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L. Berga

Chairman. Spanish National Committee on Large Dams. SPANCOLD

BENEFITS AND CONCERNS ABOUT DAMS IN SPAIN

ABSTRACT

In Spain, due to the high irregularity in the time of the flow of the rivers, and to the strong spatial unbalanced renewable water resources, it has been necessary to construct numerous large dams. Theconstruction of dams in Spain began in Roman times, of which there still remain to date in operation the Cornalvo and Proserpina Dams. At the present time there are in Spain 1,200 large dams of which 21 are under construction, with a total reservoir capacity of some 56,500 Hm3, which have made it possible to pass from a natural regulation of only 8% to a real regulation of more than 40% of the water resources, and thus situating the country in the setting of the mean natural regulation of the European countries.

In this paper the divers purposes of the dams in Spain are described, and a quantitative evaluation is made of the benefits which the dams represent in irrigation, water supply, water for industrial uses, hydropower and other applications, which in total suppose about 6% of the Gross Added Value (GAV). Likewise, the benefits of the dams in Flood Control are described.

On the other hand, diverse concerns with reference to dams are analysed, the most significant being that of Dam Safety and the Environmental aspects. The new legislations, guidelines and programmes on Dam Safety are described which are being complemented by non-structural measures, such as Dam Hazard classification and the Emergency Action Plans. Also the experiences of the studies of Environmental Impact Assessment(EIA) and the corrective measures are analysed.

1. INTRODUCTION.


The peculiar location of the Iberian Peninsula, to the South West of Europe and to the North of Africa causes the climatology of Spain to present some very specific and varied characteristics with the influence of the Atlantic fronts, the Mediterranean storms, the hot air masses coming from the North of Africa, or the cold air coming from North and Central Europe. All this gives rise to a regime of rainfall and flows in the rivers with a very high irregularity in time and space. Time irregularity, with pronounced interannual variations which can give rise to long periods of drought, and also very important seasonal variations with considerable low-water during the summer months. Space irregularity: the northern half of the country having abundant water resources, as opposed to the scarcity of the greater part of the basins of the Mediterranean watershed.

The rainfall average in Spain is 685 mm/year, which gives rise to total renewable resources of some 112 Km3/year. This represents some per capita resources of some 3,000 m3/per person/year, a figure which is of the same order of magnitude as the average of the countries of the European Union (3,200m3/per person/year). Nevertheless, the distribution of the per capita natural resources (Table Nº 1) show a great irregularity in space, which supposes that in the Spanish peninsula the Internal Basins of Catalonia are classified hydrologically as a zone of Absolute water Scarcity(with less than 500 m3/ per person/ per year of renewable resources), the Basins of the Segura and Jucar classified as of water scarcity (with some renewable resources of between 500 and 1,000 m3/per person/year), and the Basins of the South and Guadalquivir as of water stress (with values of between 1,000 and 1,700m3/per person/year).

 

TABLE Nº 1. DISTRIBUTION OF THE RENEWABLE WATER RESOURCES PER CAPITA
      RENEWABLE RESOURCES
BASIN Population
(mill. inhabitants)
(1996)
  TOTALS
(Hm3/year)
  PER CAPITA
m3/person/ year
North: 6.75  
42,088
 
6,235
Duero: 2.25  
15,168
 
6,741
Tagus: 6.36  
12, 858
 
2,022
Guadiana: 1.66  
6,165
 
3,714
Guadalquivir: 4.90  
7,771
 
1,586
South: 2.07  
2,418
 
1,168
Segura: 1.36  
1,000
 
735
Jucar: 4.19  
4,142
 
988
Ebro: 2.76  
18,198
 
6,593
Interior Basins of Catalonia: 6.17  
2,780
 
450
TOTAL PENINSULA 38.47  
112,588
 
2,927

On the other hand, the flow regime of the rivers presents a high irregularity in time, which gives rise to reduced availabilities of resources in a natural regime, with a total of some 9,200 Hm3/year (8.3% of the renewable resources) which would give rise to some mean per capita availabilities of only 240m3/per person/year, as compared with the 1,000m3/per person/year which is considered basic on a world level in order to cover the supply necessities. (1) (Table Nº. 2).
These basic data of the renewable resources together with the characteristic circumstances of the supply of water are clear indications of the Spanish situation, in which, in order to be able to attend the water demands, it has been necessary to carry out important hydraulic works and the construction of numerous large dams.
TABLE Nº 2. WATER RESOURCES IN NATURAL REGIME
BASIN Natural Regime
(Hm3 / year)
  Population
(mill. inhabitants)
(1996)
  Resources per capita
m3/person/year
           
North:
2,550
 
6.75
 
378
Duero:
840
 
2.25
 
373
Tagus:
360
 
6.36
 
57
Guadiana:
10
 
1.66
 
6
Guadalquivir:
920
 
4.90
 
188
South:
50
 
2.07
 
24
Segura:
130
 
1.36
 
96
Jucar:
710
 
4.19
 
169
Ebro:
3,460
 
2.76
 
1,254
Internal Basins
Catalonia
160
 
6.17
 
26
TOTAL SPANISH
PENINSULA
9,190
 
38.47
 
239

2.LARGE DAMS IN SPAIN


The construction of large dams began in Spain in the roman times, although in that period they were not placed in the main rivers, of which still remain the marvellous dams of Proserpina and Cornalvo. The Arabs followed with their systems of irrigation and their delightful dominating controls over the water and its distribution, from which afterwards much was learned during many years by the settlers of the south-eastern zones of the peninsula. Later, in the XVI and XVII centuries were developed the innovatory experiences of arch dams such as are the magnificent examples of theTibi, Elche and Relleu Dams, which would bea world reference during more than 200 years. They also carried out daring technical works, the El Gasco and Puentes Dams, which with their failures gave rise to the need of basing the technique of the project and construction of dams on more scientific bases (2).
At the end of the XIXth. Century there existed in Spain references of some 90 dams (3) of which 58 dams are actually in operation. In general, they dealt with reservoirs of reduced dimensions, and only three dams (Puentes, Valdeinfierno and Villar)had a reservoir capacity superior to 10 Hm3 . The capacity of the reservoirs created by these 58 dams was of 108 Hm3.
spain 1
The Fig. 1 shows the evolution of the number of large dams and of the capacity of their reservoirs during the XXth century (1900-2000). During the first third of this century the construction of dams went following the ideas of the Hydraulic Policy of the regenerationists, who based themselves on the belief that the development of Spain should be based on an adequate farming with the carrying out of extensive irrigations for which it was necessary to regulate the water of the rivers, and which were expressed by Rafael Gasset and Joaquín Costa (4) and which culminated with the hydrological planification, in which the dams played a fundamental part. So was born, with the support and direction of Don Rafael Benjumea and Don Indalecio Prieto, the first National Hydrological Plan, drawn up in the year 1933 by Don Manuel Lorenzo Pardo (5). Afterwards, the Spanish Civil War and the post-war period supposed an important restraint for the construction of new works. In the year 1950 there existed 276 large dams which created 6,142 Hm3 of capacity of reservoirs. With this in the first half of the century 218 dams had been constructed, which supposed a mean of 4 large dams per year, which had been maintained practically constant over the length of the 50 years, except for the interval of the years 1935-1940.The reservoir capacity had increased by 6,034Hm3. which had supposed a mean of some 120 Hm3 per year.
With the start of the second half of the century the construction of dams experienced a very spectacular advance, particularly from the years 1955 to 1970, and due fundamentally to the reservoirs with hydropower purposes, in which the number of dams was multiplied by 2.4, and the capacity of the reservoirs was multiplied sixfold (Table Nº3.). The mean increase of the number of dams per year, in this period, has been maintained practically constant and has been of some 18 dams per year.
TABLE Nº 3. EVOLUTION OF THE SPANISH LARGE DAMS. (1950-2000)
PERIOD NUMBER OF LARGE DAMS INCREASE
Nº MEAN
PER YEAR
RESERVOIR CAPACITY
(Hm3)
INCREASE
MEAN
CAPACITY PER YEAR (Hm3)
BEFORE 1950

276

4

6.142

120

50-60

464

19

18.167

1.200

60-70

666

20

36.919

1.875

70-80

859

19

41.717

480

80-90

1.016

16

49.315

760

90-00

1.196

18

56.500

720

MEAN 50-00

18


1.000


The average increase in reservoir capacity has been of some 1,000 Hm3 per year, with maximum values in the decade of the 1960‘s with some 1,875 Hm3 per year. It should be pointed out that in the decade of the 1990‘s the number of dams in construction has diminished significantly, since while in the year 1991 there were 62 dams in construction, at the present time there are only 31 large dams.
At the present time there are some 1,200 large dams in Spain (1,175 dams in operation and 21 under construction), which create some reservoirs with a capacity of some 56,500 Hm3. Their regulation capacity is of some 45,000 Hm3/year - that is to say a 40% of the renewable water resources, although the rate of regulation is very varied in the different basins depending on its morphological and hydrological characteristics and on the determinants and incidents of the demands (Table Nº 4 ) (8).
With this, it has been possible to pass from a natural regulation of only 9% of the resources, which was totally insufficient, to some available resources of 40% of the mean annual run off, which has situated us in the setting of the mean availabilities of the European countries. The 98% of the total reservoir capacity is concentrated in the 300 reservoirs which have a capacity superior to 10 Hm3. With this number of dams, Spain occupies the first place among the European countries, and the fourth in the world ranking, after the U.S.A., India and China. (6,7).
TABLE Nº 4. RESERVOIR CAPACITY AND REGULATED WATER RESOURCES AVAILABLE IN THE HYDROGRAPHIC BASINS.
BASIN RENEWABLE WATER RESOURCES
(Hm3/year)
RESERVOIR CAPACITY
(Hm3)
AVAILABLE RESOURCES
(Hm3/year)
  REGULATION
%
North 29.616

3.721

5.224

 

17

Duero 15.168

7.667

8.128

 

54

Tagus 12.230

11.135

7.071

 

57

Guadiana 6.168

9.619

2.975

 

48

Gadalquivir 7.978

8.867

3.632

 

46

South 2.483

1.319

504

 

20

Segura 1.000

1.223

725

 

72

Jucar 4.142

3.349

1.985

 

48

Ebro 18.217

7.702

12.998

 

71

Internal Basins of Catalonia 2.780

772

1.115

 

41

Galicia Coast 12.642

688

1.493

 

11

TOTAL 112.424

56.062

45.850

 

40.7


The greater part of the Spanish dams, the 72%, (64% gravity, 5% arch dams, 3% buttress) are of concrete or masonry, as opposed to 28% of embankment dams (17% earth, 11% rockfill). This is due to, in general, the characteristics of the foundations having been good, and that the dams of concrete are less vulnerable to the extreme floods so characteristic of the regime of the rivers. The 58% of the dams have a height of less than 30mts., and only 15% have a height superior to 60 Mts. There exist 40 large dams with a height greater than 100mts., the Almendra Dam, constructed in 1970, having the greatest height with 202mts. The reservoir of greatest capacity is that of La Serena, constructed in the year 1989, with 3,232 Hm3. There are three reservoirs with capacities greater than 2,000Hm3(La Serena 3,232 Hm3, José Mª Oriol -Alcántara 3,162Hm3 and Almendra 2,649 Hm3), and six reservoirs with capacities between 1,000Hm3 and 2,000Hm3 ( Buendia, Cíjara,Mequinenza, Valdecañas, Ricobayo and Alarcón). The population of Spanish dams is growing old. At the present time 22% of the dams have more than 50 years old, and 55% more than 30 years. For this reason, in the future, greater efforts must be dedicated to the maintenance of the dams, to their rehabilitation, as also to the upgrading of dams and reservoirs to the new standards, more demanding every day.
The greater part of the dams and their reservoirs, 75% of the dams, some 900 dams, have a single purpose. This single purpose is in the first place that of irrigation (in 41% of the cases), followed by hydropower (28%), the water supply (26%), the flood control (2%) and others such as recreation, navigation, fisheries, etc., with 3%. The remaining 25% of dams correspond to reservoirs with multiple purposes, the mean being two objectives per dam. Among these, that of irrigation constitutes the first purpose (with 40%), followed by the water supply (29%), hydropower(21%), flood control (2%) and others.So then, considering all the purposes of the dams and their reservoirs, the first purpose of the Spanish dams is that of irrigation (with 40% of the cases), followed by that of water supply (27%), hydropower (25%) and flood control (2%).

3. BENEFITS OF DAMS AND RESERVOIRS


In Spain the construction of large dams has been one of the characteristics and topics that has marked the Spanish hydraulic tradition, strongly conditioned by the great space and time irregularity of the natural flow regime of the rivers. The existing dams produce important benefits in the economy of the country, and have been a determining factor in the grade of development obtained during the last decades. In the analysis of economic viability of each dam the specific studies are developed in which are shown the benefits that are going to be obtained with the regulation of the waters. Nevertheless, we are not going to refer here to the presentation of the various most significant cases, but in a general manner we are going to present an economic evaluation of a global nature, quantifying the economic benefits which the regulated water in the reservoirs produces in the diverse sectors of the Spanish economy, such as the irrigation, water supply, water for industrial uses, hydropower, and the uses for refrigeration, recreational purposes and other applications. For this, the aspects relative to the regulated water as a productive economic factor are going to be analysed, quantifying its contribution to the GROSS ADDED VALUE at the market value (GAV). Also the benefits of the dams in flood control are going to be described. The present situation of the water demands in the diverse sectors is as follows (8):
SECTOR   WATER DEMAND
(1998) (Hm3/year)
     
Irrigation  

24,094

Water Supply  

4,667

Water for industrial uses  

1,647

Hydropower (flexible)  

16,000

Other uses (refrigeration, etc.)  

4,915


The most important demand is that for irrigation, which represents almost 80% of the demands for consumptive uses, and of the order of 47% of the total of the consumptive and non-consumptive demands, excluding the environmental demands.
The economic studies detailed sector by sector which have been carried out in Spain, based on the productivity of the water storedin the reservoirs ( 9 ), can be synthesized in the values which are shown in the Table nº 5.
TABLE Nº 5. ECONOMIC VALUE OF THE REGULATED WATER FOR THE RESERVOIRS
SECTOR M YEAR   VALUE m3   GAV(%)
           
IRRIGATION

5,000

 

0.26

 

1.06

WATER SUPPLY

5,225

 

1.4

 

1.10

WATER FOR INDUSTRIAL USES

11,529

 

7.0

 

2.40

HYDROPOWER

3,290

 

0.21

 

0.70

REFRIGERATION AND OTHER USES

2,949

 

0.6

 

0.63

TOTAL

27,993

  MEAN 0.55 m3  

5.89%


So then, the economic value of the water regulated by the reservoirs can be estimated in some 28 B year, which representsnearly 6 % of the GAV. That signifies a mean value of the regulated water for the different uses of 0.55 m3.
Apart from the benefits of the water regulated by the reservoirs that can be quantified economically, the benefits that the dams and the reservoirs produce inthe flood control can also be cited. In Spain the floods constitute the most important natural disaster and represent a grave economic and social problem. There references of more than 2,400 floods occurred in the last five hundred years, which signifies an average of five important floods per year. The floods produce a mean loss of life of 30 persons per year, together with material damages of 500 M year.
Among the diverse measures for reducing the damages produced by the floods, the dams and reservoirs constitute a very efficient structural action, as they are the only measure that can store water in a very significant manner, modifying thehydrographs and reducing the peak flows. In Spain there exist numerous real cases of beneficial effects of the reservoirs in the reduction of the damages produced by the floods (10). One very significant case was constituted by the flood of the 7th and 8th of November of 1982 in the basin of the Ebro and the Internal Basins of Catalonia which produced 14 deaths and damages superior to 300MThe study on the effect of the reservoirs in the flood routing in the most eastern rivers of the left bank of the Ebro river (Gallego, Cinca, Noguera Ribagorzana, Noguera Pallaresa and Segre rivers) and on the axis of the river Ebro itself up to the reservoir of Ribarroja, shows that in general the reservoirs were very efficient in their zone close downstream with reductions of peak flows of up to 80%. In the middle zones of thebasin, alreadywith ample zones not regulated, the routing effect of the reservoirs in the higher zones of the basin was close to 30%. On the other hand, the global effect of the reservoirs on the mouth of the River Ebro was 57% of reduction, with a peak flow in the last dam of Ribarroja of 3,200 m3/sec. (close to the limit of the capacity of the river in order not to produce important damages in the townships downstream of the dam) as contrasted with the 7,400 m3/sec. which were estimated without the existence of the dams in the basin. In the Internal Basins of Cataloniathe routing effect of the reservoirs, supposed a reduction of 80% in the River Ter in Gerona, a real peak flow of 300 m3/sec. as contrasted with a natural volume of flow without reservoirs of 1,500 m3/sec., and a reduction of 27% in the River Llobregat in Martorell, real peak flow of 1,600 m3/sec. as contrasted with a natural flow without reservoirs of 2,200 m3/sec. These figures show in this case, as in many others (11), the very important real reduction in damages in flood situations and the important benefit which supposes for the country the flood control produced by the reservoirs.

At the present time there exist 30 reservoirs the main objective of which is that of flood control, which represents about 2.5% of the existing reservoirs. Of these, there are two flood control dams under construction, the dams of Puentes II and that of Charcos, both in the Basin of the Segura.

4. MAIN CONCERNS ABOUT DAMS


The main concerns about dams in Spain refer to the dam safety and to the environmental aspects.

Inrelation to the dam safety it must be pointed out that, as it has already been mentioned, Spain figures in fourth place at a world level in relation to the number of dams constructed with a total number of close to 1,200 large dams, in accordance with the classification of ICOLD. This important number of large dams, aconsequence of the great climatic irregularity, has obliged since manyyears ago that a very singular attention be paid to their safety. As a country of relevant activity in the dam construction, Spain has suffered some important failures and various incidents. Ourstatistics, in this sense, do not differ much from those carried out by ICOLD at a world level (12, 13, 14). Also, these failures have activated the social conscience demanding the adoption of greater measures of security. The two last failures, the Vega de Tera Dam in 1959 and the Tous Dam in 1982, have promoted the development of regulations more and more demanding in the matter of dam safety.

The new Technical Regulation on safety of dams and reservoirs of 1996 (15 ) is of application to all the new dams and to those existing the owner of which is the Administration, whilst for the existing dams of private ownership the Instruction of 1967 continues to be valid. The principal safety criteria ofthe Regulation is the classification of the dams in three categories in function of the potential hazard, A high hazard dams, B significant hazard dams and D low hazard dams,applying more safety demands according to the potential hazard. Moreover to the contrary of the Instruction of 1967, the new regulation has a more general and open character which contains organizational and administrative safety criteria, instead of concrete technical solutions, which should be taken into account in order to foresee and limit the social an environmental hazards that the dams could represent. In order to complete the application of the technical safety criteria which remain indefinite in a norm of general character, the Spanish Committee on Large Dams is publishing several Guidelines on the diverse themes relative to the safety (structural, hydrological, etc.). Other relevant aspects which distinguish the actual Regulation are the great emphasis which it places on the safety, the great attention which it pays to the correct dam operation demanding periodic revisions of preventive character by independent experts, insisting on Emergency Action Plans for the dams of high and significant hazard, and demanding that the Technical Archives of the dam be maintained update (16).

At the present time more than two thirds of the Spanish large dams have been classified in accordance with the potential hazard in caseof failure, and the redaction of the Emergency Action Plans is advancing. Nevertheless, the application of the new Regulation poses some problems. On the one part ,on its application coexisting with an old norm, which is applied to some dams, an undesirable heterogeneity is produced in the application of criteria of safety which must be solved. On the other hand the application of a new norm requires an importantfinancing which, to date, has resulted insufficient for the needs established, and significant delays start to be produced in the space of time foreseen. Finally, the Regulation has a low legal status and a generalized consensus exist among the dam engineers in the sense that it would be convenient to put into operation a dam safety law which would resolve the existing competence voids.

In relation to the environmental concerns it should be indicated that the dam construction produces, inevitably, some environmental impacts of a very varied nature, some of a temporary character: excavations, noises, dusts, residues, etc. and others of permanent character such as the flooding of the reservoir, the barrier effect for certain species and, definitively, a variation of the flow regime of the river which produces several variations of the ecosystems .

The alteration of the regime of flow which produces any exploitation of the waters and the environmental effects which it involves should be limited by way of the establishment of minimum volumes of flow and reserving storage in the reservoirs for this purpose. The Hydrological Plans of the basin, actually in force in Spain, fix in the majority of the cases minimum flows, which usually is about the 10% of the mean annual inflow. Furthermore, in all of them the necessity is raised of carrying out specific studies on stretches of river in order to determine exactly these minimum flows.

In relation to the dam construction and operation, and the environmental effects which they can produce, we will mention the existing legislative framework in order to minimize them and the problems which create their application (17).

The fundamental legislative regulations existing in Spain in order to evaluate the effect on the environment of the large dams are the Royal Legislative Decree 1,302/1986, of the 28th of June, of Environmental Impact Assessing which is a transposition on the Spanish legislation of the Directive 85/337/CEE of the European Community and the Royal Decree 1,131/1988, of the 30th. of September, which is the development of the anterior. Recently theRoyal Decree- Law9/2000 of the 6th of October, and the Law 6/2001 of the 8th of May of the Environmental Impact Assessing have been approved, which incorporates fully in the Spanish law the Directive 97/11CE of the European Union.

These regulations establish the obligation to formulate the Declaration of Environmental Impact with prior status to the administrative resolution which is mandatory for the construction of large dams. Furthermore, the Law 4/89 of Conservation of the Natural Spaces and of the Flora and Fauna, and of all the European directives protective of the environment must be well accomplished. Completing this legal framework, there are i force a set of dispositions of the Autonomous Communities (the Spanish State is composed of 17 Autonomous Regions) which are obligatory within its territorial limits and which also condition the negotiation of the projects of large dams. The Autonomous Communities on legislating, in use of its responsibilities, in matters of the environment, have declared protected zones with its territory, with which, on many occasions, totally or partially interfere with the dams planed.

The process of environmental evaluation starts with the dispatch by the promoter to the competent environmental organization of the Report-Summary of the project to evaluate. It consists in general, of a synthetic document in which are described the objectives to be achieved, the various alternatives studied, the most important characteristics of the solution proposed, and the foreseeable environmental impacts that will be derived, bothin the phase of construction as also during dam operation. With the Report- Summary the environmental organization will establish a period of consultations with the people, Institutions and Administrations foreseeable affected by the construction of the project. With the replies received, the promoter will have available the basic data and significant aspects to be taken into account in the formulation of theproject and with this information he will proceed to draw up the study of the Environmental Impact Assessment. Once completed the project, with the Study of the Environmental Impact, will be submitted to Public Information process and, before definite approval, the General Direction of Quality and Environmental Evaluation should emit the obligatory Declaration of Impact. This qualifies the work as environmentally viable or no. In the first case it could include several conditions which would make it viable.

The procedure foreseen in the legislation is complicated to apply, which has given rise to important delays, but which assures an ample public participation of all population and organizations potentially affected. Up to the present time ( July 2001)of a total of 180 procedures of large dams initiated, 73 (41%) have concluded in aDeclaration of Impact, of which 4 were negative; the mean duration of the process is of three and a half years.

For example, in some of the dams in which the Declaration of Environmental Impact has been negative, the following impacts have been considered:

A. Omaña Dam (Province of León). Its purpose: Irrigation. The most significant environmental effects taken into consideration are:

  • Flooding of valuable fauna habitats.
  • The change in flows regimes downstream of the dam with the modification of biotic, physical and chemical factors of the river and the resultant effect on the aquatic and bank ecosystems.
  • Effects on large mammals in danger of extinction, such as the brown bear.
  • Socio-economic implications due to the resettlement of people expropriated.
  • Effects on the historical, artistic and anthropological heritage caused by the total or partial flooding of inhabited centres.

B. Vidrieros Dam (Palencia). Purpose: to reduce water deficits in irrigation. Both the area where the dam is going to be built and the valley to be flooded represent a valuable enclave in Europe with a high level of development. The biological indicator of this well-conserved enclave is the presence of population of brown bears whose prowling area lies in the valley that was going to be flooded.
The types of impact that would be produced by this project similar to those of the previous case.

C. Cerros Verde Dam (Badajoz). A dam for the water storage and flood control, preventing the flood damages in the farming areas downstream.
Environmental rejection is based on, amongst others, the following considerations:

  • The effect it may have on the Cornalbo Nature Park.
  • Various impacts on the valuable wildlife in the area, which includes the presence of more than 30 threatened species, some in danger of extinction, like the imperial eagle and black stork.
  • The barrier effect of the reservoir on the ecosystems, interrupting the flow of populations between the valley and the mountains. This would also affect aquatic wildlife.

Acknowledgments. To J. Yagüe, J.Cajete, y F.Giron, Members of the Spanish National Committee on Large Dams ( SPANCOLD ), and to J.M. Mendiluce, Chairman of the Spanish National Committee on Irrigation and Drainage , for their collaboration in this work.
REFERENCES
  1. - MARTÍN MENDILUCE, J.M. 1996. "Los embalses en España. Su necesidad y trascendencia económica". R.O.P. 3354, 7-24.
  2. - SMITH, N.A.F. 1970. "The heritage of Spanish dams". Servicio de Publicaciones del Colegio de Ingenieros de Caminos, Canales y Puertos.
  3. - FERNÁNDEZ ORDÓÑEZ, J.A. 1984. "Catálogo de noventa Presas y Azudes Españoles anteriores a 1900". Comisión de Estudios Históricos de Obras Públicas y Urbanismo. CEHOPU.
  4. - COSTA, J. 1911. "Política hidráulica. Misión social de los riegos en España". Edición 1975. Colegio de Ingenieros de Caminos, Canales y Puertos.
  5. - PLAN NACIONAL DE OBRAS HIDRÁULICAS. 1933. Centro de Estudios Hidrográficos.
  6. - ICOLD. 1998. "World register of dams". ICOLD. Paris
  7. - BERGA, L.1999. "Las grandes presas en el siglo XX". R.O.P. Número Especial 2º Centenario
  8. - MINISTERIO DE MEDIO AMBIENTE. MMA. 1998. "Libro Blanco del Agua en España".
  9. - BERGA, L., YAGÜE, J., CAJETE, J., GIRON, F., MENDILUCE, J.M. " Benefits and concerns about dams in Spain" 20th IcoldInternational Congress. Q-77.R35, 519-554. Beijing 2000.
  10. - BERGA, L. 1995. "Dams in river flood hazard reduction". In Reservoirs in River Bassin development. L. Santbergen, C.J. Van Westen (Ed). pp 119-128. A.A. Balkema.
  11. - SPANCOLD. SPANISH NATIONAL COMMITTEE ON LARGE DAMS. 1992. International Symposium on Dams and Extreme Floods. Granada.
  12. - ALONSO FRANCO, M. 1994. "Incidentes y accidentes en presas". Symposium on Safety of Dams. pp1-16. Spanish National Committee on Large Dams. SPANCOLD.Madrid.
  13. - ICOLD. 1995. "Dam failures. Statistical analysis". Bulletin 99. Icold. Paris.
  14. - YAGÜE, J., BERGA, L. 1997. "Dam failures and incidents in Spain. Lessons learned". 19th Icold International Congress. Q75-4. 556-559. Florence.
  15. - MINISTERIO DE OBRAS PUBLICAS, TRANSPORTES Y MEDIOAMBIENTE. 1996. "Reglamento Técnico sobre seguridad de presas y embalses".
  16. - HORVATH, E., YAGÜE, J. 2000. "Future perspectives for dam construction in Spain". Hydropower and dams, 4,140-145.
  17. - SEGURA, R., YAGÜE, J. 1995. "Criteria for storing water in Spanish bassins". In Reservoirs in River Bassin development. L. Santbergen, C.J. Van Westen (Ed). pp 65-73 A.A. Balkema.