Author(s): H. Q. Nguyen; T. T. N. Huynh; P. Van Der Steen; L. P. Ho; A Pathirana; D. H. Nguyen; M Baino-Salingay
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Keywords: Can Tho city; Health risk assessment; Monitoring; Uncertainty; Urban flooding
Abstract: Cities in developing countries, faced with rapid urbanization, encounter a number of problems that are connected to the urbanization process. Out of these urban flooding and water quality pollution are among the major ones. Increased imperviousness due to rapid urban densification, under-developed sewer systems, upstream flooding and tidal effects (in case of delta cities) are regular causes of urban flooding. Surface water pollution in urban areas come from both point and diffuses sources. While untreated wastewater from domestic, industrial activities are clearly defined pollution sources (i.e. point sources) discharging directly to local canals, other sources are diffuse, such as polluted runoff generated by the increase of impervious areas. This paper will present some initial results of flooding and water quality issues in Can Tho city based on an extensive monitoring campaign. The monitoring focused on different water bodies in Ninh Kieu District, Can Tho city, such as there are: (1): Open water (canals, rivers, lakes); (2): Flooded areas and (3): in Sewers. Flooded water quality and quantity were also considered. Sampling was before, during and after flooding events (average from 3 to 5samples/site/event). Flooded water levels on the street, in the sewer and in the rivers were measured by automatic water level logging system. Public health risk due to flooding in Can Tho city were analysed by a Quantitative Microbial Risk Assessment (QMRA) approach. The results showed that both the open water and flooded water were highly polluted according to Vietnamese standards. The pathogen concentrations are highly variable during the flood event. Based on the QMRA method, the mean infection probabilities per urban flooding event for children is 0.2%o and 40%o; for adults it is0.1%o and 14%o for E. Coli and Salmonella, respectively. The results show that further investigations in the future on the flood and health related issues in Can Tho city are highly relevant.
Year: 2014