Innovative technique for assessment of groundwater quality

Groundwater quality of a part of Chaj Doab has been assessed with innovative techniques which are not reported in literature. The concept of triangular coordinates is modified by multi-rectangular ones for the classification of major cations and anions analysed in the ground water. A Multi-Rectangular Diagram (MRD) has been developed with the combination of rectangular coordinates by virtue of which milli-equivalent per liter percentages (meq/1%) of major cations and anions could be classified into different categories more efficiently as compared to classical trilinear diagrams. Both Piper diagram and MRD are used for the assessment of 259 data sets analysed from ground water of Chaj Doab area, Pakistan. The differentiated ground water types with MRD in the study area are calcium bicarbonate, magnesium bicarbonate, sodium bicarbonate and sodium sulfate. Sodium bicarbonate type emerges as the most abundant type of ground water in the study area. A map showing spatial variation of groundwater quality has been constructed with the help of MRD. This map shows that, in the vicinity of rivers Chenab and Jhelum, calcium bicarbonate type of waters occur while the central area is mainly covered by sodium bicarbonate dominant waters. Groundwaters near the upper Jhelum canal are dominant in sodium sulfate. An important relation between calcium and sodium is proposed which explains the movement history of groundwater in the aquifer. Hydrogeochemical processes have been evaluated with new methods. Ion exchange between calcium and sodium, precipitation of calcium bicarbonate and dissolution of rock forming minerals are the major delineated hydrogeochemical processes. (author)