The study was conducted to evaluate the quality and spatial distribution of surface water
quality in Soc Trang, a coastal province using Geographic information system (GIS) and
multivariate statistical analysis. Water monitoring data was collected from 19 sampling
locations with 19 parameters were analyzed from February 2019 to August 2020. The results
indicated that water quality was contaminated with organic matters, nutrients, coliforms and
salinity. Water quality index (WQI=22–73) indicated that water quality was from poor to
medium level. Cluster analysis (CA) classified 19 monitoring sites into 7 groups and 19 months
into 3 seasons including rainy season, rainy season-early dry season, dry season-early rainy
season. CA results showed that the location and frequency of water quality monitoring could
be significantly reduced, saving up to 75% the monitoring costs. The maps of the polluted
parameters (TSS, DO, BOD, COD, TOC, NH4
+-N, NO2
-
-N, Coliform, Fe, Cl-
) illustrated that
the areas located in the interior fields and near the sea had poorer water quality compared to
the areas adjacent to the Hau River. The combination of multivariable statistics and GIS was
very useful for spatial and temporal analysis of water quality monitoring data.
Keywords
Cluster analysis; Coliform; GIS; Organic pollution; Soc Trang Province