Regional and International Aspects of Strategic Water Development in Riparian Countries of Th E Danube Watersheds

TITLE : Regional and International Aspects of Strategic Water Development i n Riparian Countries of the Danub e Watersheds

AUTHOR: Dr. Michael A . Rozengurt

THE NATIONAL COUNCI L FOR 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

individual researchers retain the copyright on work products derived from research funded b y Council Contract. The Council and the U .S. Government have the right to duplicate written reports and other materials submitted under Council Contract and to distribute such copies within th e Council and U.S. Government for their own use, and to draw upon such reports and materials fo r their own studies; but the Council and U.S. Government do not have the right to distribute, o r make such reports and materials available outside the Council or U.S. Government without th e written consent of the authors, except as may be required under the provisions of the Freedom o f Information 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 for Soviet and East European Research . The analysis and interpretations contained in the report are those of th e author. 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 environmental economic and political problems are only just beginning to evolve . Current approaches to th e 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 environmental 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 development 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 .

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 e of the Danube 32 Austria, Czechoslovakia and Hungary 32 Yugoslavia and Romania 37 Former U .S .S .R 40 Hydrochemical 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 1 Federal Republic of Germany 4 1 Austria 4 1 Czechoslovakia 42 Hungary 42 Yugoslavia 42 Romania 42 Bulgaria 42 Former U.S .S .R 42 Cities and Towns 42

iii B. Utilization of Danube Water Resources 4 3 Flood Control 44 Federal Republic of Germany 44 Austria 47 Czechoslovakia 47 Hungary 47 Yugoslavia 48 Bulgaria 48 Romania 48 Irrigation 49 Hydropower 5 1 Navigation 58 Fishery 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 ANNEXES TABLE OF CONTENTS

ANNEX I.

Declaration on the Cooperation of the Danube Countries on Water Management an d Especially 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 s and Irrigation 100

* Historical Development of Waterworks 100

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

* Dams and Irrigation 110

Austria 110 Czechoslovakia 11 1 Hungary112 Yugoslavia 11 3 Bulgaria 11 5 Romania 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-Off Fluctuations 2 1

FIGURE 9 Geographic Settings of Hungarian Plains 2 3

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 Potential Ulm City to the Black Sea (Modified Affer Fekete, 1980) 57

FIGURE 15 Existing and Planned Inner Sfates and International Shipping Canal s in 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 Northwestern Black 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 n Stretches 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 e Danube 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 e Delta 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 .

Regional and International Aspects of Strategic Water Development in Riparian Countries of th e Danube 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) th e 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 th e 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 environmentally-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 th e 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 of 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 comple x 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

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 river 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 th e 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 1 The Main Characteristics of the Danube River : Subdivided by Navigation Stretches

Stretches of Distance Lengt h Width (m) Current velocity Number Minimum depth the Danube from the of the at of (m) mouth in stretch river-bed at Low Nay . river km in km navig . Highest Nav, WL Bridges WL at Lowest channel Low Navigabl e Locks Water Level Water Level (km/h)

Regensburg - 2379 - 153 150-300 10,30-4.60 13 1 .85-2 .00 Passau -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 .50 Moldova Veche - 1048 100-180 3 .67-2 .72 - 1 .60 Moldova Veche - 1048 - 117 600-1300 6 .19-0 .96 1 3 .50 Drobeta - Turnu - 931 100-180 2 .39-0 .87 1 3 .50 Severin Drobeta - Turnu 931 - 761 600-800 8 .85-4 .25 3 2 .50 Lower 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 2 The 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 5 Altmühl 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 26,65 8 Mosonyi Duna (Lajta, 1,794 right 18,06 1 Raba, 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 ; it 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 largest 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 temperatures 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 dee p 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 temperatures 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

26° E 27°E 28° 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 th e 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 (Figur e 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 th e extreme discharges are 1 :40 at the upper section, 1 :15 at the middle (Budapest), and 1 :8 - 1 :9 at th e 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 7 1 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 mountainou s 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

2 2 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%), th e 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 particularly pronounced during winter storms . In the navigational arms of the Prorva and the Tulina, the salt wedge penetrates man y

TABLE 3 Characteristics 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 4 Extreme and Average Discharges Along the Danube Cours e

Q. Min. Q. Average Q. Max .

m 3 / s

Passau 280 1 .470 8 .70 0 Vienna 390 1 .920 10.50 0 Budapest 650 2 .340 9 .50 0 Belgrade 1 .400 5 .300 13 .50 0 River Mouth 2.000 6 .430 19.200

2 5

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 Depositio n 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 th e 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, resuspension 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 .

III. HYDROCHEMICAL REGIME AND WATER QUALIT Y

A . Water Qualit y 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 of 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-mesosaprobic). 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 requirements 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 biochemical 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 .

2 9

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

YEAR COUNTRIES TOPIC OF AGREEMENT 1948 (1960-Austria ) (Austria), Bulgaria, Czechoslovakia, Hungary , Danube Convention on navigation of R . Romania, Ukraine, U.S.S .R ., Yugoslavia Danub e 1950 Hungary, U.S.S.R . Convention to prevent floods and regulate R . Tisza 1952 Romania, U.S.S .R . Convention to prevent floods and regulate R . Prut 1954 Austria, Yugoslavia Convention concerning water managemen t questions relating to R. Drava 1954 Austria, Yugoslavia Convention concerning water managemen t questions relating to R . Mura 1955 Romania, Yugoslavia Agreement concerning control of frontie r waters 1955 Hungary, Yugoslavia Agreement concerning water managemen t 1956 Austria, Hungary Treaty concerning water management in frontier region 1956 Albania, Yugoslavi a Agreement concerning water management in frontier region 1957 Hungary, Yugoslavia Agreement concerning fishing in frontie r waters 1957 Romania, U.S.S.R . Agreement extending R. Prut conventio n (1952) to Tisza, Suceava and Siret, an d other frontier waters 195 8 Czechoslovakia, Polan d Agreement concerning use of frontier wate r resources 195 8 Bulgaria, Yugoslavi a Agreement concerning water managemen t 1959 Romania, U.S.S .R . Agreement extending R. Prut conventio n (1952) to Danube 1963 Romania, Yugoslavia Agreement relating to navigation and powe r generation Iron Gates 1967 Austria, Czechoslovaki a Treaty relating to management of frontie r waters 1969 Hungary, Romania Convention relating to control of frontie r waters 1971 F.R. Germany, Czechoslovakia Local (non-government) commission dealin g with pollution and management of frontier water 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 of 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) .

3 2

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

TRIBUTARIES WITH MAJOR CITIES' INDUSTRIAL POLLUTIO N WITHOUT OR WIT H WITH WASTE TREAT- PARTIAL WASTE TREAT - MENT MENT

2370 Regensburg FRG 2220 Passau Region FRG 2130 Linz A 2120 Enns A

1930 Wien/Vienna /A 188 0 March/Morava A/CS 187 0 Bratislava C z 180 0 Gyór Region H 176 0 Váh C S 1650 Budapest H 1250 Novi Sad Yu 1170 Sava Y U 1170 Beograd (Belgrade) Yu 1100 Morava YU

690 Jiu R

600 Olt R

530 Jantra B G

43 0 Arges R O

With population equivalent of 500,000 or more .

3 3 FIGURE 1 2

Gabsikovo-Nagymaros Hydropower Schem e

1986 ; Szanto From Lokvenc and 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 treatmen t 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) .

3 5

TABLE 7 Bacteriological Water Quality from the Danube Water Intake at Mohacs to the Distribution Network of Pecs (Geldreich, 1984 )

COLIFOR M FECAL FECAL TYPE OF WATER TOTAL (PER COLIFORM STREP. (PER CLOSTRID- SPC (37°C) NH; MG/L 100 ML) (PER 100 ML) 100 ML) IA (PER 40 PER ML ML )

Danube-Water at Mohács 5200 - 72400 200 - 4600 < 100 - 500 64 - 240 3800 - 98000 0.17 - 1 .3 2

Clarified Water of Mohács 160 - 1200 210 - 960 0 .2 - 0 .9 6

Stored Mixed Water at 40 - 2100 95 - 850 0.04 - 1 .1 0 Pecs

Water Reaching the Active 1 - 200 37- 11 0 0 .06-0 .6 0 Carbo n

Purified Drinking Water xx xx 4 - 3 2 0 .01 - 0 .3 9

Stored Drinking Water xx xx 3-43 <0.1-0.4 2

Water in the Network xx xx 4 - 9 <0 .1

x Data from the period October 1983 to March 1984 . Practically not demonstrable .

TABLE 8 Discharge of Nutrients in the Danube Water, Concentration of Nitrates and Phosphates in the Upper 25 m Layer of the Black Sea and Fish Catc h YEARS 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 11964 196 5

Discharge of nutrients 159 258 351 324 333 293 418 322 413 450 411 38 1 in thousand tons Nutrient content in the -- 22.3 32.0 27.9 30.3 30 .9 26 .0 23 .1 22.8 38 .0 45 . 6 Black Sea mg/m' Fish catch near the 5 .9 2.9 4.0 4.2 4.7 5.1 8 .5 4 .3 3 .8 2.9 4 .4 5 . 3 Bulgarian coast in thousand tons

Source : Rojdestvensky (1966)

36 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 th e 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 .

3 7 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 .1 5

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 Average Average 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- m Averag e age

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)

3 9 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 contaminated 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 (N NH +), decreases in dissolved oxygen and increases in BOD 5 (Tables 8, 9, and 10) .

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 of 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

4 2

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 ; an d 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 . Th e most important demands are : 1) rivers should be navigable by larger ships independently from wate r

4 3 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 Contro l 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 1 Water Consumption of the Danube Riparian Countries (OMFB, 1975 ; Kovacs, et al., 1983)

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

Communal Communal COUNTRIES 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 x Without the Danube-Dniester-Dnieper Canal .

TABLE 12 Land Resources and Their Utilization (Thousand Hectares )

Aus- Czechoslova- Hunga- Bulgaria Romani a tria kia* (1980) ry (- (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 1 224* * 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 0 600**

* 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 th e protection of Vienna against floods were accomplished in 1869-1875 . The core of the engineerin g works was a 26 km long riverbed for which two large cut-offs had been established . For the first time in Central Europe, the works were implemented over this whole length, including dredging th e complete width (RZdD, 1988) . Other projects were also included, such as closing structures for the Danube Canal, variou s flood control embankments, and levees. Since 1898-99, a 180 m wide waterway in the regulate d section has been provided by means of groynes, securing navigation at low water stages . From 1882 to 1920, about 200 km of flood control levees were constructed from Vienn a down to the March (Morava) river, in the Tullnerfeld and Linz areas . Following severe floods in 1954, flood protection in Linz was increased using the flood wit h a 500-year return period as a design value . The system was further improved parallel to th e construction of the barrage at Abwinden-Asten . The present flood control system in the Vienna area is being improved to handle a discharg e of 14,000 m 3 /sec, which corresponds to a peak discharge of rare probability . In the downstream direction the levee system is dimensioned for a discharge of about 13 .200 m 3 /sec with respect to th e lower lying downstream countries . Czechoslovakia Flood control embankments were built in the second half of the 19th century, and a complet e system of levees was built for the entire northern Danube bank and southern Little Danube bank . Disastrous floods, most recently in 1965, stimulated here, as well as on the opposite bank, reinforce- ment and raising of levees and improvement of drainage within the protected areas . Hungary A quarter of the Hungarian territory, about 23,000 km 2 , is a potential inundation area o f which 23% lies directly in the Danube valley . Therefore, flood mitigation and protection is of majo r importance in this country . A systematic construction of flood protection dikes and a drainag e network was started in the first half of the 19th century and completed by the end of the 19th centur y (severe floods occurred in 1881 and 1888) . In the first half of the 20th century, the levees were raised and reinforced so that safe protection against floods for a 60-year return period was provided (the total flood control line bein g

4 7 about 1,350 km) . It is supplemented by secondary lines of 260 km length and by the 18 km lon g special protection of Budapest. The significance of flood control in Hungary is evident from the following : within the potential inundation area live a quarter of the total population, and about 30% of the railway network and 20% of all highways are located there . Yugoslavia Systematic construction of flood control levees in the Pannonian Basin (Middle Danube ) started in the 19th century . By World War I a continuous protection system had been constructed , linked to the Hungarian levees, reaching on the left bank down to the mouth of the Tisza (Tisa), an d on the right bank to the mouth of the Drau (Dravá). Further downstream, the levee system on th e left river bank was still deficient at that time, while on the right bank flood control dikes were constructed only at Petrovaradin and Zemun . In the period between the two world wars, the system of levees was expanded (for instance, at Pancevo on the left bank and at Smederovo and Godominsko Polje on the right bank) . After World War II, some new sections were built to complete the flood protection and parts of old dikes were raised, reinforced, and restored . This work was triggered by experiences gained during th e catastrophic flood in 1965. At present, there is a continuous system of dikes on the left bank from the Hungarian border down to the mountainous reach of the Iron Gate (from the Hungarian border down to the mouth o f the Drau (Drava), at Petrovaradin and Zemun, as well as at Smederevo) . The crest of flood control dams is usually 1 .5-1 .7 m above the water stage of flood of a 100 - year return period . Bulgaria Over the years from 1930 to 1950, about 300 km of flood control dams were constructed to protect an area of about 72,600 ha . The height of the levees was dimensioned according to the extreme flood of 1897 . Romania The construction of flood control levees for protection of agricultural land was initiated in th e 19th century . The protected area was increased from ca . 50,000 ha in 1940 to ca. 100,000 ha in 1960, and has been further increased to ca . 400,000 ha at present . The total length of flood contro l levees is 1,000 km (RZdD, 1986) . Note that during extreme flooding the Danube may be as wide as 19 to 20 km (Figure 6) . The Tisza flood-protection project, completed at the beginning of the century, greatly reduced the ris k

4 8 of damage to settlements and arable lands along the river . Several canals and dikes are channelin g the excess into the Danube . Of the entire river, only the 800 km stretch in Romania poses a continuing threat to low-lying areas on both banks . The discharges of major Romanian rivers (the Danube tributaries) show considerable variatio n from year to year, which affect lowland areas every year . In this regard, many streams from th e Carpathian mountains and Transylvania uplands are characterized by very strong torrential characteristics. As a result, Romania suffers a double threat: first, the risk of flooding from streams draining the Carpathians in the late spring ; and second, from the cumulative Danube run-off . The latter considerably increases the inundation of vast low-lying terrains and numerous coastal cities an d villages. The Soviet towns between Izmail and Vilkovo are in danger as well . In Romania, about 2.89 million ha of land may experience occasional floods. Out of this area, about 1 .30 million ha i s protected by 3,400 km of levees . Between 1961 and 1968, on average, 0 .26 million ha were flooded each year, including 0 .10 million ha of arable land, 2 .38 thousand houses, 19 industrial units, 152 k m of roads and railway, and 182 bridges . The damages amounted to about $7 .5 million per year . Note that serious flooding in 1970, 1973, and 1975 forced an overhaul of the flood protectio n measures. For example, the disastrous flood of May 1970 was a combined result of a wet winter an d exceptionally high rainfall in May . This development caused the Somes and Mures (the Tisza' s tributaries) to swell . Continued heavy rainfall in southern and eastern districts of the Carpathian s brought further serious flooding to the Siret and Prut and above all the Olt . In late May and earl y June, the Danube valley was threatened with discharges approaching the 1895 record level of 17,30 0 m 3 /sec at Bazias and 22,000 at Tulcea . These run-offs exceeded three to four times the average of 5 .400 m 3 /sec and 6,300 m 3 /sec, respectively . Total damages amounted to approximately $50 0 million. A new land improvement program was announced in 1971 which included strengthening an d raising levees and measures to prevent erosion . Some parts of these preventive measures wee implemented in the Lower Danube in the mid 1970s-1980s . Irrigation The major consumptive use of water in the Danube basin is irrigated agriculture (Table 12) . Water use in agriculture is extremely site- and time-specific, and depends on a complex mosaic o f soils, water permeability and retention characteristics, topographic features, local climatic conditions , water quantity and quality, frequency of floods, etc . Apart from physical conditions, agricultura l development of a particular country largely depends on existing or acquired expertise in irrigation and cropping technologies, economic incentives, and water availability . Irrigation in the Danube valley underwent a relatively rapid development after World War II .

4 9 Irrigation gradually is becoming essential for meeting the volume and quantity requirements o f agricultural production for averting the consequences of adverse weather conditions . The Danubian territories along the upper German and Austrian stretches have a relativel y abundant rainfall. Considerable irrigation is carried out in the Vienna area (Austria) ; in the Slovakian Zitni-Ostrov region; in Hungary, along the Danube and mainly along the Tisza on the Grea t Hungarian Plain; in Yugoslavia, along the Danube-Tisza-Danube Canal system; in Bulgaria, on th e right side of the Danube and in the Dobrudza area ; and in Romania, in the territory between th e Carpathians and the Danube. Presently, around 4 million ha are irrigated in these areas . Over 1 6 km 3 of water are diverted from the Danube, mainly in July and August, to the irrigation network . This substantially hinders navigation on the Danube in the summer . Generally, the scope and rate of irrigation along the Danube steadily increases from West t o East, excluding, at present, fhe former U .S .S .R. (Table 11) . In West Germany, Austria, and mountainous parts of Yugoslavia where rainfalls and thawing produce excess surface water, th e drainage of potentially arable land is a major part of land amelioration programs . Drainage has led t o consolidafion of scattered holdings enabling a rational employment of agricultural machinery . In the uplands of Southern Mordava and the South and East Slovakian lowlands (Czechoslova- kia) the mean annual rainfall is close to 500 mm, and its seasonal distribution is not in accord wit h the water needs. Here several projects have been commissioned or are under construction fo r supplemental irrigation . New lands have been brought into production in areas of high run-off i n river basins draining southward from the high Tatra Mountains . In Hungary, all three components of water management (drainage, water conservation, an d irrigation) are parts of integrated developments within the Danube and Tisza valleys . Irrigation i s closely associated with construction of barrages against floods on the rivers . Thus, crop failures fro m inundation are averted and optimum water availability before and during the growth period of th e crops is assured . Meandering dead branches of the rivers, cut off from the flow by the levees an d natural depressions in the terrain, are used as reservoirs . Droughts in the plains of Yugoslavia can be disastrous for an entire crop . In 1952, cro p losses amounted to $300 million . Therefore, irrigation is considered absolutely essential fo r successful agriculture . Recently, several important projects have been prepared . Among them the Danube-Tisza - Danube and the Macedonian irrigation and drainage schemes are notable. The first will drain an area of about 1,000,000 ha while the irrigated area will be 300,000 ha . The second one is unde r construction and will assure irrigation on

50 70,000 ha . Along the lower stretch of the Danube, irrigation is one of the fastest growing parts of Romania's infrastructure. For example, the irrigated area increased ten times between 1965 and 1980 . In the Danubian plains, irrigation works are part of an integrated system combining floo d protection, road construction, relocation of settlements, and selection of alternative crops . The 197 0 catastrophic widespread flooding in Romania demonstrated that valuable lands and structures can b e lost. Since then, large tracts of lands in Romania have been diked . More than 300 km of levees have been erected along the Danube in the Bulgarian lowland to protect 70,000 ha . Drainage is also well-developed in both countries . Some lowlands cannot be completel y drained, so special crops such as rice were introduced to make use of wetlands. Reclamation projects in Romania carried out on 289,000 ha of inundatable area increased crop production by almost 600% . Selection of plants on non-irrigated reclaimed lands has also increased total yield . The main problem in Romania related to irrigation is the 400,000 ha of salinized land in th e western lowlands, the eastern side of the central mountains, and along the downstream part of th e Danube. There are plans to cope with these problems as a part of integrated development of th e lower Danube . Hydropower The longitudinal section of energy-potential (multiplied with slope) of the Danube (Figure 1 3 and 14) clearly indicates that the highest specific power resources are concentrated in two reaches : between Passau and Gönyü, and downstream from Belgrade, in the Iron Gate region . The first reach (between Passau and Gönyü) is especially energy potential and is determine d by a high slope of 150 m along about 435 km length of the river; at the second reach (downstream o f Belgrade) the high energy potential is linked to the highest river run-off. The break in the slope of the river bed at Gönyü is from the results of sediment accumulation at the breakpoint . Accordingly , the annual bed load transport at Bratislava is about 650,000 m3 while it is only 13,000 m 3 above Budapest. This is the reason for the well-known "bottle neck" in the navigation along the critica l Czechoslovakian-Hungarian reach (Benedek, 1986) . The plans for the complex utilization of the Danube's water resources involve 49 rive r barrages, of which 31 have been constructed so far (Figure 11, Tables 13 and 14) . The current utilization of the total capacity (61%) of storages and hydropower plants is assumed will increase to 90% by the turn of the century (DoKW, 1985 ; OVH, 1985) . Figure 13 gives some information o n the extensive hydropower utilization of the Austrian Danube section (DoKW, 1985) . The hydroenergy potential of the Danube basin exceeds that of any other European river .

5 1 The technically exploitable potential for the entire river might be used for hydropower plants with a capacify of 7,900 megawatts. Of this, 3,250 megawatts had been developed by 1980 (Matrai, 1980) . In 1920s-1940s, only upper reaches of the Danube were exploited for hydroelectricit y production . By 1970, numerous mountain rivers had been developed for hydroelectricity : the Isar , Inn, Salzach, Enns, Drava, Vitava, Vah, Zeta, and Bistritsa . Yugoslavia and Austria made hydro - electricity one of the important constituents of their country ' s energy mix . In 1969, about 63% of th e total energy production in Yugoslavia was derived from falling water . In Austria the role of hydraulic energy was even higher in spite of rapid development of thermal power plants using fossi l fuels . Hydroenergy development sharply increased with construction of the Iron Gates complex with a total installed capacity of 2,050 MW, jointly financed by Romania and Yugoslavia . The dam raised the water level 34-35 m for a reservoir with an area of 1,010 km 2 in the gorge between the Car- pathian and the Balkans ranges . The construction took seven years to complete (1965-1972) and called for extensive diversions of lines of communication as well as the rebuilding of the town o f Orsova . Two other jointly conceived impoundments are in the offing. Hungary and Czechoslovaki a are in the process of constructing the Gabsikovo-Nagymaros river impoundment system. It wil l consist of the storage reservoir with 60•10 6m 3 working volume, a 17 .6 km long navigable canal with maximum depth of 18 m and a hydroelectric plant with an installed capacity of 700 MW and 2,630 GWh yearly output, mainly in peak regime (VITUKI, 1985) . The Nagymaros barrage will consist o f a powerhouse, weir, and twin navigation locks . The horizontal tubular turbines will have a total o f 146 MW installed capacity . Implementation of the project is expected in 1992-1993 . Romania and Bulgaria will co-operate in a complex hydroenergy project immediately belo w the Danube - Olt confluence, including a 400 MW power plant, navigation locks, and irrigatio n supplies for 100,000 ha (Turnock, 1979) . The lake will extend upstream some 300 km and wil l require raising levees by up to 15 m . The barrage and weir systems slow down water movement and cause the freezing of the rive r to occur more frequently (Matrai, 1980) .

5 2 TABLE 1 3 Existing and Planned Hydropower Stations in the Danube Basi n (OVH, 1985 ; DoKW, 1985 )

SERIAL RIVER BARRAGE OR HYDRO-POWER CAPACITY POWER OUTPUT NO. STATIONS MW Gwh 1 .-20 . 20 hydro-power stations between Ulm and Kelheim 230 136 7 21 . Bad-Abbach 22 . Regensburg 20 130 23 . Geislin g 24 . Straubing 40 270 25 . Deggendorf 20 130 26 . Aicha - 27 . Vilshofen - 28 . Kachlet 54 31 9 29 . Jochenstein 130 850 30 . Aschach 286 164 8 31 . Ottensheim-Wilhering 179 114 3 32 . Abwinden-Asten 168 102 8 33 . Wallsee-Mitterkirchen 210 1320 34 . Ybbs-Persenbeug 200 1282 35 . Melk 187 1180 36 . Rührsdorf 150 800 37 . Altenwörth 335 1950 38 . Greifenstein 293 1720 39 . Wien 141 620 40 . Hamburg 360 2075 41 . Gabcikovo 700 2630 42 . Nagymaros 146 97 8 43 . Adony 150 77 5 44 . Fajsz 100 65 0 45 . Novi Sad 250 1500 46 . Iron Gate 1 2050 10000 47 . Iron Gate 2 400 240 0 48 . Turnu Marmureie 760 380 0 49 . Cernavoda 400 300 0 TOTAL 7959 43565

TABLE 14 The Water Storages of the Danube Watershed

STORAGES RIVERS DAT TOTAL ATTAINABLE NOTES E VOLUME MILLION M3

Germany Forggen-See Lech 1954 165 15 0 Sylvenstein Isar 1959 108 104 Grünten-See Lech 1961 16 .0 12 .2 Eixendorf Naab 1975 18 .8 18 .5 Frauenau Regen 1983 12 .5 10 . 5 Postmünster Inn 1973 13 .1 12 .6 Walchensee Isar 1924 1300 11 0 Austria Kölnbrein Drau 1979 205 20 0 Gepatsch Inn 1966 140 138 . 3 Schlegeis Inn 1973 127.7 127 . 4 Zillergründl Inn 1986 90 8 9 Mooserboden Inn (Salzach) 1956 88.0 85 . 4 Wasserfallboden Inn (Salzach) 1951 86.0 82 . 8 Achensee Isar 1927 70.2 Oberleitung 1 .d. Inn Finstertal Inn 1981 60.5 60 . 0 Tauernmoossee Inn (Salzach) 1974 56 .0 55 . 3 Durlaßboden Inn (Salzach) 1968 53 .0 52 . 5 Ottenstein Kamp 1957 73 .0 51 .0 Oscheniksee Drau (Möll) 1976 33 .0 Vorderer Gosausee Traun 1912 24 . 7 Dobra-Krumau Kamp 1955 21.0 20 .0 Großsee-Hochwurten Drau (Möll) 1975 17 .7 17 . 5 Weißsee Inn (Salzach) 1953 16 .0 16 . 0 Bockhartsee Inn (Salzach) 1984 14.8 14 . 2 Salza Enns 1949 11 .0 10 . 6 Czechoslovakia Orava Váh 1953 545.9 298 . 1 Liptavská Mara Váh 1977 360.0 320 . 5 Nosice Váh 1958 36.0 24 .0 Sinava Váh 1959 12 .2 4 .2 Kralova Váh 1985 50.8 22 . 3 Ruzina Impel 1973 14 .76 13 . 0 Bukovec Bodva 1975 23.4 21 . 4 Palomanská Masa Hornad 1956 11 .05 10 . 3 Ruzin Horned 1968 59.0 48 . 5 Zemplinska Sirava Bodrog 1965 334.0 177 . 0 Velka Domasa Bodrog 1966 185.0 146 .0

5 4

STORAGES RIVERS DAT TOTAL ATTAINABLE NOTES E VOLUME MILLION M3

Hungary K-V-3 Ost-Hauptkanal 1969 11 . 0 Fischteich v . Begecs Sebes-Körös 1960 11 . 6 Staustufe Bökeny Kamm-Körös 1906 12 . 0 Speicher v. Fehérvárcsurgó Sio Kanal 1972 14 . 2 Fischteich v . Biharuga Sebes-Körös 1958 15 . 6 Hortobagyer Alte Teiche West-Haupt-Kanal 1940 16 . 0 Staustufe Tiszalök Theiß 1959 17 . 0 Staustufe Békésszentandrás Harmas-Körös 1942 20 . 0 Staustufe Kisköre Theiß 1973 300 .0 Yugoslavia Mratinje Save (Piva) 1973 88 0 Bajina Basta Save (Drina) 1966 691 61 0 Kokin Brod Save (Uvac) 1961 250 22 0 Sjenica Save (Uvac) 190 Modrac Save (Spreca) 1964 160 154 Zvornik Save (Drina) 1955 89 23 Potpec Save (Lim) 1966 44 25 Gazivode V. Morava (Ibar) 390 Vlasin V . Morava (Vlasina) 1948 165 107 Batlava V. Morava 1962 52 Medjevrsje V. Morava (West M .) 1953 1 8 Romania Fintinele Somes 1977 225 180 Vidraru Arges 1966 470 320 Vidra Olt (Lotru) 1973 340 300 Izvorul Muntelui Siret (Bicaz) 1961 1230 930 Former U.S.S.R . and Romania Kostest Prut 450 Bulgaria Iskar Iskar 1955 673 550 Stambolijski Rosica 1950 22 180 Sopot Vit 1960 60 46

Source: Die Donau und ihr Einzugsgebiet, 1 98 6

5 5 FIGURE 1 3

Austrian Hydropower Station s

Fran DoKW, 1985 FIGURE 1 4

Schematic Profile of the Danube Slope, Discharges and Energy Potentia l Ulm City to the Black Sea (Modified After Fekete, 1980) The thermo power systems of fossil fuel and nuclear reactors throughout the Danube basi n consume and modify (temperature increases) significant volumes of run-off . Special storag e reservoirs are occasionally required ; for instance, a vast artificial lake was constructed at the junctio n of the Jiu and Tismana rivers in Romania to provide cooling water for the nearby thermal powe r station, exploiting the Oltenian lignite field for fuel . The dam (7 km long, 15 m high, and holdin g 300 million m 3 of water) has substantially changed the landscape of the surrounding terrain . Such cooling systems are commonplace, although most cooling waters are discharged directly in the nearb y streams and natural lakes, increasing their temperature throughout the year, which negatively affect s natural habitats . Navigatio n For many centuries the Danube has had considerable economic value as a major east-wes t artery through the heart of Europe (with a record 25 million tons of shipping in 1960 increasing to 5 5 million tons in 1980) . However, both political and physical obstacles have limited its shippin g capability . International cooperation of Danube countries concerning navigation is based on severa l agreements concluded since 1856 . During the Danube Conference held in August 1948 in Belgrade , the "Danube Commission" was founded with headquarters in Budapest to regulate problem s concerning navigation, and hydraulic structures serving navigation (Navigable depth, width , curvature, slope, size of lock gates, discharge capacity, etc .) for the whole navigation route fro m Regensburg to the Black Sea (Figure 15) . Since that time, the Danube Commission has provided important contributions for th e elaboration of waterway parameters and other regulations by providing recommendations tha t countries are suggested to follow when formulating their development plans . This is especially tru e for the economies of Yugoslavia, Romania, Hungary, and Austria, whose territories and populatio n lie almost entirely in the Danube watershed . Note that in the recent past, the rate of development of Danubian shipping has exceeded th e volume of goods transported yearly on the Rhine . In addition to the Danube, some tributaries are also naturally navigable, or were adapted b y the respective countries for navigation : n The Drau/Dráva up to Cadarice (105 km) , n The Tisza/Tisa up to Dombrád (about 600 km) as well as its tributary, the Bodrog, u p to the Hungarian-Czechoslovak border ,

5 8 n The Sava up to Sisak (583 km) for smaller ships, an d n The Prut on a short section of its lower course . The Backa Canal in Yugoslavia, connecting the Danube with fhe Tisza/Tisa is also navigabl e (RZdD, 1986) . The contribution of the Danube water system to goods transported on European waterway s equals 5% . This proportion may be raised up to 10-15% when the Rhine-Main-Danube Cana l interconnecting the two systems is finished . Note that proposed or partially implemented inter-river canals include : n Rhine-Main-Danube canal, providing a continuous waterway from the North Sea t o the Black Sea (Massing, 1980) ; n Danube-Odera-Elbe canal, providing links between the Baltic and the Black Seas : n Danube-Morava-Vardar-Axios canal, providing a link with the Aegean Sea (WHO , 1983), which may further aggravate the hydrological and biological regime of th e lower Danube . Three principal bottlenecks required extensive international cooperation for safe shippin g (Annex I and II). One of them was below Bratislava where the river divides into three branches an d was due to low seasonal flows, sedimentation, and evaporation during the warm season . The middl e branch has been designated as a navigable channel and was dredged to maintain a four foot (1 .3 m ) depth throughout the year . This problem has been alleviated by construction of a series of barrages . Anticipated implementation (1992-93) of the Gabsikovo-Nagymaros weir system will greatly improv e navigation conditions (Annex II) . The historical obstruction in the Iron Gate gorge has been overcome by construction of a hydropower station with two locks . These facilities allowed safe shipping of large vessels along th e length of the river to Vienna and beyond . The third obstacle was the delta where the three majo r channels were silted every year . Now at least two channels (Figure 16), the Prorva and the Sulona , are continuously dredged to allow 7 to 8 m draft vessels to pass through to the Black Sea . Construc- tion of the artificial canal Cernavoda-Constanta (see below) greatly facilitated shipping in the lowe r and middle portions of the Danube . The population of the Danube catchment area is 80 million . The Rhine-Main-Danube Cana l will ensure a direct waterway to the Rhine area with over 200 million in population . This transcontinental waterway of 3,500 km length between the North Atlantic Ocean and the Black Sea will serv e about 300 to 325 million people by the end of the century . The direct waterway connection between the two areas promotes favourable modification o f

59 FIGURE 1 5

Existing and Planned Inner States and International Shipping Canal s in Central and Eastern Europe national infrastructures (steel and coal production, oil refining, chemical industry, and energ y production) and as a result a more vigorous economic expansion . The growing trade between West and East through the completed part of the Rhine-Main - Danube Canal reached 20 million tons in 1987 . According to estimates, it was expected that the tota l Danube transport would reach 190 million tons by 1990 . The completion of the Danube-Black Sea Canal in 1984 started a new era for marine transpor t throughout the lower Danube. The new waterway, 7 .0 m deep and 70-120 m wide, extends over 64.2 km from the Danube at Cernavoda to the Black Sea at South Constant-Agigea . It runs along the Carasu Valley (the Dorogea tableland) at an elevation of 7 .5 m above sea-level and maintains thi s level in a long cut through chalk and limestone up to 70 m deep which runs from Basarabi toward s Agigea . Canal locks are located at the Black Sea, Agigea, and also at Cernavoda where th e maximum elevation of the Danube is 12 .0 m. A 200 m 3 /sec pumping station at Cernavoda can maintain the water level in the canal if the Danube should fall below 7 .5 m . The dimensions of th e canal and its locks (two chambers of 310 x 25 m at both ends) make the waterway suitable for six 3000 ton barges at once . Construction of the canal began in 1978 and involved an unprecedente d mass mobilization of labor and equipment using the style typical of a totalitarian country . The secon d stage of a canal assumes the construction of a navigable 30 km branch from Poarta Alba nea r Basarabi to Navodari and Midia. (The effects of the new canal on various sectors of the Romania n economy is discussed by Turnock (1986) and sources cited therein . ) The navigation route was shortened by 370 km . This canal, the construction of whic h required the removal of 300 million m 3 of earth (more than in the case of the Suez Canal : 275 million m 3) also provides water for irrigation of 700,000 ha of arable land in Dobrogea . The Danube-Black Sea Canal is expected to have measurable effect on the viability of th e alternative route through Sulina , former U .S.S .R. The canal requires 4% to 5% of the averag e discharge of the Danube (a significant amount as compared with normal seasonal and annua l discharges) . Besides, the canal affected the alternative route to the delta, to the point where the Sulin a channel in the former U .S .S.R. might be closed down. Quite apart from the limited capacity of th e river, there is an ever present threat from the southward-advancing Chilia delta, which supplie s material at the entrance to the Sulina channel . To protect the approaches to Sulina, dikes have bee n progressively extended into the Black Sea (1 .6 km in 1910, 3 .2 in 1934, 4.8 in 1953, and 6 .4 i n 1980), but dredging is also necessary . Utilization of the Danube-Black Sea Canal has become a sustainable component of the Danub e

6 1 FIGURE 1 6

The Locations of the Four Alternative Routes of the Danube-Dniester-Dnieper Canal Along the Coast of the Northwestern Black Sea (NWBS )

NORTHWESTERN BLACK SEA

(A) : The location of the four alternative routes of the Danube-Dnieper Canal along the coast o f the northwestern Black Sea .

( B ) : The zone of hypoxia or anoxia, and mass mortality of flora and fauna of the northwestern Black Sea .

Source: Rozaengu rt, 1974; Tolmazin, 1985; Vinogradov, 1990

6 2 international transportation system . The Soviets, on their part, clearly wished to maintain access to Izmail and Reni . The former Soviet trade through the Danube was on the rise considering the number of ships in operation an d goods delivered to and from its East European partners and the Western states (Fedorov, 1984 ; Sivko , 1984). In 1969, the amount of traffic handled at the U .S.S .R.'s Danubian ports was second to that of Hungary and continued to hold this place up to the collapse of the Soviet Union . The Soviet part o f the Danube Delta was continuously dredged to provide shipments of oil, vegetables, fruits, wine, fis h products, etc., from the Danubian towns of Reni, Izmail, Vilkovo, Kilia, and other cities of th e Danube's network to the Odessa metropolifan area . Note that a planned increase in large barge traffic between the former U .S .S .R. and Europ e will require modernization of existing port facilities . For example, the expansion of deep water area s has become extremely important, since the northward diversion of the Danube water has come to be . Increased fresh-water consumption has forced more water from the main river channel near th e branching delta points . Depletion of seasonal flow within the Danube basin was exacerbated b y disruption of movements of water through the lining of newly constructed canals, which curtaile d replenishment of ground water . The total increment in the area of the watertable exceeds the historical average by approximately 2% to 4% . However, the construction of modern barrages and dikes effectively decreases seepage and waterlogging . Shipping, returning waters from agricultural drainage networks, and hydropower plant wate r releases to maintain navigation in summer, noticeably modified river discharge patterns . Summer run-off increased up to 15%, while in spring the flow decreased to 72% of normal .

Fishery The spawning ground and fishery of the Danube basin can be divided into three regions : 1) Upper and Middle Danube, 2) Lower Danube and delta, and 3) the coastal area from the Danub e avante-delta down to Romania and Bulgaria . In the Danube, within the borders of the former U .S .S .R ., there are 61 species of fis h belonging to 19 families ; in the Danube area basins, 46 species belonging to 14 families . In the coastal waters, there were as many as 69 species of fish belonging to 32 families , including anchovies, sprats, herrings, mullet, garfish, Black Sea haddock, sole, and others . However, the most important fishery in the lower Danube-Delta coastal ecosystem is th e commercial harvest of androgenous fish . Beluga (Huso Huso Linne), Acipense r guldenstädti

6 3

colchicus V . Marti, Acipenser stellatus Pallus and sterlet (Acipenser ruthenus Linné) are of commercial importance . The first place by weight is occupied by beluga (78 .4 percent), Acipenser guld- enstädti is second (13 .8 percent) and Acipenser stellatus represents 7 .8 percent . In the catches A . stellatus occupies first place and beluga is last . Note that the impoundment of the Danube and curtailment of spawning grounds by dams hav e reduced a formerly flourishing fishery to nearly zero . For example, in 1947-54 the commercia l catches of the most valuable fish in Ukrainian waters were : beluga - 310 to 351,000 pounds ; smal l sturgeon (sevruga) - 125 to 135,000 pounds ; and sturgeon - 60 to 65,000 pounds (Vinogradov, 1969) . Today their commercial catch nearly has ceased to exist (Stepanov and Andreev, 1981 ; Tolmazin , 1985; Rozengurt, 1991) .

V. POLITICAL AND ENVIRONMENTAL INTRICACIE S

Despite the Danube's effects on the economies of a dozen countries and over 80 millio n people, its environmental infrastructure is typified by the absence of a basin-wide authority responsible for multiple issues affecting the river, including, but not limited to, water resources management , utilization, and preservation . In practice, the Bucharest Declaration of 1985 (or Danube Declaration ) deals solely with navigation under an umbrella of the Danube Commission, which is entrenched i n politics rather than institutional cooperation . Therefore, bilateral or trilateral initiatives are prevalen t rather than sustained basin-wide coordination in comprehensive monitoring of water quality , sedimentation, etc ., which makes it difficult to draw a clear picture of the water quality status alon g the river (Benedek et al ., 1978 ; Convention, 1975; Deklaration, 1985 ; ECE, 1980 ; Fekete, 1972 ; Information, 1978; Kovacs, 1986; Massing, 1980 ; OVH, 1985) . Instead, in some part of the Danube Declaration, one may find a wishful statement that the Danube basin governments will strive to develop and implement a coordinated water qualit y monitoring program "in the framework of their bi- and multilateral cooperation," and a timetable i s established . But there is no description of an institutional mechanism for assuring that such a monitoring program is either developed or implemented (Toth, 1982 ; WHO, 1982-1986). Nor are there any clear expectations of wide, multilateral, operational cooperation getting underway in th e near future. The major causes of these deficiencies are : 1. Volatile political life which precludes the establishment of the Danube watershed authority ; 2. The fear in some countries of being accused of infringement of national sovereignty ove r riparian rights by use of a non-governmental basin-wide authority ;

3. Conflicting upstream/downstream requirements for water utilization ; 4. The lack of understanding of the complexity of water quantity and quality problems, whic h differ significantly among upstream and downstream countries and even among their ow n provinces; and 5. Incompatibility of unrestrained water utilization with the natural limitation of run-off renew - ability . Some of these mismatches has been inherited from the international policies of the basin' s formerly socialist countries (Yugoslavia, Czechoslovakia, Hungary, Romania, Bulgaria) whic h specifically banned database exchanges if water quality was a subject of interest (Rojdestvensky , 1979 ; Rothschein, 1981; RZdD, 1986; Salewicz et at., 1990) . At present, with the collapse of socialist regimes much information on environmental problems, hidden in the past, has entered the public domain (Reimers, 1988) . This has paved th e way to the transfer of substantial economic aid from Western countries to former Soviet satellites t o clean up the mess left by communist rulers . However, there are some obstacles in attaining a visible success in the improvement of th e downstream part of the Danube watershed . Among them are : 1) the differences in infrastructure , 2) the lack of hard currency, 3) the never-ending discord in determination of common and priorit y tasks in water development and preservation among upstream and downstream countries, 4) th e centuries' hidden outcries for self-determination, boundaries and sovereignty (Yugoslavia-Slovenia - Croatia, Romania-Transylvania-Hungary, Romania-Ukraine-Moldova, etc .) . All of these major issue s have been well known since 1989, and each new year makes them even more entangled an d dangerous . Recognizing these inherited instabilities, there is an opinion that practical progress on th e Danube would be largely through bilateral negotiations . The GNV (Gabsikovo-Nagymaros) power project that involves the construction of a huge hydropower system along a 150 km stretch of th e Danube on the border between Czechoslovakia and Hungary is bilateral . The idea of building a series of dams and hydroelectric stations on this part of the river was originally raised in the 1950s . Because of its expense, however, the plan was dropped in 1963 . Ten years later it was revived, an d in September 1977 a final treaty was signed between Czechoslovakia and Hungary to proceed with th e project. Construction began in 1978, and completion was scheduled for 1994 (Annex II) . Since the 1970s, the GNV Project has caused controversy and disputes among differen t professional and social groups . Supporters gave three major reasons in its favor : need for improvement in navigation conditions, hydropower generation, and flood protection. In oppostition ,

65 opponents in Hungary stressed environmental impacts and costs because long-term environmental consequences and studies were not available or synthesized in an environmental impact assessment . The Hungarian National Council for Nature and Environmental Protection (Csepel, 1984) arrange d additional studies in Hungary to analyze possible adverse impacts and to propose measures that woul d diminish or neutralize the negative effects of the hydropower design (Lokvenc and Szanto, 1988) . The main concerns raised were associated with : 1) inundation of priceless arable land, 2 ) impact on groundwater, 3) the water supplies of much of Hungary, 4) The self-purificatio n capacity of the river, and 5) the natural filtering capacity of the river bed, which critics feared would be disturbed by the project . Public involvement in the decision process concerning investment and engineering structures of GNV, has caused very strong political discontent in both Czechoslovakia and Hungary . This presents severe, and in the end insurmountable problems for the project, especially in light of change s taking place every day in Hungary and Czechoslovakia . As a result, since September 1991, th e construction of the controversial Nagymaros Dam has been halted and the Hungarian Government ha s been requested to compile environmental, technical, economic, and political evaluations of the projec t before a final decision will be made . Note that without the Nagymaros dam to act downstream as a trap for water, the generator s at Gabsikovo will be forced to operate at below full capacity. In the recent past, the Czechoslova k media accused the Hungarian government of bowing to the demands of Hungarian green activities , while the ecological section of the Czechoslovak Academy of Sciences supports the opposition to th e scheme . According to the Czechoslovakian side the economic benefits of the project have been overrated, and the quality of drinking water in the Danube basin would be impaired by the artificia l channel connecting the two dams because the channel would slow down the natural process of wate r purification (Nika, January 1989) . Emil Hadak, the president of the ecological section of the Academy ; and Imre Makasek, th e editor of Nika, say that the dam would have such a huge impact on the environment that "it was a political question from the very beginning." This reflects the longstanding views of opponents of th e project, who include members of the Hungarian and Czechoslovakian Academies of Sciences . Currently, the new democratic governments of these republics have announced their intentio n to solve the fate of Gabsikovo-Nagymaros complex based on common environmental and economi c interests in cooperative utilization and preservation of Danube resources . A Memorandum of Agreement for work in recognition of this joint interest was worked ou t

by representatives from both countries in June 1989 . A. The Lower Danube Canal An agricultural and industrial powerhouse, the Ukraine (52 million people : 74% Ukrainian ; 21% Russian ; 5% Jews, Belarus, and others) produces 56% of the former U .S .S .R's corn, 25% of wheat, 47% of iron, and 23% of coal . However, the South Ukraine experiences a nearly permanent lack of water (Topachevsky, 1961) . This makes water development the highest issue for th e Ukrainian government in the quest for political and economic independence, even long before the events of 1991 (Zvonkov and Turchinovich, 1962). In the mid-1980s, the first and smallest section of the Danube-Sasyk Canal of the south-nort h water conveyance system (the Danube-Dniester-Dnieper Canal, over 300 km long) was completed a t the cost of $200 million . The total cost of this project was estimated to be between $20 and 3 8 billion (Rozengurt, 1989) . It was planned that the branches of the canal were to be extended to the Crimean Peninsula , and Zaporozh'e and Donetsk provinces of the Ukrainian Republic (Zvonkov and Turchinovich, 1962) . The major objectives of this canal and modification of Dniester and Dnieper estuaries into freshwater storages were to : 1) transfer 15 to 30 km 3 water to improve and stabilize the water balance of the population of the southern Ukraine and Moldovan republics, 2) provide water fo r irrigation of 3 million hectares of black soil, and 3) increase water supply for cooling systems o f nuclear and thermal power plants, and for the chemical and petrochemical industries of the Sout h Ukraine and Moldova regions (Rozengurt, 1974) . Note that the existing canal, which serves about 150,000 hectares of the total 216,00 0 hectares (10 .8% of the total arable land in Odessa province) has already pumped out about 5% of th e water the from the lower Danube River . About 40% of the irrigated land is used for grain productio n (rice in particular), 41 to 47% for fodder, and the remainder for vegetables, grapes, and other fruit . The construction of water conveyances and cumulative facilities were discussed at man y formal meetings between the Soviet and Romanian governments because it was planned to withdra w up to 17% of the Danube's run-off. The latter was opposed to it on the grounds that excessive water diversions from the lower Danube, compounded by upstream water withdrawals by the eight riparia n countries (28% of normal annual run-off) would be detrimental to Romanian water development an d the Danube delta, as well as to Romanian and Bulgarian coastal zone economies and environment . Nevertheless, the initial diversion scheme was pursued . The Soviet bureaucracy failed to recognize that this project would exacerbate environmenta l conditions in the Danube delta. As a result, a tense political climate between Romania and the forme r

U.S .S .R. became a deplorable reality . At that time, the Soviet bureaucracy regarded any measures t o mitigate the current and future impacts on either the environment or industrial and agricultura l development in Romania as an unnecessary burden . The Soviet policy of resource exploitation at th e expense of resource management was the primary basis for decision-making, even when th e international aspects of environmental problems within Eastern countries was involved (Meleshkin , 1981 ; Rozengurt and McCray, 1988; Rozengurt et al ., 1989 ; Rozengurt, 1989, 1991) . It was assumed that isolated and refreshed estuaries would provide additional water storag e facilities of up to 5 km3 (Baksheyev and Laskavyi, 1983) . The first and last link in this diversion program—the Danube-Sasyk--was completed in 198 7 (Figure 16: 1-5). In 1988-89, the construction was put to a halt . As was foreseen, the lower Danube-Sasyk Canal was an ecological and economic disaster because of the lack of Danube wate r and morphological and chemical peculiarities of the Sasyk estuary . In other words, the brackis h water of a new reservoir was unsuitable for irrigation; its salinity varied between 1 .2 to 4 g/L durin g the first four years as opposed to a projected average concentration of less than 1 .0 g/L (Levina and Sergejev, 1985 ; Shvebs, 1988) . Moreover, it appeared that the soil had a high level of alkalinity which produced a thick surface crust that prevented crops from growing . By 1989, nearly 32,000 hectares were destroyed despite numerous attempts to wash salt out of the fields . In addition, salinization of the ground water occurred which took out of use over 60% of all sources of drinking water in South Ukraine . The cumulative losses sustained by agriculture and the inhabitants amount to hundreds of millions of dollars. Today, strong public protests against the continuation of this ill-conceived scheme , reinforced by the results of a special assessment of project operation made by the South Center of th e Ukrainian Academy of Science (Odessa), put to a halt for good the entire Danube-Dnieper Cana l (Doroguntsev, 1990) .

B . The Degradation of the Western Black Se a The shallow and vast area of the northwestern part of the Black Sea (area, F = 48,000 km 2; Volume, V = 1,150 km 3 ; average depth, H = 23 .7 m; Figure 16) directly interacts with the Dnieper and Dniester River discharges (total historical run-off of about 64 km3) and absorbs a part of th e Danube run-off. This has created a rich diversity of organisms, including 121 marine and 3 4 freshwater species of fish, which amounted to 60% of the total biomass of the entire sea . Over 70 % of commercial landing was concentrated in this basin (Krotov, 1949, 1976 ; Vinogradov et al ., 1966) . In the 1950s and 1960s, about 50,000 to 100,000 tons of valuable commercial fish were caugh t

6 8 annually, mainly in this estuarine-coastal zone ecosystem. These fish included, but were not limited to mackerel (Scomber, scombrus), bluefish (Sard, sarda), sole (Bothus maeoticus), turbot, sturgeo n (Acipenser guldenstadti Brandt), Russian giant sturgeon, beluga (Huso, huso), sevruga (A, stellaltus Pallas), sprat (Spratella, sprattus, phalerica), anchovy (Engraulis, encrasichollus), mullet (M . cephalus, M. auratus, and M. saliens), gobies (Gobius melanostomus ; G. fluviatilis), and herring (Caspialose kessleri, pontica) . Moreover, the NWBS was known as an area teeming with edible mussels, midia (Mytilus galloprovincialis) and oysters (Ostrea taurica) (7 to 9 million tons of raw mass; Vinogradov et al ., 1966; Beklemishov et al ., 1982) . In addition, only 15 years ago over 15,000 km2 in the central part of this area were covered by the unique seaweed Phyllophora nervosa, Ph. brodiaci, and Ph membranifolia (red algae, or, by the local name, sea grape) . This seaweed area, known in scientific literature as "Zernov's Field " (Zenkevich, 1963), had a raw mass equal to 10 million tons . This seaweed was annually harvested and processed at the Odessa special plant to extract several hundred tons of valuable protein products , including agar-agar and algin or organic colloids used as thickeners in food processing, and iodine . Hence, in light of the above, it is obvious that in the past this unique sea region wa s exceptionally productive despite the fact that its area constitutes only 24% of the Black Sea (Vin- ogradov, 1969; Vinogradov and Tolmazin, 1968) . However, since the beginning of the 1970s, the impact of the Danube, Dniester, and Dnieper dams has adversely affected the ability of the western part of the sea to support, feed and shelter aquatic life, and maintain the water and biotic integrity of the ecosystem . Subsequently, this basi n has begun to experience a precipitous habitat degradation (Rozengurt and Haydock, 1991) . The following highlights some of the major phases of these developments in the NWBS . Over hundreds of years in the period of unimpaired run-off, the colder and denser mixe d (riverine-estuarine-sea) water saturated with oxygen up to 10 mg/liter moved along downslope . The kinetic energy of newly formed intermediate water masses (which controlled advection and mixing ) were able to overcome the potential energy of deep, bottom water masses . Those compensator y landward flows tended to maintain the dynamic equilibrium in the vertical column (Filipov, 1968) . In general, this process forced the renewal and oxygen enrichment of thousands of cubic kilometers o f estuarine and subsurface sea water masses for 2 to 3 months after the initial strength of spring flo w diminished (Bol'shakov, 1970) . By that time (mostly by the end of June), the temperature of dee p layers of the shallows increased, and only bottom water of winter and early spring origin preserved it s coolness in the NWBS funnel-like depressions and downslope . Annually, about 2,630 km' of sea water (2 .3 times the NWBS volume) were engaged in th e

69 renewal of water masses of the NWBS for a period of time equal to 6 to 7 months . This volume included 1,450 km3 of the NWBS outflow to the open sea . In other words, the run-offs superimpose d by wind-induced currents were able to entrain and carry out to the NWBS a volume which equalled nearly 23 times their normal combined discharges . This might explain how the marine ecosystem was capable of maintaining a dynamic equilibrium of its hydrophysical and biological characteristics fo r thousands of years prior to man's interference (Bol'shakov et al ., 1964, 1965; Rozengurt and Haydock, 1981) . However, when the run-offs controlling and moving functions were impeded by dams, its kinetic forces started to diminish . Subsequently, some significant alterations of thermohaline an d density structures; circulatory patterns ; gaseous, nutrient, and sediment regimes ; and composition and quantity of biota have occurred (Rozengurt, 1991) . Between 1955 and 1989 the NWBS was deprived of about 1,000 km' of freshwater (th e NWBS volume) from diversions of about 20 fo 28% of Danube run-off and over 40% of Dniester an d Dnieper run-off (Figure 17) . At the same time, millions of tons of biogenic matter and sediment load had not reached th e NWBS but instead settled down behind the dams ; in addition, a gradual increase of surface to botto m salinity occurred. Note that the current rate and time scale of salinization of these water bodies were foreseen two decades earlier (Rozengurt, 1974) . Consequently, the spring oxygen enrichment of deep and bottom layers of the NWBS, s o pronounced before river impoundment, diminished; correspondingly, the intensity and depths of vertical mixing were reduced significantly (Al'tman, 1982 ; Tolmazin, 1985; Zaitsev, 1989) . The summer thermo and pycnoclines nearly completed the cessation of oxygen replenishment in 60% o f the NWBS deep and bottom layers by cutting off the oxygen supply from above . The deposition and decay of organic riverine-estuarine and sea-borne matter during summer further intensified the chronic oxygen deficits . In practice, since the late 1970s, over 60 to 70% o f the NWBS has been contaminated by hydrogen sulfide (Figure 16) . This condition triggered mas s mortality of living creatures in deep and, especially, bottom layers in an area of over 20,000 km ' almost annually (Beklemishev et al ., 1982; Vinogradov, 1988) . This increased the duration of retention time (known as the dynamic index of renewal of th e water body) from 180 to 360 days in the Western Sea. At the same time, municipal and industria l discharges increased several times, 90% of which is discharged without adequate treatment . Consequently, pollutants, especially from agricultural fields, have become the major catalysts of catastrophic eutrophication over 29,000 km 2 of the sea surface (40% of the NWBS) . This, in turn ,

7 0 facilitated the suffocation of benthos which further aggravated the gaseous regime even in th e shallows of the NWBS . Today, the significant part of the NWBS habitat for plants and animals, which used to be th e granary of the entire basin, is seized by hypoxia or poisoned by hydrogen sulfide over thousands o f square kilometers (Zaitsev et al ., 1989) . There have been significant losses of the tasteful mollusk Midia and the valuable algae Phyllophora . The estimated losses of diverse valuable products extracted from the sea botto m amounted to approximately $300 to $500 million (Vinogradov, 1988) including, for fisheries, $200 t o $250 million per year (Krotov, 1976) . These losses are still climbing (Zaitsev, 1989) . In practice, the standing stock of demersal and even pelagic fish has ceased to exist (Zaitse v et al ., 1987) . In an economic sense, the extinction of 18 of the most valuable species of commercia l fishes in the North Black Sea account for losses of $2 .5 billion (Kruglyakova and Stepanov, 1985) . It is worth noticing that the population of the Black Sea dolphin (Delphinus delphis ponticus) , significantly deprived of their natural food-fish, dwindled from 2,500,000 in the 1950s to 100,00 0 specimens at present, despite the fact that their catch was forbidden in 1970 . The niche formerly occupied by shellfish, red algae, and fish has been filled by over 300400 million tons of medusae (jellyfish of the class Aurelia and Rhizostoma) . Billions of dead medusae ar e annually sinking into bottom waters, where their decomposed bodies consume the remnant of oxyge n and thereby set the stage for aggravation of summer-fall hypoxia . Besides, they are clogging th e former Golden beaches and shallows of the Soviet, Romanian, and Bulgarian shorelines, making the m unsanitary and unsuitable for millions of sunbathers . The economic losses sustained by moder n seaside recreational complexes of this region may amount in the immediate future to several hundred million dollars per year . In sum, the decades of the large scale distortion of the resilient but rather fragile riverine- estuarine coastal environment appears to be harmful to all its living resources and to many millio n people living within 100 to 150 km of the shore. The closeness of huge industrial and chemica l complexes at Odessa, Nikolaev, and Kherson has aggravated the dangerously poor water (and air ) quality to such a level that infant mortality rates in South Ukraine and Moldova have increased mor e than 30%, and outbreaks of intestinal diseases among adults are discussed almost daily by officials , the media, and environmental groups. Current developments provide strong evidence that perennial cumulative freshwater losses , due to excessive upstream diversions and spring flooding which has become truncated and short i n duration, are playing a crucial role in the modification of physical processes in the sea . As such, the

7 1 FIGURE 1 7

The Major Hydropower Plants of the Black and Azov Seas ' Watersheds

new artificial characteristics far exceed the survival tolerance levels of flora and biota. Given this , the integrated impact of many other contributors only exacerbate and hasten the demise of estuarine - sea systems (Rozengurt and Herz, 1981) .

VI. CONCLUSIONS

The environmental problems now being faced by the eight riparian countries of the Danub e watershed may seriously jeopardize the river and the Western Black Sea, the environmental conditions, and political stability of the Central and Eastern European countries with riparian rights ove r the Danube watersheds (Figure 18) . 1. The rapid socio-economic, industrial, and agricultural development of the Danube basin is resulting in significant increase in water utilization . This and returning run-off facilitate s deterioration of the water quality, the river-delta-coastal zone's living resources, and the health o f over 80 million of the population . 2. The desiccation of the Danube watershed by three dozen large dams has altered flo w patterns and the natural self-purification ability of the river network. This is typical for many river basins where traditional (linear) economic development and use of natural resources prevails (Baidin , 1980) . 3. Over 4 million irrigated hectares, as well as industrial and domestic water users hav e reduced the normal Danube's annual run-off to 72% of its historical value . At the same time the volumes of effluents and agriculturally contaminated waters fro m drainage networks and of sludges and other solid wastes of industrial and municipal origin discharged into the river network have increased . Hence, the treatment plants are not able to overcome th e pollution problems, for a considerable part of the pollution load originates from non-point sources , mainly from urban and agricultural run-off. The nitrate content of the groundwater along the Danub e is primarily due to agriculture . This is particularly true with respect to nutrients, which intensify th e eutrophication and fungi growth that affect the oxygen balance of the Danube . 4. Use of water is often hampered by micropollutants (mercury, cadmium, and organi c compounds of higher molecular weight and of less polar character, such as polyaromatic hydrocarbons, several mineral oil fractions, and oil derivatives) mostly bound to the suspended sediment ; silting causes the accumulation of pollutants in the bottom sediment . This jeopardizes bank-filtered water quality, while in suspended form it aggravates the quality of drinking water and irrigatio n water-intakes (Benedek-Laszlo, 1980; VITUKI, 1988) .

7 3

5. Sediment transport, with associated bio-resistant substances such as heavy metals an d polyaromatic hydrocarbons, is a major long-term problem with potential effects both on human healt h and the ecosystem. When the bottom deposit is over-polluted with inorganic material, hypoxia o r even anoxia might occur in the benthos . 6. The riparian countries are faced with a large amount of work concerning the various water quality problems, some of which cannot be solved within individual countries, and extende d co-operation is becoming increasingly necessary . 7. As a consequence, the conventional technology (disinfection via chlorination for healt h protection) may not be satisfactory for potable water and the introduction of post-withdrawal treatmen t may be necessary along the Middle Danube . This is especially true for Czechoslovakia (Bratislava uses 160,000 m 3/day of bank filtered water from the Danube) and Hungary, where about 22% of the population relies directly on th e Danube for its drinking water. In addition, about one-half of the industrial water is obtained from th e river . The Budapest Municipal Water Works obtains approximately 310 million m 3/year of drinkin g water from bank-wells located along the Danube upstream and downstream of Budapest for a distanc e of 90 km . Yugoslavia (Belgrade and Zagreb) obtains 95% of its total needs via this system ; in Romania all water requirements are satisfied by bank-well filtration supplies located along the banks

of the Danube (Craiova and Galati cities) and other rivers (OVH, 1985 ; Laszlo and Homonnay, 1985 ;

Kovacs et al., 1986) . It seems the water quality of the bank-filtered wells is endangered by the increase in pollutio n load to the Danube mainly because of the following : n Simultaneously with the deterioration of "raw water" the purification capacity of the filter layer also decreases . n Accumulation of micropollutants in bottom sediment . n Anaerobic conditions in the filtration layer . 11. The conflicts between upstream and downstream interests are numerous and potentially dangerous . Disruption of the drainage patterns has been accomplished by the increase of the heigh t of the watertable over large areas. Note that the completion of hydroelectric dams at Slainburg (Austria) and the Gabsikovo-Nagymaros complex (Czechoslovakia and Hungary) will furthe r exacerbate the disruption of the drainage patterns, and aggravate water quality for Hungarian an d Czechoslovakian intakes . 12. The salt regime of the lower Danube is typified by a distinguished antibathi c

7 4 correlation between the mineralization of the water and the run-off (a hyperbolic curve) . During the winter, the mineralization of the water does not exceed 400 mg/L, but in the late summer, salinit y may increase up to 0 .8 to 1 .5 gram/Liter . The major causes of this increase are 1) the lack of run-off, and 2) untreated agricultura l discharges . The hydrochemical conditions of the delta differ greatly from the hydrochemical conditions of the river and its tributaries . Here the salinity of the water fluctuates from 0 .3 to 12 gm/L. Correspondingly, the ratio of the concentrations of the various ions exhibits significan t deviations from their normals . The Danube's historical average run-off carried to the Black Sea a substantial volume of salt s (60 .0 million tons), 940,000 tons of biogenetic substances, and 2 million tons of organic matter . In the recent past, the annual hydrochemical load was in good agreement with the run-off (Almazov , 1962). However, water withdrawals to recharge the numerous reservoirs and agricultural network s gradually compromised the hydrochemical regime of the delta and coastal zone . The Chernavody - Constanta Canal further facilitated salinization of the fore-delta and increased the intrusion of sal t water into the Danube delta . When the run-off is less than 1000 - 1500 m3 /sec, the salinity of the fore-delta and delta may reach up to 2 to 4 gm/L at the surface, and 10 to 16 gm/L in the shippin g channels at a distance of 20 to 40 km from the avante-delta in summer (Polonsky, 1982) . 10. The Romanians plan to freshen their southern lagoons with Danube water to intensify agriculture ; at the same time, a portion of their water is exported to Bulgaria at the expense of othe r riparian countries, especially Moldova and Ukraine . Romania has dredged a canal across its territor y to the seaport Constanta . This 400 km short cut provides Romania with transit fees collected in th e past by the Soviets. As a result, Romanians intend to extract concessions from the Ukraine on trad e and subsidy issues in exchange for stopping water withdrawals from the lower Danube . Note that an increase of nuclear power generating capacity within the Danube catchment ma y substantially increase the risk of nuclear or thermal pollution of ambient waters . The Danube international watershed requires the development of aggregated systems o f ecologic, societal, and economic models that can provide decision makers with information at variou s hierarchical levels. This, in turn, will facilitate the effective participation of policy making authoritie s in determining a scope of politically balanced alternatives . However, if this approach does no t prevail, then international complications over water development and uncontrolled discharges of wast e in the Danube may threaten both the environment and the relations of Danube riparian countries . In sum, the eight riparian countries of the Danube basin are lacking an international progra m of comprehensive watershed planning : there is no guidance for uniform implementation of the bes t

7 5 management practices for reducing the adverse effects of the unbalanced operation of over 30 majo r dams and myriads of point and non-point sources of waste discharges into the main riverbed and it s tributaries . To consider the current situation of the Danube basin merely as "family business" means t o overlook the significance of its watershed to the development of Russian and Slavic culture as a whole. Many who suspect a unified regional resource development posture between the indigenou s people and the Russian and Ukraine governments will find a reality quite distinct from that assump- fion. Today, a nationalist spirit lives on in the Ukrainians' make-up, the largest non-Russian ethni c group in the former U.S .S .R. who constitute over 85% of the total Ukraine population. Regional concerns for environmental degradation and resentment of imperialistic agro-industrial managmen t policies of the recent past, together with distinct language and cultural traditions have fueled stron g nationalist sentiments . As a result, nationalism and self-determination -- and their influence upo n regional resource management policies -- have become a new reality of the Danube basin . In thi s regard, the disintegration of the Yugoslavic and Czechoslovakian Republics may serve as an ominou s example . In light of what has been said, the Upper, Middle, and Lower Danube watersheds urgentl y need the following : A. Comprehensive regional and interregional water and land development and qualit y monitoring programs ; long-term statistical analysis of the availability and renewability of run-off fo r typical wet, normal, dry, and drought conditions ; the cooperation of national institutions responsibl e for planning, operating, and maintaining water conveyance and storage facilities; and compatibility analysis of the coexistence of different water users . The water quality monitoring program should be standardized in terms of methods, timin g (seasons), and areas to cover with samplings. The uniformity of the reporting and evaluatio n techniques should be based on the systems approach to analysis of multifaceted regional an d interregional water quantity and quality, living resources problems, and compliance with internationa l and national regulations . B. Risk assessment analysis of prognoses of water development alternatives to provid e the following : n Quantitative evaluation of all major pollutant inputs and their roles in the deterioratio n of the surface and ground water supply of the Danube, especially in those sites where impoundment is the major cause of reduction of river self-purification . n Short- and long-term cost effectiveness and environmental evaluation of the compati -

7 6 bility of existing and planned projects with surrounding environmental and public needs, t o project a necessary mechanism for balanced decision making (the latter may assume th e elimination of some projects if their justification is based on strictly local interests harmful t o the river watershed and its resources) .

Soviet experience in southern rivers' resources management illustrates that in the absence o f regional balanced priorities and strategies for sound resource management, the intensified exploitatio n of those resources under egocentric pressures from national or regional short-term interests ca n rapidly lead to their depletion and despoliation . Suffice it to say that some publications of Sovie t federal institutions underscore the fact that assuming no policy implementation with regard to wate r allocation and land development beyond those already planned, the dimension of the chronic water deficits of the 1970s and 1980s will be doubled by the year 2000 .

77 VII. REFERENCES

Alheritiere, D. (1985). Settlement of Public International Disputes on Shared Resources , Elements of a Comparative Study of International Instruments Natural Resources Journal, 25 , July, pp. 701-711 .

Almazov, A.M . (1962) . Hydrochemistry of Estuaries . Kiev: Academy of Sciences .

Al'tman, E.N. (1982). Possible salinity changes of northwestern Black Sea upo n diversion of some river water for economic needs . Hydrobiological Journal , 4:80-83 .

Al'tman, E .N. and T .P. Panayotov (1988) . The major results of the Soviet-Bulgarian cooperation in the field of hydrometeopological investigation the Black Sea's regime . In Problems of Hydrology and Hydrochemistry of the Black Sea . pp. 3-11 . Leningrad: Gidrometeoisdat .

Atsikhovskaya Zh . M. (1977). Intensity of water exchange as a criteria of possible waste water loads in the Northwestern Black Sea . Marine Biology, 41 :8-12 . Sevastopol : Ukraini- an Academy of Sciences .

Baidin, S .S . (1980) . Redistribution of River Run-off Between Sea Basins and ifs Role in the Environmental Complex of Seas and River Mouths. Soviet Hydrology : (Selected Papers ) 19:86-93 . Washington, D .C . : American Geophysical Union .

Baksheyev, V .A and V.S . Laskavyi (1983) . Dnieper-Bug hydrocomplex, pp . 43-47 . Kiev : Hydrotechnique and Melioration .

Bartais, E . (1984). Biological water quality of the Danube reach Rajka-Nagymaros 24 . Arbeitstagung der IAD . Szentendre, Ungarn, I. 203206 .

Bayerisches Landesamt für Wasserwirtschaft (1972) . Zusammenstellung der Messwerte und Frachten Donau, Müncen .

Beklemishev, K.V ., A.V . Zhirmunskiy, Yu . P . Zaitsev, and O.A . Skarlato (1982) . Continental shelf biology : the utilization, protection, and reproduction of cove resources . Hydrobiological Journal, 18 :1-11 . Moscow: Academy of Sciences .

Benedek, P . (1986). On the water quality of the Danube (under publication) .

Benedek, P . et al. (1980). Specific features of water pollution control on the Danube . Water Research Centre, Stevenage Laboratory, River Pollution Control Conference, Sessio n 1, Paper 2, London .

78 Benedek, P . and László, F . (1980). A Large International River : the Danube. Prog . Wat. Tech. V . 13, pp. 61-76 . Great Britian: Pergamon Press .

Benedek, P. and Hammerton, D . (1985). Chemical Hazards to Health in Waters of the Danub e Basin . WHO ICP/CWS 002/506 .

Benedek, P., Literathy, P., and Lászlo Somlyody (1978). Monitoring and modeling effort s on the large international river (Danube) . Prog. Wat. Tech . V. 10:147-167 . Great Britain : Pergamon Press Ltd .

Blatov, A.S ., M.A. Rasulov, and I.I. Chechel' (1983) . Circulation of the Northwester n Black Sea and its relation to anthropogenic influence on river discharge . Water Resources , 4:30-37 .

Bol'shakov, V .S . (1970). Transformation of River Waters in the Black Sea . Kiev : Naukova Dumka .

Bol'shakov, V .S ., M . Rozengurt, and D . Tolmazin (1964) . The Horizontal Circulations i n the Black Sea . Izvestia, Geophysical Series, 6:562-565 .

Bol'shakov, V .S ., M. A. Rozengurt, D. Tolmazin, and N.S . Balinskaya (1965) . Oceanographic Properties of the Northwestern Black Sea . In: Proceedings of Odess a Biological Station, 5:45-61 . Kiev : Naukova Dumka .

Braginsky, L .P . (1986). Hydrobiology of Danube and Limans of the northwestern Blac k Sea. Kiev: Naukova Dumka .

Convention relative au regime de la navigation sur le Danube, Belgrade 1948, Editio n 1975 . Budapest

Csepel, A . (1984). Hungary Goes Gold on Project to Divert the Danube . New Scientis t #13, 1986 .

Curcin, M. (1985). The growing of Lenciscus idus and Barbus barbus in the surroundings of the Iron Gate Reservoir . Wissenschaftliche Kurzreferate 25 . Arbeitstagung der IAD : 376-379 , Bratislava .

Danecker, F . et al . (1981) . Gewässerstau-Gewässer-güte, Wasserwirtschaft- Gewässerschutz, Wiener-Neustadt .

Deklaration über die Zusammenarbeit der Donaustaaten in Fragen der Wasser Wirtschaft der Donau. Insbesondere zum Schutz des Donauwassers gegen Verachmutaung , (1985), Bukarest .

79 DoKW (Donau-Kraftwerk, 1985) . Strom aus dem Strom. Vienna .

Domokos, M . and I . Sass (1986) . Langjährige Wasserbilanzen für die Teileinzugsgebiete und di e einzelnen Staatsgebiete im Donauraum . Deutsche Gewässerkundliche Mitteilungen, 30 Jg ., H.5, October .

Dowling, M. and J . Linnerooth (1984). The Listing and Classify of Hazardous Wastes . WP-84-26, IIASA, Laxenburg, Austria .

ECE (UN Economic Commission for Eurome, 1980). Draft Report on Longterm Prospectives for Water Use and Supply . Water (R.81), Geneva .

Fekete, G . (1972) . The significance of the Danube as international water system o f Danube-Main-Rein. Office of Coordinated Utilization of Shipping . Union of Economi c Cooperation (SEV) . Moscow .

Fekete, G. (1980). The Danube River - Some Aspects of its Multipurpose Utilization . Committee on Navigation of the Hungarian Waters . Budapest: Academy of Sciences .

Filipov, D.M. (1968). Circulation and Structure of Waters in the Black Sea . Moscow : Nauka .

Frischherz, H . and Bolzer, W . (1984). Problems with bank-well filtrated water i n Austria. Budapest: WHO Working Group .

Geldreich, E .E . (1984) . Bacteriological Water Quality in the Danube . WHO Report HUN/CWS 001 .

Gerasimov, I .P . and et al . (Eds ., 1972). Ukraine and Moldavia . Moscow : Nauka .

IAEA (International Atomic Energy Agency) (1979) . International Studies on the Radioecology of the Danube River . IAEA-TECDOC-219, Vienna .

Information About Major Trends in Development Shipping Along the Danube (1976) . Moskow : SEV .

Jankar, B. (1987) . Environmental Management in the Soviet Union and Yugoslavia . Durham: Duke University Press .

Jankó, B . (1978) . The water use and navigation system of the Iron Gate . Közlekédéstudomanyi Szemle, XXVIII .evf.1 .sz .

80 Katona, E . (1984). Manual for Water Quality Protection in Case of Accidental Pollution. Budapest: VIZDOK .

Kovács, et al . (1983). Forecast of Water Resources Development . Budapest: VMGT .

Kovács, G. (1986) . Decision Support Systems for Managing Large International Rivers (LIR). Pape r presented at the Workshop on Management of International River Basin Conflicts, IIASA , Laxenburg, Austria, Sept . 22-25, 1986 .

Kovács, I. and D. Lasvio (1977). Joint use of International Water Resources, AMBIO .

Kresser, W . (1984). Die Donau - Verkehrsweg durch die Jahrkundeste . In: Fluss und Lebensraum. Verlag P. Parey, Hamburg und Berlin (DVWK-Schriften, 69) .

Krotov, A .V. (1976) . Economic assessment of losses of fishery in the Black and Azo v Sea basins due to the river water control . In: Problems of Sea Economics . Odessa : Ukranian Academy of Sciences .

Lászlo, F . and Homonnay, Zs . (1985). Study of Effects Determining the Quality of Bank-well Filtered Water (Manuscript) .

Levina, O. and Sergejev, A . (1985) . The succession of the zoobenthosbiocenosis a t Sasykliman after its desalination by Danube-water . Wissenschaftliche Kurzreferate 25 , Arbeitstagung der IAD, pp. 301-303, Bratislava .

Liepolt, R. (1967) . Limnology of Danube. E . Schweizer-Gartische , Verllagsbuchhandlung. Stuttgart .

Liepolt, R. (1979). Danube and its ecosystem, Water Quality Bulletin, Environment, 4 , pp . 78-80 .

Linnerooth, J . (1985) . The Transportation of Dangerous Substances . Unpublished Draft Report. Laxenburg, Austria: International Institute for Applied Systems Analysis .

Linnerooth, J . (1980) . Negotiated River Basin Management Implementing the Danub e Declaration. IIASA. Laxenburg .

Literáthy, P. and Lászió, F . (1980). Bottom deposit pollution of Hungarian surfac e waters (Manuscript) .

8 1 Lokvenc, V. and M. Szanto (1986) . Hungary/Czechoslovakia - The Binational Gabsikovo - Nagymaros Project. International Water and Dam Construction, 38 (11 ) November .

Massing, H . (1980). The River Rhine - transnational river basin management developing programm e to meet new challenges . Progress in Water Technology, 13 :77-91 .

Matrai, I . (1975) . Canalization of the Danube and related water management problems . Seminar on Systems Analysis in Water Quality Management . UNDPIWHO Project "Hungary 3101," Budapest, 2-8 February .

Meleshkin, M.T. (1981) . Econologic Problems of the World Oceans . Moscow : Economics .

Mikhailov, V.N. (1971) . Fluvial and Channel Dynamics in Tideless River Mouths . Moscow: Gidrometeoizdat .

Nikiphorova, Y .D . and D'iakonov (Eds) (1963) . Hydrology of Lower Danube . Moscow : Gidromereizdat .

OVH (Hungarian National Water Authority, 1984a) . Water Quality of Surface Waters . The sampling network . MI-10-172/2/84, Budapest .

OVH (1984b) . Water Quality of Hungarian Water Resources . Budapest : VGI .

OVH (1985) . Environmental Protection of the Danube . Budapest: OVH .

OeKo (Oekosystemstudie Donasten-Altenwörth, 1984) . Projektübersicht der Oesterreichischen Akademie der Wissenschaften (manuscript) .

Pichler, F . (1973). Die Donau Kommission und die Donaustaaten : Kooperation und Integration. Wien: Wilheim Baumüller .

Polonsky, F. (1982) . Computation and analyses of possible changes of the Danube Delt a advanced sand bars . In Hydrology and Hydrochemistry Sease and Rivers , V . 161 :54-68 . Moscow: Gidrometeoizdat .

Ponomarenko, V .D. (1980). Canal Danube - Dnieper Moscow . Hydrotechnique an d Melioration, 11 :10-13 .

Rado (1985) . Great World Atlas . Budapest: Kartogratia Vullalat .

8 2 Raiffa, H. (1985). Mock Psuedo-Negotiations with Surrogate Disputants, Negotiations .

Reimers, H. (1988). The Danube-Dnienper Battle . Report for the Federal and Ukrainian Government . Moscow . Central Economic and Mathematic Institute Academy o f Sciences of the U .S.S .R .

Report of the United Nations Water Conference . Mar del Plata 14-25 March 1977 , United Nations, E Conf . 70, 29: Sales No E. 77 II. A . 12, New York .

Rhein, Maine, Donau Aktiengesellschaft (1975) . Baubericht 1974, 8000 München, 40 Leopoldstr. 28, Apr .

Rojdestvensky, A .V. (1979) . Peculiarities of the lower Danube hydrochemistry and i n adjacent Black Sea . In: Jubilaumstagung Donauforschun, Bulgarische Akdemie der Wissen- schaften, Sofia, XIX, pp. 82-86 .

Rothschein, J . (1976) . Forecasting of the changes in water quality of the Danube as a consequence o f building hydraulic structures . Práce a studie 82 . Bratislava: Vyskumny Ustav Vodneh o Hospodarstva, Bratislava .

Rothschein, J. (1981) . Results of pollution investigation of Danube by organic materials . Vizgazdalkodasi Közl . KGST, VVE: 22-24 .

Rozengurt, M .A. (1962). "Islands" of freshwaters in the Black Sea . Nature

Rozengurt, M .A. (1971). Analysis of the impact of the Dniester River Regulated Run - off on Salt Regime of the Dniester Estuary, Kiev, "Scientific Thought ." (Library of Congress GC 12LR6) .

Rozengurt, M .A. (1974). Hydrology and Prospects of Reconstruction of Natura l Resources of the Northwestern Part of the Black Sea Estuaries . Kiev : "Scientific Thought . " (Library of Congress GB2308 .B55R69) .

Rozengurt, M .A. (1989). Water Policy Mismanagement in Southern USSR : The Ecological and Economic Impact on Natural Resources of Southern Seas . Technical Repor t 14, TCES and SFSU, Washington D .C . : National Council for Soviet and East European Research .

Rozengurt, M .A. (1991). Strategy and Ecological and Societal Results of Extensiv e Resources Development in the South of the USSR . In Proceedings "The Soviet Union in th e Year 2010," Symposium sponsored by USAIA and Georgetown University, pp . 26-27, Jun e 1990, Washington, D .C .

8 3 Rozengurt, M .A. and I. Haydock (1981) . "Methods of Computation and Ecologica l Regulation of the Salinity Regime in Estuaries and Shallow Seas in Connection with Water Regulation for Human Requirements ." In R.D., Cross and D .L ., Williams (Eds .) : Proceed- ings of the National Symposium on Freshwater Inflow to Estuaries . V .II : 474-507 . Washington D.C . : U.S . Department of the Interior .

Rozengurt, M .A . and I . Haydock (1991) . Effects of Fresh Water Development and Water Pollution Policies on the World's River-Delta-Estuary-Coastal Zone Ecosystems . In Proceedings Ocean-91, Long Beach, CA .

Rozengurt, M .A. and M.J. Herz (1981) . Water, water everywhere but not so much t o drink. Oceans, 5:65-67 .

Rozengurt, M .A. and T .R. McCray (1988). Strategic Role of Water Resources Development in the Economy of the USSR . The Romberg Tiburon Center, San Francisco State University ; for the National Council for Soviet and East Europe Research, Washingto n D.C .

Rozengurt, M .A . and V. Sitnekov (1973) . The prospectives of influencing water user s activity on the water balance of the Black Sea, Problems of Economy of Sea and the Worl d Ocean. Ukr. SSR: Acadamy of Sciences, 2, pp . 71-77 .

Rozengurt, M .A., D .M. Tolmazin, and H. Douglas (1989) . Soviet Water Policy Management : A Case Study of Southern USSR . Technical Report 13, TCES and SFSU , Washington D .C . : National Council for Soviet and East European Research .

RZdD (Regionale Zusammenarbeit der Donaulander, 1986) . Die Donau und ihr Einzugsgebiet, Ein e hydrologische Monographie, Tell 1, München .

Salewicz, K.A ., D .P. Loucks, and A.M . McDonald (1990) . Decision Support Systems for Managing Large International Rivers . Report International Institute for Applied Syste m Analysis, A-2361 Laxenburg, Austria .

Sevrikova, C.D. (1988). Probable anthropogenic hydrochemical effects on the coastal zone of the northwestern part of the Black Sea . In Problems of Hydrology and Hydro - chemistry of the Black Sea. pp. 181-189 . Leningrad : Gidrometeoizdat .

Shvebs, G .I. (1988) . Liman-River Mouth Complex of the Northwestern Black Sea . Leningrad: Nauka .

Simonov, A .I. (1969). Hydrology and Hydrochemistry of Estuarine and Coastal Zone Systems . Moscow: Gidrometeoizdat .

8 4 Singleton, F . (Eds ., 1985). Environmental Problems in the Soviet Union and Eastern Europe. Proceedings of the Third World Congress for Soviet and East European Studies . October 30 - November 4. Washington D .C . Boulder-London: Lynne Rienner Publishers .

Sokolovsky, V .G . (Ed ., 1988) . The Environment Conditions in the U .S .S .R . in 1988 . Moscow : Goshompriroda .

Sokolovsky, V .G. (Ed ., 1991) . Scientific and Techological Aspects on Preservation of Surrounding Environmenf . Moscow : VINITI .

Somlyody, L. and Hock, B. (1985). The quantity and qualify of the Hungarian water resources . Vizügyi Közlemenyek, 1 .

Sorokin, Yu . I . (1983) . The Black Sea, pp . 253-292. In: Estuaries and Enclosed Seas . Ecosystems of the World . B .H . Ketchum (Ed .) Amsterdam: Elsevier .

Stepanov, V.N. and V .N . Andreev (1981) . The Black Sea: Resources and Problems . Leningrad: Gidrometeoizdat .

Stolylik, G. (1987) . Moldavia. Moscow: Novosti Press Agency .

Tolmazin, D . (1977) . Hydrological and hydrochemical structures in the area of hypoxi a and anoxia of the Northwestern Black Sea . In: Marine Biology, 43 :12-17 .

Tolmazin, D ., A. Ostrogin, J. Kudrian, A. Balashev, and Z . Bulanaya (1977) . Analysis of hydrometeorological and hydrochemical factors in the places of hypoxia between th e Danube and Dniester . In: Marine Biology, 43 . Kiev: Naukova Dumka .

Tolmazin, D.M . (1985) . Changing Coastal Oceanography of the Black Sea . Progress in Oceanog ., 15. Great Britain : Pergamon Press .

Topachevsky, A .V. (Ed., 1961). The Danube and Its Lakes within the Border of th e U .S .S .R. Kiev: Ukrainian Academy of Sciences .

Tóth, J . (1982) . Anthropogeneous effects in the changes of the biological state of the Danube . MTA Bio. Oszt. Közl ., 25 :449-458 .

UNDP/FAO (1982-85) . Prevention of Non-Point Source Pollution . UNDP/FAO/ MEM- OVH/HUN/82/004, Project, Budapest .

8 5 Vendrov, S .L. (1979) . Problems of Transformations of River Systems in the USSR . Gidrometeoizdat : Leningrad.

VGI (1982). Accidental pollutions in Hungry in 1982 . Budapest: VGI .

Vinogradov, K .A . (Ed ., 1969) . Biology of the Northwestern Black Sea . Kiev: Naukova Dumka .

Vinogradov, K .A. and D .M. Tolmazin (1968) . Salinity and marine life . Earth and Universe, 6 :26-32 .

Vinogradov, K .A., M.A . Rozengurt, and D.M . Tolmazin (1966) . Atlas of Hydrological Characteristics of the Northwestern Black Sea. Kiev: Naukova Dumka .

VITUKI (1978) . List of water quality sampling network, 1968-77 . Budapest: VITUKI .

VITUKI (1985) . Investigation of the Gabcikovo-Nagymaros Barrage System in Connection wit h Water Quality. Budapest .

VITUKI (1986) . Connection between the water supply and sewage treatment of Budapest. Budapest : VITUKI .

Von der Emde, W . and Fleckseder, H . (1977). Gewässergüterfragen an der österreichischen Donau : Versogende Planungen mit Bilan und Prognose der Belastungsverhältnisse (manuscript) .

WHO (1982a) . Study and Assessment of the Water Quality of the River Danube - preliminar y activities, project findings and recommendations . ICP/RCF 204 0301 I, Geneva .

WHO (1983) . Water quality problems of the bank-filtered water supply (the Hungarian experiences) . Budapest: Working Group on Bankwell Filtration, ICP/CWS 002 (m03)/6 .

WHO (1984) . River Bankwell Filtration for Potable Water Supply . Budapest: Report on Workin g Group . ICP/CWS 002/m03), Copenhagen .

WHO (1986) . Water Quality Protection of the River Danube . ICP Proposal 2009i, Copenhagen : WHO.

WHO (World Health Organization) (1976) . Pilot zones for Water Quality Management in Hungary . Project Report, HUN/71/505, Budapest : WHO .

Zvonkov, V.V . and V.T. Turchinovich (Eds ., 1962). Regime and Utilization Water Bodies . Moscow: U.S .S .R. Academy of Sciences .

8 6

ANNEX I (Draft translation from Hungarian )

DECLARATION O N THE COOPERATION OF THE DANUBE COUNTRIE S ON WATER MANAGEMENT AND ESPECIALLY WATE R POLLUTION CONTROL ISSUES OF THE RIVER DANUB E

Accepted in Buchares t 13 December 1985

At the Bucharest Conference dealing with the issues of water management of the Danube, representatives of the governments of the Danube countries

n being aware of the high importance of the rational management and pollution control of the Danube water for the welfare and the health of the people of the Danube countries as well a s for the economic and social development thereof ,

n being convinced that besides the coordination of national efforts and necessary measures among the neighboring Danube countries, the efficiency of actions against pollution of the Danub e water could essentially be increased by means of multilateral cooperation of all Danub e countries ,

n taking into account the importance of the educational work to be performed in wide circles of the youth in the interest of protecting, preserving, and especially improving the quality o f Danube water ,

n guided by generally accepted principles and rules of international law, including the Constitu- tion of the United Nations, in accordance with the interests and the sovereignty of all Danub e states ,

n striving for consideration of the content of the Closing Document of the Conference fo r European Security and Cooperation as well as of the theses of the Closing Document accepte d at the Madrid meeting of representatives of the European countries, in order to promot e regional cooperation aiming at pollution control and utilization of water resources ,

declare the following : 1 . The preservation and rational utilization of water resources, and the prevention, termination, an d control of their pollution, constitute an organic part of the national water management and environment

protection policies of the Governments of the Danube countries . Taking into consideration the fact that the water of the Danube is being utilized for various purposes , among others for water supply of the population, the Governments of the Danube countries - in th e interest of present and future generations - are ready to take measures, according to the laws valid i n the different countries and within the frame of techno-economic possibilities, to safeguard the water of the Danube from pollution, with special regard to dangerous and radioactive substances, and t o gradually decrease the degree of pollution, taking into account also ecological requirements connecte d with the water of the Danube . The Governments also effectuate on their respective terrifories a systematic monitoring of the wastewaters released into the Danube and authorize the introduction of thes e waters only in accordance with the legal rules valid in the different countries ; they also control the accomplishment of the conditions of introduction and at the same time observe changes in wate r quality .

2 . The complex measures, worked out for long range by the proper efforts of the Governments of th e Danube countries, and especially the execution of these measures, can be completed and confirmed, in a way corresponding to the goals defined above, by means of bi- and multilateral internationa l cooperation .

For this purpose, the Governments of the Danube countries strive for the following :

2.1 In the framework of their bi- and multilateral cooperation they carry out systematical observations o n the water quality of the Danube, on the basis of programs and methods enabling the collection o f comparable data . To that end, they work out appropriate programs and methods not later than withi n one or two years following the signing of this Declaration .

The water quality observations will be performed in the cross-sections where the Danube steps from the national territory of one Danube country to that of another; when the Danube constitutes the state border, in the beginning and final cross-section of the common frontier reach, or in other section s determined in the frame of bilateral relations . If it is necessary, the Danube countries interested ca n determine, in the framework of their bilateral relations, other cross-sections as well, such as those u p and downstream of the major tributaries of the Danube, up and downstream of major towns an d impounding reservoirs, and further in the main branches of the Danube delta at the Black Sea thos e representative cross-sections, downstream of which no anthropogenic impact can modify the wate r quality further .

In six months time, after having fixed the methodology, water quality observations and analyses will be

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started, according to that methodology . Im two years after the start of the observations the water quality characteristics of the Danube, as observed during the given period, will be determined by dat a processing according to the methodology fixed .

2 .2 The Governments inform each other about their organs competent for monitoring the pollution of th e water of the Danube and establish the methods and the program of water quality observations ; they also designate their organs to which the results and evaluations regarding the water quality of the Danube as well as all urgent information connected with accidental pollution and measures aiming a t their removal, mutually have to be reported .

2.3 The Governments will study the possibility of automation of the observation of the Danube's water quality and of the installation of automated monitoring systems in the cross-sections mentioned above .

2 .4 The Governments will inform each other, through their above-mentioned competent organs, wheneve r necessary but at least every two years, about the results of analyses and evaluations of the observation s conducted at the cross-sections . They will inform each other of their measures aiming at the protectio n of the Danube water from pollution as well as about the agreements taking effect between Danub e countries to this purpose, including the results achieved by means of their realization ; they also inform each other about the technical solution of sewage treatment, about water analyses, investigations o f water resources and the internal state norms for water quality protection .

2.5 The Governments promote, whenever necessary, but at least every two years, the organization of a meeting of the representatives of the competent organs of the Danube countries aimed at comparing th e results of the analysis and maintenance of the Danube's water quality as well as at the solution of othe r problems arising in the course of the cooperation to be realized on the basis of this Declaration .

2 .6 The Governments inform each other about their competent organs working out the balances of wate r resources and needs, and about the results of these works whenever they concern a frontier reach o f the Danube . Within a year after signing this Declaration, a harmonized method for comparing th e water balances of fhe Danube countries will be developed in order to obtain comparable results in th e border sections. On this basis, they will strive to compile a summarized water balance of the Danube .

3 . In the interest of realizing the goals of this Declaration, the Governments of the Danube countries wil l gradually strive to arrange, by means of bi- and multilateral agreements, the concrete issues of th e water quality control of the Danube which are of basic interest to the respective states .

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4. In order to fight against floods on the Danube and against dangerous ice phenomena causing floods, th e Governments of the Danube countries will inform each other, through their competent organs, abou t the development and passing of floods as well as about the ice phenomena forecast for the cross- - sections selected by agreements .

5. The Governments of the Danube countries continue - among other ways by means of creating lega l rules - to strive to take measures for protecting, preserving, and improving the environment and for th e enforcement of increased responsibility, particularly in the field of protecting waters from pollution .

6. In order to realize the measures foreseen by this Declaration, the competent organs of the Danub e countries - to be appointed to take these measures - will coordinate their measures in alternation wit h each other, beginning with the competent organ of the state taking the initiative and continuin g according to the order of succession agreed upon at the first meeting .

7. In order to successfully carry out the measures laid down by this Declaration, the Governments of th e Danube countries will take advantage of the possibilities of cooperation with the United Nation s Organization and with its specialized organs, as well as with other interested international organiza- tions .

The original copies of this Declaration will be guarded by the Government of the Romanian Socialist Republic . The Government of each Danube country will receive from the Government of the Romanian Socialist Republi c an attested duplicate of this Declaration . Each Danube state will make public and disseminate the text of this Declaration and ensure its widesprea d knowledge . The Government of the Romanian Socialist Republic is invited to hand over the text of this Declaration to th e Secretary General of the United Nations Organization, in order to pass it, as an official working document of th e United Nations Organization, to all members of that Organization ; furthermore, to hand it over to the Secretary General of the World Meteorological Organization, to the Managing Director of the United Nations Educational , Scientific and Cultural Organization, to the Director of the World Health Organization, to the Managing Secretar y of the United Nations Organization's Economic Commission for Europe, to the Director General of th e International Atomic Energy Agency, to the President of the Danube Commission, and to the Director of the Unite d Nations Organization's Program for Environmental Protection . The representatives of the Danube countries have signed the Declaration aware of the high importance of thi s document. Accepted in Bucharest, on the 13th of December 1985, in the Bulgarian, Czech, Hungarian, German , Russian, Romanian, and Serbo-Croatian languages .

90 ANNEX II

ENVIRONMENTAL IMPACT ASSESSMENT OF TH E GABCIKOVO-NAGYMAROS DAM SYSTE M

In September 1977, an agreement was signed between the Governments of Czechoslovakia and Hungar y on the implementation of a joint project aimed at better use of the stretch of the Danube between Budapest an d Bratislava, where the river is the common border between the two countries for about 140 kilometers (km) . The project includes two subsystems . n The upper one has a dam at Dunakiliti closing the main arm of the Danube and diverting the discharge int o a derivation canal of 30 km . On the canal there is a hydropower plant and a navigation lock at Gabcikovo . The tailwater canal returns to the main arm at Palkovicovo . n The lower subsystem is a river dam at Nagymaros . It is composed of three main parts : weirs closing th e bed, a hydropower plant, and a navigation lock .

Construction of the system started in 1978 . Since then the derivation canal has been almost completed . Construction of the structures at Gabcikovo is also well-developed. At Dunakiliti the foundation of the dam was finished. According to the timetable the power plant on the derivation canal was to be in operation in 1990 . At Nagymaros only preliminary work has been done until now . The plan was to start construction in 1987 and finish in the early 90's so that the whole system would be completed before 1994 . In the meantime some environmental concerns were raised in connection with the modification of the rive r regime . The Hungarian National Water Authority, which is responsible for planning and designing the system , has an environmental impact assessment prepared in cooperation with the National Environment Authority . Th e results of numerous earlier investigations were utilized for this study, together with the recommendations of severa l special committees set up by the Hungarian Academy of Sciences for analysis of the environmental and agricultural impacts of the dam system . The purpose of this paper is to give a short evaluation of this environmental impac t assessment .

DEVELOPMENT OF WATER MANAGEMENT IN THE DANUBE VALLE Y

Water management in large river valleys aims at the utilization of natural resources (water, energy, bed load) and other economic advantages (transport, recipient of wastes, recreation) offered by the river . Four main phases can be distinguished in its development : n flood-plain management, when man adapts his activity to the natural conditions determined by the rando m character of the water regime and utilizes the advantages provided by the presence of water considering the limitations determined by these conditions ; n primary control of the water regime (river training, flood control, and water control over the catchment) , when larger areas become arable, navigation is improved and settlements move near the river, and establishment of closer contact with the water to decrease the damages which could be caused by rando m hydrological events ; n river canalization, the main purpose of which is stabilization of the water level, decrease of its fluctuation , and utilization of the energy in the river by constructing dams and maintaining stretches with low slope s between them ; n complete (quantitative and qualitative) control of runoff, which can be achieved by regulating the discharge according to demand, using the retention capacity of large reservoirs, and by efficacious treatment o f wastes released into the river. Naturally there are no sharp limits between these phases . They overlap each other and may be interwove n in space and time . The subsequent phases can be well recognized, however, as the main character of wate r resources development in any river valley . In the Danube valley, the river was always a decisive factor influencing the socio-economic developmen t of the riparian countries . Until the eighteenth century, this relationship was extensive ; the societies tried to utiliz e the advantages provided by the river (navigation, fishery), but development was limited by random event s characterizing the water regime (particularly by severe floods) . The transition to the second phase of wate r management (i .e . primary control by constructing flood protecting structures and river training) took plac e gradually depending on the level of economic development at various stretches of the Danube, and it wa s completed practically in the whole basin at the beginning of this century . The need for canalization also followed economi c development, and it became almost a general requirement for the fifties . Most of the dams along the Uppe r Danube were completed between 1925 and 1985 . In the basin of the Middle Danube construction started in the forties, and the work is still going on . Along the Lower Danube canalization has so far reached only the plannin g phase .

THE PURPOSE OF THE GABCIKOVO-NAGYMAROS DAM SYSTE M

The need for canalization along the stretch of the Danube upstream from Budapest was raised at first b y navigation. Member countries of the Danube Commission have assumed an obligation to ensure the undisturbe d traffic of ships having submergence of 2 .5 meters (m) between their borders and have accepted a recommendatio n to increase this depth to 3 .5 m if possible. Between Bratislava and Györ, this goal cannot be achieved by normall y applied river training . The navigable depth is only about 2 .0 m during the largest part of the year and is even les s

92 in low-water periods, although a considerable amount of money is spent for dredging and river training structures . The importance of this East-West European waterway will be even increased after completion of the Rhine-Danub e Canal, a fact that urges the improvement of navigation conditions along this stretch . It is obvious that the flood risk should be decreased as the value of the protected area increases . Not onl y the enormous damages caused in both Czechoslovakia and Hungary by the large floods in 1954 and 1965, but als o the high costs of flood protecting activity in other years when the floods were not so extremely high but were similarly dangerous, indicate the need to improve the protecting systems . The multipurpose structures o f canalization can also meet this requirement . There are still areas where random hydrological events may cause considerable damage to agriculture . Such areas are the higher flood plains not yet endiked which may be inundated by high floods, and lowlands without efficient control of surface runoff or where the groundwater level is influenced by the water level of th e Danube, which may create unfavorable conditions in extreme cases . Necessary water control can be solved in a more economical way in these cases when it is combined with the construction of structures serving the purpos e of canalization . Experts working in the energy industry have different opinions of the reasonable rate of construction o f thermal, nuclear, and hydro stations, the capacity of which should always cover the ever increasing demands o f society. The judgment of environmentalists on the impacts of such stations also differs . In spite of divergence s in opinions it can be stated that one of the main goals of canalization is the utilization of the Danube's energy . It is a waste to leave the discharge of the Danube, which is a continuously renewed energy resource not requirin g the use of any raw material, to run down in its bed without doing the work that it can do for our society . Th e investment required to construct a hydropower station is higher than that needed in the case of a thermal or nuclea r plant, but the difference is reimbursed in a few years by the almost negligible operation cost . Economic analysi s has shown, for instance, that the cost of a thermal or nuclear power plant having the same capacity in energ y production as the Gabcikovo-Nagymaros system can cover not only the price of the hydropower stations, but abou t 63% of the total investment of the whole canalization if the costs of investment, operation, and maintenance ar e converted into capital for a period of twenty years . Since the life span of hydraulic structures is considerabl y longer than 20 years, the comparison is more favorable for hydropower generation. Although the living conditions of aquatic ecosystems are modified by the control of both water level and velocity, air pollution or radiation hazar d from other power sources may cause much more serious damage to the environment . Another advantage o f hydropower is its flexibility ; namely, the production can be changed rapidly according to the increase or decreas e of consumption . This is a very important aspect, especially in energy systems with a high proportion of nuclea r plants, in which frequent changes of output is not desirable .

THE TASK OF PLANNING AND DESIG N

In Hungary, an office having the same structure and responsibilities as a ministry (the National Wate r

93 Authority) coordinates all activities related to water resources development . Hence, the planning and design o f the dam system was also the responsibility of NWA. Details related to the activities of other economic branches were coordinated with the relevant ministries and authorities (e .g . capacity of the hydropower plants with th e Ministry of Industry section responsible for the energy industry, navigation conditions with the Ministry o f Transport, and mitigation of environmental impacts with the National Environment Authority) . The Hungarian Academy of Sciences also gave assistance by providing the planners with scientific recommendations prepared b y various commissions of the Academy. The research, design, and management of construction were and are continuously implemented mostly by institutes belonging to NWA (Research Center for Water Resource s Development, Design Bureau for Hydraulic Structures, Investment Bureau for Water Management), but other institutes were also involved in solving special problems requiring interdisciplinary approaches . Considering all the aspects listed and comparing the goals to the development conditions along the stretc h of the Danube upstream from Budapest, it was obvious that the demands could be met economically only b y constructing a multipurpose water resources system, i .e. by the canalization of the river . Apart from the interests of the main users (i .e. navigation, water management, power generation), some further aspects also needed to be taken into account, such as the increasing demand for recreation, the utilization of the gravel dredged from the rive r bed by the building industry (which has already caused a 60-70 centimeter (cm) lowering of the water level in lo w flow periods at the most sensitive stretch), and last but not least the preservation of the quality of life an d environment in the Danube valley. The task in the planning period was to compare a large number of possibl e variants and select the one which would satisfy all these demands in the best combination, ensuring at the sam e time a reasonably positive cost-benefit balance . It is obvious that there are unavoidable damages caused by constructing dams which should be considere d as an additional cost of the project (e .g . the value of the land occupied by the structures or inundated) . Most of the harmful impacts foreseen can, however, be prevented by constructing and operating sufficient supplementar y structures . Naturally, all expenses should be allocated as an integral part of the total investment . An example of such preventive measures is the recharge of groundwater where the lowering of the water table is expected due t o the change in the water regime of the river . There are also positive secondary effects the utilization of whic h should be planned (e.g. the stabilized water level and the large water surface upstream from the dams provide an excellent opportunity for recreation and water sports) . In general it can be stated that new natural and socia l environments created by the construction of the barrage system would not be worse than the earlier conditions, i f sufficient measures are taken to prevent harmful changes and to utilize the advantages offered by the ne w conditions . Apart from selecting the best variant of the system, another important task was therefore to predic t its secondary effects in the natural and social environment as well as to design structural and operational measure s needed to prevent - or at least to minimize - the undesired impacts, and to make use of the positive ones . The planning required a long series of international negotiations not only because the stretch of the Danube to be utilized is the common border between Czechoslovakia and Hungary, but also because, according to th e Belgrade Convention, the agreement of the member states of the Danube Commission is necessary for every larg e

94 scale modification of the navigation conditions along the Danube . Another important aspect of intermationa l harmonization was the determination of the locations of dams . Some locations had to be regarded as fixed point s (e.g. a dam had to be constructed downstream from the Iron Gate to improve navigation conditions along th e gorges located there) . The large cities located at relatively low levels (Vienna, Bratislava, Budapest, Novi Sad , Belgrade) limited the rise of water levels along their banks . It was also necessary to ensure a continuous navigable waterway and the possible highest utilization of energy by limited overlapping of backwater stretches .

HISTORY OF PREPARATORY PLANNIN G The planning period of the Gabcikovo-Nagymaros barrage system started in 1951 and ended in 1977 whe n the intergovernmental agreement was signed by Czechoslovakia and Hungary for the multipurpose utilization o f the common stretch of the Danube . Although the task of planning was very diversified as was summarized above , there were other reasons requiring such long preparation . At the beginning the cost-benefits ratio of the hydropower plants seemed to be favorable compared to coa l thermo-plants, but in the fifties oil gradually took the place of coal and the hydroplants were not able to compete with the very low oil prices of that time . Such economic aspects prolonged again and again the decision s concerning construction of the dams . Delay was also caused by the fact that financially favorable conditions were needed simultaneously in bot h participating countries for them to accept the responsibility of inyesting large capital sums into a system whic h contributes only partially in direct production and serves partially as an improvement of infrastructure. Othe r aspects of internal policy (e .g . the proportional development of the various regions in the countries) could reduce over time the willingness of the interested parties to start the construction of a large dam system . After the first oil crisis when economic prosperity was still increasing, it was reasonable to approv e implementation of the canalization . The agreement was signed and construction started immediately in 1978 . The long planning period caused by the fluctuating interest of the participating parties imposed considerabl e financial and mental efforts, but it had several advantageous consequences . The plans, reworked again and again , took into consideration the results of rapid technical development, thus gradually increasing project efficiency . The policy makers did not want to give a definite yes or no, intending only to delay the final decision . They requested , therefore, the investigation of new variants or the analysis of some expected impacts. Although these studies were not synthesized in an environmental impact assessment - this term was not yet used or even known in the fiftie s and sixties - they contained most of the important information needed for the evaluation of environmental changes . The detailed survey of the natural and socio-economic conditions, evaluation of several practical option s of the system and studies analyzing the most serious impacts made it possible to select the most realistic versio n of the hydraulic structures immediately after a green light was given for construction . The same studies were used for the preparation of an environmental impact assessment when environmental objections were raised against th e project. The availability of a large number of feasibility studies facilitated the preparation of the assessment in a relatively short time .

95 ENVIRONMENTAL CONCERNS RELATED TO THE PROJEC T

As anxiety for the preservation of the environment gradually increased all over the world, the preparatio n of detailed impact analyses became a general requirement in connection with all large structures. At the beginning of the eighties more and more environmental objections were raised against the dam system . It was therefore necessary to summarize the studies prepared earlier, to carry out supplementary research and to answer question s in the form of a comprehensive assessment of the expected environmental changes . The object of this assessmen t was not only to survey impacts but also to propose measures needed to avoid undesired processes, and to determin e positive changes the utilization of which might increase the efficiency of the system . Some of the most importan t points and results are listed below . Because of the 30 km long derivation canal the water level would be lowered considerably in the river , which would also cause lowering of the groundwater table, if no protective measures were applied . Two option s were investigated: (1) to supplement by irrigation the water provided earlier by capillarity, or (2) to construct a combined drainage and recharge system which could control the water table according to the requirements o f agriculture . The second alternative was chosen in the final design because it not only prevents damages but als o improves agricultural conditions . Field and laboratory experiments, simulation models and several similar system s already in operation, e.g. along the canalized stretches of the Rhine and the Rhone, demonstrate the relatively high reliability of groundwater control . Some discharge should be released through the natural river bed even in low water periods when almos t the total amount of water is conveyed to the power station in the derivation canal . Opinions concerning the size of this discharge were, however, very different : the interest of power generation was to minimize the release , while the larger the discharge the smaller the change in the aquatic ecosystem . Requirements for the minimu m allowable discharge varied from 50 to 500 cubic meters per second (m n Si), where the minimum natural discharge is about 700 m n S-1 and the multiannual average value is 2,000-2,200 m n S - ' . Unfortunately, the science o f hydrobiology is not developed enough to be able to quantify biological processes . It was not possible, therefore , to predict the quality of aquatic life depending on the size of the discharge released in the natural bed . It was decided that the final value should be determined on the basis of operational experiments between 50 and 200 m n S1, but that some river training should be implemented, to maintain a unified bed even in the case of such small discharges . The next problem was the maintenance of the self-purification capacity of the river . Velocity decrease s considerably upstream from dams, a fact that modifies both the oxygen balance and the structure of the aquati c ecosystem. Simulation of the chemical processes indicated that the expected lowering of oxygen content would b e negligible because two opposite actions (decrease of velocity and increase of surface area) almost compensate on e another. The effect of aeration at the dams might even surpass the lowering of dissolved oxygen along th e backwater stretches . Research aiming at the determination of the relationship between the biotop and the hydraulic character of rivers is only now a developing topic in hydrobiology . Therefore, it was not possible to giv e quantified predictions concerning the expected biological impacts of canalization .

9 6 Considering the results of the chemical models and the experiences gained at already canalized rive r stretches (according to which the improvement of water quality is more probable than its deterioration) it was state d that harmful changes were not expected . Field experiences proving the validity of this statement include a detaile d evaluation of the long series of quality data collected along the canalized stretches of the river Tisza, and th e information on the impacts of dams in operation for decades along the Upper Danube. The analysis emphasized the need for more efficient treatment of sewage released from settlements and industrial plants into the backwate r stretches . Since one of the most serious obstacles to the utilization of the Danube's water resources is the rapidl y growing pollution of the river, it is a positive feature of the dam system that its construction urges the improvemen t of sewage treatment in the basin . The most important source of water supply in the region is bank-filtered water. Wells tapping the alluvial gravel of the flood plain provide the water, which is directly recharged from the river . The gravel layers act as natural filters, and therefore, the water is suitable for direct consumption without any pretreatment . Canalization may endanger the quantity and quality of bank-filtered water along the backwater stretches by the deposit of fin e silt over the gravel layer, which increases resistance against percolation and may create anaerobe conditions in th e groundwater, resulting in an increase of iron and manganate content . Downstream from the dams the lowerin g of the water level may also decrease the yield of wells, if considerable dredging is accomplished to increase th e head utilized at the power station . In the case of the Gabcikovo-Nagymaros system downstream dredging was planned below the Nagymaro s section. In the meantime, however, a considerable amount of gravel was exploited here for construction, causin g the sinking of low water levels from 50 to 70 cm, which is more than the value envisaged in the plan . The remaining task is only to improve the tracing of the bed, which aspect was not considered during exploitation . Thi s activity improves rather than damages conditions. Undesirable effects can be caused, however, if the bed is furthe r deepened due to the drag force of water poor in suspended sediment after crossing the dam . Prediction of th e modification of bed morphology would require better knowledge of bedload movement than that existing at present , especially under the very complicated conditions prevailing in the stretch in question (influence of stabilized banks , strong contractions, rocky thresholds, etc .) . Further research is needed and the relatively slow development o f processes allows the implementation of protective measures on the basis of the evaluation of changes monitore d during the operational period . Several examples indicate that the most reasonable way to protect the bank-filtered water supply plant s exploiting against the impacts of silting along backwater stretches is the regular dredging of the fine material fro m the surface of the gravel . The most detailed experience concerning the impacts of impoundment on the operatio n of bank-filtered water supply schemes was gained at the well field providing water for Linz . Although the water level was raised considerably in the river, the yield of wells decreased due to the deposit of a silt layer over th e aquifer. The change in water quality indicated also the development of anaerobic conditions below this cloggin g layer. Several experiments were carried out to improve the production of wells but results were achieved only b y dredging the clogged layer . A slight decrease of the yield from the wells at Belgrade was also observed due to the

97 backwater effect of the barrage constructed at the Iron Gate . Although the detailed survey was not able to make clear distinction between the impact of the barrage and the normal ageing of wells, it was proposed as a conclusion of research that dredging be carried out here also for the improvement of the well fields . Considering thes e experiences the regular dredging of the bed in front of the plants exploiting bank-filtered water was included in th e operational plan of the barrage system as a part of the normal maintenance service . The detailed design of thi s activity requires first of all the continuous monitoring of changes in bed morphology . Further research of bed load and sediment movement in natural beds may also assist the managers to determine an efficient policy for protectin g the quantity and quality of bank-filtered water resources .

SOME GENERAL CONCLUSIONS OF THE IMPACT ASSESSMEN T

The most important conclusion of the environmental impact assessment of the Gabcikovo-Nagymaros dam system was the statement that no harmful impact was foreseen so serious that it might give grounds for basi c modification of the accepted plan or for stopping the construction in progress . In some cases the objections raised against the system provided good ideas to improve both the design and the plan of operation. The application o f groundwater control, the development and maintenance of a unified small water bed where the derivation cana l lowers the discharge of the river, and the need for regular dredging as a part of the maintenance service can b e mentioned as examples . In several other cases the anxiety was not justified . It is obvious that natural processes are influenced by numerous random events . Therefore, to reach a safety of 100% in any prediction would be an unrealistic target . It is necessary, however, to indicate the rang e of uncertainty and the task of design is to construct flexible systems, the operation of which can be adapted to th e actual conditions developing in the environment. To achieve this goal continuous observation of environmenta l changes is needed . The monitoring system is, therefore, an indispensable part of any large hydraulic structure an d water management system . The uncertainty caused by the randomness of influencing factors is further increased by limited knowledg e of the development of natural processes. To increase the reliability of impact assessments, scientific researc h should be continued to better understand of the hydrological cycle and its interactions with the environment . I n the present case, the weakest link in the chain of the various branches of sciences is hydrobiology . Here ou r knowledge is limited to the description of different aquatic ecosystems and is not sufficient to quantify expecte d changes. Similarly, further research is needed in the field of river morphology and sediment transport . It is also worthwhile to mention that the raising of environmental obstacles against the dam system wa s intensified simultaneously with the worldwide economic depression in the early eighties . Most of the variou s interest groups in competition with the system to get a larger share from the very limited funds for investment hid e their direct goals behind the shield of environment . The groups of different lobbies (e .g . coal, oil, nuclear , hydropower within energy industries) were enlarged by people having individual reasons to oppose th e implementation of the dams (e .g . those whose property was expropriated) . It was very difficult to make a

98 distinction between real environmental concerns and obstacles raised omly to impede the implementation of th e system . Although it was evident that this group could not be convinced, their questions had to be answered equally even when the objections had no physical, scientific background at all .

99 I

HISTORICAL WATER DEVELOPMENT : WATERWAYS, DAMS, AND IRRIGATI ON'

Historical Development of Waterwork s

The development of waterworks and water usage along the Danube and her watershed is strongly connecte d with the development of the population, agriculture, culture, and technology in this area . Actions to build always occurred when there was a strong need and always in relationship with what was necessary when combining th e natural conditions with the then existing technical waterworks possibilities . The first works along the Danube started at the time of the Roman Empire. Much later, at the end of the 18th century, when the population and th e trade connections were more developed, bigger and more important actions occurred . Since then the requirement s of rivers and water systems have escalated continuously . Navigation for always larger ship units was necessary independent of the existing waterway . The often flooded and wet riversheds were more and more needed fo r agriculture and housing . The usage of the existing water for the needs of the people, animals, and industry for drinking water and irrigation, production of electricity and sewage removal became constantly more demanding . To reach the set goals a great number of waterworks and water-usage systems were developed, changing the shap e of the riverbeds, waterlevels, cascades, the quality of water and the direction of many river runs completely . Man y of the waterworks and the usage of water are no longer independent of each other . Even in the past, during the planning and completion of larger projects it was necessary to inform the other neighbor states along the Danube , taking their needs into consideration, and sometimes even to do projects together with them . The problem for all is to use the existing water from the Danube and its watershed to the optimum, sav e the environment and fight together the dangers of floods and dry periods . This brought a new realization of th e need for all the countries along the Danube to work together .

Solutions for Shipping

The Danube, especially the middle and lower Danube, has been of great importance as a means o f transportation for thousands of years . The transport of heavy loads on waterways was at all times much easier tha n on land. Only the dimensions have changed today . So the first known construction was created for shipping i n the area of the "Iron Gate" along the 117 kilometer (km) long cataracts . Navigation below this area in the flatlands could be done with great ease, but above this it was extremely difficult to find a usable channel in the riverbe d among so many currents, especially because these changed with each different waterlevel . At low waterlevel ,

' The following material is taken from The Danube and its Drainage Area, a Hydrological Monograp h (Munich : Part 1, 1986, in German) areas existed where no navigation was possible at all . At the time of the Roman Emperor Trajan around 100 A.D . a path was created along the right bank of the river through the steep rocks of the narrows of Kazan, which coul d also be used to pull ships up the river . Beside the cataracts there were numerous barriers in the Danube that blocked shipping . Especially in th e Austrian Danube there were breaks, because narrows were filled with rock banks or huge mountain rocks . In the wide valleys there was enough space for the Danube to create a riverbed according to he r morphological character . In the alpine areas it is still somewhat difficult even now to keep a channel open throug h the shallows in this branched and forever changing riverbed . Work being done for the improvement of navigation is carried over from the 14th century, such as th e removal of silt in the shipping channels near Vienna with the help of waterplows . Until the end of the 18th century only local and not very important work in that respect was done . Since the end of the 18th century much has been done to solve problems with the goal of cutting through stone areas in the mountains to create a broad and deep channel for shipping . In the areas where 'waterlevels were not stable an attempt was made to control a low and a medium waterlevel constant . After a while even those results were not good enough for the ever higher demands of shipping . There were also areas where no stable riverbed could be maintained because of the morphological conditions . All thes e problems can be solved by creating different elevations and locks in the Danube . Navigation is therefore the mai n reason for building locks . In order to promote agreements between all countries along the Danube, conventions have been held sinc e 1856. The existing Danube Commission was created during the conference in Belgrade in 1948 . This commission , whose meetings are always held in Budapest, handles common problems about waterworks and water usage . After recommendations from this commission, measurements were taken for the total length of the shipping channel between Regensburg and the Black Sea, including depth, width, curve radius, lock measurements, and possible shi p heights . The constant growth of shipping volume shows the great success of this commission . Beside the Danube some of her tributaries are naturally usable for shipping and have been worked on b y each country : Drau to Cadarica (105 km) . Theiss to Dombrad, her tributary to the Hungarian-Czechoslovakian border . Save to Sisak (583 km) for smaller ships . Prut for a short distance . The Backa Canal (Yugoslavia) connects the Danube and the Theiss . An ancient dream of the people was a connection between the rivers Main and Danube and therefore between the North Atlantic and the Black Sea . As early as the year 793, Karl the Great tried to connect the two river systems near the city of Treuchtlingen i n Germany (today's name), where they are only 2 kilometers apart and the water table difference is only 10 meters . It is believed that a chain of moorings was planned for the one ton river ships then in use . The still existin g "Karl's Ditch" shows the work, which was stopped after the excavation of circa 780,000 cubic meters because of

1 0 1 constant rain, soil problems, and the difficulty of feeding and taking care of 6000 workers . From 1836 to 1845, a 177 km long canal was built between Kelheim and Bamberg with 100 locks . It i s called the "Ludwig-Danube-Main " Canal. The canal quickly lost importance, because the horse-drawn ships coul d not compete with trains that were developed at this time . The canal was in use until 1945 . From 1949 on it finall y was left open . Since 1959 a new Main-Danube-Canal has been under construction . Width at the water surface is 5 5 meters ; at the river bottom it is 31 m . Depth is 4.0-4.25 m . The measurements of the locks are 12 m in width and 190 m of usable length, constructed for 1500 ton ships of 90 m length as well as for ships up to 3300 tons of th e type "Europe II", with a width of 11 .4 m and a length of 185 m . The 204 km long stretch between Regensbur g and Bamberg consists of 18 river confinements ; 103 km with 10 confinements are created as a still-water canal and 101 km created by widening and correcting the river bed . With another two dams, shipping proceeds on th e Danube to Kelheim and there branches into the Aitmuehl . In connection with the new Main-Danube Waterway, which is to be completed the end of the first half o f the decade 1990-2000, 15.0 cubic meters per second (m3/s) of the Danube water is to be transferred into the Mai n area. The water release will only occur if the water level of the Danube is above the middle flow (mean ne t discharge) . In 1984, Romania opened a 64 km long Danube-Black Sea Canal between Cernavoda and Constanta . The average 90 m wide and 7 .5 m deep waterway, for the moment only for internal use, has double locks on both end s 310 m long and 25 m wide . This canal saves shipping 370 km . The canal was built by removal of 300 millio n cubic meters of earth and needed more excavation than the Suez Canal with 275 million m3 . Its purpose is t o insure the irrigation of about 700,000 hectares (ha) of agricultural land in Dobrudscha . For hundreds of years a Danube-Theiss Canal has been planned in Hungary . The canal is supposed to serve shipping and release about 200 m3/s of water from the Danube into the Theiss area for irrigation purposes . Construction started in 1950 but had to be stopped for economic reasons . Continuation of the work is not expected before 1995 . During the development of better waterways many harbors and docks were constructed, but they will no t be further discussed . A stretch of river allowed to flow free changes most of the time into wide fast flowing lakes . The river no longer changes its riverbed, and therefore most of the time the river tends to cut a deeper bed . Only durin g flood conditions do the old characteristics of the river return . Then the transport of suspended matter is once agai n possible . For a long time to come, the river dams will be the last and final phase of the regulation of the Danube . It is very questionable whether a complete chain of river dams will make the Danube navigable as it has done wit h other rivers. There are reasons why such a development is not wanted . in short stretches where the drop of elevation is great, good results are not clearly seen . The following will show the most important works of each country along the Danube .

1 02 Germany

The length of the Danube from the spot where the two spring waters Brigach and Breg unite to the Austrian border is 550 km . About 180 km of that are narrows, where the Danube breaks through mountainous rock . Approximately 400 km lead the Danube through wide valleys .

Regulation of the Riverbed

The approximately 85 km stretch of the Danube from Sigmaringen to the flow of the river into the Ille r near Ulm was worked on mostly from 1850 to 1889. From Ulm to Weltenburg work was done over the total length of that stretch ,6 on, mostly 182 9 to 1885 . By making numerous excavations to cut off river loops and bends, the river run was shortened by 21 % and a medium water level was created . After that time only three loops were cut off between Regensburg an d Vilshofen . Between 1931 and 1970 the stretch from Regensburg (2376 km) and Vilshofen (2250 km) was corrected for low water control for better navigation . Unluckily the results were unfavorable because the riverbed i s deepening continuously, so sooner or later river dams will have to be constructed instead .

Flood Safet y

The levees from around Dillingen (2540 km) to Donauwoerth (2510 km) that were constructed 1894-189 7 still permit the river to overflow at flood conditions and flood an area of 115 square kilometers . The levees from Ingolstadt (2460 km) to Eining ((2427km)) were erected 1930-1956 . They protect an area of 120 km2, but the flood area between Regensburg and Straubing could only be protected occasionally . After two big floods in 1954 and 1965, all the levees had to be enlarged and a better drainage system constructed . Flood safety has been partially improved by constructing several river dams . The plans for the future are to improve the safety of the cities Kelheim and Regensburg to protect the m from floods . The flood safety in Passau will consist at this time of altering the bottom floors of old buildings, s o water cannot enter .

River Dam s

The dam at Kachlet bei Vilshofen (2230 km), built 1924-1927, was the very first dam built along th e Danube. It was mainly done to improve conditions for shipping in the mountainous area at the "Hilsgartsberge r Kachlet" . Down the river the dam at Jochenstein followed, constructed 1952-1955 at the Austrian-German border with the help of both countries . Between 1952 and 1984 a whole chain of 15 dams was built from Ulm t o

1 0 3 Ingolstadt . Most of these dams will release water even now into the formerly flooded areas only to prevent a n overabundance of flood water reaching the lower lying countries at the Danube . The release of the water is controlled by directing the water into back dam areas that are enclosed . Forest areas are also flooded frequently ; agricultural areas only under the worst circumstances . Three dams, Bad Abbach (2401 km), Regensburg (2381 km), and Geisling (2354 km), are used to lengthe n the navigation waters of the Danube to Kelheim in the direction of the unfinished Main-Danube Waterway . At this time another dam is under construction near Straubing (2324 km) to improve navigation . Plans are being made for the future, to continue building dams to improve navigation to connect up to th e dam at Kachlet . Another plan exists to build two more dams below Ingolstadt to prevent further deep erosion i n the riverbed .

Austria

The Austrian Danube has a length of 350 km, of which 21 km form the border with Germany and 8 k m the border with Czechoslovakia; 150 km lead the Danube through narrows in which the river cuts throug h mountains . Approximately 200 km flow through the valleys of four large basins . The drop is about 150 m .

Regulation of the Riverbe d

The first government body that planned a broader regulation of the Danube was established by Kaiseri n Maria Theresa in 1773 . The institution was called "Kaiserliche Navigationsdirektion" and existed till 1885 . Thi s one, and the one that followed, concentrated on improving navigation along the dangerous rock formations of th e river by constructing towing paths . 1778-1791 was the time when the most dangerous stretches of the river wer e regulated along the "Greiner Strudel" area by blasting and bank changes . Work followed at the "Aschacher Kachlet" in 1829 and improvements continued at the "Brandstaetter Kachlet" and the "Hausstein Felsen" by Grei n 1850-1866. Completion of most corrections in the area of "Strudengau" did not occur before 1905 . The first attempt to regulate the Danube in the basin area was made around 1850 . The original Danube in the basin was split into several branches and constantly changed channels . Strong bends in the river were eliminated and nothing but one main channel was left open, so the Danube finally had an average waterbed o f 320-410 m in width with all banks strengthened uniformly . Until 1920 most regulation was done by creation o f low water minimums .

Flood Safety

Because of two great floods in 1830 and 1864 extreme safety measures were taken to protect the city o f Vienna, beginning in the years 1869-1875 . The center of all work was a 26 km long stretch regulated in doubl e

1 04 profile ; for this two big cuts had to be accomplished . This was a first in Middle Europe . The whole length and width of the riverbed was excavated; until then it was usual to let the river do part of the work . Accordingly, 16 .5 million m3 of earth were removed. Part of the work included : a lock, to cut off the waters from the Danub e Canal; improvements for the canal; and several levees . In 1898-1899 a 180 m wide channel was created, usabl e at low water levels .

From 1882 to 1920 levees totalling 200 km in length were erected to prevent flooding from Vienna to th e March, as well as in the -runner Feld and in the area of the city of Linz . After the flood of 1954, the flood safety of the city of Linz was changed to prevent even a flood size tha t occurs only every 500 years . In addition, another river dam was constructed near Abwinden-Asten . Work is continuing in the vicinity of Vienna to allay a flow of 14,000 m3/s, equal to the rarely occurring highest crest of flood water . For this a special channel was built, which is separated from the Danube by a 17 k m long and 200 m wide flood free island . Down river the dam system measures a flow of 13,200 m3/s ; during severe happenings the Marchfeld cannot be spared, so that the lower lying countries are protected . To minimize th e damage during flooding, another dam is being constructed 2 .3 km in length .

River Dam s

After the river dam at Jochenstein was completed in the year 1954, a combined effort of Germany an d Austria, a systematic development of river dams started . So far 250 km of the 350 km length of the Austria n Danube have been converted into river dams . It is planned to complete the rest of the stretch . Thanks to the construction of dams in the lower Danube basins, many areas with settlements can be protected from flooding. The greater fields that are prone to flooding are kept for that purpose, even afte r construction of energy plants . Altogether, there were five lowland dams constructed so the over flow can b e controlled through these diversion dams . Also, the former practice of flooding the forests is still partially possible . Czechoslovaki a

The Czechoslovakian part of the Danube stretches from the left northern bank to the mouth of the Marc h about 172 km down the river to the mouth of the Ipel/lpoly . Their part of the right bank is only 22 .5 km long , because the Danube forms the border with Austria for 8 km, and 142 km form the border with Hungary .

Regulation of the Riverbed

The part of the river between the March and the mouth of the Mosoner Danube at Goenyue, which is half the length of the Danube in this country, sits on a huge mountain of gravel . From there the Danube enters th e Pannonische Becken (basin) . In this area it is extremely difficult to control the river because of massive amount s

1 05 of silt constantly changing the run of the river . Between 1886 and 1896 one main channel was created from al l the numerous riverbeds. Curves were flattened, excavations undertaken, and side channels closed off. A stable waterway for shipping could not be built under the circumstances . The low water regulation was done by the us e of 1900 dikes, but even with constant dredging it is more than difficult to keep a shipping channel open . Thi s channel is only 2 .0 m deep and 80-120 m wide .

Flood Safet y

Levees were already constructed in the 19th century . Except for two stretches in the valley betwee n Boerzsoeny and the Pilis mountains, all necessary levees had been constructed, including the entire northern bank of the Danube and the southern bank of the Little Danube . Big floods, like the one in 1965, caused all levees t o be strengthened and the discharge improved .

River Dam s

Since 1978 a river dam has been under construction at Gabcikovo, a joint project with Hungary . The drain channel is so massive that it differs from all existing and all planned river dams of the Danube . The combined electricity- creating waterway and shipping channel will leave the Danube for a distance of 30 km at the Dam o f Dunakiliti (1942 km) with a flow of 5200 m3/s . It is further planned together with Hungary to build another dam at Nagymaros. Only when this work is completed can the waterworks at Gabcikovo be put into use . With both of these dams, flood safety will be guaranteed at last .

Hungary

The Hungarian Danube has a length of 417 km ; 142 km of that form the border with Czechoslovakia . I t starts at the border of the Pannonischen Plain and stretches approximately to the middle of this basin .

Regulation of the Riverbe d

Planned work started in 1870 after exact figures from the total Danube were known and considered reliable. The most important reason to start the work was ice-floods . The original riverbed meandered and formed narrow loops and could not hold the ice that stacked up and then suddenly broke loose with great force . Great floods and much destruction were the result . The first step was to create one main riverbed in the upper part o f the river with straightened lines between Devin (1880 km) and Venek (1791 km) . Tributaries were cut off, shar p bends straightened, cuts made and all banks firmed . Mainly because of the great flood in 1838, when 15% of housing in Buda and 50% of housing in Pest wa s

1 06 destroyed, the construction in the Budapester stretch was immense. The Danube tributary Sorksar was shut off, the main channel dredged, and all through the capital levees and walls were erected . The biggest part of the work had been completed prior to the start of the First World War, and had brought major improvements in eliminating flood waters and pack ice. The original length of the Danube was cut in 3 0 areas and shortened from 472 km to 417 km . Navigation developed last after the corrections were done . At the end of the 19th century, work was started to remove shallows and low water regulations were initiated . A waterway for shipping was constructed 2 .5 m deep and at least 150 m wide .

Flood Safety

One quarter of Hungary, about 23,000 km2, is flood area . Only 23% is in the Danube Valley . That is the reason why the importance of flood safety has always existed . Even in the 16th century levees were built. The systematic construction of dams already had started in the first half of the 19th century . When in 1840 a lawfu l basis for waterworks was initiated, about 500 km of dams in the Danube Valley were in prior existence, protectin g about 2000 km2 of flood area . When the government took over flood regulation, dams and levees were constructe d and everybody had to pay for them . Decisions on further construction and the completion of a systematic da m system occurred 1881-1888 . By the end of the 19th century the safety system had been more or less completed . After completion of the total system, the Danube reached higher water levels between the dams and it wa s necessary to redo many of the former levees, because they were not high enough . In the beginning of this century all the levees were rebuilt to protect even against an extreme high flood occurring every 60 years . Since safety was not just a local issue, laws were changed and the government started controlling all work . From a length of 4183 km in safety lines, 1350 km are in the Danube Valley . Twelve waterwork commissions tak e care of these lines plus a very important secondary line 4183 km in length and an additional line of 18 km tha t leads through the capital of Budapest . With those, flood safety was very much improved . The goal to make the most important dams capable of protecting against a 1000-year flood and the rest against a 100-year flood has bee n accomplished . Included in the work are constant repairs or replacement of dams, according to new modern eart h mechanics . The importance of flood safety in Hungary is apparent: in possible flood areas lives one quarter of the population, and exist about 30% of the railroad system and 20% of all roads .

River Dams The river dam at Gabcikovo, a combination project with Czechoslovakia, and plans for another dam a t Nagymaros have been mentioned .

1 0 7 Yugoslavia The longest stretch of the Yugoslavian Danube (587 km) runs through the Pannonische Plain (358 km) . In this first part there is a drop in the gradient of the river slope from 0 .05 to 0.04 0/00. Before the river enters the area of the Iron Gates, where the Nera flows into the Danube, the river becomes the border to Rumania an d continues thus to where the Timok joins .

Regulation in the Pannonischer Plain

The correction work started in 1895 from Saks (Hungary) on. The same disciplines were applied as i n Hungary. All small channels were closed, curves flattened, banks strengthened and low water control regulated . Important work was done by making three large cuts above the area, where the Drau joins the Danube . The stretc h to where the Theiss joins was completed by the start of the First World War. The shipping channel reached a depth of 1 .8 m and a 100 m width . During the time between the two world wars, the work in the lower part o f the river below the Theiss was completed .

Regulation of the Iron Gates (Djerdap or Portile de Fier )

The first work ever done for shipping in the cataract area of the Iron Gate was the construction of th e Trajanways on the right bank of the river during the time of the Roman Empire . Nothing else followed until 1834- 1837, when the well known Szecheny-Strasse was cut into the rock to give shipping assistance during low water levels . At that time small detonations were used to remove cliffs or huge rocks near the cataracts of Kozla-Dojk e to create a small channel . After more planning and an international agreement large corrections were undertaken in the cataracts to improve navigation . They consisted mainly of five canals 50 m wide and 2 m deep that wer e built through the cataracts. Also the rock tip of Greben was shortened by 150 m . Even with today's technology it was extremely difficult to cut a channel into the rock : 650,000 m3 of roc k had to be removed, half of it under water, and 1 .2 million m3 of loose rock also . The shipping channel was 7 3 m wide and 3 m deep; the strong water current in this shipping channel would reach a speed of 5 meters per secon d (m/sec) . Because of this, navigation was limited . During the First World War a towing railway was built that would pull ships through the cataracts with the help of strong locomotives . Pilots were always necessary for the ships and sometimes navigation was impossible altogether . The final solution to all the problems came with the erection of a dam at Djerdap/Portile de Fier I, tha t controls the total stretch of the cataracts . The two 2-step locks are 34 m wide and 310 m long . The lock on the Yugoslavian side was more developed than the commission recommended . Its channel has a 5 .5 m depth and a 13.5 m Lichtraum profile and can therefore be used for 5000 ton barges or incoming ocean ships . Only a 4 .5 m depth and a 10 .5 m Lichtraum profile were recommended .

1 0 8 Flood Safet y

The only areas that are in danger of flooding and need to be protected are along the middle part of the Danube in the basin (Pannonische Plain). A systematic build-up of levees first started in the 19th century . Prior to the First World War a safety system was constructed in connection with the Hungarian dams, mainly on the left bank to the mouth of the Theiss and on the right bank up to the mouth of the Drau . Down river were a few bigge r stretches where levees were missing (at Pancevo near the mouth of the Karas) . The right bank of the river showed levees only in the stretch at Petrovaradin and at Zenum . Between the two world wars, work on dams was continued at Pancevo on the left bank and at Smederev o and Godominski Polje at the right bank . After the flood of 1926, many of the existing dams were strengthened and some of them were renewed . After the Second World War, more levees were constructed, necessary for flood safety . After the flood of 1965 and with new understanding of the problem, levees were reinforced and height added . Today a complete dam system exists on the left bank from the Hungarian border to the mountains of th e Iron Gates . On the right bank, only a few levees had to be built, because of local conditions ; from the Hungarian border to Petrovaradin and Zenum, and also down river from Smederevo . Those levees were necessary for any overflow from the river dam at Djerdap/Portile de Fier I . The flood crest is estimated 1 .5 to 1 .7 m above the 100-year flood .

River Dam s

To solve the difficulty of navigation and to use the great water energy potential, Yugoslavia and Romani a built a combination river dam at Djerdap/Portile de Fier I . This construction occurred 1964-1972. Along a stretch of 942 .95 km, the low water level is kept at 32 m . At low water levels, the water reaches a distance of 270 k m up to the mouth of the Theiss. During flood conditions, the water is lowered to 6 .5 m and the water extends 120 km to Veliko Gradiste . Upstream in the Danube as well as in the tributaries are long stretches where the river water can flow free , which causes problems when there is ice . In 1984 the river dam Gruia/Portile de Fier II was completed . It connects directly with the river dam Djerdap/Portile de Fier I, so the waters can be used to create energy. These waterworks were constructed wit h the cooperation of Yugoslavia and Romania .

Bulgaria

Down river below Yugoslavia, the Danube forms the border between Romania and Bulgaria for a distanc e of 472 km .

1 09 Between 1930 and 1950, levees about 300 km long were constructed to protect an area of 72,600 hectare s (ha) . To determine the height of the levees, the flood of 1897 was used as a guide .

Romania

Romania has the biggest stretch of the Danube flowing through her country, a distance of approximatel y 1075 km, starting at the mountains in the area of the Iron Gates . Between Nera and Timok the Danube forms th e border with Yugoslavia for about 229 km and then the border with Bulgaria for a stretch of 472 km, from the spo t where the Prut enters the Danube for about 80 km to the flow into the Chilia/Kilija tributaries and from there to the Black Sea.

Regulation of the Riverbed

The correction work at the cataracts near the Iron Gates at the border with Yugoslavia was describe d earlier . In order to also permit larger ocean-going vessels to enter the Danube, Romania constructed the Sulin a tribtary in the Danube Delta between 1857 and 1902 . Ten river cuts produced a reduction from 85 to 62 km, a depth of 7.3 m and a width of 80 m . The channel reached the harbor of Tulcea . Today the channel extends to Braila, about 170 km inland, but constant dredging has to be done to hold the channel open . Only 10% of agricultural land is being drained to be able to use it . Irrigation is only being done in a small area of about 10 0 ha for vegetable growing .

Austria

The regulation of the Austrian Alpine rivers occurred between 1830 and 1930 . In a few stretches, levees were constructed at a later date . Because of the high volume of water existing and the big differences in elevatio n in the alpine region, there is a great potential for water power, which use started early in 1898 . The Inn flows through three countries, and four countries use its water power . The energy of the river is already being used in Switzerland, through massive work on the three Oberengadiner Lakes. Against the permission to build a large water storage in Livigno, Switzerland permitted the diversion of about 90 million m 3 of water from the Italian Inn to the Adda. The loss of water in the Inn is evened out by averaging the flow of 170 million m3 with the winter flow . At the Austrian Inn are two hydropower stations that work independently from one another . In contrast to that, there are 10 river dams that form a closed chain in the German stretch adjacent to the Austrian territory , that continues into the border stretch with another five steps from the Salzach to the Danube . More work i s planned .

1 1 0 In the territory of the Inn and the Salzach there are water storages totalling about 750 million m3 of water . Besides this, water in the amount of 209 million m3 is being discharged into the Rhine River and 127 million m 3 into the Drau . Between the Danube and the mouth of the Inn (Switzerland, Austria, Germany) there are at thi s time energy storage areas of one billion m3 created for long time storage . If you divide this flow for five month s from the summer into the winter, you get a change of flow in average of 75 cubic meters per second (m3/s) . There are only a few river dams on the Traun, between Traunsee and the mouth of the Traun, that are used for energy production . On the 130 km long stretch of the Enns 14 river dams were constructed, forming a closed chain . Thi s occurred between 1942 and 1972 . On the upper part of the river there is also a small hydropower station . Along the border the March was regulated in the time span from 1911 to 1964 . The Drau from Villach to the border shows the construction of a complete chain of seven river dams . On her tributary Mur the only interruption in a chain of nine river dams is at the city of Graz . A two-country projec t plans the construction of more hydropower stations on the Austrian-Yugoslavian border . In the upper part of th e Mur are three larger water storages . In Austria's mountain areas the control of wild streams is of great importance . The goal is to protect the small living spaces in the mountain valleys from floods, from being cut off, from avalanches and landslides . A drainage system has been constructed for about 150,000 ha of agricultural land . Irrigation systems for 50,000 ha of land are in use and are planned for another 130,000 ha .

Czechoslovaki a

The controlled stretch of the March on the border has levees to protect against a 100-year flood . The upper March has four multi-purpose water storages . The regulation of the Vah started in 1919 . A systematic development went into effect after 1945 . The middle part of the river between Zilina and Hlohovec already shows an almost completed chain of river dams . Along a 100 km stretch of the lower river are levees, protecting against floods . Plans exist to open up the lowe r part of the river for shipping by constructing river dams . In the upper part of the river there are numerous wate r storages. The two largest man-made lakes contain a volume of 706 million m3 . The lower run of the Nitra was diverted into the Vah . In the upper part of the Hron there exists a stored water volume of 44 million m3 for irrigation, drinkin g water, and flood safety . Regulations and levees have existed on the Bodrog since the last century . Systematic and intense work has been done since 1950. The water storage areas at Zemplinska and Velka Domasa with a volume about 55 0 million m3 are used mainly for irrigation and water usage . In Slovakia there are at present about 2300 km of levees along all the rivers, including the Danube . Thes e protect an area of 450,000 ha from being flooded . The largest part of the lower valleys, about 300,000 ha, have

1 1 1 to be guarded against the constant water flow from the rest of the country . In order to do so, pump stations drai n the rivers artificially, because of the long lasting high water crests. All the pumps together are capable of drainin g about 256 m3/s, that is, 851 cubic meters per second per square kilometer (/s km2) . Because of the existing climate, irrigation is the most important requirement for increasing agricultura l production. Approximately 800,000 ha of land need to be irrigated . This total contains the areas that have to be protected from floods and have to be artificially drained, because they need irrigation during the rest of the yea r due to the climate . In 1952, an area of 1400 ha was irrigated, in 1970, about 140,000 ha and in 1975 abou t 180,000 ha. Approximately 100,000 ha belonged to large area systems . The yearly need for water is 2200 cubic meters per hectare (m3/ha) . This need is covered by water from storages for 110,000 ha and by water from th e Little Danube for 30,000 ha . As a result of the new construction of the river dam at Gabcikovo, it will be possibl e to irrigate much larger areas in the future . There are also fish ponds throughout Slovakia, covering a total area of 1100 ha .

Hungary

Any discharge is extremely difficult in the flat Pannonischen Lowland . There is very little change i n elevation and a very small water net . Since the first part of the century an area of 23,000 km2 is marsh and a 16,000 km2 area is sometimes flooded . The draining is so slow that many areas of land are under water fo r months. The majority of the swampy or flooded areas are along the Theiss and her tributaries . In Hungary yo u can differentiate several phases in the development of waterworks ; that is true for other countries as well . The regulation of the larger river runs occurred mostly in the 19th century . The Hungarian stretch of th e Theiss was shortened from 1000 to 600 km in length by making 12 cuts in the river bed . Levees were built at the same time . They were completed by the beginning of the 20th century . The safet y system in the Theiss Valley has a length of 2800 km, including the levees on the tributaries Bodrog, Koeroes an d Berettyo, stretching approximately twice as long as the Danube levees . In the first half of the 20th century correction work was undertaken on the dam systems and low wate r regulation accomplished. All the levees on the smaller tributaries were completed . In the second part of the 20th century construction measures have been taken to increase dam heights an d strengthen levees, but improvements in flood prediction, levee protection and the fight against ice packs also hay e been stepped up. Hungary's goal is to increase the main safety lines against a 100-year flood, more important areas against a 150-year flood and the highest values like big cities and industry against a 1000-year flood . Work is i n progress for several river dams and water storage areas, for multi-purpose use . A system for the total area of the country is in the planning stages . The river dams Tiszaloek (built 1959) and Kiskoere (built 1973) are multi-purpose . They are for energy production, improvement of flood safety, irrigation and the lengthening of the river channel all the way up t o Dombrad and in the tributary Bodrog up to the border . There are plans for several river dams along the Theis s

1 1 2 and Koeros for combined shipping and irrigation use . The Sio, a tributary that is totally diverted into a canal, gets its waters from the Plattensee. At the end of the lake is a lock to control the water going into the canal and another controls the flow at the mouth of th e Danube, to control the outgoing volume. Four more locks are in planning . The biggest part of the Drau forms the border to Yugoslavia . The first regulations were already finished by the end of the 19th century . The main work was completed at the end of the 19th century . It is planned t o construct river dams together with the neighbor country . The discharge of water from reclaimed land already was a requirement at the time of the construction o f levees. It is necessary to use 80% of the former flood areas for agriculture . With the intensification of agricultur e since 1930, it has become of great importance to discharge water coming from inland and stop other water fro m seeping in from the river front . Since the land has only a minute drop in elevation, ditches and canals had to be built and pump station s installed. About 33,000 km of discharge canals exist and with a pumping capability of 650 m3/s, approximatel y 251/s km2, the damaging waters can be discharged from the reclaimed land within 14-19 days . The plan for th e future is to accomplish this in 7-12 days . Plans are also being made to store water for longer periods . The irrigation of agricultural land, 14,000 ha in 1947, increased to 437,000 ha in 1970 . Two-thirds i s located in the Theiss Valley, one-third in the Danube Valley ; two-thirds of the total land is being irrigated . Th e water volume needed is 3500-3700 m3/ha per year, up to 217 m3/s . More than half of the irrigated land lies insid e a large irrigation area with a canal net 4400 km in length . The largest irrigation system with 120,000 ha of land , together with 6300 fish ponds, is provided with water from the Theiss at the Tiszaloek river dam . The two mai n canals with a volume of 55 m3/s connect the two valleys of the Theiss and Koeroes . During recent years th e capacity of the system was not fully used . Plans are to revive agriculture to help the economy .

Since the end of the 19th century half of the country's land has been improved for agriculture amd the wate r net has been made safe for 3-10 year floods. In the last two centuries improvements were made consisting o f discharge regulations, water storage, irrigation, discharge, and also erosion safety . Irrigation and discharge function together, because both can be handled by the canals and ditches . Two thirds of the irrigation is undertaken with approximately 19,000 ha of fish ponds, that contain up t o 150 million m3 of water. Half of the ponds are located in the neighborhood of the Theiss . The most well know n are the Hortobagy fish pond, the Feherto by Szeged and the Biharugra pond system .

Yugoslavia

The regulation work on the Drau started at the beginning of the 20th century . Besides correcting the river bed, levees were erected to a length of 220 km out of a total length of 350 km . Most of these, about 95 km, are located on the left bank. The land protected from floods has an area of 20,000 ha . In the upper part of the Drau ,

1 1 3 from the Austrian border to Maribor, are six river dams . The Theiss was regulated in the 19th century ; 11 larger cuts were made in the river bed . Through thi s the river became navigable . At the same time levees were erected and strengthened again in the 20th century . Regulation work on the Save started at the end of the 19th century at the mouth of the river . This consisted mostly of cuts totalling about 43 km in length and about 50 km of levees . With approximately 550 km of levees on each side, an area of 650,000 ha is protected against floods . In the upper part of the Save are 1 1 water storage areas with a volume of 2.4 billion m3 . Two of the storage areas are on the Save, two on the Drina , two on the Uvac, and several others near other tributaries . The storage at the Drina near Piva is the largest wit h 880 million m3 . At the Velika Morava and her two tributaries, the Southern and Western Morava, cuts were made into th e river 167 km in length . Several levees and a few hydropower plants were also constructed. With 430 km of levees an area of 93,000 ha is protected from floods . In the upper part of the Velika Morava there are six larger water storage areas. The Gazivode water storage can hold the largest volume of 390 million m3 .

Discharge and Irrigatio n

The Danube-Theiss-Danube waterworks commenced in the 17th century . They started with the construction of a channel for shipping, the Danube-Theiss-Danube Canal between Backo Gradiste and Back i Monoester. For this project it was necessary to regulate the Begej and the Tamis, discharge the water from th e swamps along the Backa, broaden the natural river run, and construct a system of discharge canals in the Bana t area. In spite of all this the land was not protected against floods . The basic concept of the Danube-Theiss-Danube Canal was mainly to drain or irrigate the land with th e help of pump stations and to use the main canals for shipping . This canal was started in 1948 . By 1972 more main canals had been constructed totalling 470 km in length ; for this it was necessary to excavate 127 million m3 o f earth. In addition, there exists a stretch of old canals 270 km in length . The two main canals that lie in the Backa region start at the Danube at Bexdan and Bobjevo . There ar e big pump stations for water discharge . At Novi Sad there is another connection to the Danube . The connection to the Theiss is located near Novo Becej and Zabalj . The main canals in Banat start at three spots on the Theiss . (At the mouth by Ziatica, by Noyi Bejec and by Titel .) They end at three spots on the Danube . (By Pancevo, ove r the Tamis by Centa and by Banatska Palanka near the mouth of the Nera . ) The largest construction of the system is the river dam at the Theiss by Novo Bejec . The first phase water discharge of 60 m3/s is supposed to be enlarged to 120 m3/s ; with that 300,000 ha of land can be irrigated . There are altogether 20 gates along the Backa that allow the discharge of water . After the completion of the first phas e 760,000 ha of land can be drained and 360,000 ha can be irrigated . An increase in irrigation is possible up to on e million ha .

1 1 4 a Bulgaria

Between 1950 and 1970, river regulations were under way for all the major tributaries and levees were constructed . For intensive agriculture, irrigation was needed for 30% of all land along the lower part of the Danube . In contrast to other Danube countries, Bulgaria has always been known as the irrigation country . At the end o f the last century irrigation covered an area of 30,000 ha . Since 1950 the irrigation systems were enlarged ; 1 3 systems are sending water from the Danube with the help of pump stations to 128,000 ha of land . To do so wate r has to be pumped up about 100 m . There are more irrigation systems by Sofia and Cerven-brjag, as well as i n the upper runs of the rivers Iskar and Vit . The delivery of water to the systems that do not get their water fro m the Danube can only be done by means of large water storage areas . For that reason a storage area was create d in the upper part of the Bulgarian Danube, that holds about 150 million m3 of water per year . through the diversion of the river Struma to the Iskar the flow of water into the Danube is increased by 200 million m3 pe r year .

Romania

Some stretches of the rivers leading to the Theiss and Danube are regulated and some have river dams . Some water storages were built, the largest one in Bicaz Lake. There are water systems in the Romanian lowland s that get their water supply through pumps from the Danube. The total area of land that can be irrigated thus far is 700,000 ha .

UKRAINIAN SSR

Since 1863, numerous regulations have been made on the Theiss and her tributaries . Levees wer e constructed extending 440 km . More regulations and additional levees with a length of 150 km are planned . I n the mountains wild water streams are being controlled . On the upper Theiss there is a water storage with th e volume of 50 million m3 . Other water storages are being planned by the year 2000 . On the Prut a water storage was constructed together with Romania that holds 450 million m3 of water . It is being used to generate hydropower and for irrigation .

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