azucarera abre la campaña el 12 junio y prevé molturar 500.000 toneladas de

remolacha.

Junta de Andalucia (2011) Demarcación Hidrográficadel Guadalete y Barbat.

Diputacion de Grenada (2010). Sustainable water management through common responsibility

enhancement in Mediterranean river basins.

Kristensen P. 2004. The DPSIR Framework. National Environmental Research Institute, Denmark.

Rivero, J.C.M.; Villarán, I.L.; Camacho, D.A.; Zurita, C.A. (2004) “Zonas idóneas para el desarrollo de la

acuicultura marina en las provincias de Huelva, Sevilla y Cádiz”. Ministry of agriculture and fisheries,

Andalusia

Salgot M., Priestley G.K. and Folch M. (2012). Golf course irrigation with reclaimed water in the

Mediterranean: a risk management matter. Water 2012, 4, 389-429

Stefano De L. 2004. Freshwater and tourism in the Mediterranean. WWF

Velicia, H.; Morillo-Velarde, R. (1996). INICIO Y SUSPENSIÓN DEL RIEGO

WWF 2001. Tourism threats in the Mediterranean. WWF background information.

Internet sources:

http://www.abeinsa.com/web/en/noticias_y_publicaciones/noticias/historico_noticias/2011/27042

0112_noticia.html

http://www.abeima.com/web/en/construccion/agua/tratamiento/index.html

http://www.befesa.com/web/en/prensa/historico_de_noticias/2008/20080303.html

http://hispagua.cedex.es/sites/default/files/hispagua_articulo/dyna/53.pdf

http://www.smallwat.org/2007/pdf/reuse/paper/6paper_poster21.pdf

http://www.ugr.es/~iagua/LICOM_archivos/Tema1_Vertidos_IS.pdf

http://andaluciainformacion.es)

http://www.monachus-guardian.org/library/wwftou01.pdf

Rutas Rurales en Cádiz (http:/ / hotelesandalucia. es/ es/ rutas-en-cadiz/rutas-rurales-en-cadiz. html) at hotelesandalucia.es

(Spanish)

El río Guadalete (http:/ / www. riosycuencas. com/ cuencas/ atlanticaAndaluza/ rios/guadalete/ ) at riosycuencas.com

(Spanish)

European Environment Agencny http://www.eea.europa.eu/themes/water/european-waters/reservoirs-and-

dams

56


Hydrology

Internet sources:

http://en.wikipedia.org/wiki/Guadalete

tides.mobilegeographics.com

Chemistry

Internet sources:

http://www.plantedtank.net/forums/showpost.php?p=1741558&postcount=133

http://www.eoearth.org/article/Inorganic_nitrogen_pollution_in_aquatic_ecosystems:_causes_and_

consequences

Biology

Identification literature:

A.C.Campbell. Tirion gids van strand en kust: flora en fauna.

Bos, F. Libellen.

Coesel, P. De desmidiaceeen van Nederland.

Eggelte, H. Veldgids Nederlandse flora.

Gittenbe. De Nederlandse zoetwatermollusken: recente en fossiele weekdieren uit zoet en brak water.

H.Stegenga. Flora van de Nederlandse zeewieren.

Hayward, P. Handbook of the marine fauna of North-West Europe.

Heukels flora van Nederland.

Higler, B. De Nederlandse kokerjufferlarven: determinatie en ecologie.

Macro-invertebraten en waterkwaliteit: determineersleutels voor zoetwatermacro-invertebraten.

Pot, R. Water- en oeverplanten.

Quigley, M. Invertebrates of streams and rivers: a key to identification.

Tempelman, D. Water- en oppervlaktewantsen van Nederland.

Voshell, J. A guide to common freshwater invertebrates of North America.

57


Waterpissebedden: een determineertabel voor de zoet-, brak- en zoutwaterpissebedden van

Nederland.

58


Appendix I: Example of erosion calculation

1. Calculate R (Hydraulic radius).

R=A/O;

• R1=14.94/26.16

• R2=5.92/11.68

2. Calculate Ck factor

• Ck1=18log*((12*0.57)/0.0002714)=79.2

• Ck2=18log*((12*0.26)/0.0000036)=106.9

3. Calculate Vm (Critical velocity)

‘a’ for sand is 0.28 and 0.12 for clay

• Vm=0.28*79.2*SQR(0.000151)=0.272 m/s

• Vm=0.12*106.9*SQR(0.000002)=0.018 m/s

4. Compare the actual velocity with the critical velocity

• Vm1>Va1, hence, no erosion

• Vm1<Va1, hence, erosion

Location Sample Grain size (m) D50 (m) D90 (m) a R Ck vm(m/s) Actual v (m/s) Erosion (Yes/No) TS g/l

20 a 1 0,000315 0,000151 0,0002714 0,28 0,57 79,2 0,272 0,0065 No 0,1002

35 b 2 0,000004 0,000002 0,0000036 0,12 0,26 106,9 0,018 0,1009 Yes 0,2572

90

12log18

d

RCk =

50dCav km ⋅⋅=

59


Appendix II: Cross-sections and hydraulics

Cross-sectional area : 22.0 m

2

Average velocity : 0.0069 m/s

Discharge : 0.15 m3/s


2



-0,2

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

0 5 10 15 20 25 30

De

pth

in

me

ters

Width in meters

Cross-section (20-α-BCH)

-0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

0 2 4 6 8 10 12

De

pth

in

me

ters

Width in meters

Cross-section (30-α-CH)

60



2




2



0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0 2 4 6 8 10

De

pth

j in

me

ters

Width in meters

Cross-section (35-β-BCH)

-0,2

0

0,2

0,4

0,6

0,8

1

1,2

0 2 4 6 8 10 12 14 16

De

pth

in

me

ters

Width in meters


61



2




2



-0,2

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

0 2 4 6 8 10 12 14

De

pth

in

me

ters

Width in meters

Cross-section (60-α-CH)

-0,5

0

0,5

1

1,5

2

0 1 2 3 4 5 6 7 8 9 10

De

pth

in

me

ters

Width in meters


62



2




2



-0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

0 5 10 15 20 25

De

pth

in

me

res

Width in meters


-0,2

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

0 5 10 15 20 25

De

pth

in

me

ters

Width in meters


63



2




2

Average velocity : -0.7670 m/s

Discharge : -367.79 m3/s

-0,5

0

0,5

1

1,5

2

2,5

3

0 10 20 30 40 50 60

De

pth

in

me

ters

Width in meters


-1

0

1

2

3

4

5

6

7

8

0 20 40 60 80 100 120

De

pth

in

me

ters

Width in meters


64


Appendix III: Flow velocity

0

0,02

0,04

0,06

0,08

0,1

0,12

0,14

0,16

0,18

0 20 40 60 80 100 120

Ve

loci

ty

(m/s

)


Weir

WWTPSide river

65


Appendix IV: Time lapse pictures of water level fluctuation at weir

66


Appendix V: Field and laboratory data chemistry

Sampling point* Conductivity Salinity Dissolved oxygen Oxygen saturation pH Temperature Distance from start

mS/cm g/l mg/l %

°C km

10-α 1,50 0,5 1,74 20,9 7,43 24,7 0

16-α 0,94 0,2 2,15 26,3 6,99 23,9 4

20-α 0,87 0,2 4,70 55,6 7,08 23,9 6

30-α 1,06 0,4 8,50 93,7 8,17 20,4 23

32-β 0,98 0,3 4,68 52,7 6,96 21,0 n.a.

33-β 0,75 0,1 9,01 99,4 7,76 19,9 n.a.

34-β 0,96 0,3 5,04 56,6 7,11 21,2 n.a.

35-β 1,46 0,7 8,59 97,8 7,97 22,2 n.a.

40-α 1,21 0,5 8,54 94,9 7,98 20,6 24

50-α 1,38 0,6 7,74 87,2 7,78 21,3 50

60-α 1,25 0,5 7,85 87,9 7,70 20,8 56

75-β 2,04 1,0 7,56 82,4 7,74 19,8 n.a.

100-α 1,15 0,6 6,83 76,2 7,61 20,8 72

110-α 2,27 1,2 6,31 72,7 7,56 20,6 83

120-α 2,32 1,0 5,92 56,6 7,59 20,4 89

125-β 2,16 1,4 2,12 23,9 7,48 21,5 n.a.

130-α 2,32 1,0 4,63 52,5 7,47 21,4 91

140-α 1,43 0,7 4,29 48,0 7,45 21,9 100

145-β 1,72 0,8 4,55 49,4 7,62 23,5 n.a.

150-α 1,74 0,7 2,91 32,6 7,17 21,6 102

152-α n.a. n.a. n.a. n.a. n.a. n.a. 104

153-α 1,51 0,7 n.a. n.a. 7,53 21,4 104

155-β 0,91 0,2 5,58 62,9 7,09 21,6 n.a.

170-α 36,70 22,3 3,55 45,9 7,34 22,3 120

180-α 39,40 24,9 4,10 54,0 7,48 23,7 124

* α = Guadalete River, β = tributary

67


Sampling point*

NH4+-N

(1)

NH4+-N

(2)

NH4+-N

(avg)

NO2--N

(1)

NO2--N

(2)

NO2--N

(avg)

NO3--N

(1)

NO3--N

(2)

NO3--N

(avg)

DIN PO43-

(1)

PO43-

(2)

PO43-

(avg)

PO43-

-P Distance

from start

mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l km

10-α 6,15 6,10 6,13 0,034 0,033 0,034 0,3 0,5 0,4 6,56 0,71 1,13 0,92 0,30 0

16-α 3,30 3,30 3,30 0,311 0,316 0,314 1,7 1,5 1,6 5,21 2,28 2,31 2,30 0,75 4

20-α 2,04 2,04 2,04 0,298 0,295 0,297 1,2 1,9 1,6 3,89 1,82 1,81 1,82 0,59 6

30-α 0,07 0,08 0,08 0,017 0,017 0,017 1,0 1,1 1,1 1,14 0,06 0,10 0,08 0,03 23

32-β 0,05 0,07 0,06 0,010 0,010 0,010 0,5 0,7 0,6 0,67 0,07 0,10 0,09 0,03 n.a.

33-β 0,12 0,13 0,13 0,009 0,004 0,007 0,5 0,5 0,5 0,63 0,07 0,08 0,08 0,02 n.a.

34-β 0,10 0,11 0,11 0,006 0,005 0,006 0,4 0,5 0,5 0,56 0,05 0,03 0,04 0,01 n.a.

35-β 0,19 0,16 0,18 0,060 0,061 0,061 1,7 1,8 1,8 1,99 0,11 0,31 0,21 0,07 n.a.

40-α 0,12 0,13 0,13 0,033 0,032 0,033 1,7 1,5 1,6 1,76 0,08 0,07 0,08 0,02 24

50-α 0,13 0,13 0,13 0,022 0,021 0,022 1,3 1,5 1,4 1,55 0,21 0,14 0,18 0,06 50

60-α 0,07 0,07 0,07 0,019 0,019 0,019 1,3 1,4 1,4 1,44 0,10 0,20 0,15 0,05 56

75-β 0,14 0,14 0,14 0,125 0,125 0,125 4,3 4,6 4,5 4,72 0,10 0,14 0,12 0,04 n.a.

100-α 0,16 0,17 0,17 0,081 0,076 0,079 1,8 1,6 1,7 1,94 0,16 0,18 0,17 0,06 72

110-α 0,16 0,16 0,16 0,083 0,081 0,082 2,4 2,6 2,5 2,74 0,11 0,06 0,09 0,03 83

120-α 0,25 0,26 0,26 0,077 0,078 0,078 1,3 1,5 1,4 1,73 0,16 0,27 0,22 0,07 89

125-β 17,25 17,25 17,25 0,489 0,498 0,494 1,9 1,7 1,8 19,54 2,54 2,59 2,57 0,84 n.a.

130-α 0,52 0,53 0,53 0,105 0,102 0,104 1,6 1,6 1,6 2,23 0,39 0,45 0,42 0,14 91

140-α 0,83 0,81 0,82 0,124 0,128 0,126 1,4 1,4 1,4 2,35 0,66 0,64 0,65 0,21 100

145-β 29,00 29,25 29,13 0,038 0,042 0,040 0,2 0,2 0,2 29,37 5,20 5,90 5,55 1,81 n.a.

150-α 7,00 7,25 7,13 0,096 0,095 0,096 0,7 0,6 0,7 7,87 5,20 4,80 5,00 1,63 102

152-α 7,00 7,05 7,03 0,141 0,146 0,144 0,7 0,9 0,8 7,97 0,31 0,43 0,37 0,12 104

153-α n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 104

155-β 0,29 0,30 0,30 0,003 0,002 0,003 0,3 0,5 0,4 0,70 0,29 0,21 0,25 0,08 n.a.

170-α 0,40 0,40 0,40 0,147 0,148 0,148 1,0 1,1 1,1 1,60 0,20 0,22 0,21 0,07 120

180-α 0,39 0,39 0,39 0,125 0,123 0,124 1,1 1,3 1,2 1,71 0,24 0,23 0,24 0,08 124

68


Appendix VI: Result tables macrofauna

Sampling point 20

Order EFWD

class

Abundance

class Taxa Individuals

Crustacea (subphylum) 0 1 Talitridae hyalella 3

Diptera 0 3 Chironomidae plumosus 8

Diptera 0 4 Chiromidae thummi 19

Ephemeroptera 0 3 Caenis (genus) 11

Heteroptera K 1 Aquarius najas 1

Heteroptera 0 1 Rheumatobates (?) 1

Heteroptera 0 2 Corixidae (family) 2

Hirudinea N 5 Helopdela stagnalis 34

Odonata 0 1 Calopterygidae hetoenna 1

Odonata K 1 Gomphidae gompus 1

Odonata K 1 Calopteryx (genus) 1

Oligochaeta (subclass) 0 3 Branchiobdellidae (family) 12

Total of taxa 12

Total of individuals 94

Sampling point 32

Order EFWD

class

Abundance



Crustacea (subphylum) 0 3 Orconectes immunis 5

Crustacea (subphylum) 0 2 Amphipoda (order) 3


Heteroptera 0 3 Aquarius najas 5

Mollusca K 5 Vivaparus spec. 60

Mollusca K 3 Ancyclus fluviatilis 10

Odonata 0 2 Ophiogomphus serpentinus 2

Odonata 0 1 Cercion lindeni 1

Odonata K 1 Gomphaeschna spec. 1

Total of taxa 10


Sampling point 40

Order EFWD

class

Abundance


Ephemeroptera 0 2 Caenidae (family) 3

Mollusca (phylum) 0 3 Bithyniidae (family) 8

Mollusca (phylum) 0 1 Unionidae pseudanodonta 1

Mollusca (phylum) 0 1 Pseudunio auricularia 1

69


Mollusca (phylum) 0 2 Corbicula fluminea 2

Odonata K 5 Hydropsychlidae (family) 55

Oligochaeta (subclass) N 3 Tubificidae limnodrilus 8

Oligochaeta (subclass) Lumbricidae (family) 2

Plecoptera 0 4 Perlodidae perlodes 14

Trichoptera K 2 Trichoptera polycentropodidae 3

Total of taxa 10


Sampling point 135

Order EFWD

class

Abundance


Crustacea (subphylum) 0 2 Ornectes immunis 4

Crustacea (subphylum) 0 3 Mysidae (family) 7

Total of taxa 2


Sampling point 150

Order EFWD

class

Abundance


Crustacea (subphylum) 0 2 Orconectes immunis 3

Heteroptera 0 6 Sigara hellensi 105

Mollusca (phylum) 0 1 Mesalia mesal 1

Odonata 0 1 Odonata anisoptra 1

Oligochaeta (subclass) 0 1 Nereis pelegice 1

Total of taxa 5


Sampling point 158

Order EFWD

class

Abundance


Oligochaeta (subclass) 0 1 Nereis pelagica 1

Total of taxa 1


Sampling point 170

Order EFWD

class

Abundance


? 0 Spaennium nicole 49

Crustacea (subphylum) 0 Biaickivro (?) 2

Oligochaeta (subclass) Nereis pelagica 19

Total of taxa 3

70



71


Appendix VII: Result tables macrophytes

Samplingpoint 20

Yardstick for abundance of growth forms

Growth forms Bad Insufficient Moderate Good Very

good Reference

Submers 0-1 % 1-5% 5-20%

80-100%

20-30%

60-80% 30-60% 45%

Floating 0-1 % 1-5% 5-10%

90-100%

10-20%

50-90% 20-50% 25%

Emers 0-1 % 1-3% 3-5%

90-100%

5-10%

50-90% 10-50% 20%

Filamentous green algae 70-100% 40-70% 10-40% 5-10% 0-5% 2%

Duckweed 70-100% 40-70% 10-40% 5-10% 0-5% 2%

Shoreline vegetation 0-10% 10-20% 20-40% 40-60% 60-100% 80%

Samplingpoint

32



good Reference

Submers, floating and emers <1% 1-5% 5-10%

70-100%

10-20%

40-70% 20-40% 30%

Filamentous green algae >50% 10-50% 5-10% 1-5% <1% 0,10%

Samplingpoint 40



good Reference

Submers 0-1 % 1-5% 5-20%

80-100%

20-30%

60-80% 30-60% 45%

Floating 0-1 % 1-5% 5-10%

90-100%

10-20%

50-90% 20-50% 25%

Emers 0-1 % 1-3% 3-5%

90-100%

5-10%

50-90% 10-50% 20%


Duckweed 70-100% 40-70% 10-40% 5-10% 0-5% 2%


72


Samplingpoint 135



good Reference

Submers 0-1 % 1-5% 5-20%

80-100%

20-30%

60-80% 30-60% 45%

Floating 0-1 % 1-5% 5-10%

90-100%

10-20%

50-90% 20-50% 25%

Emers 0-1 % 1-3% 3-5%

90-100%

5-10%

50-90% 10-50% 20%


Duckweed 70-100% 40-70% 10-40% 5-10% 0-5% 2%


Samplingpoint 158



good Reference

Submers 0-1 % 1-5% 5-20%

80-100%

20-30%

60-80% 30-60% 45%

Floating 0-1 % 1-5% 5-10%

90-100%

10-20%

50-90% 20-50% 25%

Emers 0-1 % 1-3% 3-5%

90-100%

5-10%

50-90% 10-50% 20%


Duckweed 70-100% 40-70% 10-40% 5-10% 0-5% 2%


Samplingpoint 150



good Reference

Submers 0-1 % 1-5% 5-20%

80-100%

20-30%

60-80% 30-60% 45%

Floating 0-1 % 1-5% 5-10%

90-100%

10-20%

50-90% 20-50% 25%

Emers 0-1 % 1-3% 3-5%

90-100%

5-10%

50-90% 10-50% 20%


Duckweed 70-100% 40-70% 10-40% 5-10% 0-5% 2%


ecological assessment of guadalete river, spain 2012

Education