New Hope and Security Issues of Wireless Ad Hoc Networks: a Comprehensive Study

The study area in and around Bhopal lies between Latitude 23°10'-23°22'N and Longitude 77°15' 77°13'E on the Survey of India toposheet Nos. 55-E/7 and 55-E/8 covering an area of about 550 km2. In the present study quality of surface and sub-surface water have been worked out considering the geological formations namely Vindhyans and Deccan trap lava flows which forms the geographica distinguishable area of Bhopal city. In order to assess the quality of surface and sub-surface water of the study area for irrigation purpose the physico-chemical character of water samples were studied at the sampling point in the field and the chemical characters have been determined in the laboratory. Water has value only when its quality is suitable for which it is being sought or explored. The suitability of natural water for a particular purpose depend upon the criteria or standard of acceptable quality for that use. In order to evaluate the suitability of surface and sub-surface waters for irrigational purposes, various specifications based on different standards have been proposed from time to time by various agencies and workers like A. G. Asgar, A.N. Puri and E.M. Taylor (1936), W.P. Kelly, S.M. Brown and G.F. Liebig (1940), L.V. Wilcox (1948), F.M. Eaton (1950), U.S. Salinity Laboratory Staff (1954) and many others. In the present study, the specifications as proposed by Kellys et al. (1940), Eaton (1950), U.S. Salinity Laboratory Staff (1954), Wilcox (1948) and K.V. Paliwal (1972) have been used to assess the quality o water. These specifications are mostly based on the chemical characters of natural waters and their effects on plant growth. The calculated values of these specifications are given in Table 1 and 2.

Base map of the study area has been prepared usmg Survey of India toposheet Nos. 55-E/7 and 55-E/8 to show the location of collected water samples. In all 50 water samples have been collected from various part of the area, by dividing the area into rectangular grid system. These samples were taken from surface and sub-surface water bodies, collected samples were analyzed physically and chemically using pH meter, conductivity meter, flamephotometer, spectro photometer etc. Cations and anions were analysed using analytical techniques laid down by Rainwater and Thatcher (1960) and Greenburg et al. (1985) Table 1 and 2. Qualitative and quantitative estimations were carried out for total alkalinity, total hardness, tota dissolved solids, chemical oxygen demand, Biochemical oxygen demand, sodium, potassium magnesium, chlorides, sulphate, nitrate, fluoride, phosphate, carbonate and bicarbonate.

To understand the suitability of water for irrigation purpose, certain ratio and diagrams are of fundamental importance and described as : The SAR is an important parameter for determination of suitability of irrigation water because it is responsible for the sodium hazard (U.S. Salinity Laboratory Staff, 1973). Sodium Adsorption Ration (SAR) which is defined as Where, all concentrations are expressed in equivalent per million. The SAR value of the surface and sub-surface water of the study area varies from 0.133 to 10.82 (Rose garden) in pre-monsoon periods while 0.622 to 9.845 in posttmonsoon period. (Table 3 and 4) The recommended water classification for SAR values are given below (Todd, 1959) SAR water class < 10 Excellent 10-18 Good

18-26

Fair > 26 Poor Water samples of the study area have SAR value less than 10 (Table 3 and 4) indicating their suitability for irrigation purposes. The Kelly's Ratio (KR) for the water samples of the area was estimated by using the following formula: The water having KR  1 is considered to be of good quality for irrigation, on the other hand KR of more than 1 is considered to be unsuitable for irrigation and it causes alkali hazard in the soil (Kamath, 1987). The KR values for the surface and sub-surface water samples of the study area for both the seasons are less than 1 which indicates good quality of water for irrigation purpose (Table 3 and 4). The Soluble sodium percentage (SSP) for the samples of the area and calculated by the following formula: The SSP values of  50 indicate good quality water for irrigation and if it is more than 50, it indicates the unsuitable nature of water for irrigation. The SSP values for the surface and sub-surface water of study area are less than 50 indicating that the surface and sub-surface waters are suitable for irrigation purpose (Table 3 and 4). The excess of bicarbonate and carbonate of water is denoted as residual sodium carbonate (U.S. Salinity Laboratory Staff, 1973). It is calculated by the following formula: RSC = (HCO3- + CO32-) – (Ca2+ + Mg2+) If the RSC values are  1.25 it indicates safe quality of water for irrigation, 1.25 to 2.5 indicates marginally suitable water and if it is more than 2.5 then the water is unsuitable for irrigation purpose. The RSC values for the surface and sub-surface water of study area are less than 1.25 which indicate that the water is safe for irrigation purpose (Table 3 and 4).

In the previous section, the classification and chemistry of waters are discussed based on the criteria which only incorporate the individual or paired ionic concentrations. However, by considering the combined chemistry of all ions rather than individual or paired ionic concentrations, better results regarding the classification, geochemical studies and suitability standards of waters for different purposes can be obtained (Hem, 1959; Handa, 1964, 1965; Romani, 1981). Hence, with a view to bring out the similarities and differences in chemical composition of waters of different geochemical characteristics, and for a simpler, quicker visual inspection, several graphica methods have been suggested by different workers. Collin's (1923) bar diagram, Stiffs (1951) horizonta pattern diagram, pie diagram, logarithmic diagram of Schoeller (1962) and Taussig's (1961) zigzag diagram are widely used to demonstrate the proportion of ionic concentrations in individual water analysis. In the present investigation, Stiffs (1951) horizontal pattern diagram, USSL diagram and Gibb's (1970) diagram are used for their simplicity and inherent advantages.

The U.S. Salinity Laboratory proposed a salinity diagram (Fig. 1a and 1b) for the classification of irrigation waters with respect to salinity and sodium hazards (Richards, Ed. 1954). On the basis o

specific conductance and SAR values the diagram gives the classification of water samples into C1, C2

C3, etc., which represent water classes with increasing salinity hazards. Also S1, S2, S3, etc., represen water classes with increasing hazards of exchangeable sodium. Good quality waters are taken as those falling into C1S1 and C2S1 groups. Water samples falling into C1S2, C2S2, C3S2 and C3S1 are considered as of moderate quality; whereas waters belonging to groups other than these, generally are considered as poor quality waters. In the present investigation, all the plots fall in good to moderate water zone. Stiffs (1951) proposed a graphical method using four parallel horizontal axis and one vertical axis used in making comparisons of water, especially highly mineralized ones. Four cations are plotted along axis to the axis to the left of the zero point and four anions on the right. Concentrations are expressed in equivalent per liter, connecting points representing anions and cations give a closed figure, whose shape is more or less characteristic of a given kind of water (Fig. 2a i-ii and 2b i - ii). The mechanisms that significantly control the chemical composition of the dissolved salts of the waters of the earth in major proportion have been discussed by Conway (1942); Gorham (1961); Mackenzie and Garrels (1965, 1966); Sillen (1967) ; Gibb's (1970) and Ramesam et al. (1973). Among all the investigators the contribution of Gibbs (1970) in describing the mechanisms of controlling the chemistry of different types of waters happens to be most appropriate. He proposed a diagram in which the domain of each of the three major controlling mechanisms and factors i.e., atmospheric precipitation, rock dominance and evaporation-crystallization process has clearly been demonstrated Following the method given by Gibbs (1970) the ratios (Na+K)/(Na+K +Ca) and CI/(C1+HC03) agains TDS are plotted (Fig. 3a and 3b). In both the diagrams, the plotted points of analyses of water fall within the rock dominance zone indicating the geological control, followed by the precipitation dominance control in the study area.

The suitability of natural water for irrigation is contingent upon the effects of mineral constituents of the water on both the plant and soil (Todd, 1959). The important factors that influence the water quality for irrigation are TDS concentration (which is broadly related to the specific conductance of water), percen sodium and relative proportion Ca & Mg of sodium to calcium and magnesium. Salts may harm and interfere with plant growth by toxicity or by changing soil properties. Excessive amount of salts in general and sodium in particular affect the soil permeability, soil structure and create toxic conditions for plants, particularly those sensitive to sodium, Sodium toxicity is evidenced by leaf bum, defoliation and stunted growth. On the basis of aforesaid discussion the quality of surface and sub-surface waters o the study area may be concluded as under: 1. The pH value of water varies from 6.5 to 8.4 ppm in post monsoon and 7.0 to 8.62 in per monsoon session. These values of pH shows that the water is slightly alkaline in its nature. 2. The Kelly's ratio is less than unity in all the surface and sub-surface water samples of the area while the sodium adsorption ratio (SAR) is less than 10 in all water samples indicating their suitability for irrigational purposes. 3. All water samples have less than 1.25 RSC values, which clearly indicate their suitable nature for irrigational purposes. 4. Soluble sodium percentage (SSP) value for all the water samples of the area is less than 50% which indicates their suitability for irrigational purposes. 5. In some parts of the study area, the hardness of water in very high, exceeding permissible limit. This may be due to sluggish movement of water in calcium and magnesium rich rocks like basalts. 6. It is evident from the US Salinity Staff diagram that the majority of surface and sub-surface waters fall in C2-S1 class followed by C2-S1 class which reveal low alkali hazard and moderate salinity hazard of surface and sub-bsurface waters from irrigational point of view. 7. As per the Gibbs (1970) diagram, water samples fall within the rock dominance zone indicating the geological control followed by the precipitation dominance control in the study area.

The authors are thankful to Dr. (Smt.) Swarnalata Tiwari, the then Principal and Dr. Kusum Sharma Head, Department of Chemistry, Govt. Motilal Vigyan Mahavidyalaya, Bhopal (M.P.) for providing necessary facilities during the course of the work. Authors are also thankful to Shri V.K. Joshi, Chemist G.S.I., Bhopal, Shri Yashwant Rai Garpade, PHE Department, Municipal Corporation, Bhopal, Dr. Rajendra Jain, Scientist, EPCO, Bhopal and Shri Rakesh Singh, Geohydrologist, CGWB, Bhopal for providing necessary help during the analytical work.

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