Quality of Underground Water of Tehsil Khanewal- An Overview

Agriculture is the back bone of Pakistan’s economy of Pakistan with 21 % contribution to GDP and providing livelihood to about 45 % of the total labor force of the country. The industry of Pakistan is mainly agro based (Economic survey of Pakistan, 2009-10). Due to change in climate and thereby extended drought, surface water resources of the country had reduced by 70% in 2003, compared with normal years (Kahlown et al., 2003). Unfortunately, canal water is not sufficient to meet requirements of soil and crop under intensive cropping system. A water quality study has shown that out of 560,000 tube wells in Indus Basin, about 70% are pumping sodic water which in turn is affecting the soil health and crop yield (Kahlown et al., 2003).The ground waters of different areas and depths have different types of salts which deteriorate the soil accordingly (Masood and Gohre, 2000). It is also reported that 73.38% (681) of the 922 water samples analyzed by the soil and water laboratory Vehari during the year 2006-07, were unfit for irrigation purpose, while 11.93% (110) were marginally fit and only14.21 (131) were found fit for irrigation purpose (Ashraf et al., 2008). According to the estimates, discharge of 50-60 % of the existing wells was brackish in nature (Ashraf et al., 2009) and still more formidable figures of Lahore district declaring that groundwater of 76.6% villages of the district was detrimental for crops and soil health (Ali et al., 2009).According to Shakir et al. (2002), 64 water samples were collected from new tube well bores from various locations of district Kasur to check the quality of under-groundwater for irrigation purpose. The results show that electrical conductivity of the samples varied from 524 to 5700 μS cm-1, sodium adsorption ration of the samples ranged from 0.49 to 26.00, while residual sodium carbonate ranged from 0.00 to 17.00 meL-1. Out of 64 samples, 26 samples were fit, 8 marginally fit and 30 unfit for irrigation.The successful crop production on sustainable basis, mainly depends on the quality of groundwater. The common characteristics considered are electrical conductivity (EC), sodium adsorption rations (SAR) and residual sodium carbonate (RSC) (Idris and Shafiq, 1999). The concentration and composition of dissolved constituents in water determine its quality for irrigation use. It is difficult to define the critical limits of EC, RSC and SAR because the effect of different qualities of water of soil health and crop yield is also governed by the type of soil, climate and management practices (Singh et al., 1992).Gravity of the situation of groundwater of the majority districts of Pakistan implies that something will have to be done without further loss of time to prevent the rapid conversion of productive fertile lands of Pakistan into unproductive barren lands. Besides, making investment on creating awareness among farming community about bio-saline technology/ saline agriculture by the private and public sectors, a watchful eye on the quality and quantity of ground water of every district of Pakistan by all the stakeholders and timely tackling the detrimental impact of brackish groundwater by using the available technology to the possible extent is imperative.