Abstract:
Water quality is a term used to describe the chemical, physical and biological characteristics of
water. Water quality parameters in various hydrologic systems have been closely linked to the
types of land use within a watershed which are closely related to the characteristics of human
activities. As water drains from the land surface, it carries the residues from the land and these
residues carried into hydrologic systems through drainage or runoff processes. Hence, this study
aimed to assess the impacts of land use on water quality in inlet and outlet water canals
connected to Nuwarawewa in Anuradhapura. Seven major inlets and one outlet canals connected
to Nuwarawewa were identified. Water samples were collected from each selected location in
one-month interval for three months period. Soil samples (0-30cm) were collected from each
location at second time point and reference soil samples were collected from the nearby
locations. Water quality parameters such as pH, EC, DO, TDS, NO3
--N, NH4
+-N, available
phosphorus (Av.P), alkalinity and heavy metals (Cd and As) concentrations were determined in
each water sample. Soil samples were analyzed for pH, EC, NO3
--N, NH4
+-N, Av.P, total Cd and
total As. The results showed that pH, DO, TDS, NH4
+-N, and Av.P of some of the water samples
tested were higher and other parameters were within permissible levels according to WHO
drinking water standards. Higher average N and average P were observed in all soil samples
compared to the reference values in literature. Soil As level was within the permissible levels
according to European Regulatory Standards for soils and Cd were not at detectable level. A
temporal variation of water quality parameters was observed in the inlet and outlet canals during
the study period. The results conclude that, impacts of surrounded land use on water pollution in
inlet water canals connected to Nuwarawewa are higher and implementation of pollution
management plan is required to prevent further pollution by conducting future researches.
