I believe that groundwater quality mapping should include more parameters rather than just EC, TH and TDS. Inclusion of more parameters will give the real mapping as many of important constituents and their interactions will be missed if you select minimum variables.

Further EC and TDS are very basic parameters and its quite difficult to draw any conclusion only on the basis of these parameters.

For ground water quality mapping, only EC, TH and TDS are not sufficient parameters. More importance should be given to various other chemical constituents which may be expected base on geological strata. Fluoride and arsenic are burning problems. pH can not be ignored. Data collection before and after Monsoon is also very important. Periodic monitoring and analysis may give necessary information. 

These parameters can be used for groundwater quality mapping, but more prameters are also required for groundwater quality mapping, because groundwater quality is determined by many parameters, not just TDS, total hardness and EC.

I agree with all the answers that you received so far.

In rural regions (of Ukraine) main groundwater  quality problems are linked to nitrate (and pesticides). I use EC as a first indicator to detect nitrate in village wells. Under similar conditions (sandy soils etc.) I will not find more than 50 mg/L nitrate when EC is lower  (as let's say 50 mS/m). For this practical approach the correlation between EC and nitrate was satisfactory.

  Michael you are correct, if in our area some contamination problem may be expected to exist , a detailed study need to be required. In such case ,those parameters  may be given more importance for ground water mapping. I appreciate, you find a good correlation between nitrate and EC and able to delineate the source of pollutants too.

Virendra I agreed with your comment.Water scarcity and exploitation leads to vary water parameters within month.In such a way their use Water quality index with earlier datas.

Chhipa, Thanks.

A couple additional thoughts. When looks at gw quality we should look at the intended uses of the water. For example if we look at a small area and the primary use is for livestock then the perameters to look at would include those critical for livestock (see the FAO water quality guides one is http://www.fao.org/docrep/003/T0234E/T0234E00.HTM

Another thought is -- is the concern ground water becoming contaminated you might want to look at this USGS guide. http://pubs.usgs.gov/circ/2002/circ1224/

Basic quality as other have suggested Nitrates  -- but also Chlorides. The concern of trends or changes in chemistry and physical parameters with time might also be important conciderations.

Just a few thoughts -hope they help

Broast,

Thanks for your information

I agreed that Basic quality also on Chlorides present in water.

The concern of trends or changes in chemistry and physical parameters with time might also be important considerations.

Dear  Dasapta 

Weightage  of such parameters for Water Quality are more effective ,our investigations shows on the Project of  "Water Quality Index of Jaipur".

In my opinion Th,TDS,EC pH are more relevents  with the Quality of water .

More may be  Nitrate ,Chloride and Sodium.

Accordingly ,it is very difficult to get  precise  water sample when take analysis.

There are fluctuation of water characteristics :Ground water level fluctuations, addition of number of pollutants, climate changes,geographical modifications and bio diversification threats and more.

It is easy to get information for water quality by analyse  above parameters .

of my research Fellow 

Yes! TDS gives a measure of the quantum of dissolved solids, which can be used to judge the sample's salinity. The geology of a basin is a key factor in determining the concentration and composition of dissolved solids and hence quantifying TDS is very important. For example, in a basin underlain by low-solubility crystalline silicate bedrock such as granite or gneiss, even water that has been in residence for a long time will have low TDS. In contrast, waters in carbonate bedrock like limestone or dolomite typically have high TDS due to the high solubility of carbonate minerals. Moreover, TDS values can be used for a simple method of classifying waters, as given by Freeze and Cherry (1979).

First-order ground water characterization often includes measurements of  specific conductance, temp,  pH and dissolved oxygen.  The four measurements are made in a flow-through chamber that contains actively pumped well water.  Sampling for more complete chemical analyses should commence only when these four parameters are stable.  Note that specific conductance is well-correlated with TDS.

stephan

You added DO  

This parameter also explains pollutionrelation with water sample

I agree with earlier contributors.  pH, TDS, EC and  TH comes first in water quality analysis although TDS can be influenced by geology

I think that both parameters (EC and TDS) are sufficient for a preliminary assessment of groundwater quality. EC and TDS are closely interrelated and can be easily measured directly in wells or indirectly through the application of geophysical (geoelectric) methods, especially when we are dealing with contamination plumes.