Abstract:
In southern Sri Lanka, irrigation in uences the concentrations of
faecal bacteria and inorganic toxic contaminants in groundwater.
We develop a groundwater vulnerability map describing the
potential human health implications of harmful constituents in
the Uda Walawe Basin, by overlaying geological and land use data
with information describing the irrigation system, the oxygen iso
tope composition of water bodies, and the concentrations of
selected contaminants. Given the limited data available, we exam
ine the spatial distribution of harmful constituents and the poten
tial human health risks. Fluoride poisoning from groundwater is
the greatest health threat in our study area, where uoride concen
trations ranging from 0.1 to 9.2 mg/L are associated with a geologic
origin. Arsenic occurs in high concentrations, up to 0.4 mg/L, in
areas with low recharge, although the source of arsenic is not clear.
Nitrate concentrations are low, ranging from 0.4 to 23mg/L,
despite high fertilizer inputs, except in areas with low recharge
and non-favourable reducing conditions, where concentrations
