Temporal and spatial water quality assessment of Thay Cai – An Ha canal system, Vietnam

Abstract

The Thay Cai–An Ha Canal located in the districts of Cu Chi, Hoc Mon, Binh Chanh – Ho Chi Minh City, apart of Long An Province with an area of approximately 50 km2. This system was important of Ho Chi Minh City, providing water for agriculture, drainage and even navigation in local area. Data from 16 sites from the Thay Cai-An Ha Canal in the districts of Cu Chi, Hoc Mon, Binh Chanh – Ho Chi Minh City, and a part of Long An Province were collected in April 2013, 2014, 2015 and 2016 analyzed for pH, total suspended solid (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), amoni (NH4+), phosphate (PO43−), and coliform. Then all data were used for calculation and mapping. The ArcGIS 9.3 software, Inverse Distance Weighting (IDW) interpolation, and hydrologic variables in April 2013, 2014, 2015 and 2016 were applied to build the maps of water quality for the Thay Cai–An Ha Canal. The results classified water quality of the Thay Cai-An Ha Canal System at 3 classes, as described by The Vietnam Environmental Protection Agency, usage for water use for irrigation (1); water use for navigation (2); and, heavy pollution (3). Additionally, the results of environmental variables at 16 sites in the Thay Cai-An Ha Canal System sampled April 2013, 2014, 2105 and 2016 showed that the water quality at almost sites were so polluted with TSS values at 73 − 156 mg/L, DO from 0.1 to 2.9 mg/L; NH4+ from 1.07 to 7.89 mgO2/L; PO43− from 0.05 − 2.65 mg/L, and coliform from 2.3 × 103 to 5.2 × 105 MPN/100mL. Last but not least, two main prior approaches of water quality improvement for the Thay Cai − An Ha were suggested. It could not be used for water supply and protection of aquatic communities.