To assess the seasonal variation of quality of groundwater of two adjoining towns of the hill state, Himachal Pradesh in the north of India, a study has been carried out. The specific study zone covering an area of about 120 sq. km. was selected near the industrial townships of Nalagarh and Baddi in district Solan. A total of 25 and 40 groundwater samples were collected, from 65 different locations during post-monsoon season of 2011 and pre and post-monsoon seasons of 2012. The overall residual sodium carbonate (RSC) of groundwater was ranged from -7.794 to 1.673 and -7.857 to 1.953 at Nalagarh and Baddi industrial areas respectively. The overall averaged residual sodium carbonate value at Nalagarh and Baddi industrial areas were less than 1.25, hence suitable for agriculture purposes. The findings also suggest that values of residual sodium carbonate of groundwater were far below the recommended standard value. Therefore it is suggested that regular attention should be given to the agricultural authorities, policy and decision makers to both the areas for better agriculture production. However, proper treatment of effluents from urban and industrial areas is highly desirable to maintain the residual sodium carbonate of groundwater in such areas to check further deterioration. Keywords: Groundwater, Residual sodium carbonate, Platykurtic, Nalagarh, Baddi.
I. INTRODUCTIONIn general water quality refers to the degree of suitability for a specific purpose and is largely depends on the physico-chemical characteristics/composition of its water [1]. Irrigation water contains certain quantities of dissolved salts originating from different sources i.e. either geogenic or anthropogenic. The suitability of water for irrigation purposes should therefore be assessed on the basis of its ability to create favourable conditions for crop growth or yield. However, the suitability of irrigation water has to be assessed on the basis of specific conditions like different agro-climatic conditions, types of crops (sensitive, semi-tolerant, tolerant), its varieties and cultural practices. There are some attempts have been made to classify/measure the quality of water for irrigation purpose [2,3,4,5,6,7,8,9,10,11]. Several measurements/guidelines are also developed and used to classify the suitability of water for irrigation, including sodium adsorption ratio (SAR), percent sodium (%Na), soluble sodium percentage (SSP), magnesium hazard (Mg haz.), Kelly's ratio (KR), residual sodium carbonate (RSC), base exchange (base exch.), meteoric genesis (met. gen.) etc. Due to differences in climatic as well as topographic conditions in different areas, one can consider the above computed parameters for evaluating irrigation water quality. The concentration of bicarbonate and carbonate influences the suitability of water for irrigation purpose. One of the empirical approach was based on the assumption that calcium and magnesium precipitate as carbonate. Considering the above hypothesis the concept of residual sodium carbonate (RSC) wa...