Joint Field Survey for Promoting the Integrated Manila Bay-Laguna Lake and Surrounding Watersheds Environmental Study Project

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1) Field survey on hydraulic and water quality environments in Manila Bay-Laguna Lake coupling system and development of numerical simulation modelsIntensive field surveys were performed at Manila Bay, Laguna Lake and Pasig River in 2001 October (wet season), at Laguna Lake in 2002 February (dry season) and at Manila Bay 2003 February (dry season). With these surveys, the characteristic features of the hydraulic and water quality environments in these periods were clarified. Especially, the importance has been revealed for the effects of the spatial non-uniformity of the wind field on Laguna Lake, the environmental loads from the tributaries of the Pasig River through the Metro Manila area, the 3-D structure of the currents in Manila Bay and others. Further, by conducting a long-term continuous field measurement at Laguna Lake and Pasig River for the period from March to June, 2002, it was succeeded in observing the phenomenon that the brackish water from Manila Bay intrudes into the L … More aguna Lake in the end of the dry season. In addition to these field surveys, it was also attempted to develop numerical simulation models for currents in Manila Bay and Laguna Lake, respectively. For the former, with the basis of dual-sigma POM, a 3-D current model by Nadaoka & Nihei, nesting techniques and the effect of non-hydrostatic pressure distribution were examined. For the latter, on the other hand, a field survey to examine the hydrodynamic effects of the fishpen was conducted in Laguna Lake in 2003 March.2) Field survey on distributions and sources of heavy metals in relation to surrounding watershedsAnalyses have been made for the existing samples of bottom mud taken in Manila Bay and newly obtained bottom mud samples taken in Pasig River and Laguna Lake, revealing the characteristic distributions of various heavy metal components and their possible source areas. Special attention has been paid on the lead, as its distribution may show appreciable human effects. As one of the possible sources of the lead, roadside dust was sampled and analyzed.3) Numerical simulation of mudflow in Mt. Pinatubo watershed areaA two-dimensional numerical model of mudflow was developed and applied to the watershed area of Mt. Pinatubo, giving reasonable results. Less