Changes of Water Quality in Hamilton Canal in Sri Lanka
DOI:
https://doi.org/10.31357/fesympo.v18i0.1910Keywords:
Salinity, Heavy metals, Water qualityAbstract
The Hamilton canal is a manmade watercourse that was constructed along the westernboundary of the Muthurajawela wetlands. The canal has two segments that connect Kelaniestuary and Maha oya estuary to Negombo lagoon. The present study has been carried out toidentify the spatial and temporal water quality changes in the Hamilton canal. Sampling wascarried out in 8 locations using 40 samples with respect to surface, middle and bottom layersof each sampling point and at the two banks of the same sampling point. In situ testing ofElectrical Conductivity (EC), salinity, pH, turbidity and temperature were carried out inmonthly intervals during October 2012 to March 2013. Laboratory tests were performed todetect heavy metals, zinc, copper and chromium for five selected water samples.
EC values of water in all three layers of the entire canal varied between 337 and 48,320μs/cm. Spatial variation of the salinity of the water varied between 0.2 and 29.6 ppt. Thevariation of EC and salinity increased vertically from top to bottom owing to the density ofwater. pH varied from 6.6 to 7.9 maintaining an environmentally sound level. Turbidity of thewater ranged from 1 to 78 NTU while temperature fluctuated between 27-340C during theconsidered period. Concentration of Heavy metals was very low during the study period. Zincconcentrations ranged between 0.25-0.54 ppb and chromium between 0.28-0.54 ppb. Copperconcentrations ranged between 0.22-0.65 ppm and concentration of all the cationswere below the threshold level for human consumption.
Results revealed that the EC and Salinity levels demonstrate a negative relationship withprecipitation while EC, salinity and turbidity levels demonstrate a positive relationship withdepth of the water column. There were no significant changes in pH of the canal water. It canbe concluded that the salt dynamics of the canal is significantly different in its two segmentswhich is due to the influence of the lagoon and interconnected estuaries.
