Decision Support System for Water Pollution Reduction of Lake Chao, China

1. IFAT China 2008 Decision Support System for Water Pollution Reduction of Lake Chao, China Günter Meon and Fucai Yin Leichtweiss-Institute of Hydraulic Engineering and Water Resources, University of Braunschweig, Germany Anhui Environmental Protection Bureau

2. Contents Problemstellung • Problem • Objectives and Approach • Ecohydrologic Model for Catchment • Lake Model for Water Quality • Decision Support System • Conclusions Untersuchungsgebiet Modellierung Anwendung Strategien

3. Project “Minimization of Eutrophication in Lake Chaohu” • Project Duration • 2 phases, 4 years until end of 2009 • Coordinator • Dept. of Hydrology, Water Resources Management and Water Protection, Leichtweiss Institute, University of Braunschweig • Partners • Anhui Environmental Protection Bureau, Province Anhui, PR China • Leibnitz-Institute for Water Ecology and Inland Fishery, Berlin (IGB) • Institute for Waste Water and Environmental Engineering, University of Braunschweig • Ecotech Company, Bonn • Funded by • German Ministry of Education and Research BMBF • Chinese Ministry of Science and Technology MOST

4. Lake Chao and catchment 1 Problem Chao-hu Shanghai

5. Lake Chao and catchment 1 Problem • Lake Chao • 5th largest freshwater lake of China; part of Yangtze River system. • located in Anhui Province length: 53 km from east to west 22 km from south to north shore: 188 km • surface: 760 km² • used for (fresh) water supply, irrigation, shipping, fishery, tourism, etc. • Catchment • 14.000 km² with 3 large cities including Hefei City (capital of Anhui Province) and Chaohu City • Population 10 Mio (16% of Anhui Province) Hefei

6. Extreme pollution Strong pollution Eutrophication of Lake Chao 1 Problem • Completely mixed shallow lake, mean depth 3 m • Regulated outflow (water level) • In catchment: intensive agriculture, chemical fertilizers • Domestic and industrial wastewater (only few treatment plants)  Lake water pollution from point and non point sources

7. Cyanobacterial bloom in Lake Chao, August 2005 Eutrophication of Lake Chao 1 Problem • During summer: often blooms of blue algae (dominated by cyanobacteria) • Cyanobacteria produce toxins (microcystines <-> nerve system, cancer)

8. Objectives and approach 2 Approach • Analyse and model the water balance and nutrient budget of the catchment – lake system • Quantify the anthropogenic effects on water quality in the catchment – lake system • Developa concept for waste water treatment in the catchment • Develop a decision support system “DSS Chaohu” (incl. economic and ecologic performance indices and ranking procedures) • Perform experiments for removal of microcystines in the lake water during algae blossom (short to medium term measures); design of large scale ecotechnical measures • Operate DSS under AEPB • With DSS: develop strategies for reduction of eutrophication to an acceptable level (medium to long term measures)

9. Objectives and approach – Project Phase 2 2 Approach DSS CHAO LWI and AEPB incl. models

10. DSS and experiments – Project Phase 2 2 Approach DSS CHAO LWI and AEPB incl. models Experiments 1 Ecotechnical ponds at landside Enclosures inside lake -> Microcystines in lake sediment -> Toxicity analyses IGB, LWI and AEPB

11. DSS and experiments – Project Phase 2 2 Approach DSS CHAO LWI and AEPB incl. models Experiments 1 Ecotechnical ponds at landside Enclosures inside lake -> Microcystines in lake sediment -> Toxicity analyses IGB, LWI and AEPB Experiments 2 Biofiltration of lake water Biofiltration in laboratory tests ISWW and AEPB

12. DSS and experiments – Project Phase 2 2 Approach Design Concepts for large scale structures for ecotechnical lake water treatment LWI and AEPB DSS CHAO LWI and AEPB incl. models Experiments 1 Ecotechnical ponds at landside Enclosures inside lake -> Microcystines in lake sediment -> Toxicity analyses IGB, LWI and AEPB Experiments 2 Biofiltration of lake water Biofiltration in laboratory tests ISWW and AEPB

13. DSS and experiments – Project Phase 2 2 Approach Concepts for waste water sanitation of point emissions in catchment ISWW and AEPB Design Concepts for large scale structures for ecotechnical lake water treatment LWI and AEPB DSS CHAO LWI and AEPB incl. models Experiments 1 Ecotechnical ponds at landside Enclosures inside lake -> Microcystines in lake sediment -> Toxicity analysis IGB, LWI and AEPB Experiments 2 Biofiltration of lake water Biofiltration in laboratory tests ISWW and AEPB

14. DSS and experiments – Project Phase 2 2 Approach Concepts for waste water sanitation of point emissions in catchment ISWW and AEPB Design Concepts for large scale structures for ecotechnical lake water treatment LWI and AEPB DSS CHAO LWI and AEPB incl. models Experiments 1 Ecotechnical ponds at landside Enclosures inside lake -> Microcystines in lake sediment -> Toxicity analyses IGB, LWI and AEPB Experiments 2 Biofiltration of lake water Biofiltration in laboratory tests ISWW and AEPB

15. Rice terraces and runoff processes 3 Eco-Hydrol. Model Source: Shan, 2001, Ambio, Vol. 30 No. 60 Source: Brinck, 2005, LWI

16. Input data for eco-hydrologic model NAXOS 3 Eco-Hydrol. Model Drainage network and subcatchments Land use Soil groups DTM

17. Sub-catchments (hydrological units) of eco-hydr. model 3

18. Subcatchment Fengle River, Taoxi Station 3 Eco-Hydrol. Model

19. Subcatchment Fengle River, Taoxi Station - observed and simulated discharge - 2003 3 Eco-Hydrol. M.

20. Multipond-systems in lake catchment 3 Eco-Hydrol. M. Example: Liuchahe River (C. Yin and B. Shan, Research Center for Eco-Environmental Sciences, Beijing 2001) Source: Shan, B. et al., 2002

21. Factors influencing daily nutrient budget Triple cropping system: - Early rice (May - Aug) - Late rice (Aug - Nov) - Wheat / rape (Nov - April) Irrigation water provided by ponds or partially by Lake Chao is enriched by nutrients Use of chemical and organic fertilizers (1 - 2 times per cropping season = 3 - 6 times per year) Waste water of rural households (non-treated); 4.5 Mio people in the countryside (0.6 g P, 10 g N/capita x day) 3

22. Nutrient modeling for Lake Chao catchment 3 Other Land-Uses Rice Fields

23. Nutrient modeling in Lake Chao catchment 3

24. Consequences for hydro-ecological modeling 3 • Water cycle in Lake Chao watershed is strongly influenced by anthropogenic actions • Retention of discharge is increased through multipond-systems • Multipond-systems retain particle-bound nutrients • Nutrients are partially recycled within the catchment • Challenge: combining natural processes and the effects of human interference in modeling

25. Water quality model for Lake Chao 4 Lake Model • deterministic dynamic model of the lake (modified CE-QUAL model), combined with catchment model • simulation of hydrologic and hydrodynamic processes • simulation of dynamics of ecosystem: suspended load, primary production, algae,.. • Simulation of scenarios for different nutrient imports and their influence on algae bloom

26. Lake model: temperature 4 Lake Model

27. Lake model: DO for western and eastern Lake Chao 4 Lake Model DO

28. Experimental ecotechnical pond 1 - operating

29. DSS Chaohu: decision process workflow 5

30. DSS Chaohu: decision process workflow 5

31. DSS-Chaohu: possible measures (scenarios) 5 Lake water treatment by ecotechnical plants Pre-Dams Cultivation of water plants Change of land-use Waste water treatment plants Restore multipond systems Optimisation of fertilization

32. Conclusions 6 Water quantity and water quality could be modelled fairly well; development of DSS is underway Models had to be modified to deal with available data and simulate reasonable scenarios of the project Ecotechnical plants reduce microcystines very efficiently Combination of modelling, DSS and experiments is a useful and promising way to meet the demands of the project Continuous and close cooperation with our Chinese partners Strategien

33. Pilotprojekt Chao-See Thank you ! g.meon@tu-bs.de