Assessment of Deep Groundwater Quality in Kathmandu Valley Using Multivariate Statistical Techniques

Abstract

This study was carried out to assess the overall water quality and identify major variables affecting the deep groundwater quality in Kathmandu Valley, Nepal. Forty-two deep wells were sampled during premonsoon and monsoon seasons in 2007 and analyzed for the major physicochemical variables. The water quality variables such as NH 4 + -N, Fe, Pb, As, and Cd at most of the sampling locations exceeded the World Health Organization guideline levels for drinking water. Multivariate statistical techniques such as factor analysis and cluster analysis were applied to identify the major factors (variables) corresponding to the different source of variation in deep groundwater quality. Factor analysis indentified six major factors explaining 74.77% of the total variance in water quality; and the major variations are related with the degree of groundwater mineralization, decomposition of organic matter, and reduction of groundwater environment. The water quality of deep groundwater is influenced by the natural hydrogeochemical environment. The wells are broadly divided into two major groups based on the similar groundwater characteristics using cluster analysis. Results show that water quality of deep groundwater does not vary significantly as a function of season.

Assessment of Arsenic Contamination in Deep Groundwater Resources of the Kathmandu Valley, Nepal

“…Additionally, contribution of anthropogenic metal contaminations is reluctant in the studied timeseries in the groundwater wells. These findings are consistent with the results of previous study which pointed out seasonal variability has no significant effect on deep groundwater quality [17]. The similar studies also indicated no seasonal variability of arsenic in the groundwater [15] [16].…”

“…A study reported negative ORP value up to −195 mV in deep groundwater [14]. Likewise, another study indicated low ORP value in deep groundwater with mean value of −82 mV in pre monsoon and −56 mV in monsoon [17]. The groundwater wells in the study area are relatively anoxic, as indicated by low ORP values.…”

Assessment of Heavy Metals in Deep Groundwater Resources of the Kathmandu Valley, Nepal

“…Most of the groundwater wells of group (B) with high mineralization are located in CGWD, whereas many groundwater wells of group (A) with low mineralization are located in the NGWD and SGWD (Figure 10). Chapagain et al [19] also reported similar result in the groundwater of the valley, indicating that the high mineralization in the CGWD. The high mineralization in the CGWD may be attributed to geochemical heterogeneity of the sediment in groundwater districts of the Kathmandu Valley where there is a presence of finer particles and trace elements in the sediments of central part of the valley [43].…”

“…Most of the water quality parameters examined were not normally distributed except temperature. Therefore, Spearman's rank correlation coefficient was applied as a non-parametric measure of correlation between the monitored variables [19] [27]. Kaiser-Meyer-Olkin (KMO) and Bartlett's test were employed to examine the suitability of data for PCA.…”

Spatial Distribution and Seasonal Variation of Arsenic in Groundwater of the Kathmandu Valley, Nepal

“…As a result there is an immense pressure on groundwater resources in the valley. The ground water is depleting due to over extraction and surface water catchments are becoming degraded (ADB/KUKL, 2010 (Khatiwada et al 2002;Maharjan et al 2006;Chapagain et al 2009;Shrestha et al 2010;Chapagain et al 2010 (CBS, 2008). The precipitation is dominated by monsoon rainfall, which lasts for the months of July to September and contributes 80% of annual precipitation (JICA, 1990).…”