Geochemical Classification of Groundwater Quality and Its Mapping in a Dry Sub Climate (A Case Study of Lasbela Region)

Abstract

The study was conducted on effect of ground water quality and its effect on soil and crop productivity during June 2012-13 in Tehsil Uthal, District Lasbella. Field data was collected through questionnaires. Water and soil samples were collected from 32 randomly selected sites. In groundwater samples Electrical Conductivity, pH, TDS, sodium, calcium, magnesium, carbonate, bicarbonate and sulphate were determined from water as well as from soil samples except sulphate.  After analysis of  groundwater samples 97%  were moderate saline  range, 3%  of water samples were greater than 3 dSm^-1 (highly saline).About 78% of groundwater samples were in category of moderate range with SAR values between 3-6, while 22% were of severe class range (SAR >9). The pH of groundwater samples ranged from 6.8 to 8.2 with an average of 7.5.The average value of TDS was 1365 mgL^-1 ranged 697-2032 mgL^-1.Carbonates were totally absent in the groundwater samples. Bicarbonate concentrations were ranged from 1.8 to 2.5 meql^-1. Sulphate ranged between 7.9 to 14.1 meql^-1 with an average value of 11 meql^-1.

Keywords:Salinity, Sodicity, Groundwater, Electrical Conductivity, SAR, Total Dissolved Salts