Impact assessment of global environmental changes on safety and stability of water systems in Asian coastal mega cities

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In 2004, a survey on pathogenic microorganisms in contaminated river in HCMC was conducted. As a result, the concentration of coliform group and viruses in contaminated rivers in HCMC was found to be the same level as sewerage in Japan. In 2005, a survey was conducted in January and February, on the health impact of flooding in the communities along the Chiliwung River, and the following conclusions were obtained:1)The major source of drinking water in the flooded are is shallow groundwater, which was contaminated with flood water.2)The flood water that went into houses stay long hours, and the levels of coliform group were higher than Chiliwung River.3)In the flooded area, the cases of diarrhea, skin diseases and influenza, were much higher than in the non-flooded area.As a results of this survey, it was concluded that, in addition to the direct damage such as drowning, flood events force the local residents a long evacuation lives, and bring about health impacts.In 2005, a similar flood survey as Jakarta was conducted in HCMC. In 2006, water quality monitoring was conducted along Sai Gon River and canals that flow into Sai Gon River. There is no tidal gate in Sai Gon River; hence the water level fluctuates a lot due to tidal fluctuation. There is no central wastewater treatment plant in HCMC, and both domestic and industrial wastewaters go Sai Gon River only after simple treatment like sedimentation. Hence it was found that the contaminated water from HCMC goes up the point of the city's water intake. If the water level goes up due to Global Environmental Changes, Asian coastal mega-cities such as Jakarta and HCMC will suffer more severely from flood events, and the cases of health effect will go up.