LAKE BALATON

From the rooftop of Balaton Limnological Research Institue, Tihany

Photo.
Photo: A. Kurata




A. LOCATION

  • Somogy and Veszprem, Hungary.
  • 46:42-47:04N, 17:15-18:10E; 104.8* m above sea level.

    • * Adriatic.





B. DESCRIPTION

    Lake Balaton was formed mainly by tectonic forces 12,000-20,000 years ago. Prior to the opening of Sio-canal in 1863, its water level was 3 m higher and its surface was about twice larger than at the present. With its surface area of 593 km2, Lake Balaton is the largest lake in Central Europe, but its mean depth is only 3.2 m.
    The main inflow, the Zala River, empties into the southwestern end of the lake, while the Sio-canal drains the water from the eastern basin into the River Danube.
    The lake is covered by ice in winter. In summer the average water temperature is 23deg C. The strong waves swirl up much sediments, rendering the transparency low.
    The major ions of the water are Ca2+, Mg2+ and HCO3-. The pH is 8.4, rising to higher values during intensive primary production. Oxygen deficiency is formed only temporarily in the western part of the lake in calm summer periods with algal blooms.
    The distribution of macrophytes is restricted by strong waves to a relatively narrow belt. Only 3 percent of the lake surface is covered by reeds, and even less by submerged macrophytes. The major primary producers are phytoplankton. Zooplankton is not abundant. Zoobenthos represents an important food for the fish. The annual commercial fish catch is 1200 tons.
    The southern shore of the lake consists of sandy beach, while on the northern shore there are mountains of volcanic origin with old ruins on their tops and vineyards on their slopes. The picturesque landscape and the water ideal for swimming and other water sports attract 2 million tourists annually.
    The sewage discharge from rapidly developing towns in the watershed, the growing use of fertilizers in agriculture and large animal farms increased the nutrient loading to the lake in the last decades. A rapid eutrophication became apparent by increased production and biomass of phytoplankton. Blooms of blue-green algae are frequent in the most polluted western part of the lake.
    A eutrophication control program has been formulated, based on intensive scientific researches. Most of the municipal sewage is now diverted from recreational areas. Phosphorus removal was introduced at other sewage treatment plants. A reservoir was constructed to retain the nutrients carried by the Zala River. Pollution due to liquid manure was reduced. Construction of more reservoirs on major tributaries of the lake and a soil protection program are in progress (Q).


C. PHYSICAL DIMENSIONS

    Surface area [km2] 593
    Volume [km3] 1.9
    Maximum depth [m] 12.2
    Mean depth [m] 3.3
    Water level Regulated
    Normal range of annual water level fluctuation [m] 0.3
    Length of shoreline [km] 236
    Residence time [yr] 2
    Catchment area [km2] 5,181


D. PHYSIOGRAPHIC FEATURES (2)

D1 GEOGRAPHICAL

  • Bathymetric map: Fig. EUR-04-01.
  • Names of main islands: None.
  • Number of outflowing rivers and channels (name): 1 (Sio-canal).

D2 CLIMATIC

  • Climatic data at Siofok

    Mean temp. [deg C]*1
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    -1.4 0.6 5.0 10.7 15.6 19.4 20.8 20.2 16.3 10.8 5.6 1.0 10.4
    Precipitation [mm]*2
    36.5 37.7 35.6 44.7 60.4 80.8 73.3 62.4 48.4 42.9 65.5 45.7 633.9
    *1 1947-1963. *2 1951-1980.
  • Number of hours of bright sunshine (1951-1980): 2,052 hr yr-1.
  • Solar radiation (1931-1960): 12.2 MJ m-2 day-1.

    Fig. EUR-04-01
    Bathymetric map (Q).


  • Water temperature [deg C]


    1947-1963
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1 - - 4.5 11.5 17.6 21.9 23.2 22.9 19.2 13.3 6.9 2.0
  • Freezing period (1927-1963): 4 January-24 February.
  • Mixing type: Polymictic.


E. LAKE WATER QUALITY (3)

E1 TRANSPARENCY [m]

    Keszthely, 1979-1983
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    - - 0.49 0.38 0.50 0.47 0.50 0.35 0.41 0.46 0.50 0.65
    Szemes, 1979-1983
    - - 0.72 0.48 0.49 0.56 0.69 0.45 0.64 0.53 0.60 0.52
    Siofok, 1979-1983
    - - 0.71 0.45 0.45 0.71 0.67 0.55 0.69 0.70 0.57 1.25

E2 pH

    8.4, rising to 8.9 in the western part of the lake during summer algal blooms.

E3 SS [mg l-1]

    Keszthely, 1979-1983
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1 - - 34.1 39.6 27.6 40.6 23.1 31.7 23.4 25.8 - 14.5
    Szemes, 1979-1983
    1 - - 20.7 22.2 22.5 13.9 16.4 29.1 13.5 22.6 56.0 13.4
    Siofok, 1979-1983
    1 - - 16.1 19.7 23.9 13.7 25.0 23.1 13.6 18.6 20.1 4.9

E4 DO [mg l-1]

    The dissolved O2 concentration is usually close to the saturation level. Strong oversaturation at the surface and O2 deficiency near bottom sediment are found only in the western part of the lake in calm summer periods during algal blooms.

E5 COD [mg l-1]

  • Determined by KMnO4 method.

    Keszthely, 1979-1983
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1 - - 7.86 8.60 6.50 7.38 9.80 7.72 7.96 8.00 8.07 9.80
    Szemes, 1979-1983
    1 - - 5.96 5.10 5.00 4.68 6.32 5.64 6.04 6.45 5.95 5.00
    Siofok, 1979-1983
    1 - - 4.88 4.80 4.02 3.26 4.70 4.46 4.46 4.67 4.43 4.90

E6 CHLOROPHYLL CONCENTRATION [micro g l-1]

    Keszthely, 1979-1983
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1 - - 34.0 30.8 19.8 20.4 33.5 51.4 38.4 41.4 42.8 42.9
    Szemes, 1979-1983
    1 - - 12.4 19.4 10.6 7.4 8.8 22.6 19.5 16.7 15.4 16.1
    Siofok, 1979-1983
    1 - - 7.2 9.2 8.5 4.4 5.4 9.8 11.7 10.0 6.8 5.1

E7 NITROGEN CONCENTRATION

  • Total-N [mg l-1]

    Keszthely, 1979-1983
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1 - - 1.81 1.85 1.23 1.50 1.39 2.01 1.51 1.57 1.72 1.94
    Szemes, 1979-1983
    1 - - 1.25 0.98 0.90 0.92 0.87 0.99 0.87 1.19 1.09 0.63
    Siofok, 1979-1983
    1 - - 0.93 0.80 0.72 0.61 0.70 0.79 0.71 1.07 0.69 0.59

E8 PHOSPHORUS CONCENTRATION

  • Total-P [mg l-1]

    Keszthely, 1979-1983
    Depth [m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1 - - .075 .089 .068 .089 .101 .104 .114 .089 .143 .078
    Szemes, 1979-1983
    1 - - .032 .052 .036 .033 .035 .037 .039 .040 .059 .043
    Siofok, 1979-1983
    1 - - .024 .028 .034 .022 .027 .028 .033 .043 .031 .028


F. BIOLOGICAL FEATURES

F1 FLORA (4)

  • Emerged macrophytes: Phragmites australis, Typha latifolia.
  • Floating macrophytes
    Lemna minor, L. trisulca, L. gibba, Spirodela polyrrhiza, Wolffia arrhiza, Hydrocharis morsus-ranae, Nymphaea alba, Nuphar luteum, Trapa natans.
  • Submerged macrophytes
    Potamogeton perfoliatus, P. crispus, P. pectinatus, Najas marina, Stratiotes alloides, Ceratophyllum demersum, Myriophyllum spicatum.
  • Phytoplankton
    Spring Nitzschia acicularis, Cyclotella ocellata, C. bodanica, Stefanodiscus hantzschii. Summer: Eastern part Ceratium hirundinella, Melosira granulata, Botryococcus braunii. Summer: western part Anabaenopsis raciborskii, Anabaena spiroides, A. aphanizomenoides, Aphanizomenon flos-aquae.

F2 FAUNA (5)

  • Zooplankton
    Polyarthra vulgaris, Keratella quadrata, Pompholyx sulcata. Daphnia cucullata, D. galeata, Eudiaptomus gracilis, Mesocyclops leucarti, Cyclops vicinus.
  • Benthos
    Ectinosoma abrau, Darwinula stevensoni, Potamothrix hammoniensis, Tanypus punctipennis, Lithoglyphus naticoides, Dreissena polymorpha.
  • Fish
    Abramis brama*, Cyprinus carpio*, Stizostedion lucioperca*, Aspius aspius, Pelecus cultratus, Esox lucius, Anguilla anguilla*. * Economically important.

F3 PRIMARY PRODUCTION RATE [mg C m-2 day-1](6, 7)

    Keszthely, 1973
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    312 447 524 594 726 858 6,640 6,628 2,265 126 434 373 613*
    Szemes, 1976
    127 96 447 432 496 988 1,551 1,132 841 386 214 159 210*
    Siofok, 1977
    103 105 248 616 633 951 1,228 847 638 313 203 41 181*
    * [g C m-2 yr-1].

F4 BIOMASS

  • Zooplankton: 2.5 [g (dry wt.) m-2].
  • Zoobenthos: 2.7 [g (dry wt.) m-2].
  • Fish [ton(wet wt.) per lake]
    Abramis brama: 9578. Stizostedion lucioperca: 578.

F5 FISHERY PRODUCTS

  • Annual fish catch [metric tons]
    1985: 1,315.

F6 PAST TRENDS: Fig. EUR-04-02, 03, 04, 05 and 06.

    Fig. EUR-04-02
    Trend of increase of primary production in the Keszthely-basin (6).


    Fig. EUR-04-03
    Trend of increase of algae counts in the Keszthely-basin (4).


    Fig. EUR-04-04
    Trend of increase of algae counts in the Siofok-basin (4).


    Fig. EUR-04-05
    Trend of increase of phytoplankton biomass in the Keszthely-basin (4).


    Fig. EUR-04-06
    Trend of increase of phytoplankton biomass in the Siofok-basin (4).



G. SOCIO-ECONOMIC CONDITIONS (8)

G1 LAND USE IN THE CATCHMENT AREA

    1982

    Area [km2] [%]
    - Natural landscape
    Woody vegetation 1,343 25.9
    Herbaceous vegetation 362 7.0
    Swamp 106 2.0
    - Agricultural land
    Crop field 2,428 46.9
    Pasture land 505 9.7
    - Residential area 437 8.4
    - Others - -
    - Total 5,181 100.0
  • Main types of woody vegetation
    Deciduous forest (Carpinus betulus, Quercus petraea, Acer campestris, Quercus pubescens, Quercus cerris, Fraxinus ornus).
  • Main kinds of crops: Wheat, maize, hay, grape and fruits.
  • Levels of fertilized application on crop fields
    Heavy (121 kg N + 90 kg P2O5 + 126 kg K2O ha-1 yr-1).

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE

    1980
    No. of persons engaged No. of establishments
    Primary industry 46,400
    Animal husbandry 334
    Secondary industry 65,200 741
    Tertiary industry 78,900
  • Numbers of domestic animals in the catchment area
    Cattle 90,000, Sheep 110,000, Swine 220,000, Poultry 1,500,000.

G3 POPULATION IN THE CATCHMENT AREA

    Population Population density [km-2] Major cities (population)
    Urban 180,500 Zalaegerszeg, Tapolca,
    Rural 224,300 Marcali, Keszthely,
    Total 404,800 64 Siofok, Balatonfured


H. LAKE UTILIZATION

H1 LAKE UTILIZATION

    Source of water, navigation and transportation, sightseeing and tourism (no.of visitors in 1982: 1,800,000), recreation (swimming, sport-fishing,yachting) and fisheries.

H2 THE LAKE AS WATER RESOURCE

    Use rate [m3 sec-1]
    Domestic 0.273
    Irrigation 0.079
    Industrial 0.330
    Power plant -
    Others -


I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION

  • Extent of damage: Not serious.

I2 TOXIC CONTAMINATION (9)

  • Present status: Detected but not serious.
  • Main contaminants, their concentrations and sources (lake average)

    Name of contaminant Range of concentration [ppm] in*1 Main sources
    Water Bottom mud Fish*2 Other organisms
    1982 1984 1982 1982*3 1982*4 1982*5
    Cu (0.005) (10) (3.12) (12.3) (18.6) (42.5) Waste
    Zn (0.057) (90) (64.3) (468) (73.5) (111) dumps and
    Ca (0.0008) (1.5) (0.65) (3.7) (3.99) (1.47) agriculture
    Hg (0.0007) (-) (0.36) (1.22) (1.88) (1.08)
    Pb (0.002) (30) (3.59) (48.5) (22.1) (12.3)
    *1 For water on volume basis mg l-1; for bottom mud, fish and other organisms on dry weight basis mg kg-1.
    *2 Abramis brama, muscle.
    *3 Anodonta oygnea, pill.
    *4 Chironomidae larvae, whole animals.
    *5 Crustacean plankton.

I3 EUTROPHICATION

  • Nuisance caused by eutrophication
    Unusual algal bloom (Dominant species of algae Aphanizomenon flos-aquae, Anabaenopsis raciborskii, Anabaena aphanizomenoides, Anabaena spiroides).
  • Nitrogen and phosphorus loadings to the lake [t yr-1]
    whole lake basin,

    1975-1981
    Sources Industrial Domestic Agricultural Natural Total
    T-N - 382 1,973 - 3,148
    T-P - 89 150 - 314
  • Supplementary notes
    The following measures are being taken to prevent further eutrophication.
    1. Development of sewerage and sewage treatment plants.
    2. Phosphorus removal at sewage treatment plants.
    3. Diversion of a greater part of treated effluents produced in recreational areas from the watershed of the lake.
    4. Establishment of reservoirs on larger tributaries to retain plant nutrients.
    5. Elimination of large livestock breeding farms from the watershed or the assurance of full agricultural utilization of their wastes (mainly liquid manure).
    6. Removal of the surface layer of lake sediments in areas of high phosphorus accumulation.
    7. Land reclamation and soil amelioration.


J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

    f) Extensive development of the catchment area with provision for municipal wastewater treatment.

J3 SANITARY FACILITIES AND SEWERAGE

  • Percentage of municipal population in the catchment area provided with
    adequate sanitary facilities (on-site treatment systems) or public sewerage: 100%.
  • Percentage of rural population with adequate sanitary facilities (on-site
    treatment systems): 100%.
  • Municipal wastewater treatment systems
    No. of tertiary treatment systems: 6 (64,000 m3 day-1); P removal by aluminum sulphate. No. of secondary treatment systems: 17 (75,000 m3 day-1).


M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED

  • Names of the laws (the year of legislation)
    1. Hungarian Water Act (1964)
    2. Environment Protection Act (1976)
    3. Revision of the Water Resources Development Program of the Lake Balaton Area (1979)
    4. Resolution of the Council of Ministers on Restoration of Water Quality of Lake Balaton (1983)
  • Responsible authorities
    1. National Water Authority
    2. Ministry of Public Health
    3. Ministry of Agriculture
    4. Ministry of Construction and Town Development
    5. National Authority for Environment Protection and Nature Conservation

M2 INSTITUTIONAL MEASURES

  1. National Water Authority

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES

  1. Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany
  2. Research Centre for Water Resources Development
  3. National Public Health Institute
  4. Karl Marx University of Economics
  5. Scientific and Design Institute for Urban Planning
  6. Institute for Environmental Protection
  • Supplementary notes
    Thirty other research institutes, university chairs and other agencies participated in the research program coordinated by the above institutions.


N. SOURCES OF DATA

  1. Questionnaire filled by Dr. S. Herodek, Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany.
  2. Illes I. (ed.)(1981) Our Lake Balaton. Natura Press, Budapest (in Hungarian).
  3. National Meteorological Service-Data Bank.
  4. Research Centre for Water Resources Development-Data Bank.
  5. Voros, L. (1985) Phytoplankton changes in space and time in Lake Balaton. D. Sc. Thesis (in Hungarian).
  6. Ponyi, J. E. (1986) Pelagic and benthic invertebrates of Lake Balaton and their ecology. D. Sc. Thesis (in Hungarian).
  7. Herodek, S. & Tamas, G. (1976) The primary production of phytoplankton in the Keszthely-basin of Lake Balaton in 1973-1974. Annal. Biol. Tihany, 42: 175-190.
  8. Herodek, S., Voros, L. & Toth, F. (1982) The mass and production of phytoplankton and the eutrophication in Lake Balaton III. The Balatonszemes basin in 1976-1977 and the Siofok basin in 1977. Hidrol. Kozl., 62: 220-229 (in Hungarian with English summary).
  9. National Authority for Environment Protection and Nature Conservation (1984) Balaton 1982.
  10. Salanki, J. V., Balogh, K. & Berta, E. (1982) Heavy metals in animals of Lake Balaton. Water Research, 16: 1147-1152.