Abstract:

For assessing vulnerability to contamination of groundwater Dong Nai province, the author uses DRASTIC system, This system uses 7 factors related to transport and diffusion of contaminants in groundwater, being: depth to water, recharge, aquifer media, soil media, topography, impact of vadose zone and conductivity of the aquifer. Each factor is considered regarding impact to groundwater contamination and its role in the system. Based on study data in the area, the author has determined its DRASTIC index (DI) changing in range from 64 to 186. On the basic to DI, the area was divided into 5 zones that display various vulnerabilities to groundwater contamination in Dong Nai province as follows: zone of extremely low vulnerability (DI  80) is located on distribution area of Cretaceous effusive rocks, this zone has total area of 171.3km2, forming about 2.91% of area of the province and is located in mountainous region, being small spots in Vinh Cuu, Tan Phu, Xuan Loc ... districts; zone of low vulnerability (80 < DI  110) is located in Jurassic terrigenous sediments of steep topography or in Pleistocene sediments that has soil media of silty clay, this zone has total area of 1,469km2, forming about 24.92% of area of the province and is located in mountainous region, being small spots in Vinh Cuu, Tri An, Tan Phu, Southwest Xuan Loc, South of Long Thanh districts; zone of moderate vulnerability (110 < DI  130) is located in Jurassic terrigenous sediments of steep topography or in Kainozoic sediments that has soil media of silty clay, this zone has total area of 1,216km2, forming about 20.63% of area of the province and is located largely in Vinh Cuu, Tri An, Bien Hoa city, Long Thanh, Nhon Trach and some spots in Tan Phu, Xuan Loc...; zone of high vulnerability (130 < DI  150) is located in basaltic effusive rocks of steep topography, Holocene sediments along Dong Nai river or separate blocks of Triassic, Creataceous rocks, this zone has total area of 747.4km2, forming about 12.68% of area of the province and is located largely Tan Phu, Long Thanh, Trang Bom, Xuan Loc...; zone of extremely high vulnerability (DI > 150) is located in basaltic effusive rocks of gently slope topography. The soil media is shrinkable clay. The aquifer media consists of poorly to highly water bearing fractured basaltic rocks, this zone has total area of 1.937km2, forming about 32.85% of area of the province and is located largely Long Thanh, Xuan Loc, Tan Phu, Dinh Quan...