Abstract:
The people of the Jaffna Peninsula completely rely on groundwater for all of their water
requirements. The Vallipuram water supply scheme has been started by National Water
Supply & Drainage Board (NWS&DB) with the construction of four groundwater wells in
the Vadamarachchi sand dune aquifer. However, due to the over-extraction of groundwater
from these wells, there could be a severe groundwater imbalance in the area, where
aquifers are depleting and the water table is lowering. Therefore, the present study was
designed to identify the availability and quality of the well water surrounding a 1.5 km
radius from the four NWS&DB dug wells, and 120 domestic wells were selected for the
study. This study aims at the assessment and mapping of groundwater quality parameters
and assessing the Water Quality Index (WQI) to determine the potability of groundwater.
Sample collection and water quality analyses were conducted according to using standard
procedures. The coordinates of each sampling location were established using Global
Navigation Satellite System (GNSS) RTK Receivers at the site and an interpolation
technique was used to analyze the spatial patterns of drinking water quality parameters in
the case study area. The Weighted Arithmetic Water Quality Index method was used to
find the suitability of water for drinking purposes. The test results revealed that turbidity,
colour, TDS, total hardness, total alkalinity, Chloride, Fluoride, Total Iron, Calcium, and
Sulphate concentrations exceeded the Sri Lankan drinking water quality standards values.
Further, pH, nitrate, nitrite, and total phosphates are within the Sri Lankan Standards for all
120 wells. Heavy metals such as Arsenic and cadmium were not detected in any of the
samples but lead contamination was detected in six samples. The microbiological results
indicate that the entire study area was contaminated with total coliform and E.coli bacteria.
According to the physical and chemical parameters, the WQI value varies from 4.5 to
287.2 and 72 wells are suitable for drinking purposes. When microbiological parameters
were incorporated, a mere 3 wells were deemed suitable for drinking purposes. Therefore,
it is highly recommended to conduct regular chlorination or disinfection of the wells.
