Study and evaluation of the physico chemical groundwater quality of an agricultural region around beni mellal city

An attempt was made to find whether or not the quality of ground water in the areas of study suitable for human consumption. Ground water samples were collected from wells in different locations within a radius of 25 km of Beni mellal city. These water samples taken from 10 sampling points in each one of 4 areas were analyzed for their physicochemical characteristics. The results show that the conductivity in the four areas is an average of about 1138 μScm-1 that is far exceeds the national standard and WHO regulatory limit of about of 500 μScm-1. The pH is in the range of values that was found usually in the groundwater. The turbidity in some samples recorded 4.74 NTU which is strictly achieved maximum limit 5 NTU for WHO norms of acceptable water for human consumption that it must to be below 1NTU. The high values of turbidity are due to high soil erosion. The values of chlorides have recorded 550 and 750 mg l-1 in some sample in the 4 areas, which are higher than the permissible safe limit of about 250 mg.l-1. This could give water an aggressive (corrosive) character and can so free the constituent metals of the pipelines, which are toxic for human. The values of the total hardness of the water (TH) ranges between 159.2 mg l-1 of CaCo3 (15.9 F °) and 308.8 mg l-1 of CaCo3 (30.8 F °) in 4 areas. This value is also within the hard level. The Complete Alkalimetric Title CAT in many samples presents an average of about 329.2 mg.l-1, which is above the prescribed limit 250 mg.l-1. Magnesium and calcium are slightly overcoming the desirable limit of 100 mgl-1, but remain below permissible limit of about 150 and 200 mgl-1. The average value of nitrate NO3- of about 60.3 mg l-1 is higher than permissible limits in order of 50 mg l-1, sometimes the value has overcome 133 mg l-1. However, the contents in nitrites, and ammonia are very lower than all the standards. The same thing for sulphates SO42- has not overcome permissible limit. The parameter DO or dissolved oxygen of these waters are good. The results of these analyses were treated by multivariate statistical methods including Principal Component Analysis normalized (PCA) and cluster analysis. The application of Principal Component Analysis normed to these results shows that there is a close relationship between all chemical and physical parameters of the groundwater. The analysis of the plan factorial F1 and F2 shows that more of 49 % are well expressed. The analysis in this plan shows that all parameters are expressed and represented well. A meaningful interrelationship has been demonstrated between the electric conductivity and the chloride (r=0.86), Calcium (r=0,8)  et also with the nitrate (r=0.77). There is also a good interrelationship between chloride and calcium (r=0.68) and magnesium (r=0.6). From these results, this study shows that the water resources of the studied areas are strongly influenced by human activities regarding nitrate and this is probably due to an agricultural contamination by nitrogen fertilizers, and/or to infiltration of wastewater to waters underground. So, groundwater in region requires precautionary measures before to drinking them so as to prevent adverse health effects on human beings. As well as, it should awareness of the local population on the importance of protecting water quality and to establish strategies for exploiting their natural water resources.