A Study on Ground Water Quality Used for Irrigation in Prakasam District of A.P, India using Geographical Information Systems

The ground water samples collected from different mandals of prakasam district are analyzed in the laboratory for electrical conductivity (EC) , pH, cations (Na+,K+,Ca2+ and Mg2+) and anions (CO32- , HCO3-,Cl- and SO4-). The water samples are categorized as per criterion developed by Central Soil Salinity Research Institute, India. It has been found that, out of 55 Mandals, 35 Mandals have been found to be good in quality for irrigation at the district. Whereas 13 Mandals were found Saline (Marginally Saline (B1)-6, Saline (B2) - 2, High SAR Saline (B3) -5) and 7 Mandals are found as in Alkali category (Marginally Alkali (C1)-NIL, Alkali (C2)-3, Highly Alkali (C3)- 4). In general, these waters were of Ca-Na-Mg type with the dominance of HCO3 and CO3 in case of good quality waters. The poor water quality belonged to categories of B1, B2, B3, C1, C2 and C3, which are either having accumulation of salts (high EC) or high Sodium adsorption ratio (SAR) or Residual Sodium Carbonate (RSC). Thematic maps are generated on the basis of different categories of ground water samples using ARC GIS 9.3 software depicting the places of saline and alkali water in the district.