Spatio-Temporal Water Quality Assessment and Pollution Source Apportionment of Lake Chamo using Water Quality Index and Multivariate Statistical Techniques

Despite the current management effort to reduce pollution of water bodies,
lakes are far more vulnerable to pollution than the ocean and rivers. Point
and non-point pollution are ending on the lake bodies and concerned
bodies should trigger interventions. This study aims to assess the effect of
pollution on the water quality of Chamo lake using the weighted arithmetic
water quality index (WQI) and multivariate statistical methods. Fifteen
monitoring points are used to collect water samples from the lake for dry
and rainy periods. Twenty-three physical-chemical parameters were
analyzed in the water quality laboratory of Arba Minch University, out of
which five parameters were analyzed using a multi-meter at the field. The
physicochemical water quality analysis result of Lake Chamo revealed that
the constituent’s concentration did not show significant variation spatially.
The factor analysis result in the Lake Chamo revealed that it had extracted
seven principal components that can be explained with a total variance of
86.3%. More than 65% of the monitoring stations in Lake Chamo have an
acceptable water quality for irrigation. Moreover, some of the monitoring
stations, closer to high human activities, are relatively more polluted than
others. Besides, some sensitive parameters such as turbidity have clearly
shown that the WQI value can be changed with the parameters changing.
Based on clustering analysis, most (47%) of the monitoring are
characterized by the recipients of uncontrolled public and state farm and
agricultural wastes. The study recommends integrated watershed
management and source-based pollution control, which could significantly
decrease the pollution level in Lake Chamo after identifying the pollution
hotspot areas. Continuous Lake water quality monitoring is necessary for
deciding lake pollution.