Environmental Monitoring and Assessment (2006) 117: 45–57
DOI: 10.1007/s10661-006-7675-5
c
Springer 2006
ASSESSMENT ON SEASONAL VARIATION OF GROUNDWATER
QUALITY OF PHREATIC AQUIFERS – A RIVER BASIN SYSTEM
C. M. LALURAJ
1,∗
and GIRISH GOPINATH
2
1
National Institute of Oceanography, Regional Centre, Cochin, India;
2
Department of Marine
Geology and Geophysics, Cochin University of Science and Technology, Cochin, India
(
∗
author for correspondence, e-mail: lalu@niokochi.org)
(Received 8 March 2005; accepted 19 May 2005)
Abstract. Spatial distribution of pH, electrical conductivity (EC), total dissolved solids (TDS),
fluoride and total iron content of ground water samples collected from the muvattupuzha river basin,
Kerala, India, has been studied for pre monsoon and post monsoon periods of year 2001. Results
showed the groundwater of the basin is acidic for which the pH values ranged between 5.5 and 8.0.
Average EC was found to be less than 100 μS/cm, for most of the study region. The pre monsoon
minimum and maximum TDS were found as 25.6 and 227.84 mg/L respectively, where as post
monsoon values ranged between 16 and 162.56 mg/L. The relatively low EC and TDS values found
both during the seasons in the lateritic terrain of the river basin signifies the lower residence time
of ground water with the country rock. This makes the groundwater quality of this river basin as
good. Pre monsoon season samples showed high total iron content than that during the post monsoon
period. During the study period values of the fluoride contents were found to be within the permissible
limits.
Keywords: groundwater quality, phreatic aquifers, pre and post monsoon periods, river basin
1. Introduction
Increased industrialization, urbanization and agricultural activities during the last
few decades have deteriorated the surface water and groundwater quality of Kerala,
the southern most state of India (Nageswara Rao and Ramadurai, 1970; CGWB,
2002). Understanding the special distribution of pH, electrical conductivity (EC),
total suspended solids (TDS), fluoride and total iron content will help to identify the
quality of ground water. Groundwater contamination can often have serious ill ef-
fects on human health. Groundwater with low pH values can cause gastrointestinal
disorders, such as hyper acidity, ulcers, stomach pain and burning sensation. pH val-
ues below 6.5 cause corrosion of metal pipes, resulting in the release of toxic metals
such as Zn, Pb, Cd, Cu etc. (Trivedy and Goel, 1986). Electrical conductivity (EC)
of groundwater is considered as an important parameter for irrigation and industrial
purposes. Total dissolved solids help to identify the potability of groundwater. Total
iron content may not have direct effects on human health but is of importance due
to aesthetic reasons. The excess presence of iron in groundwater causes stains to
cloths and fixtures and has a bad taste and odour. These problems arise when iron