TITLE : Regional and International Aspects ofStrategic Water Development i nRiparian Countries of the Danub eWatersheds

AUTHOR: Dr . Michael A . Rozengurt

THE NATIONAL COUNCILFOR SOVIET AND EAST EUROPEAN

RESEARC H

1755 Massachusetts Avenue, N .W .Washington, D .C. 20036

PROJECT INFORMATION :*

CONTRACTOR :

United States Global Strategy Counci l

PRINCIPAL INVESTIGATOR :

Michael A . Rozengurt

COUNCIL CONTRACT NUMBER :

804-2 2

DATE :

March 24, 199 3

COPYRIGHT INFORMATION

individual researchers retain the copyright on work products derived from research funded b yCouncil Contract. The Council and the U .S. Government have the right to duplicate written reportsand other materials submitted under Council Contract and to distribute such copies within th eCouncil and U.S. Government for their own use, and to draw upon such reports and materials fo rtheir own studies; but the Council and U.S. Government do not have the right to distribute, o rmake such reports and materials available outside the Council or U.S. Government without th ewritten consent of the authors, except as may be required under the provisions of the Freedom o fInformation Act 5 U.S.C. 552, or other applicable law .

The work leading to this report was supported by contract funds provided by the National Council forSoviet and East European Research . The analysis and interpretations contained in the report are those of th eauthor.

ABSTRACT

The catastrophic degradation of watersheds of major rivers of the south of the forme r

U .S .S .R . along with soil pollution has raised international awareness about vulnerability of river-

estuary-sea ecosystems . Yet, international procedures and institutions for coping with their environ-

mental economic and political problems are only just beginning to evolve . Current approaches to the

management of surface water have lacked an international cooperation in preservation of limited wate r

resources, for they have concerned mainly the economic utilization of water resources ; the problems

of water depletion and ecological degradation have generally not enjoyed the same status .

During the past few years, there has been a growing international concern about environmen-

tal and socio-economic impacts and conflicts associated with the extensive use of Danube wate r

resources by the eight riparian countries : Federal Republic of Germany, Austria, Czechoslovakia ,

Hungary, Yugoslavia, Romania, Bulgaria, and the Soviet Union . In addition, relatively smal l

territories of Italy, Switzerland, and Albania belong to the Danube catchment area .

Four post-war decades of trial-and-error water development policies have led to the unprece-

dented environmental degradation of the lower Danube-Black Sea ecosystem . Consequently, the

current degraded environment constitutes a limiting factor in regional economic and societa l

development and threatens to damage international stability among riparian countries . There are

severe shortcomings concerning compatibilities of projects as opposed to societal demands fo r

upgrading the general quality of life .

A new approach of the International Danube Commission stresses public acceptance an d

environmental safety of resource development alternatives, although this approach has not yet becom e

the managerial banner for the Danube riparian countries .

Faced with the need to make decisions regarding the growing water, soil, and energy defici t

in the region, a set of aggressive programs has developed, which might upgrade the societal an d

economic conditions of the Danube basin with primary investment costing about $100 billion over th e

next 10 to 12 years .

This project analyzes the role and quantifies the weight of various factors (ecological ,

demographic, economic, and political) affecting economic development in the Danube basin .

Particular attention is given to internal and international aspects of water development policy in thi s

crucial and sensitive area where soil and water both are major monetary and political tools i n

pursuing local and international aims.

The project also identifies and provides environmental and political risk assessment analysis

a

regarding infrastructural resource planning and development . The study illustrates the links betwee n

economic growth and the sustainable capabilities of regional natural resources . This study shed s

considerable light on the cause-and-effect problems of the eight riparian countries' environmental

economy .

The study addresses some of the crucial issues regarding the hydrologic regime and majo r

water resources problems of the Danube watersheds . The project aims to provide a comprehensive ,

preliminary analysis of the significance of the Danube for the economic development of its riparia n

countries, as well as of the role of existing and proposed dams for flood control, municipal an d

industrial water supply, hydraulic power, navigation, and irrigation on the lower Danube and th e

adjacent part of the Black Sea .

Accordingly, substantial attention is paid to an analysis of conflicting utilization of limited

river water resources which inevitably have triggered the deterioration of physical and other wate r

quality properties of the Danube environmental systems .

The study underscores that in the course of the current unbalanced socio-economic develop-

ment of the Danube riparian countries, the necessity for international co-operation has become

imperative in order to maintain the political and economic stability of Western and Central Europe .

The study's conclusions are on pages 73 to 77 .

ii

TABLE OF CONTENTS

I .

INTRODUCTION 1

II . WATER RESOURCES OF THE DANUBE BASIN 6

A. Geographical and Geophysical Settings 6

B. Flow Characteristics 1 6

C. Sediment Transport and Deposition 26

III . HYDROCHEMICAL REGIME AND WATER QUALITY 2 8

A. Water Quality 2 8

B. The Role of the River Impoundment on the Hydrochemical Regim eof the Danube 32Austria, Czechoslovakia and Hungary 32Yugoslavia and Romania 37Former U .S .S .R 40Hydrochemical Regime of the Lower Danube 40

IV. INTERNATIONAL IMPORTANCE OF THE DANUBE BASIN 4 1

A .

The Major Natural Resources of the Danube Basin 4 1Federal Republic of Germany 4 1Austria 4 1Czechoslovakia 42Hungary 42Yugoslavia 42Romania 42Bulgaria 42Former U .S .S .R 42Cities and Towns 42

iii

B. Utilization of Danube Water Resources 43Flood Control 44Federal Republic of Germany 44Austria 47Czechoslovakia 47Hungary 47Yugoslavia 48Bulgaria 48Romania 48Irrigation 49Hydropower 5 1Navigation 58Fishery 63

V . POLITICAL AND ENVIRONMENTAL INTRICACIES 64

A. The Lower Danube Canal 67

B . The Degradation of the Western Black Sea 68

VI. CONCLUSIONS 73

VII . REFERENCES 78

i v

ANNEXESTABLE OF CONTENTS

ANNEX I .

Declaration on the Cooperation of the Danube Countries on Water Management an dEspecially Water Pollution Control Issues of the River Danube 87

ANNEX II .

Environmental Impact Assessment of the Gabsikovo -Nagymaros Dam System 9 1

* Development of water management in the Danube Valley 9 1

* The purpose of the Gabsikovo-Nagymaros Dam system 92

* The task of planning and design 93

* History of preparatory planning 95

* Environmental concerns related to the project 96

* Some general conclusions of the impact assessment 98

ANNEX III.

Historical Water Development : Waterways, Dam sand Irrigation 100

* Historical Development of Waterworks 100

v

Germany 103Austria 104Czechoslovakia 105Hungary 106Yugoslavia 108Bulgaria 109

* Dams and Irrigation 110

Austria 110Czechoslovakia 11 1Hungary112Yugoslavia 11 3Bulgaria 11 5Romania 11 5

vi

LIST OF FIGURES

FIGURE 1 The Danube River Watershed and Riparian Countries 2

FIGURE 2 Bottom Slope Conditions of the Danube 7

FIGURE 3 Precipitation Over the Danube Watershed 1 2

FIGURE 4 Hydrographic Network of the Lower Danube and its Delta 1 5

FIGURE 5 Left/Right Run-Off Inputs by Major Danube Tributaries 1 7

FIGURE 6 The Flood-Minus-Low Water Fluctuations Along the Delta 1 9

FIGURE 7 Sideways Distribution of Highest and Lowest Marks on Water 20

FIGURE 8 Daily and Seasonal Upper (Vienna) and Lower (Reni) Danube Run-OffFluctuations 2 1

FIGURE 9 Geographic Settings of Hungarian Plains 23

FIGURE 10 Relationship Between the Sediment Load and Danube Run-Off 27

FIGURE 11 Hydropower Plants and Sforage of Danube Watersheds 3 1

FIGURE 12 Gabsikovo-Nagymaros Hydropower Scheme 34

FIGURE 13 Austrian Hydropower Stations 56

FIGURE 14 Schematic Profile of the Danube Slope, Discharges and Energy PotentialUlm City to the Black Sea (Modified Affer Fekete, 1980) 57

FIGURE 15 Existing and Planned Inner Sfates and International Shipping Canal sin Central and Eastern Europe 60

FIGURE 16 The Locations of the Four Alternative Routes of the Danube -Dniester-Dnieper Canal Along the Coast of the NorthwesternBlack Sea (NWBS) 62

FIGURE 17 The Major Hydropower Plants of the Black and Azov Seas' Watershed 72

vi i

LIST OF TABLES

TABLE 1 The Main Characteristics of the Danube River Subdivided by Navigatio nStretches 8

TABLE 2 The Major Tributaries of the Danube 9

TABLE 3 Characteristics of the Danube Flow 25

TABLE 4 Extreme and Average Discharges Along the Danube Course 25

TABLE 5 Some Multilateral and Bilateral Agreements Having an Impact on th eDanube 30

TABLE 6 Major Pollution Sources Along the Entire Danube 33

TABLE 7 Bacteriological Water Quality 36

TABLE 8 Danube Organic Discharges to the Black Sea and Fish Catch 36

TABLE 9 Some Indicative Hydrochemical Parameters of the Danube Water . . 38

TABLE 10 Average Seasonal Distribution of Phosphates and Nitrates Near the Danub eDelta 3 9

TABLE 11 Water Consumption of Danube Riparian Countries 45

TABLE 12 Land Resources and Their Utilization 4 6

TABLE 13 Existing and Planned Hydropower Stations in the Danube Basin 53

TABLE 14 The Water Storages of the Danube Watershed 54

v

ACKNOWLEDGMENT

The author would like to thank first of all the National Council for Soviet and East Europea n

Research for the funding and patience that allowed him to initiate and carry on the study . The author

would like to extend his appreciation to Dr . Robert Randolph, Dr . Vladimir Toumanoff (NCSEER)

and Dr . Dalton West for their thoughtful support of this study . The author would also like to expres s

his thanks to the United States Global Strategy Council who supported this project .

He would like to express special thanks to his assistant, Mr . Elena London, M .S ., whos e

enormous help made this study complete .

vi

Regional and International Aspects of Strategic Water Development in Riparian Countries of th eDanube Watersheds

Dr. Michael A. Rozengurt

I .

INTRODUCTION

The demand of policy makers and managers to find environmentally sound and sustainabl e

economic development requires the interdisciplinary analysis of versatile systems consisting of natural ,

economic, and social elements of the environment .

The formulation of environmentally sound management policy for land-use and wate r

resources development requires the reliable prediction of the impacts of different human interventions

in order to mitigate conflicts between population and infrastructure, and to preserve the quality of lif e

(Alheritiere, 1985 ; Salewicz, et al ., 1990) .

In this respect, the Danube watershed comprises all controversial features because of : 1) the

international character of the river (there are eight riparian countries and four others sharing a smal l

part of the catchment; Benedek and Lászlo, 1980) ;

2) extensive utilization of water (impoundment, canalization, transboundary pollution, seasonal wate r

shortage); and

3) the self-centered efforts of the riparian countries for water resources development within their

respective parts of the basin (e .g ., an upstream water use ignoring the needs of downstream

countries) .

The Danube River crosses the borders of eight European countries with different politica l

regimes, levels of economic development and ethnic characteristics (Figure l) . Three of the riparia n

states (Austria, Hungary, and Romania) lie completely within the Danube catchment area . Here the

water-related sectors of the economy and large-scale ecosystems are entirel y

dependent upon the water resources of the Danube or its tributaries . Even the countries which li e

along only short stretches of the Danube or touch the river marginally (Czechoslovakia, Bulgaria . and

the former U .S .S .R.) have introduced large-scale schemes for extensive exploitation of the Danub e

via diversions or hydroenergy projects .

Rapidly increasing demands for multipurpose exploitation of the river calls for environmental-

ly-sound, coordinated international management compatible with national development schemes . Thi s

trend in international cooperation is buttressed by growing concern over degradation of diverse natura l

ecosystems closely related to complex surface and groundwater settings (Linnerooth, 1988 ; Domokos

and Saas, 1986: Sokolovsky, 1988, 1991) . In recent years, national integrated river basin develop -

1

P O L E N

N

ment schemes have been marked by enthusiasm at the prospect of generous revenues from the touris t

industry and from improved and expanded navigation through the Rhine-Main-Danube and th e

Danube-Labe-Elbe (ECE, 1980 ; Fekete, 1980; Information 1976). In addition to the construction o f

numerous impoundments and flood control facilities on the tributaries and the river itself (Matrai ,

1975), large-scale irrigation and drainage schemes have become one of the major priorities of th e

Danubian countries. Among them, Moldova and South Ukraine are the two countries whose interes t

in Danube water utilization makes other countries, especially Romania and Bulgaria, very suspiciou s

and resentful .

The southwest area of the former Soviet Union, which gravitates to the Dniester and Danub e

basins, is of critical importance to the Moldovan and Ukrainian economies . It produced 25% of the

former Soviet food supply and 30% to 50% of Soviet iron, steel, and machinery . The region also

lies in a vital path of commerce, infrastructure, and environment of other central European states an d

trade with the outside world .

The Southwestern Economic Region (SWER) of the former U .S .S .R . contains over 3,000

natural lakes of 2,000 km 2 surface area and over 18,000 reservoirs that have inundated 8,000 km 2, or

18% of the total reservoir-flooded area in the old Soviet Union . The SWER is drained by 23,00 0

streams and rivers with a combined length of 90,000 km . Of their total runoff, 62% ultimately drain s

to the Black Sea, 27 .7% through the Dnieper (54 km 3 ) and 23 .7% via the Dniester (10 .2 km 3), and

9 .3% via the South Bug (8 km 3 ) . The Danube River's current regulated run-off equals 170 to 200

km 3 per year .

The SWER is about the size of Texas and slightly larger than France . Over 71% of the total

area of 60 .4 million hectares is agricultural . The region has the densest irrigation network in th e

former Soviet Union, consuming 60% to 85% of its total water resources . Almost 5 .5 million

hectares (nearly 25% of all Soviet irrigated land) spread over the northern Crimea, Dnieper-Donbas ,

Dnieper-Krivoy-Rog, and Danube-Dniester regions . In 1987, the 53 million people of the SWE R

produced over 26% of the former Soviet Union's wheat, 32% of its corn, 58% of its sugar beets ,

42% of its sunflowers, 38% of its vegetables, 23% of its milk, 30% of all cattle and hogs, and 20% -

25% of the nation's wine. Rich "chernozem" (black earth) soils support the densest farmin g

population found anywhere in the former U .S .S .R . and include patches of its most bountiful farmlan d

(Gerasimov, 1972 ; Stolylik, 1987) .

The cascade of ten hydropower plants (two on the Dniester, and eight on the Dnieper) jointl y

represent the single greatest power generation network in the European portion of the forme r

U.S .S .R. (Baksheyev and Laskavyi, 1983) . Still, these plants produce almost 30% less power than

3

anticipated due to the lack of adequate flow to reservoirs to drive these plants . In addition, they give

up 20% of water to evaporation and 15% to 40% to the agricultural drainage network, thereb y

exacerbating the regional water shortage . Heavy impoundment of numerous rivers has retarded th e

hydrological processes, stimulating eutrophication and leading to increased pollution in the majority o f

water bodies and ground water of the SWER. Atomic and thermo power plants heat the streams with

their coolant discharge and represent a continuing threat to Southwest population and environment .

Thus, the quality of freshwater intakes serving nearly 60 million people is affected . Regional losses

to the fishing industry amount to several hundred million rubles annually (Braginsky, 1986 ; Rozen-

gurt, 1991) .

On the average, annual per capita water consumption in the Soviet Union is 20,000 meters 3 ,

while in the SWER consumption varies between 1,100 meters 3 in the north and 226 meters 3 in the

south of the region .

A provocative circumstance is that this chronic water shortage occurs in close proximity to th e

Danube, for less than 1% of Danube run-off originates from Soviet land and the river skirts only 13 4

km of Soviet territory (about 4 .7% of the stream's total length) . Yet Soviet planners have proposed

withdrawing up to 28 km 3 annually from the Danube to irrigate an additional 1 .5 million hectares of

the SWER arable land for this area faced with a dire water shortage for irrigation, industry, power

generation, and drinking (Zvonkov and Turchinovich, 1962) .

The projected appalling destruction of soil, ground water supply, fisheries, and othe r

resources in the previously healthy Romanian productive coastal zone has stirred up a vigorou s

political and environmental campaign of protest from the Romanian authorities and scientifi c

community . (Oddly, under the shadow of environmental and economic disasters in Soviet Centra l

Asia, and despoliation of Aral Sea, the environmental problems of the Black Sea and the southwes t

region of the former U .S .S .R. have largely escaped international scrutiny . )

At the same time, independent Romania has its own plan for water and other river resources .

Romanian riparian claims stem from the natural course of the Danube River--40% of the Danube' s

length lies in Romania as well as over 80% of its residual run-off and most of the Danube Delta . The

Danube serves 60% of the irrigated land in Romania, 85% of its valuable fisheries, and internationa l

shipping. Moreover, Romania is planning to provide a significant amount of water to Bulgaria

(Rojdestvensky, 1979) .

As a result, the rising conflicts between national and international interests concerning wate r

allocation between the infrastructures of neighboring countries have reached alarming proportions .

To cope with a formidable array of diverse problems, the Danube Committee was created in the late

4

1960s . The rationale for this committee was to get actively involved in environmental, political, an d

economic issues of acute consideration (such as water availability versus economic development ,

pollution, and indiscriminate exploitation of the Danube Delta), to seek alternative environmenta l

policy measures designed to mitigate the distortion of natural resources, and to preserve a "brother -

like" relationship between neighboring countries . However, almost two decades of uncertainties i n

economic priorities and in the political fate of the leadership, as well as rival interests of upper ,

middle, and lower river development, have downgraded the effectiveness of many programs addresse d

to the restoration and preservation of natural values of water, fish, and soil in the different parts o f

the river course . Some of these problems of resources utilization are examined in this projec t

(Al'tman, 1982; Salewicz et al ., 1990) .

The economic activities in the Danube basin are documented in numerous publications an d

initial appraisals were prepared for basic water projects (Zvonkov and Turchinovich, 1962 ; Fekete ,

1972) . However, the man-induced modifications in volume and flow patterns of the Danube at it s

exit to the Black Sea have been subjected to superficial evaluation . The same is true for the complex

interactions between various surface and underground water systems along the river. In addition, the

water consumption records have not ordinarily made distinctions between the Danube and its tributary

basins, particularly for the countries with multi-basin hydrography . As a result, the accumulation o f

uncertainties coupled with the construction of barrages have raised serious environmental concern s

among riparian countries (for example, in Hungary and Czechoslovakia in connection with th e

Gabsikovo-Nagymaros barrage system now under construction [Appendix III) . The problems o f

upstream and middle Danube have been further complicated by the degradation of the Danube delta .

Note that the Delta functions as a huge hydraulic and chemical plant which redistributes the rive r

discharge, affects sediment transport and resuspension, and transforms the chemical makeup of th e

Danube water by biochemical interactions between fresh and sea waters and their rich vegetation ,

river borne organisms, and brackish water biota (Almazov, 1962 ; Simonov, 1969 ; Tolmazin et al . ,

1977) .

In this regard, particular emphasis is given in this report to those regions and activities which

have reduced water availability either through negative hydraulic reshaping of the basin, or wher e

negative trends in chemical composition of run-off can be traced . Information on the various aspects

of the Danube regime and related activities has been generalized from scientific reports, pres s

releases, and other documents written in the languages of the riparian countries (German, Hungarian ,

Czech, Slavic, Bulgarian, and Romanian), as well as in English .

There are three annexes to this report : the first is the Declaration by the riparian countries

5

signed in December 1985 ; the second is a summary evaluation of the environmental impac t

assessment of the Gabsikovo-Nagymaros barrage system ; and the third provides a historical view of

water development in the Danube watershed .

In the Declaration, representatives of the eight riparian countries recognized that the obstacle s

hindering the reasonable utilization of water resources could be removed only by joint efforts . They

also reached understanding concerning the institutional framework of the programs to be implemente d

in the fields of water quality control, flood protection, and general water management among th e

relevant authorities of the eight countries .

The following description of the entire Danube drainage system is intended to identif y

vulnerable spots where the flow characteristics are most prone to anthropogenic modifications .

II. WATER RESOURCES OF THE DANUBE BASIN

A .

Geographical and Geophysical Settings

The Danube is the 21st longest river in the world and the second longest in Europe . Its basin

of 817,000 km 2 represents 8% of the area of Europe (Figure 1) . The creeks Breg and Brigach, with

their springs in the Black Forest at a height of 1078 m get a new name--Danube--downstream of thei r

confluence at Donaueschingen . Between this point and the Delta the elevation difference is 678 m

and the length of the river is 2857 km. Figure 2 . shows the bottom slope conditions of the rive r

Danube .

About 120 rivers flow into the Danube (the most important tributaries are given in Table 2) .

The Danube is divided by mountain ranges into three sub-basins : The Upper Danube, for the

headwaters to the mouth of the Morava River ; the Middle Danube, from the Morava mouth to th e

Iron Gate Gorge; and the Lower Danube, from there to the Black Sea .

The Danube receives waters from high mountains and their foothills, from highlands, plains ,

lowlands, and depressions. Therefore, its character varies from a high-mountainous stream to a

lowland river (Table 1) .

The Upper Danube basin covers the territory from the source streams in the Black Fores t

6

FIGURE 2

Bottom Slope Conditions of the Danube

TABLE 1The Main Characteristics of the Danube River :

Subdivided by Navigation Stretches

Stretches ofthe Danube

Distancefrom the

Lengthof the

Width (m) Current velocityat

Numberof

Minimum depth(m)

mouth in stretch river-bed at Low Nay .river km in km navig . Highest Nav, WL Bridges WL at Lowest

channel Low Navigabl eWater Level

(km/h)

Locks Water Level

Regensburg - 2379 - 153 150-300 10,30-4.60 13 1 .85-2 .00Passau -2226 40-100 4 .70-2 .80 1 1 .20

Passau - Linz 2226 - 91 200-400 11 .60-6.60 4 2 .00- 2135 120-150 6 .30-4 .20 3 2 .00

Linz - Vienna 2135 - 206 250-400 11 .60-11 .30 14 2 .00- 1929 120-150 7 .20-6 .30 3 1 .30

Vienna - Gönyü 1929 - 138 300-500 11 .40-7.00 10 2 .50- 1791 75-150 7 .10-3 .90 - 1 .30

Gönyü - Budapest 1791 - 144 350-600 7 .80-6 .70 6 2 .50- 1647 100-180 3 .90-3 .10 - 1 .30

Budapest - 1647 - 599 600-1300 7 .80-5 .69 12 2 .50Moldova Veche - 1048 100-180 3 .67-2 .72 - 1 .60

Moldova Veche - 1048 - 117 600-1300 6 .19-0 .96 1 3 .50Drobeta - Turnu - 931 100-180 2 .39-0 .87 1 3 .50Severin

Drobeta - Turnu 931 - 761 600-800 8 .85-4 .25 3 2 .50Lower Severin - Braila - 170 150-180 3 .60-1 .83 l .80

Braila - Sulina 170 - 170 800-150* 6 .98-6 .34 - 7 .30- 0 1i J-60* 2.81-1 .94 7 .30

* Sulina-Canal

SOURCE :Annuaire statistique de la Commission du Danube pour 1976, Commission du Danube . Budapest - 1977 .

8

TABLE 2The Major Tributaries of the Danube (RZdD, 1986)

Mouth at Danube kin Side Length km Catchment area A, km 3

Iller 2,588 right 172 2,125

Lech 2,497 right 254 4,12 5Altmühl 2,411 left 224 3,25 6

Naab 2,385 left 191 5,508

Regen 2,379 left 191 2,874

Isar 2,282 right 283 8,964

Inn 2,225 right 515 26,130

Traun 2,125 right 146 4,277

Enns 2,112 right 349 6,08 0

Ybbs 2,057 right 131 1,293

Kamp 1,981 left 147 2,13 4

March/Morava 1,880 left 329 26,658

Mosonyi Duna (Lajta, 1,794 right 18,06 1Raba, etc . )

Val 1,766 left 378 10,64 1

Hron 1,716 left 284 5,46 5

Ipel' 1,708 left 233 5,15 1

Sid 1,497 right 190 14,72 8

Drau/Dráva 1,384 right 707 40,150

Tisza/Tisa 1,215 left 966 157,220

Sava 1,171 right 940 95,71 9

Temes 1,154 left 371 16,224

Velika Morava 1,103 right 245 37,444

Timok 846 right 184 4,630

Jiu 692 left 331 10,07 0

Iskar 637 right 368 8,646

Olt 604 left 670 24,01 0

Jantra 537 right 286 7,86 2

Vedea 526 left 215 5,45 0

Arges 432 left 327 12,59 0

lalomita 244 left 400 10,43 0

Siret 155 left 726 47,61 0

Prut 134 left 967 27,540

9

Bottom Slope Conditions of the Danube Mountains down to the Devin Gate eastward from Vienna . I t

includes in the north the territories of the Swabian and Falconian Mountains, parts of the Bavarian

Forest and Bohemian Forest down to the Austrian Mühl and Waldviertel, and the Bohemian-Moravia n

Uplands .

Southward from the Danube extends the Swabian-Bavarian-Austrian foothill belt, comprisin g

major parts of the Alps up to the watershed of the Central Alps .

a. The Upper Danube forms a narrow valley across the wooded slopes of the Bavaria n

plateau and the Austrian Alps . Tributaries, particularly the Inn (Figure 1) cause the river to swell .

Climatically, the upper reaches in the Federal Republic of Germany and in Austria lie in a transitio n

zone between the maritime north-west of Europe and the continental masses of the former U .S .S .R. .

The average annual temperature in the valleys ranges between 7°C and 10°C ; in the mountains it may

drop to below -6°C . The snow cover lasts from 30 to 90 days in the valleys ; in the mountains th e

snow does not melt before the first summer month .

b. The Middle Danube basin, a magnificent and unique geographic unit, spreads fro m

the Devin Gate, dividing the last promontories of the Alps (Leitha Mountains) from the Littl e

Carpathian where the confluence of the March/Morava and Danube takes place, to the mighty faul t

section between the Southern Carpathians and the Balkan Mountains near the Iron Gate Gorge . The

Middle Danube sub-basin is the largest ; it is confined by the Carpathians in the north, by th e

Karnische Alps and Karawanken, Julische Alps in the east and southeast, and by the Dinari c

Mountains in the west and south . This closed circle of mountains embraces the South Slovakian an d

East Slovakian Lowland, the Hungarian Lowland, and the Transylvanian Uplands . This agricultural

land is known as the Little Hungarian Plain ("Kissaföld") . From there the river passes through a

gorge between the Western Carpathians and the Transdanusian Mountains (near Nagymaros) onto th e

Great Hungarian Plain .

The Danube, meandering through the Hungarian plains, has caused the flooding of their low -

lying shores . Approaching the Iron Gate Gorge, the volume of the Danube flow is increased by run -

offs of the Sava, Drava (from the Dinaric Alps), and Tisza (from the Carpathians) .

The Drava (Drau, the Italian Alps) drains the slopes and glaciers of the Austrian Alps ; i t

provides a natural border between Yugoslavia and Hungary . This river empties into the Danube at

the lower end of the Great Hungarian Plain .

The Sava (933 km long) originates near the Yugoslavian-Italian border and drains portions o f

the Dinaric Alps and the mountainous slopes of Bosnia and Herzegovina. This river is the larges t

Danubian tributary below its confluence with the Drina, which drains the southernmost parts o f

1 0

Yugoslavia . The Mediterranean climate of this region is characterized by average summer tempera-

tures of 22-25°C, and 7-11°C in winter . The total average annual rainfall over Yugoslavia equal s

975 mm, but its distribution is irregular and erratic (Figure 3) . Frequent droughts occur in th e

plains .

The Tisza receives its water from the Upper Western Carpathians and from numerou s

tributaries lying to the east along the course of the river .

The Danube valley has a mostly continental climate influenced by air currents from th e

Atlantic Ocean and the Mediterranean Sea . The weather is marked by significant interannual

variations in humidity . Wet periods of three to four years may be followed by subnormal or dr y

periods of seven to nine years, including two to three extremely dry years . However, the Danub e

run-off may not follow these climatic variations since most of its water originates from upper reache s

of the Danube network .

The annual mean air temperature within the plains is about 11°C, ranging from minus 8°C i n

January, to 30-35° in July - August . The average value of the evapotranspiration is 600-700 mm pe r

year, and in dry periods may rise up to 1,000 to 1,500 mm . The average precipitation ranges from

550 mm ± 300 mm/y in the plains to 800 mm in the hilly area west of the Danube, of which abou t

8% originates from snow . The amount of precipitation rapidly increases southwest in the mountain s

of Yugoslavia .

The average precipitation over the Danube basin is as much as 1,200 mm, but it is typified b y

large spatial variations . The highest rainfall is observed in July and August . In Moravia (Czechoslo-

vakia) the climate is more continental with average rainfall of about 500 mm . Here the rainfal l

season is spring .

c .

The Lower Danube basin is composed of the Romanian-Bulgarian lowland, the Sire t

and Prut river basins, and the surrounding upland plateaus and mountains . It is confined by the

Carpathians in the west and the north, by the Bessarabian upland plateau in the east, and by th e

Dobrogea and the Balkan Mountains in the south . At the Prut mouth the Dobrogea promontorie s

project into the Bessarabian upland plateau .

The lower Danube crosses the lowlands of the Wallachian Plain which constitutes about 33 %

of Romanian territory . The elevation increases to the north, forming hills and tablelands . The deep

interior depression of Transylvania has an average altitude of 400-600 m and is bounded to the nort h

by the Carpathian Mountains (altitudes over 2,500 m) . South Transylvania is separated from th e

lowland by a belt of low hills less than 1,000 m in height . There are several rivers which drain to

1 1

FIGURE 3

Precipitation Over the Danube Watershe d

1 2

1 3

FIGURE 3 (P2) the west into the Tisza . Large tributaries -- the Siret, Bistritsa, and Prut -- join th e

Danube at its final turn to the Black Sea . Smaller rivers such as Jalomita, Arges, Olt, and Jiu

originate in the hilly belt . To the south of the Lower Danube is the hilly Danubian plain with

altitudes ranging from 100 to 600 m, but further south the height generally increases up to 2,900 m

(fhe Balkan Mountains) . From the northern, Bulgarian side, the principal tributary is the Iskar River .

After turning north from the Romanian-Bulgarian border, the Danube divides two tablelands ,

Dobrodgea to the east and the Moldavian tableland to the northwest . Below confluence with the las t

tributary, the Prut, the river again turns east . The Danube is crowned by a huge delta of 5,460 km 2

where three major tributaries direct the Danube water to the Black Sea (Figure 4) .

The lower Danube has a temperate continental climate of a transitional type, with sligh t

oceanic influences from the west, Mediterranean influence from the southwest, and continenta l

influence from the north . The summer is milder than in the Hungarian Plains with average tempera-

tures of 22°C to 24°C in July and August . In winter, the average temperature drops below minu s

3°C . The annual average temperature ranges are 10° to 11°C in the plains, 7° to 10°C in the

foothills, and less than 6°C in the Carpathians . The hilly and mountainous regions in Bulgaria are 2 °

to 4° warmer than in Romania .

The average annual precipitation steadily increases from the lowlands 400-600 mm to 800 -

1400 mm. The bulk of precipitation falls from October to June . Many areas experience an annua l

drought because of the uneven precipitation pattern and increased evapotranspiration in the summer .

The distribution of the Danube among its riparian countries is as follows :

In the Federal Republic of Germany, from the confluence of the streams Brigach and Bre g

down to the Austrian border, the Danube flows a distance of 550 km . A reach about 180 km long i s

narrows where the Danube cuts its way through mountain ridges . On a stretch about 400 km long ,

the Danube passes through wide valleys (RZdD, 1986) .

The Austrian Danube is about 350 km long, including a 21 km frontier reach with the FR G

and one of about 8 km with Czechoslovakia. About 150 km in sections are narrows in which th e

Danube cuts its way through mountains . About 200 km of the Danube pass through the valleys o f

four large basins . The descent of the Danube in Austria is about 150 m .

The Czechoslovak portion of the Danube on the left (northern) river bank reaches from th e

mouth of the Mach/Morava River about 172 km downstream to the mouth of the Ipel'/Ipoly . The

Czechoslovak section of the right (southern) river bank is only 22 .5 km long, the remainder being an

8 km frontier with Austria, and a 142 km border with Hungary .

The Hungarian Danube reach is 417 km long, including 142 km of the border wit h

1 4

FIGURE 4

Hydrographic Network of the Lower Danube and its Delta

27°E

28°E

29° E

27°E

28° E26° E

Czechoslovakia . The Danube starts on the mighty alluvial fan of the stream at the upper margin o f

the Pannonian Basin and extends as far as the center of this basin .

The Yugoslavian Danube is about 587 km long, with 358 km in the Pannonian Basin . Along

this first reach, the slope of the river is only 0 .05-0.04 per mile . Upstream from the fault gorge

section at the Iron Gate, close to the mouth of the Nera River, it creates a common border wit h

Romania and remains a frontier river down to the Timok mouth, about a 229 km stretch . In the

downstream direction, the Danube is a frontier river between Romania and Bulgaria on a 472 km

reach. The Romanian Danube flows through a 1075 km reach of the country, starting in the middl e

Danube above the mountainous reach of the Iron Gate and extending to the Black Sea ; therefore ,

Romania occupies the largest portion of the Danube course . Out of this total length, 229 km border s

Yugoslavia between the Nera and Timok rivers, and the 472 km long section is the border with

Bulgaria . Downstream from the Prut, the Danube forms the border with the former Soviet Unio n

(about 80 km down to the bend of the Kilia branch of Danube Delta and thence to the Black Se a

estuary . (RZdD, 1986) .

The Danube Delta, covering an area of 5640 km 2 . is the second largest one in Europe (Figure

4). Eighty percent of it belongs to the former Soviet Union and 20% to Romania .

B.

Flow Characteristics

The Danube basin exhibits a large variety of topographic features that affect the regimes of it s

watercourses . The abundance of water in the dense and branching river network is guaranteed by a

snowpack over high elevations in the Bavarian plateau, the Austrian and Dinarie Alps, and th e

Carpathian Mountains to the north . These mountains solicit moisture from the cyclonic atmospheri c

patterns of an adjacent part of the Atlantic Ocean and the Mediterranean which frequently pas s

Southeast Europe . The Danube basin contains about 300 tributaries . Mountainous flows contribute

up to 66% of the total river run-off . The right-shore tributaries provide more than two-thirds of th e

total flow (Figure 5) .

Although the range of instantaneous river run-off may vary considerably ,

the interannual variability in the total river discharge is relatively small . For the period 1861-1975 ,

the mean value was 6283 m 3 /s (198 km 3/yr), the minimum value was as low as 3340 m 3 /s (105

km2/yr) in 1863, and the maximum reached 9540 m 3 /s (301 km 3 /yr) in 1915 (Almazov, 1967;

Reimers, 1988) .

The Danube water regime due to its alpine character is relatively balanced . The rates of the

extreme discharges are 1 :40 at the upper section, 1 :15 at the middle (Budapest), and 1 :8 - 1 :9 at the

downstream reaches. The annual historical run-offs equal 44 km 3 at Passau,

1 6

FIGURE 5

Left/Right Run-Off Inputs by Major Danube Tributarie s

1000 Cubic Meters Per Second

17

74 km 3 at Budapest, and 200 to 209 km 3 at the Black Sea (as computed for 55 to 60 years of

unimpaired run-off conditions) . The difference between the extreme water stages is about 8 to 9 m

along the river .

Water exchanges between surface and ground waters in the Danube basin determine losses o f

water via evaporation and evapotranspiration . These processes largely affect the seasonal run-of f

fluctuations, which are by themselves topographically dependent . An example of observed seasonal

fluctuations along the Danube (Figure 6) shows that the highest fluctuations in the alpine section o f

the river (between Ulm and Linz) is clearly related to rapid changes in flow rate in the mountainous

rivers . The floodwater is substantially lower and less variable along the stretch downstream o f

Bratislava to Komaron for here, immediately below the Hungarian Gates Gorge near Bratislav a

(Czechoslovakia), the Danube enters the Little Hungarian plain .

After emerging from the Visegrad Gorge between the foothills of the Western Carpathian an d

the Transdanubian mountains, the Danube flows along the western margin of the Great Hungaria n

Plain. Along this reach, water level fluctuations are relatively small . Further south, flux of the thre e

major tributaries, the Sava, the Drava, and Tisza, in combination with the constriction at the Iro n

Gates, causes the local development of typical seasonal fluctuations (Figure 7) .

In the course of the 800-kilometer lower stretch of the Danube, floodwater heights above th e

low water are essentially uniform ; downstream from Braila and to the delta, floodwaters can b e

affected by the wind-induced surges along the coast .

The flood-minus-low water curve along the river length (Figure 6) is nicely complemented b y

the curves of sideways spreading of water during the highest and lowest waters (Figure 7) . Two

constrictions at Visegrad and at the Iron Gates clearly separate three flatland regions, the Little an d

Great Hungarian Plains, and the Wallachian Plain where the width of the river changes dramaticall y

with the seasons .

Patterns of flow variability by time at different stretches of the river can be exemplified b y

comparison of year-round daily fluctuations of run-off in various places . At a site near Vienn a

(Figure 8) the flow still preserves its original alpine characteristics (sharp fluctuations, non-unifor m

nature) . Near the delta (Reni), the seasonal run-off pattern is greatly modified by topographical an d

hydraulic features of the tributaries . In the lower Danube, day-to-day variations are much smaller

than upstream, but the seasonal character is well-pronounced .

1 8

FIGURE 6

The Flood-Minus-Low Water Fluctuations Along the Delta

FIGURE 8

Daily and Seasonal Upper (Vienna) and Lower (Reni) Danube Run-Off Fluctuation s

Discharge in 10 3m 3/s

Little and Great Hungarian Plains

After the Danube enters the Little Hungarian Plain (Figure 9) the velocity of its run-off is

significantly reduced . Along the 10 km common Czechoslovakian-Hungarian stretch, the botto m

slope decreases from 4 cm/100 m to 1 .5 cm/ 100 m and becomes nearly constant at 0 .6 cm/100 m

near Komaron . The flow transport capacity abruptly decreases, so that gravel and sand settle on th e

bottom . As a result, the river divides into three branches . (Note that this site has a shallo w

underground reservoir of 10 to 12 km 3 which occupies about 1620 km 2 near Zitni Ostrov [Benedek

and Lászlo, 19801 . This storage recharges the Danube in the summer and provides a domestic supply

for the nearby settlements at a rate of 17 m 3 /sec . )

Below the Budapest metropolitan area the meandering Danube flows across the vast Great

Hungarian Plain . The riverbed is shallow and marshy because of erosion . This aggravates navigation

and necessitates intensive dredging (Matrai, 1980) .

The southernmost flow regime of the middle course is controlled by the hydroenergy comple x

built near the Iron Gates (Janko, 1978) . The backwater from the dam reaches upstream as far as

Belgrade . The dam reduced annual suspended sediment loads from 23 .8 x 106 tons to 3 .5 x 106 tons .

These sediments fill the numerous potholes in the bed of the reservoir . Prior to control, thes e

sediments were deposited on the Wallachian Plain or the seaward edge of the delta .

The Lower Danube

The lower Danube is mostly controlled by the run-off from the Carpathian reach of Romani a

and to a much lesser degree by run-off from the Bulgarian side . Romania has 115,000 km of natural

waterways, equivalent to a density of 0 .49 km/km 2 of territory, but the figure falls to 0 .27 if

consideration is restricted to the 66,000 km of rivers exceedin g

5 km in length. In general, this density varies across the country from 0 .50-1 .30 in the mountains to

0.30 between the Siret and Prut and falls below 0 .1 in the Wallachian plains . The total flows of th e

interior rivers (excluding the Danube) average approximately 1,200 m 3/sec (38 km 3 /yr) . With the

Danube water supply, the total increases to 5,450 m 3/sec (172 km 3 /yr) . However, a significant

volume (nearly 85%) of renewable water gravitates to the main course of the Danube (norther n

Romania) . Substantial water deficits are obdserved in all counties of southern and eastern Romania .

Romania's considerable fresh ground water surplus equals 8 .5 km 3 /yr, of which 4 .5 are

economically exploitable . Such waters are of crucial importance for Dobrogea where they provide fo r

the sharply-rising demands of Constanta and the Black Sea holiday resorts . However, the rest of the

ground water surplus (nearly 75% of the total) consists mainly of highly mineralized waters wit h

22

FIGURE 9

Geographic Settings of Hungarian Plains

curative properties, arising from contact with salts and gas emanations at depth .

The Danube Delta

The Danube Delta covers 5,640 km 2 . This area is divided into the fluvial delta (47 .5%), the

fluvio-marine delta (30 .2%), and the southern Razelm-Simoe Lake complex (20 .3%) (Figure 4 in

circles 7 and 8) .

Much of the delta consists of artificial canals, small lagoons, ponds with dense vegetation, an d

many sandbanks which support inner delta agriculture and settlements (Shvebs, et al ., 1988) .

The branching point of the delta, where the river divides into the Chilia and the Tulcea arms ,

lies several kilometers upstream . The Chilia arm, in turn, ramifies into several arms of which the

Dehakov and Haro-Stanbul arms are the largest . One of fhe arms, the Prorva, has been converted b y

Soviet authorities into a navigation channel .

In the upper reaches the Chilia arm is 400-600 m wide and 18-26 m deep, but become s

shallower (4-6 m) and narrower seaward . The Tulcea channel is also large (300-500 m wide an d

about 7 m deep) . About 17 km downstream the Tulcea arm bifurcates into the Sulina and the St .

George arms . The Sulina arm of 69 km length and 120-200 m width is the major navigation route i n

the delta; its 8 m depth is maintained by dredging . Jetties extending into the Black Sea provide saf e

entrance into the Sulina branch . These were some of the major shipping branches in 1950 through

1960 .

The St. George (Sfintu Gheoghe) is the most sinuous arm in the entire delta. It is 109 km

long and 300-400 m wide . The depth steadily decreases from 5-8 m in the upper and lower reache s

to 1 .5 m in the mouth .

In the north the Danube delta borders the low-lying Budzhak plateau . Several large lakes

with mineralized waters are hydraulically connected with the Chilia branch (Figure 3) . These lakes ,

the Yalpukh, Kurgul', Katlabukh and Kitai collect water draining from the north via a number o f

small streams . The western boundary runs from the branching point along foothills of the Dobroge a

flatland and includes the Razelm-Sinoe lake-lagoon complex .

Water levels vary with flows (Table 3) . Floodwaters may occur at any time of the year, bu t

maximum flood usually is in spring and early summer . Minimum flows occur from October to

January . High water causes flooding over 95% of the delta . Storm surges play an important role i n

the level regime . Usually their influence is restricted by the marine edge of the delta . However ,

during low-flow periods, wind-induced oscillations may reach the delta apex . This effect is particu-

larly pronounced during winter storms .

In the navigational arms of the Prorva and the Tulina, the salt wedge penetrates man y

24

TABLE 3Characteristics of the Danube Flow

MONTHS WITH FREQUENT

REGION RIVER RUN-OFF IN M'/SE C

Low Water

Mean Water

High Water Low Water

High Wate r

The upper course (after the conflu - 850 2050 10900 X - III V - VIII

ence with the Morana)

The middle course (Iron Gates) 1800 5600 16000 VII - IX V - VI, X

Before branching in the delta 2000 6430 19200 VII - VIII V- VI,IV - X

The Chilia arm 4244 VII - VIII V - VI, IX - X

The Sulina arm 386 VII - VIII V - VI,IX - X

The St . George arm 1800 VII - VIII II - VI,IX - X

SOURCE: Atlas (1972-1986) .

TABLE 4Extreme and Average Discharges Along the Danube Cours e

Q. Min. Q. Average Q. Max .

m 3 / s

Passau 280 1 .470 8 .700Vienna 390 1 .920 10 .500Budapest 650 2 .340 9 .500Belgrade 1 .400 5 .300 13 .500River Mouth 2.000 6 .430 19 .200

25

kilometers upstream, particularly in low flow years (Simonov 1969 ; Bondar, et al ., 1973) . The

interface between freshwater and Black Sea water is marked by a vertical salinity gradient of about 3 -

4 ppt/m .

C .

Sediment Transport and Deposition

The sediment regime of the Danube is typified by two features : the bed-load at the upper

section and the suspended load at the downstream section .

The annual average bed load is 0 .5 million tons at Linz and 1 .0 million tons at Vienna ;

downstream of Bratislava, on the upper (common Czechoslovakian-Hungarian) section, 0 .6 million

tons/year of gravel has to be dredged .

Before excessive river impoundment of the downstream section, suspended load was

predominant. On the middle section, the average annual suspended load was equal to 5-6 millio n

tons ; at the river mouth it was up to 40-60 million tons/year (the historical sediment load to th e

Danube Delta and the Black Sea) .

The construction of dams caused considerable changes in the sediment regime . In the

Austrian and German backwater reaches (the upper section), most of the bed load now settles, and i s

removed yearly by regular dredging . The current sediment transport between the middle and lower

Danube has been reduced by 85% . Before 1970, the turbidity and sediment load were clearl y

correlated with the stream flow (Figure 10) . For the period 1948-1970, i .e ., before impoundment o f

the Danube at the Iron Gate, the mean multiannual value of suspected silts and clays was 1051 kg/se c

at Orsova and 1428 kg/sec at the branching point . Corresponding numbers for turbidity were 19 0

g/m 3 and 218 g/m 3 , respectively . After the damming, the mean values for the period from 1970 t o

1975 were reduced to 414 kg/sec at Drobeta-Turni Severin (slightly downstream from the Iron Gates )

and 1304 kg/sec at the branching point in the delta . The suspended sediment concentrations dropped

to 73 g/m 3 or less. The Danube delta experiences ever increasing erosion by the sea waves, and

significant efforts are required to prevent the Soviet part of navigational channels from being silted b y

the alongshore sediment transport .

The current total volume of the sediment load is equal to less than 40% of that of th e

historical norm . The processes of sedimentation in the delta, vegetation growth and decay, re-

suspension of light material, etc . greatly affect the final composition of the Danube water entering th e

Black Sea . It is thought that deltaic processes substantially affect concentrations of trace elements .

The chemical composition of the Danube water is invariably related to waste discharges into the river .

It has been repeatedly demonstrated by Rojdestvensky (1979) that concentrations of various nutrient s

is well-correlated with effluent waters passing through the observation site .

26

III. HYDROCHEMICAL REGIME AND WATER QUALIT Y

A.

Water Quality

Numerous studies have been conducted in various Danubian countries on water pollution .

The upper and middle courses of the river are continuously monitored, particularly within Austria and

Hungary . This part of the river is considered moderately polluted . Only a small portion fro m

Vienna to Bratislava is considered heavily polluted, as well as some tributaries near industrial centers .

Benedek and Lászlo(1980) and Shvebs (1988) demonstrated that concentrations of toxic elements

including mercury, lead, and cadmium had increased .

International activities for better water quality are conducted by the Society of International

Limnology and by several neighboring countries according to bilateral agreements . In 1976, a set o f

water quality criteria for the Danube were established for all countries upstream from the Iron Gates '

dam .

In the framework of the research activities of SIL (Society of International Limnology) and it s

national brances considerable research is underway . In Austria the socio-ecological effects of th e

impoundments are being studied (Oeko ., 1984) . In Czechoslovakia bacteriological and zooplankto n

research is emphasized (Rotschein, 1976, 1981) . In Hungary, fish fauna, primary production an d

oxygen balance have been extensively studied by many (Bartais, 1984 ; Geldreich, 1984 ; Toth, 1982) .

In Yugoslavia, saprobiological and fish-faunistical investigations, and in Bulgaria zooplankton an d

zoobenthos studies, are carried out. Soviet and Romanian experts had been involved in research o f

the Delta hydrology, its phyto- and zooplankton and reeds, as well as fish-faunistical investigation s

(Curcin, 1985 ; Simonov, 1969 ; Shvebs, 1988 ; Vinogradov, 1969 ; Tolmazin et al ., 1977 ; Topa-

chevsky, 1961 ; Sokolovsky, 1991) .

The activity of SIL in Austria covers the following three fī elds :

n Description of the main characteristics of the river .

n Continuous survey of the changes in these characteristics .

n Investigation on the impacts of human activities .

Along most reaches of the Danube, a water quality of biological grade II ( β-meso-saprobic)

can be measured, but downstream of major polluting discharges, quality drops to grade III (a-meso-

saprobic) . This indicates that current pollution control measures are inadequate, which could lead t o

future restrictions on water uses and higher treatment costs (UNDP/FAO, 1982-1985 ; VGI, 1982 ;

Salewicz et al ., 1990) . Potentially harmful materials resistant to natural degradation are becomin g

2 8

more common constituents of Danube waters from a complex range of chemicals and by-product s

produced in riparian countries and discharged to the Danube . However, major bilateral and

multilateral arrangements have concentrated on sharing water quantity rather than directed t o

controlling water quality (Table 5) .

The multipurpose utilization of the Danube water is of vital importance to the approximatel y

71 million inhabitants in the river basin . Economic development in the riparian countries, and th e

increase of navigation accelerated by the Rhine-Main-Danube canal (which interconnects the two mos t

important transcontinental waterways of Central and Western Europe, as well as the North Atlanti c

Ocean with the Black Sea), are causing water quality problems . This in turn considerably affects th e

economics and environment of riparian countries' public health (Sevrikova, 1988 ; Toth, 1982 ;

Vendrov, 1979 ; WHO, 1976, 1986 ; Beklemishev et al ., 1982) .

Construction of dams and other regulatory structures significantly alters the hydrauli c

conditions in a river and has an effect upon the water quality of aquifers . Reduced velocity in th e

river bed leads to increased deposits of the smaller-grained, silt-like material, and causes a reductio n

in dissolved oxygen content of the river water . This subsequently aggravates water quality (solubilit y

of iron and manganese, reduction of sulfates and nitrates, problems of taste and odor, etc . ; WHO ,

1984) .

The high concentrations of nutrients discharged into the Danube as constituents of sewage an d

other effluents increase eutrophication, so that much of the brown color of the river is associated wit h

assimilated brown pigments from diatoms growing on those nutrients . The effects of biological

growth and decay on the quality of impounded water can influence the use or the treatment require-

ments of the water (WHO, 1982) .

Bio-resistant materials, persisting in the water, are accumulated by aquatic organisms or

absorbed on the suspended solids in the water course and are deposited in the sediments . Upstream

and downstream water diversions and withdrawals exacerbate cumulative effects of pollutants on bio-

chemical contamination of the river . In addition, the dredging of shipping channels whose botto m

deposits are saturated with contaminated toxic metals and organic chemicals, compounded by the lac k

of spring floods, further facilitates the deterioration of water quality, especially in the Middle an d

Lower Danube . Note that an increase of navigation through the inter-river canals not only encourage s

urban, industrial, and agricultural development in the river basin but also increases the risk o f

pollution of the Danube because of a potential risk of shipping accidents .

29

TABLE 5Some Multilateral and Bilateral Agreements Having an Impact on the Danube (WHO, 1982 )

YEAR

COUNTRIES

TOPIC OF AGREEMENT

1948 (1960-Austria )

1950

1952

1954

1954

1955

1955

1956

1956

1957

1957

1958

1958

1959

1963

1967

1969

1971

(Austria), Bulgaria, Czechoslovakia, Hungary ,Romania, Ukraine, U.S .S .R ., Yugoslavia

Hungary, U.S .S.R.

Romania, U .S .S .R .

Austria, Yugoslavia

Austria, Yugoslavia

Romania, Yugoslavia

Hungary, Yugoslavia

Austria, Hungary

Albania, Yugoslavi a

Hungary, Yugoslavia

Romania, U.S.S.R.

Czechoslovakia, Polan d

Bulgaria, Yugoslavi a

Romania, U .S .S .R .

Romania, Yugoslavia

Austria, Czechoslovaki a

Hungary, Romania

F.R. Germany, Czechoslovakia

Danube Convention on navigation of R .Danub eConvention to prevent floods and regulate R.Tisza

Convention to prevent floods and regulate R.PrutConvention concerning water managemen tquestions relating to R. Drava

Convention concerning water managemen tquestions relating to R . Mura

Agreement concerning control of frontie rwatersAgreement concerning water managemen t

Treaty concerning water management infrontier region

Agreement concerning water management infrontier region

Agreement concerning fishing in frontie rwaters

Agreement extending R . Prut convention(1952) to Tisza, Suceava and Siret, an dother frontier waters

Agreement concerning use of frontier wate rresources

Agreement concerning water managemen t

Agreement extending R. Prut convention(1952) to Danube

Agreement relating to navigation and powe rgeneration Iron Gates

Treaty relating to management of frontie rwaters

Convention relating to control of frontie rwaters

Local (non-government) commission dealin gwith pollution and management of frontierwater s

3 0

FIGURE 1 1

Hydropower Plants and Storage of Danube Watersheds

B.

The Role of the River Impoundment on the Hydrochemical Regime of the Danube

Austria

At the water intake site of Godworth supplying Linz, upstream from the power station o f

Ottensheim-Wilheving, the Danube water level has risen by 9 m above the original level . This has

resulted in reduced flow velocities and an increase in deposit of organic matter in the riverbed ,

causing blanketing and a subsequent reduced capacity of the bank-well filtration plant . This has

resulted in oxygen depletion in the upper part of the river and an increase in organic matter in th e

river sediments that has triggered anaerobic conditions . As a result, post-extraction treatment t o

produce a drinking water of acceptable quality has been introduced .

Czechoslovakia and Hungary

The Czechoslovakian part of the Danube basin accumulates domestic and industrial pollutant s

from Germany and Austria, plus sewage and chemical effluent from Bratislava itself and its numerou s

factories . This in turn leads to contamination of the Hungarian Danube . According to Slovak radio

(as cited in Singleton, 1985), nearly half of the republic's 3750 miles of rivers, which drain towar d

the Danube, were significantly contaminated by agricultural, domestic, and industrial waste . As a

result, many tourist centers have been closed and no swimming or bathing is allowed . There is

strong opinion among scientists and the population that the chronic water shortage and eradication o f

fish in over 4,300 miles of streams are strongly correlated with pollution . Reduced water quality

forced millions to use mineral water for cleaning teeth and to boil potable water before its utilization .

It has been assumed that full scale operation of the Gabsikovo-Nagymaros barrage system may

result in further decrease of suspended solids from the present 30% over a river stretch of about 7 0

km downstream from Bratislava to 55% after construction of the dam (Benedek et al ., 1978, 1980 ;

Benedek and Hammerton, 1985 ; Rothschein, 1976) .

Additionally, the decomposing organic and pathogene micro-organism content originatin g

from untreated municipal wastes will obviously result in anaerobic decomposition and consequently a n

oxygen loss in the bottom sediment .

Industrial pollution of the Danube may be potentially more serious in the upper reach, as

more industrial plants are sited there and lower volumes of flow are available for diluting th e

resulting effluents (Table 6) .

32

TABLE 6Major Pollution Sources Along the Entire Danube (Benedek, 1986 )

2370

2220

2130

2120

1930

Wien/Vienna /A

1880

187 0

180 0

176 0

1650

1250

1170

1170

1100

690

600

530

43 0

With population equivalent of 500,000 or more .

CITIES'

WITHOUT OR WIT HWITH WASTE TREAT- PARTIAL WASTE TREAT -

MENT

MENT

TRIBUTARIES WITH MAJORINDUSTRIAL POLLUTIO N

Regensburg FRG

Passau Region FRG

Linz A

Enns A

March/Morava A/CS

Váh CS

Sava Y U

Bratislava C z

Gyór Region H

Budapest H

Novi Sad Yu

Beograd (Belgrade) Yu

Morava YU

Jiu R

Olt R

Jantra B G

Arges R O

3 3

FIGURE 1 2

Gabsikovo-Nagymaros Hydropower Schem e

From Lokvenc andSzanto;1986

As a result, in the Hungarian Danube section water quality is mainly determined by pollutio n

of industrial origin from the upstream countries . Their discharges are saturated with heavy metal s

and derivatives from oil, paper, iron and steel mills, petroleum refineries, chemical plants, cement

works, and coal .

The Hungarian Research Center for Water Resources Development (VITUKI) attempts to

forecast the combined effect of the dams and waste discharges on chemical properties, primar y

production, and planktonic communities . It was found that the number of algae and their biomass i s

substantially higher in the Hungarian section than in the upper Danube . This raises the mesotrophi c

community up to a level typical for an impounded basin and substantially aggravates the water quality

of the lower stretch of the Danube (VITUKI, 1978, 1986, 1985 ; Rothschein, 1981) .

One of the biggest pollution sources of the Danube is Budapest with two million inhabitants

and a rather developed industry, and whose wastewater treatment is more or less out-of-date .

The ratio of accumulated heavy metals in the bottom deposit in the Hungarian Danube and it s

tributaries is as high as 2 to 20 times the background values (Somlyody and Hock, 1985) . As a

result, lignin sulfonic acid and high concentrations of heavy metals are emptying into the Middl e

Danube .

At the same time, bacterial counts and organic load in the river exceed the permissible limit s

for irrigation or aquatic recreation (Tables 7 and 8) . The teriophages and enteroviruses show hig h

survival rates in the Danube and may even resist the water treatment processes currently given t o

some potable supplies .

Correspondingly, the hygienic situation is rather severe downstream from major wastewate r

discharge points, such as Bratislava and Budapest . Table 9 shows a typical bacteriological picture of

the Danube at the water intake of Mohács and in the water distribution system of Pecs for which th e

water is provided by this intake (Geldreich, 1984) .

The common characteristic of Danube cities is that they - with a few exceptions - do not hav e

sewage and wastewater treatment plants ; or, if they do, the treatment

efficiency is not adequate . Therefore, the Danube and its tributaries receive significant organic an d

inorganic loads (Table 10) . Moreover, there is no adequate warning and emergency system betwee n

the riparian countries ; accidents which result in water pollution are of particular concern in the mai n

river course and adjacent sea (Tolmazin, 1977 ; Stepanov and Andreev, 1981 : Singleton, 1985) .

35

TABLE 7Bacteriological Water Quality from the Danube Water Intake at Mohacs

to the Distribution Network of Pecs (Geldreich, 1984 )

TYPE OF WATERCOLIFOR M

TOTAL (PERFECAL

FECALCOLIFORM STREP. (PER CLOSTRID- SPC (37°C) NH; MG/L

100 ML) (PER 100 ML)

100 ML) IA (PER 40 PER MLML )

Danube-Water at Mohács 5200 - 72400 200 - 4600

< 100 - 500 64 - 240 3800 - 98000 0.17 - 1 .32

Clarified Water of Mohács 160 - 1200 210 - 960 0.2 - 0 .9 6

Stored Mixed Water at 40 - 2100 95 - 850 0.04 - 1 .10Pecs

Water Reaching the Active 1 - 200 0 .06-0 .6037- 11 0Carbo n

Purified Drinking Water xx xx 0 .01 - 0 .3 94 - 3 2

Stored Drinking Water xx xx 3-43

In the past, the most serious accidental spills occurred in Vienna, Bratislava, and Vác (40 km

north of Budapest) . In 1976, at the Nussdorf water works near Vienna, alcylphenols in the wate r

caused a long quarantine of this plant (Frischherz and Bolzer, 1984) ; and in 1980 at Vác, organi c

solvents resulted in the same situation. Significant hazard was caused to the Bratislava water works

by the leakage of oil resources at a nearby oil refinery (WHO, 1982) . In all these cases the

rehabilitation of the contaminated wells either lasted for an extended period or the wells had to b e

abandoned .

At the current level of development of nuclear power stations along the river, there is a

potential danger from radioactive discharges .

Yugoslavia and Romani a

The role of the Iron Gate dam (Djerdap) on the environment of the Yugoslavian-Romanian

stretch of the Danube can be summarized as follows :

n The turbidity in the lacustrine part of the reservoir has decreased and there has been intensiv e

sedimentation of suspended organic and inorganic particles ;

n The temperature stratification became relatively stable in summer (August) ;

n The oxygen deficiency was higher in the lacustrine part than in the fluent area ; available

oxygen is lacking for the decomposition of organic matter ;

n There is an increase in the content of soluble organic matter ;

n The phosphate and ammonia content as well as the concentration of total solubles were als o

higher in the lacustrine part of the reservoir than in the fluent part ;

n Vertical stratification in the distribution of phosphates, ammonia, dry residuals, and sulfate s

has occurred .

In the Romanian stretch of the Danube most major polluting enterprises discharge their waste s

into tributaries, particularly into the Tisza; only a few enter the Danube directly . In the 1960s ther e

were more than 1,500 point sources of pollution ; in the 1970s industrial discharges had increased by a

factor of 4 .2 but there were only 100 treatment works and these were mostly overloaded .

37

TABLE 9

Some Indicative Hydrochemical Parameters of the Danube Wate r

Near Russia During Various Periods

PERIOD 02 mg/L 02 % OXIDATION SUSCEPTIBILI-

TY mg OIL

Max Min Average Max Min Average Max Min Average

1966-1972 10 .26 4 .64 7 .06 135 .0 74 .9 90 .6 7.12 2.73 4 .15

1973 8 .73 5 .09 6 .75 98 .5 71 .8 86 .5 5.86 2.00 4 .3 3

1974 9 .04 4 .57 7 .21 114 .1 64 .6 93 .0 7 .67 2.90 4 .90

1975 10 .02 4 .36 7 .15 126.0 67 .9 92 .9 6 .27 1 .68 3 .90

PERIOD NO- 3 mg/L NH- 4 mg/L Po --4 mg/L

Max Min Average Max Min Average Max Min AverageAverage Discharge m 3/sec

1966- 20 .00 0.35 7.52 1 .20 0.01 0.15 7 .60 0.00 0.19 618 1

197 2

1973 15 .00 2 .50 0.35 0.04 0.11 1 .00 1 .00 0 .00 0.16 5910

1974 11 .00 1 .20 6.04 0.30 0.05 0.10 1 .25 0 .01 0.34 7150

1975 10 .50 2 .00 4.29 0.35 0.04 0 .14 1 .45 0 .00 0.35 7940

Source : Rojdestvensky (1979)

3 8

TABLE 10

Average Seasonal Distribution of Phosphates and Nitrate s

Near the Danube Delta

10 N MILES FROM THE DELTA

20-50 NMILES FROM THE DELT A

Depth Winter Spring Summer Fall Yearly Depth Winter Spring Summer Fall Yearly

m Aver-

age

m Averag e

Phosphates (P'mg/ n3 )

0 115 .1 13 .0 1 .5 53 .6 48.3 0 40 .4 3 .1 1 .3 15 .2 15 .0

5 123.6 8 .2 3 .3 19 .0 38 .5 10 51 .6 7 .8 0.3 13 .7 18 . 4

10 30.7 2.5 1 .6 30 .0 16 .2 25 17 .4 3 .1 1 .8 8 .3 7 . 7

15 28 .4 1 .6 13 .1 37 .5 20.2 50 32.1 7 .8 9 .3 0 12 . 3

25 58.9 2 .3 19 .6 16 .3 24 . 3

Nitrates NO -3

0 569.4 136 .0 35.3 73 .5 203 .6 0 39 .4 3 .4 1 .4 77 .8 12 . 8

5 57 .9 45 .2 4.5 2 .9 27.6 10 9 .6 2 .7 0.5 0 3 . 2

10 41 .8 2.3 2 .3 2 .5 12 .5 25 10 .2 1 .4 1 .3 0 3 . 2

15 10 .0 0.6 1 .1 1 .7 3 .4 50 11 .8 2 .8 1 .6 0 .5 4 . 2

25 7 .7 1 .1 0 .6 5 .0 3 .6

After Rojdestvensky (1979)

39

Former U.S.S .R.

Limnological investigation of the Danube, conducted by the Institute of Hydrobiology of th e

Academy of Sciences of the Ukrainian SSR in 1958-1988 throughout the Soviet section of the rive r

from the confluence of the Prut to the mouth of the Danube, yielded data for the determination of th e

degree of contamination of the water (Almazov, 1962; Nikiphorova and D'iakonov, 1963 ; Simonov ,

1969 ; Shvebs, 1988) .

Of the 202 species and varieties entering into the composition of the phytoplankton of th e

river, 47 species (or 23 .2%) were so-called significant organisms .

Of these only one species (Oscillatoria tenuis Ag.) proved to be a-mesosaprobic, 19 wer e

β-mesosaprobic, and the other 27 were oligosaprobic .

The total content of bacteria and their biomass, the quantity of saprogenic and phosphorus -

mobilizing bacteria showed that the quantity of bacterioplankton in this region was very high an d

fluctuated from 2 to 45 .5 million cells per mL. The biomass of the bacterioplankton equalled 0 .5 to

17 mg per liter . The monthly bacterial discharge varied from 14 to 103 thousand tons . A study o f

the dynamics of the quantity of bacterioplankton showed that it depended chiefly on the content o f

suspended alluvium and organic substances .

The distribution of saprogenic bacteria fluctuated from 300 to 3000 cells per mL . In the bay s

of the Kilia fore-delta, the number was as high as 8 to 11 thousand cells per mL . The number o f

bacteria depended on the content of organic nitrogen, the temperature, and the discharge of water .

Thus, the degree of contamination of the river may be defined as oligo-mesosaprobic . The

highest degree of contamination of the river water occurred during early autumn and winter . An

investigation of waters flowing from the sections of Danube above the borders of the former U .S .S .R .

showed considerable contamination, which was β-mesosaprobic and determined the degree o f

contamination of the Soviet section of the river .

The total microbe count and the con index were fairly high, which is explained by contami-

nated water coming from the higher reaches of the river .

Hydrochemical Regime of the Lower Danub e

Prior to construction of the Iron Game dam, average mineral concentrations of the Danubian

water showed gradual increases . Average concentrations during 1950-1954, 1954-1961, and 1962 -

1965 were respectively 292, 318, and 321 mg/L, most likely due to increasing sulfates and chlorides .

Nitrate concentrations also rose during the same period . River pollution caused fluctuations i n

ammonia (NNH +), decreases in dissolved oxygen and increases in BOD 5 (Tables 8, 9, and 10) .

40

The effects of the Danube's outflow on nutrients in the Black Sea are revealed in Tables 8 and

10 . Concentrations of P and NO- at the surface near the Danube is elevated if compared with water

samples taken from the deeper layers or at greater distances from the shore (Table 10) .

Since 1973, the coastal areas north of the Danube delta have been struck by acute oxyge n

deficit (Atsikhovskaya, 1977 ; Tolmazin, 1977, 1985) because the lack of run-off and insufficien t

mixing, which in concerf have triggered catastrophic eutrophication. The coastal waters south of th e

Danube delta are polluted by agricultural discharges, in particular (Braginsky, 1986) .

The Upper Danube exhibits a reasonable self-purification capacity for polluting discharges, at

least with respect to degradable materials . However, the middle and lower Danube suffer fro m

pollution, especially in the winter when ice cover and low temperatures reduce the rates of oxidatio n

and different kinds of organic and inorganic materials subsequently affect the taste and odor o f

potable water supplies derived from the river .

The presence of high concentrations of ammonia has also been identified as a possible facto r

endangering the use of some reaches of the Danube as sources of potable water supply . The

maximum ammonium-ion concentrations occur in winter when the water temperature is low and th e

nitrification processes are suppressed, while striking nitrate concentrations are typical in early sprin g

owing to the high surface run-off from cultivated areas ( Lászlo and Homonnay, 1985) .

IV. INTERNATIONAL IMPORTANCE OF THE DANUBE BASIN

As was said, the eight riparian countries share the Danube waters, a small part of whic h

originates from the non-riparian countries : of Italy, Switzerland, Poland, and Albania . In addition ,

the Danube connects the two different socio-economic groups of West and East European countries .

A.

The Major Natural Resources of the Danube Basi n

Federal Republic of German y

Southern Bavaria possesses natural gas, oil, brown coal, and forest resources . In the vicinity

of the Czechoslovakian border pyrite, lead, zinc, tin, and brown coal are found . Agriculture assets

include meadow, ploughland, grassland, and livestock breeding .

Austria

The nation has brown and black coal, various metals, natural oil and gas, and significan t

forest resources . Crop lands occupy the Vienna Valley and the southeast zone of the country . Non-

fertile areas are confined to the Alps where snow and ice prevail all year around .

4 1

Czechoslovakia

Oil and natural gas exist along the lower reach of the March/Morava River, and in the Hro n

and Váh Rivers' watersheds various metal ores, natural gas, and brown coal are found . The valley o f

the Morava River and the southern part of Slovakia are the major ploughland regions . Forests with

pastures and meadows are typical for two-thirds of Slovakia .

Hungary

A typical agro-industrial country, Hungarian valleys produce wheat, maize, sugar beets ,

potatoes, grapes for wine, fruits, fodder, vegetables, and livestock . Mining and mineral resources

include bauxite, brown coal, natural gas and oil, lignite, uranium, bentonite, gravel, and pyrite .

Yugoslavi a

Coal and ore resources are abundant (copper and bauxite being the most important), while oi l

and gas resources are scattered. Cropland culture dominates in the north, and grassland and pastur e

in the south . Forests cover the land at higher elevations .

Romania

Still possess significant amount of oil (Ploesti region) and black coal . The major part of the

country is cropland . The mountainous regions of the Carpathians and the Transylvanian Middl e

Ranges are covered with forests and extensive pastures . In this area non-ferrous metals can be foun d

at several locations .

Bulgaria

The nation consists mainly of agricultural land . In the vicinity of Sofia brown coal, and along

the north-west border, black coal resources, can be found . Forests cover the ridges of the Balkan

Mountains along the basin .

Former U.S.S.R.

Most of this part of the Danube basin belongs to the catchment of the Prut river, and i s

mainly agricultural land . There are no significant mineral resources .

Cities and Town s

Along the banks of the Danube, there are ten major cities with populations exceedin g

100,000: Regensburg (125,000), Linz (260,000), Vienna (1,650,000), Bratislava (250,000), Budapes t

(2,000,000), Novisad (170,000), Beograd (1,100,000), Braila (120,000), Galati (150,000), and Rus e

(176,000) . Other major cities of over 100,000 inhabitants in the Danube basin are Munich ,

Augsburg, Innsbruck, Salzburg, Graz, Miskolc, Debrecen, Szeged, Pecs, Györ, Nyiregyháza ,

Székesfehévár, Kecskemét, Zagreb, Osijek, Subotica, Bucaresti, Brasov, Cluj-Napoca, Timisuara ,

Iasi, Craiova, Oradea, Arad, Sibiu, Bacau, Pitesti, Tirgu-Mures, Baie Mare, Satu Mare, Sofija, an d

42

Pleven (Radó, 1985). In the former U .S .S .R., Izmail, Reni, and Vilkovo have populations 100,000 .

Other

In the Danube basin, tourism also represents a significant economic factor and

among the water users, fishery plays an important role with a total catch of 4,400 tons/year (Table 8) .

A further 45,000 tons/year are taken from ponds in the floodplains and the delta (Gerasimov et al . ,

1969 ; Liepolt, 1973) .

B.

Utilization of Danube Water Resources

The multi-purpose utilization of the Danube includes :

n Municipal, industrial, and agricultural ;

n Flow regulation and flood control ;

n Sediment and ice control ;

n Hydroelectric power generation (a total capacity of 7900 MW) ;

n Local and international shipping between Danube and the Black Sea (The opening of th e

Rhine-Main Danube Canal will extend the waterway to the Atlantic Ocean with a total length

of 3500 km) ;

n The irrigation of about 4 million ha, with up to a planned 5 million ha ;

n Processing of drainage discharges from the watershed or pollution control ; and

n Recreational and commercial fishery, parks, and preservation zones .

Water management of the Danube basin is determined by : 1) geographical location of each

riparian country ; 2) the degree of economic development ; and 3) efficiency of the implementatio n

of major objectives of the Danube Commission among these countries . In the upper part of the basin ,

morphological and climatic conditions limit the development of irrigation . In this region, the major

uses of water are industrial and drinking water supply and hydroelectricity generation (Figure 11) .

Dams, canals, and regulated water elevation facilitate the utilization of the continuously renewin g

energy of the river, improve navigation, and reduce the risk of floods .

The same is true for the middle and lower reaches of the Danube, where flood protection ,

river regulation, and agricultural, industrial, and domestic water supply are the dominant water uses .

The water demand data within the basin estimated for the year 1980 and predicted for 200 0

are summarized in Table 11 (Information, SEV, 1976 ; Kovács, et al ., 1983) . Note that the predictio n

assumed an annual increase of 4-6% in water demand . Considering the world-wide economi c

recession which has strongly affected this region, the estimated increase might be exaggerated . The

most important demands are : 1) rivers should be navigable by larger ships independently from wate r

43

availability, 2) the inundation of valleys, developing settlements, and arable land should b e

eliminated, 3) continuous and safe supply of water of suitable quality for communities, industry, an d

irrigation should be warranted, 4) the river energy output should be thoroughly utilized, and 5 )

since rivers are recipients of wastes their self-purification capacity should be maintained . However ,

long before these goals were outlined, a large number of hydrotechnical constructions and wate r

conveyance systems had already been put into operation (Annex III) . Consequently, river beds ,

suspended sediment and bedload transport, the water quality, and even the flow discharges have bee n

changed considerably along several stretches . Dams and water transfer facilities have large radii o f

influence; therefore, their cumulative impacts are interwoven . Unfortunately, this interrelation wa s

realized by the neighboring countries only after a significant delay . As a result, the middle and lowe r

Danube, its delta, and the coastal ecosystem of the Black Sea are suffering a great deal of losses i n

water quality, fishery, and optimal utilization of fresh water intakes (Baidin, 1980 ; Al'tman and

Panayotov, 1988 ; Shvebs et al ., 1988) . This in itself has already contributed considerably toward

creating a new consciousness of interdependence and cooperation among the Danube countries at

present and in the future (RZdD, 1986) .

Flood Control

Historically Danube basin development has not been in close accord with the hydrologica l

regime of the Danube watershed . Riparian countries used their natural resources to their advantag e

and sometimes caused substantial changes in flow characteristics . The strengthening of river beds ,

deforestation of the slopes, and the desiccation of large areas by local dams significantly jeopardize d

large tracts of fertile lands and surrounding cities and villages .

Federal Republic of German y

Flood protection levees built in 1849-1897 from 2,540 km (Dillingen) to 2,510 km (Don-

auwörth) hindered thenceforth the floods from overflowing the banks and inundating an area of about

115 km 2 . Flood protection levees from 2,460 km (Ingolstadt) to 2,427 km (Fining) were built i n

1913-24 and reinforced in 1965-75 . They protect an area of 80 km 2 . Flood protection levees fro m

2,376 km (Regensburg) to 2,256 km (Hofkirchen) were constructed in 1930-56, protecting an area o f

about 120 km2 , but giving only partial protection for the territory between Regensburg and Strau-

bingen . On the basis of experiences gained during the floods in 1954 and 1965, these levees and th e

inland drainage were reinforced .

44

TABLE 1 1Water Consumption of the Danube Riparian Countries

(OMFB, 1975 ; Kovacs, et al., 1983)

1980 (10' m 3 /year) 2000 (10' m 3 /year )

Communal CommunalCOUNTRIES and Irriga- Fisheries Total and Irriga- Fisheries Total

Industrial tion Industrial Lion

FRG 170 - - 170 303 - - 303

Austria 120 237 - 357 207 682 - 88 9

Czechoslovakia 220 1970 12 2202 591 3740 12 4343

Hungary 411 4710 265 5386 729 9297 282 10308

Yugoslavia 224 1220 95 1539 381 4056 95 4532

Romania 595 12760 623 13979 984 26934 698 2861 6

Bulgaria 148 5680 - 5828 201 8608 - 8809

U .S .S .R . 82 1029 18 1129 85 1738 20 1843 x

TOTAL 1970 27606 1013 30589 34.81 55055 1107 59643

45

x Without the Danube-Dniester-Dnieper Canal .

TABLE 12Land Resources and Their Utilization (Thousand Hectares )

Aus-tria

Czechoslova-kia* (1980)

Hunga-ry (-

Bulgaria Romani a(1979) (1980)

(1978) 1978 )

Land Area 8,272 12,552 9,303 11,070* 23,034

Arable Land 1,547 5,112 5,423 4,400* 9,834

Permanent Crops 98 134 1,574 N/A 66 3

Permanent Pasture 2,071 2,071 1,307 N/A 4,46 7

Under Irrigation 46 244 450 1,182* 2,30 1224* *

Under Irrigation in 1990 N/A 525 N/A 1,700 -2,300

Total Irrigation Potential 200 1,366 .4 N/A N/A 5,400

Under Drainage 120 755 4,113 128** 39 0

Water Used for Irrigation 106m'/yr 350 500 -600 3,200* 3 .60 0600**

*

Including basins of all rivers .**

From the Danube alone .

Sources : Tumock (1979), Ponomarenko (1980), Tivko (1983), and Annex III .

46

Numerous completed dams and impounding reservoirs took over a part of the flood protectio n

by lowering flood peaks (Bayerisches, 1972 ; Danecker, 1981, DoKW, 1985 ; Kresser, 1984) .

Austria

Subsequent to flood disasters in 1830 and 1864, the first more extensive measures for