DONG-HU (LAKE DONG)

A view from the survey boat on the lake

Photo.
Photo: T. kira


A. LOCATION

  • Hubei Province, P.R. China.
  • 30:33N, 114:23E; 20.5 m above sea level.


B. DESCRIPTION

    Dong (east) -hu (lake) is a small lake in the Wuchang Ward of Wuhan City, the capital of Hubei Province. It obtained its name from being located at the eastern end of this big city. Dong.hu is a natural dammed lake formed in the early Holocene as a so-called "lateral lake" attached to the right bank of the Chang Jiang which flows through Wuhan, and is only five kilometers away from the river.
    The lake area, especially the northwestern coast, is a park and recreation area for the citizens of Wuhan, with museums, a botanic garden, observation towers, restaurants, sanatoria, beautiful groves of exotic swamp cypress, swimming sites and sightseeing boats. The Wuhan Institute of Hydrobiology established by the Academia Sinica in 1954 is located on the westernmost shore of the lake. Its research activity made Dong-hu one of the most familiar lakes of China to world limnologists.
    It is also intensively utilized for fish production. Many small bays are separated from the main lake by causeways for artificial stocking of fish. Introduction of such planktophagous fishes as the silver carp and the bighead carp, increased the fish production by more than four times in a seven-year period. The increasing density of fish as well as the inflow of waste water from the city and industrial factories, however, has caused a rapid change in the lake's biota. Accelerated eutrophication is producing noxious effects which now hinder the utilization of lake water and recreational activity. A plan for establishing a waste water treatment plant for domestic sewage and the diversion of treated water to Chang Jiang, is now being carried out by the Municipality of Wuhan (Q).


C. PHYSICAL DIMENSIONS

    Surface area [km2]28
    Volume [km3]0.062
    Maximum depth [m]4.8
    Mean depth [m]2.2
    Water levelRegulated
    Normal range of annual water
    level fluctuation [m]0.5
    Length of shoreline [km]9.2
    Residence time [yr]0.4
    Catchment area [km2]97

D. PHYSIOGRAPHIC FEATURES (5)

D1 GEOGRAPHICAL
  • Bathymetric map: Fig. ASI-12-01.
  • Names of main islands: None.
  • Number of outflowing rivers and channels (name): 1 (Qingshan Canal).
D2 CLIMATIC
  • Climatic data at Wuhan, 1961-1970 (1)
    JanFebMar AprMayJun JulAugSep OctNovDecAnn.
    Mean temp. [deg C]2.94.8 9.915.821.625.5 28.828.523.217.4 11.05.116.2
    Precipitation [mm]305190148132 17518115295364351,450
  • Number of hours of bright sunshine (1982): 1,624 hr yr-1 (2).
  • Solar radiation (1982): 12.53 MJ m-2 day-1 (2).

    Fig. ASI-12-01
    Bathymetric map (Q).

  • Water temperature [deg C](Q)

    Middle lake sampling station, 1982
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.56.15.310.616.623.4 25.929.129.224.821.514.76.5
  • Freezing period: January or February (if ever happens).
  • Mixing type: Polymictic (Q).
  • Notes on water mixing and thermocline formation Strong mixing; practically no thermocline formation.

E. LAKE WATER QUALITY (Q)

E1 TRANSPARENCY [m]

    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    2.872.123.172.431.97 1.631.070.620.550.620.982.25
E2 pH

    Middle lake sampling station, 1983-1985
    Depth. [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.57.978.308.218.30 8.488.78------
    3.58.128.348.218.388.55 8.699.298.978.698.668.368.13
E3 TDS [mg l-1]

    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.5166.3137.3196.5258.0236.3 200.5195.5142.2129.0121.2152.5150.0
    3.5152.2184.8183.8222.5261.5 189.7133.0136.8121.5119.0144.2138.8
E4 DO [mg l-1]

    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.510.94 11.78 9.177.258.39 9.007.917.926.628.058.0010.29
    3.511.23 10.85 9.598.077.51 8.467.007.225.987.06* 7.7510.19
    * Mean for 1983 and 1985.


E5 COD [mg l-1]
    Determined by KMnO4 method.

    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.55.895.214.584.573.22 2.584.576.384.684.914.733.02
    3.55.815.154.034.723.04 2.964.225.65*5.324.874.883.02
    * Mean for 1983 and 1985.


E6 CHLOROPHYLL CONCENTRATION [micro l-1]

    Middle lake sampling station, 1982
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.56.121.453.276.853.21 12.58 28.4135.4038.1945.1810.250.70
    3.53.061.001.365.594.60 12.0228.4138.6643.7840.5213.970.70
E7 NITROGEN CONCENTRATION
  • NO3-N [mg l-1]

    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.50.2410.2630.3230.4890.175 0.1380.0240.0130.0070.0210.060 0.156
    3.50.2530.2620.3590.4550.242 0.1730.0240.0200.0070.0200.0660.124
  • NH4-N [mg l-1]

    0.57
    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.50.320.240.320.350.47 0.180.090.500.100.060.670.35
    3.50.320.250.350.29 0.170.190.290.090.030.390.32
E8 PHOSPHORUS CONCENTRATION
  • PO4-P [mg l-1]

    Middle lake sampling station, 1983-1985
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.50.0100.0070.0100.0160.0040.006 0.0040.0230.0300.0020.0140.021
    3.50.0110.0080.0150.0210.0080.007 0.0010.0370.0370.0030.0090.012
  • Total-P [mg l-1]

    Middle lake sampling station, 1982
    Depth [m]JanFebMarAprMayJun JulAugSepOctNovDec
    0.50.1080.0580.0400.0130.015 0.0160.0320.0400.0270.0340.0150.027
    3.50.0940.0200.0220.0160.0170.014 0.0360.0200.0480.0400.0580.029
E10 PAST TRENDS : Fig. ASI-12-02, 03, 04, 05 and 06.

    Fig. ASI-12-02
    Trend of transparency at 0.5 m depth, Middle lake sampling station.

    Fig. ASI-12-03
    Trend of pH in the depth 0.5 m, Middle lake sampling station.

    Fig. ASI-12-04
    Trend of NO3-N of the depth 0.5 m, Middle lake sampling station.

    Fig. ASI-12-05
    Trend of NH4-N in the depth 0.5 m, Middle lake sampling station.

    Fig. ASI-12-06
    Trend of PO4-P at 0.5 m depth, Middle lake sampling station.


F. BIOLOGICAL FEATURES

    Middle lake sampling station for plankton, whole lake for macrophytes and benthos, during 1972 -1978, except for submerged macrophytes (recorded in 1964)(Q).


F1 FLORA (4, 5)
  • Emerged macrophytes
    Phragmites communis, Echinochloa crus-galli, Leersia japonica, Typha angustifolia Nelumbo nucifera.
  • Floating macrophytes
    Trapa natans, Nymphaea tetragona, Eichhornia crassipes, Limnanthemum indicum, Lemna minor.
  • Submerged macrophytes
    Najas major, Myriophyllum spicatum, Ceratophyllum demersum, Potomogeton maakianus, Hydrilla certicillata.
  • Phytoplankton
    Microcystis, Merismopedia, Anabaena, Cyclotella, Melosira, Cryptomonas, Chroomonas, Scenedesmus, Schroederia, Chlamydomonas, Crucigenia, Oscillatoria, Aphanizomenon.
F2 FAUNA (4, 5)
  • Zooplankton
    Askenasia, Cyclidium, Didinium, Halteria, Tintinnidium, Tintinnopsis, Strombidium, Vorticella, Diurella, Polyarthra, Trichocerca, Asplanchna, Brachionus, Conochilus, Filinia, Pompholyx, Synchaeta, Pedalia, Daphnia, Cyclops, Mesocyclops, Mediaptomus, Neutrodiaptomus.
  • Benthos
    Alocinma logicornis, Bellamya aeruginosa, Parafossarulus striatula, Anodonta woodiana, Limnodrillus hoffmeisteri, Brachiura sowerbyi, Chironomidae (Pelopia, Procladius, Einfeldia).
  • Fish
    Hyophthalmichthys molitrix, Aristichthys nobilis, Cyprinus carpio, Carassius auratus, Megalobramma amblycephala, Ctenopharyngodon idellus.
  • Supplement note on the biota: cf. F7.
F3 PRIMARY PRODUCTION RATE
  • Phytoplankton production rate [mg O2 m-2 day-1]
    Middle lake sampling station, 1981
    JanFebMarAprMayJun JulAugSepOctNovDecAnn.
    Net production1.510.370.205.323.994.63 6.889.495.561.911.500.263.49
    Dark respiration1.050.571.143.542.992.55 2.794.097.670.821.991.932.61
    Gross production2.560.941.348.866.987.18 9.6713.58 13.23 2.733.492.196.08
F4 BIOMASS (3)
  • Zooplankton [mg (wet wt.) l-1]
    Middle lake sampling station, 1980 3.54
F5 FISHERY PRODUCTS (Q)
  • Annual fish catch* [metric tons]
    1978: 801.5. * In a managed area of 1,700 ha.
  • Fishery products other than fish
    Shrimp and shellfish are of no fishery significance here. Stocking of the mitten crab (Eriocheir sinensis) was successful, but abandoned because of the damage to fish nettings and the difficulty of harvesting.
F6 PAST TRENDS
  • Primary production rate [mg O2 day-1]
    Middle lake sampling station
    Year Maximum daily gross production rate
    19634.7
    19646.3
    19735.6
    19745.8
    19777.4
    19838.8
F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS (5)
    Remarkable decrease in the biomass of submerged macrophytes, which had been widespread and grown luxuriantly in the lake up to 1967, took place in 1967- 1975 owing to the increased stocking of grass carp (Ctenopharyngodon idellus) fingerlings. This was especially the case with Potamogeton maackinus that had once been the dominant species but is now absent from the lake.
    The depletion of macrophytes proved favorable for the growth of phytoplankton, but adversely affected the populations of certain gastropods, aquatic insects and fish which laid eggs on aquatic vegetation.
    Blooms of blue-green algae have developed rapidly and altered the species composition and population density of phytoplankton. The dominance of Phyrrophyta and Bacillariophyta was replaced by that of Cyanophyta and Chlorophyta. This was associated with the rise of primary production rate of phytoplankton.
    The population density and biomass of zooplankton, particularly Protozoa and Rotifera, have increased steadily.
    Intensive stocking of planktophagous silver carp (Hypopthalmichtys molitrix) and bighead carp (Aristichthys nobilis) has increased the annual fish yield of the Lake 4.4 times in a seven-year period. Stocked silver carp and bighead carp account for more than 90% of fish yield, but the diversity of fish fauna seems to have been much reduced.

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (Q)
    1981
    Area[km2][%]
    Agricultural land34.235.3
    Orchard and hilly area36.037.0
    Residential and26.827.6
    industrial areas
    Total97.0100.0
  • Main Types of woody vegetation
    No natural woody vegetation; rows and groves of trees, mainly Taxodium distichum, are planted around the lake.
  • Main kinds of crops: Rice, wheat, tea and cotton.
  • Level of fertilizer application on crop fields: Moderate.
  • Trends of change in land use in recent years (Q)
    Land for growing vegetables and rice has been increasingly turned into land for house-building.
G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (Q)
    Beside agriculture, fishery (aquaculture) is also an important primary industry. There are several sanatoria and hospitals and about one hundred factories (including a big steel plant) around the lake.

G3 POPULATION IN THE CATCHMENT AREA (Q)
    1981
    Populationdensity [km-2]Major cities(population)
    Total>200,000>2,062Wuhan* (3,900,000)
    * Not all the city area is included in the catchment area.

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q)
    Source of water, navigation and transportation, tourism, recreation (swimming, yachting) and fisheries.

H2 THE LAKE AS WATER RESOURCE (Q)
  • Domestic and industrial (1981): 300-350x1.0E+3 [m3 day-1].
    Over one million m3 day-1 of cooling water used by a steel plant is recycled in the lake.

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS


I1 ENHANCED SILTATION (Q)
  • Extent of damage: Not serious.
  • Supplementary notes
    Rate of sedimentation is low, but larger in the northern part of the lake than in the southern part.
I2 TOXIC CONTAMINATION (Q) : No information.

I3 EUTROPHICATION (Q)
  • Nuisance caused by eutrophication
    Unusual algal bloom: Microcystis flos-aquae, M. aeruginosa, Anabaena spiroides, Aphanizomenon flos-aquae, Oscillatoria limosa, etc. Disturbed filtration in cleaning beds. Foul smell of tap water. Harms to fishery products: summer-kill of tilapias in net-cages occasionally occurs in sultry weather.
  • Nitrogen and phosphorus loadings to the lake [t yr-1](7)
    1979-1980
    Total dissolved nitrogen (N) 536.3 t yr-1 or 19.22 g m-2 yr-1Total dissolved phosphate (PO43-)87.8 t yr-1 or 3.15 g m-2 yr-1
    Industrial+Domestic59.2%74.7%
    Surface runoff34.0%24.2%
    Atmospheric6.8%1.1%
  • Supplementary notes
    The increasing urbanization and the rapid development of industry, agriculture and animal husbandry in the drainage basin pour hundreds of semi-treated effluent. The lake at its present stage can be regarded as an eutrophic lake on the way to a hyper-eutrophic stage (4). The construction of the sewerage system leading to a wastewater treatment plant has been under way since 1985.
I4 ACIDlFICATION (Q)
  • Extent of damage
    None. Acid rain has been detected, but so far no damage is reported for forestry, crop and architecture. The lake ecosystem is practically unaffected because of its high buffering capacity.

J. WASTEWATER TREATMENTS

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA (Q)
    d) Measurable pollution with limited wastewater treatment.

K. IMPROVEMENT WORKS IN THE LAKE (Q)

    A plan for establishing the waste water treatment plant for domestic sewage is now being carried out by the Municipality of Wuhan. The treated water will be discharged into the Chang Jiang.

L. DEVELOPMENT PLANS (Q)

    No information.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED (Q)
  • Names of the laws (the year of legislation)
    1. Bulletin for Strengthening the Work of Protection and Management of Scenic Spots, promulgated by the State Council of the Peoples Republic of China (1981).
  • Responsible authorities
    1. Provincial Bureau of Urban Construction, Hubei Province.
  • Main items of control
    1. Sources of serious pollution must be properly treated, or else removed away; Effluents from sanatoria, restaurants, etc. should conform to the standards of permissible drain. M2 INSTlTUTlONAL MEASURES (Q)
    2. Bureau of Environmental Protection, Provincial Government of Hubei, Luojiashan, Wuhan
    3. Administrative Board of the Dong-Hu Scenery Area, affiliated to the Municipal Government of Wuhan, Wuchang, Wuhan
M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES (Q)
  1. Provincial Institute of Environmental Protection of Hubei, established in the early 1970s, Luojiashan, Wuhan
  2. Institute of Hydrobiology, Academia Sinica, moved from Shanghai to Wuhan in 1954, Luojiashan, Wuhan

N. SOURCES OF DATA

  1. Questionnaire filled by Dr. Liu Jiang-Kang, Institute of Hydrobiology, Academia Sinica, Wuhan.
  2. Tokyo Astronomical Observatory(ed.)(1987) Chronological Scientific Tables (in Japanese). 916pp. Maruzen, Tokyo.
  3. Provincial Hydrographic Station of Hubei, according to the questionnaire.
  4. Huang, X., Chen, X., Wu, Z. & Hu, C. (1984) Studies on the changes in abundance and biomass of zooplankton in Lake Dong Hu, Wuhan. Acta Hydrobiologica Sinica, 8(3): 345-358.*
  5. Jao, C. & Zhang, Z. (1980) Ecological changes of phytoplankton in Lake Dong Hu, Wuhan, during 1956-1975 and the eutrophication problem. Ibid., 7(1): 1-17.*
  6. Liu, J.K. (1984) Lakes of the middle and lower basins of the Chang Jiang (China). In "Ecosystems of the World", vol. 23, Lakes and Reservoirs (ed. by Frieda Taub), pp. 331-355. Elsevier, Amsterdam.
  7. Liu. J.K. (1984) Pollution studies on three Chinese lakes. Proceedings of Shiga Conference 84 on Conservation and Management of World Lake Environment, pp. 73-80. Shiga Prefectural Government, Otsu.
  8. Zhang, S., Liu, Q. & Huang, Y. (1984) The main sources of nitrogen and phosphorus in Lake Dong Hu, Wuhan. Oceanologia et Limnologia Sinica, 15(3): 203-213.*

    9. * In Chinese, with English summary.