Hydrogeological characterization and assessment of groundwater quality in shallow aquifers in vicinity of drain of NCT

Shashank Shekhar and Aditya Sarkar Department of Geology, University of Delhi, Delhi 110 007, . ∗Corresponding author. e-mail: [email protected]

Najafgarh drain is the biggest drain in Delhi and contributes about 60% of the total wastewater that gets discharged from Delhi into river . The drain traverses a length of 51 km before joining river Yamuna, and is unlined for about 31 km along its initial stretch. In recent times, efforts have been made for limited withdrawal of groundwater from shallow aquifers in close vicinity of coupled with artificial recharge of groundwater. In this perspective, assessment of groundwater quality in shallow aquifers in vicinity of the Najafgarh drain of Delhi and hydrogeological characterization of adjacent areas were done. The groundwater quality was examined in perspective of Indian as well as World Health Organization’s drinking water standards. The spatial variation in groundwater quality was studied. The linkages between trace element occurrence and hydrochemical facies variation were also established. The shallow groundwater along Najafgarh drain is contaminated in stretches and the area is not suitable for large-scale groundwater development for drinking water purposes.

1. Introduction of this wastewater on the groundwater system is even more profound. There is considerable contam- The National Capital Territory (NCT) of Delhi ination of groundwater by industrial and domestic (figure 1) is one of the fast growing metropoli- effluents mostly carried through various drains tan cities in the world. It faces a massive problem (Singh 1999). of voluminous generation of wastewater. This The Najafgarh drain is the biggest drain in wastewater is mainly contributed by numerous NCT Delhi, discharging 287.5 million litres per day drains of NCT Delhi that have considerable impact (MLD) (0.2875 million m3/day) wastewater into on surface water and groundwater systems of the river Yamuna (NEERI 2002). The Najafgarh drain territory. The effect on surface water is visible contributes about 60% of the total wastewater from river Yamuna where upstream of Wazirabad, that gets discharged from Delhi into river Yamuna the colour of river water is bluish/greenish which (Kumar et al. 2006). changes to dark grey downstream of Wazirabad, The Najafgarh drain enters Delhi from from where the Najafgarh drain joins river Yamuna from the south-west corner of Delhi. It traverses (figure 1). Henceforth, a series of 19 drains joins a length of 51 km before joining river Yamuna river Yamuna, making it a giant drain. The impact (INTACH 2003). In its initial stage through

Keywords. Delhi; Najafgarh drain; contamination; groundwater salinity; hydrochemical facies; correlation matrix.

J. Earth Syst. Sci. 122, No. 1, February 2013, pp. 43–54 c Indian Academy of Sciences 43 44 Shashank Shekhar and Aditya Sarkar

Figure 1. Delhi map with inset of India map, showing Najafgarh drain. south-west district of NCT Delhi, the drain carries 2011;INTACH2003; Shekhar 2006) suggesting flood water, wastewater from Haryana and surface limited groundwater withdrawal coupled with arti- runoff from the adjoining catchment. Out of the ficial recharge in this stretch of aquifer along the 51-km stretch of the drain, nearly 31-km stretch of Najafgarh drain from Dhansa to Kakraula. How- the drain passes through south-west district from ever, it was also argued that unlined drains in near Dhansa to Kakraula (Jindal 1975) (figure 1). recharge areas act as a source of pollution to Thus, nearly 60% of the length of Najafgarh drain groundwater (Kumar et al. 2006). In this perspec- flows through south-west district of NCT Delhi and tive, it becomes important to assess groundwater this entire stretch of the drain is unlined. More- quality in shallow aquifers in the vicinity of the over, from Dhansa to Kakraula (figure 1), very few Najafgarh drain. (may be 2–3 drains) subsidiary drains join this big drain and subsequently after Kakraula, nearly 38 big and small drains (figure 2) join Najafgarh drain (WAPCOS 1999). Thus, apparently (on visual 2. Hydrogeology of the study area observation) the quality of water flowing through the drain is better in the stretch from Dhansa to The Najafgarh drain traverses through south-west, Kakraula (figure 1). There were proposals (Bajpai west, north-west and north districts of NCT Delhi Assessment of groundwater quality in shallow aquifers 45

range of 200–300 mbgl (Shekhar 2004). As the drain in its later part takes a bend from N–S orientation to nearly E–W and flows eastward to join river Yamuna, it is gradually moving towards surface exposure of hard rocks (CGWB 2006) (figure 3). Thus, thickness of the non-indurated aquifers that are more prone to contamination decreases towards later part of the drain. The Najafgarh drain and its tributaries show the effect of recharge from the water being car- ried by drain and it is evident in the form of greater depth to fresh/saline interface in ground- water (Shekhar et al. 2005). Shekhar et al.(2005, 2006) envisaged an elongated fresh groundwa- ter lens along the Najafgarh drain in south-west Figure 2. Map showing drains joining Najafgarh drain: district stretch of the drain. The salinity of ground- 1. Palam drain, 2. Bupania drain, 3. Pankha road drain, water increases as depth increases. The shallower 4. drain, 5. Nilothi drain, 6. Sayed Nangloi groundwater all along Najafgarh drain and its close drain, 7. Keshopur drain, 8. Subhash Nagar drain, 9. Khyala vicinity has lower salinity. The fresh groundwater drain, 10. Jawalaheri drain, 11. Raghubir Nagar drain, 12. Madipur drain, 13. Ring Road drain, 14. Basai Dara- aquifer thickness along Najafgarh drain is more in pur drain, 15. Ramesh Nagar drain, 16. Moti Nagar drain, the unlined section of the drain. The surface water 17. Punjabi Bagh drain, 18. Jaidev Park drain, 19. Shakur level along the drain from Dhansa to Kakraula Basti drain, 20. Tulsi Nagar drain, 21. Anand Nagar drain, (figure 1) is such that there is some depth of 22. Kanhiya Nagar drain, 23. Daryai drain, 24. Rana Pratap water in the drain throughout its length even when Bagh drain, 25. Shakti Nagar drain, 26. Shakti Nagar drain-2, 27. Gur Mandi drain, 28. G.T. Road drain, there is no flow. This situation helps in recharg- 29. Kamala Nagar drain, 30. Roop Nagar drain, 31. Vijay ing groundwater in favourable conditions (when Nagar drain, 32. Hansraj drain, 33. Patel Chest drain, water table is below the water level in the drains). 34. Mall road drain, 35. Mall road drain-2, 36. Timarpur Bajpai (2011) established through remote sens- drain, 37. Power house drain, 38. Wazirabad drain. ing study that the Najafgarh drain and its trib- utaries in its initial stretch through south-west district of Delhi (figure 1) flows through a natu- (figure 1). The stretch of the drain through south- rally defined valley setting. Thus, the hydrogeolog- west and west districts is unlined, while stretch ical equilibrium of the water in the drain and the of the drain through north-west and west districts adjacent aquifer in its initial stretch is similar to is lined. The borehole data and geophysical study stream–aquifer interaction. reveals that subsurface formation along the area Shekhar et al.(2006) mentioned that in aquifers closely adjacent to drain has alternate fluvial and adjacent to the Najafgarh drain, there are iso- aeolian bands distributed sporadically. The alluvial lated patches showing concentration of fluoride deposits are Pleistocene in age with interbedded, beyond permissible limit. Since groundwater in lenticular and interfringing deposits of silty sand, the fluoride-affected areas has higher salinity, it is clay and kankar. The proportion of finer sediment possible that the high level of fluoride is due to is higher. Goel (1990) in sieve analysis of borehole localized effects of natural sources. sediments from Dhulsiras (figure 1) revealed that in-depth range of 0 to 45 m below ground level (mbgl), nearly 60% is finer sand composition and 2.1 Depth to water level in the study area rest is mixture of silt and clay. INTACH (2003) reported average rate of infiltration at the bed of A regional depth to water level map (figure 4) the Najafgarh drain in south-west district of Delhi including areas much beyond close vicinity of the as 0.21 mm/h. They mention permeability of the Najafgarh drain was prepared to gain an insight subsurface formations below and adjacent to the into regional and local variations in depth to water Najafgarh drain in the stretch of the drain from level of the area. The depth to water level in Dhansa to Kakraula (figure 1) as ranging from the areas closely adjacent to the drain varies in 3to6m/day to 28.11 m/day and transmissivity the range of 3 to 16 mbgl (figure 4). The shal- of the formation as ranging from 63.05 m2/day to lower depth to water level is noticed in initial part 927.7 m2/day. of the drain where it enters Delhi and in later Throughout south-west district and major part part of the drain where it meets river Yamuna. of west district, the depth to bedrock below The relatively deeper water levels are found in Najafgarh drain and its adjacent area is in the middle stretch of the drain. In areas to right in 46 Shashank Shekhar and Aditya Sarkar

Figure 3. Depth to bedrock map in the study area.

Figure 4. Depth to water level map in the study area. Assessment of groundwater quality in shallow aquifers 47 downstream of the drain, depth to water level adjacent to the drain and others converge towards increases as one moves in south-east direction and it. Thus, in this stretch of the drain on left-side reaches a maximum of 65 mbgl, some kilome- areas, groundwater flow seems to be away from the tres ahead (these areas are adjacent to the hard drain, while on right side of the drain, groundwa- rocks). Shekhar et al.(2009) also mentions about ter flow is towards the drain (figure 5). In later deeper depth to water level in the range of 40– half stretch of Najafgarh drain apparently on left 60 mgbl in these areas of Delhi shown in figure 4. side of the drain, groundwater flow is towards the In areas to left of the drain, relatively shallower drain. While in areas on right side in downstream depth to water level is found, reaching to maxi- of the drain, in some stretches, there seems to mum of 20 mbgl in Najafgarh and Ojwah areas be not much of groundwater flow; and in some (figure 4). The groundwater in areas with relatively areas/stretches, groundwater seems to be flowing shallower depth to water level is more vulnerable away from the drain (figure 5). In areas where to anthropogenic contamination. groundwater flow is away from the drain, there is possibility that contaminants entering the ground- water system are transported to relatively greater 2.2 Water table elevation in the study area distance by advection along with the groundwa- ter flow direction. The above-mentioned hydro- A regional water table elevation map (figure 5) geological characteristics of the area (depth to including areas much beyond close vicinity of water level, water table elevation, aquifer parame- Najafgarh drain was prepared to gain an insight ters, aquifer material, infiltration rates, etc.) hint into regional and local variations in water table at dynamic interaction between the water flow- elevation of the area. The water table elevation ing through the drain and groundwater, thereby in areas adjacent to Najafgarh drain is found in affecting the quality of groundwater. the range of 197 to 206 m above mean sea level (mamsl) (figure 5). The higher water table eleva- tion is noticed in initial part of the drain where it enters Delhi and in later part of the drain (later half segment of the drain before it joins river Yamuna). 3. Methodology for assessment The lower water table elevations are found in the of groundwater quality N–S stretch of the drain (figure 5). The regional water trough near Ojwah defined by 194 mamsl The approach to assessment of groundwater qual- contour has a tremendous influence on groundwater ity in shallow aquifers in the vicinity of Najafgarh flow to the extent that in first half stretch of drain of NCT Delhi involved groundwater sam- the Najafgarh drain, groundwater flow from areas pling at evenly distributed locations all along the

Figure 5. Water table elevation map of the study area. 48 Shashank Shekhar and Aditya Sarkar drain. The sampling was done mainly during pre- AquaChem software was used for creating multi- monsoon period in May from hand pumps in the ple parameter plot (Hill–Piper trilinear plot) and areas adjacent to the drain. correlation matrices (Sarkar 2011). Acid-treated samples were collected for trace element/heavy metal analysis and normal samples for major element analysis. The samples were anal- ysed at Central Ground Water Board (CGWB) 4. Results chemical laboratory at using atomic absorption spectroscopy (AAS), ion chromatogra- In perspective of BIS standards for drinking water phy and volumetric titration techniques (Shekhar (1991), 88% of the collected groundwater samples 2008). Sampling locations varied from sites located showed concentration of iron beyond permissible approximately at a distance of 3–600 m from the limit prescribed for drinking water of 1 mg/litre drain (figure 6). It was observed subsequently dur- (BIS 1991) and 23% of groundwater samples ing analysis that the samples, which were rela- showed concentration of manganese beyond their tively away from the drain, had lesser amount prescribed permissible limit for drinking water of of anthropogenic contaminants. The variations in 0.3 mg/litre (BIS 1991). It must be mentioned that concentration of the chemical components were WHO (2011) gives no specific guidelines for per- studied in the perspective of permissible limit of missible limit of iron and manganese in drinking drinking water following Bureau of Indian Stan- water. In about 42% of the samples, concentration dards (BIS 1991) and World Health Organization of nitrate exceeded the permissible limit prescribed standards (WHO 2011). The variation in chemi- for drinking water of 45 mg/litre (BIS 1991); while cal constituents in groundwater was also studied in perspective of WHO (2011) standards, about to observe the pattern of similarity/dissimilarity 35% samples had concentration of nitrate beyond in various chemical constituents in space, and to the permissible limit prescribed for drinking water account for the observed patterns. The study of of 50 mg/litre. Arsenic exceeded their prescribed hydrochemical facies of the groundwater was con- permissible limit for drinking water of 0.01 mg/litre ducted with the help of Hill–Piper Trilinear plot. (BIS 1991), (WHO 2011) in about 3% of the The Hill–Piper trilinear plot was prepared for 21 samples. Cadmium exceeded their prescribed per- groundwater samples where all the necessary data missible limit for drinking water of 0.01 mg/litre for hydrochemical facies classification was present. (BIS 1991) in about 3% of the samples; while in

Figure 6. Map showing sampling locations of the study area. Assessment of groundwater quality in shallow aquifers 49

Figure 7. Line plots showing spatial variation in cadmium (Cd), lead (Pb), copper (Cu) and chromium (Cr) for 1. Rawta, 2. Shikarpur road, 3. Shikarpur-2, 4. Nanakheri, 5. Isapur Khera, 6. Dhulsiras, 7. Chhawla, 8. Kutub Vihar, 9. Dwarka Sec. 19, 10. Dwarka Sec. 16 STP, 11. Dharampura, 12. Dwarka Sec. 16 J Flat, 13. Nand Vihar, 14. Ghasipura, 15. Deep Enclave, 16. Vikash Nagar, 17. Ranhola, 18. Nathan Vihar, 19. Chander Vihar, 20. Nihal Vihar, 21. Karampura, 22. Shashtri Nagar, 23. Roop Nagar, 24. Timarpur, 25. Nehru Vihar D-9, 26. Nehru Vihar C-280 groundwater sampling locations.

Figure 8. Line plots showing spatial variation in Iron (Fe) and Manganese (Mn) for 1. Rawta, 2. Shikarpur road, 3. Shikarpur- 2, 4. Nanakheri, 5. Isapur Khera, 6. Dhulsiras, 7. Chhawla, 8. Kutub Vihar, 9. Dwarka Sec. 19, 10. Dwarka Sec. 16 STP, 11. Dharampura, 12. Dwarka Sec. 16 J Flat, 13. Nand Vihar, 14. Ghasipura, 15. Deep Enclave, 16. Vikash Nagar, 17. Ranhola, 18. Nathan Vihar, 19. Chander Vihar, 20. Nihal Vihar, 21. Karampura, 22. Shashtri Nagar, 23. Roop Nagar, 24. Timarpur, 25. Nehru Vihar D-9, 26. Nehru Vihar C-280 groundwater sampling locations. perspective of the WHO (2011) prescribed per- drinking water of 0.01 mg/litre as per WHO (2011) missible limit for drinking water, it exceeded the guidelines; while in perspective of BIS (1991) limit of 0.003 mg/litre in about 69% of the sam- standards for drinking water, about 19% samples ples. As per WHO (2011) guidelines, chromium had lead concentration in groundwater above the exceeded the prescribed permissible limit for drink- prescribed permissible limit of 0.05 mg/litre. The ing water of 0.05 mg/litre in about 12% of the sam- groundwater quality database used in the study is ples; while in perspective of BIS (1991) prescribed attached as supplementary material with the paper permissible limit for drinking water, all the sam- (Appendix A). ples were well within the prescribed permissible The concentration of chemical constituents limit of 0.1 mg/litre. In about 69% of the samples, such as chromium, copper, lead and cadmium in lead exceeded the prescribed permissible limit for groundwater when plotted with respect to the 50 Shashank Shekhar and Aditya Sarkar sampling location showed roughly cyclic behaviour (figure 7). Similar patterns were observed for con- centration versus sampling location plots for iron and manganese (figure 8). The spatial variation in the above-mentioned chemical constituents in the groundwater samples was prominent. These cyclic patterns may be on account of numerous subsidiary drains joining Najafgarh drain, acceler- ating the anthropogenic enrichment in groundwa- ter. However, such trends were not observed for other constituents such as arsenic, nickel, magne- sium and fluoride due to their absence in samples or unavailable data from some locations. These plots are useful in assessing spatial varia- tion in concentration of different groundwater con- taminants but they are not enough to relate the similarity/dissimilarity among chemical contami- nants. Hence, a correlation coefficient matrix was prepared for 21 out of 26 sampling locations, which provided sufficient information for all analysed chemical constituents (table 1). The high correlation coefficient value of elec- trical conductivity with chloride pointed to the fact that salinity could be mainly chloride con- trolled. The higher salinity in groundwater is attributed to longer retention time of groundwa- ter and lack of flushing in general and in very shallow water level areas, repeated oxidation and evaporation may have led to salinity enrichment in groundwater. The significant positive correlation coefficient value between nitrate and sodium, nitrate and potassium, nitrate and magnesium and nitrate and chloride established degradation in groundwater quality due to infiltration of the wastewater from Najafgarh drain. The inference is further authenti- cated by relatively high correlation coefficient value between chloride and sulphate.The significant pos- itive correlation coefficient value between fluoride and bicarbonate coupled with high level of fluoride in a few locations (see Appendix A) suggests con- tamination of the groundwater at a few locations by excess use of fertilizers. In most sampling locations, nickel was absent in the groundwater. However, in places where traces of nickel was found, it showed good correlation with Iron (Fe), chromium (Cr) and zinc (Zn). It is pos- sible that the trace heavy metals in groundwater were introduced as anthropogenic contamination from industrial wastes of metal processing indus- tries present in the catchment of the Najafgarh drain system. Moturi et al.(2004) established that solid wastes from the industrial belt of Delhi had high

mean level of toxic metals and opined that these Correlation matrix for the groundwater quality data. toxic metals are produced by small-scale metal processing industries. Banerjee (2003) analysed

dust samples from some of the industrial areas Table 1. Assessment of groundwater quality in shallow aquifers 51 in Najafgarh drain catchment and concluded that major physiochemical parameters and trace ele- these samples had high concentration of heavy met- ments, but hydrochemical facies could be further als such as chromium, copper and nickel which are used to assess the nature and portability of ground- linked to industrial sources. water. The Hill–Piper plot is one of the pre- Manganese showed significant positive correla- mier graphical plots for delineating hydrochemi- tion coefficient value with arsenic indicating a com- cal facies. The Hill–Piper plot was prepared for mon source for both of them. In about 23% of the 21 samples, which provided sufficient informa- the samples, manganese concentration in ground- tion. The plot (figure 9) revealed that the major water was beyond the prescribed limit for drink- water facies types in the studied locations were ing water of 0.3 mg/litre (BIS 1991). Since it has Na-Mg-Cl-HCO3, Na-Mg-HCO3-Cl, Na-Cl-HCO3, been established that high concentration of heavy Na-HCO3-Cl, Na-Mg-Ca-HCO3-Cl, Na-K-Cl-SO4 metals is linked to industrial sources, it is possible and Mg-Na-Ca-Cl-HCO3 types (Sarkar 2011). It that higher concentration of manganese in ground- becomes clear from the trilinear plot (figure 9) that water is also contributed by industrial wastes. It the dominant cations in the hydrochemical facies suggested that the geogenic inputs of manganese are prominently sodium with magnesium, while the in groundwater system was further enhanced by anions vary mainly from chloride to the bicarbon- anthropogenic sources. Since arsenic correlated ate end of the plot. As mentioned earlier, the bicar- well with manganese, its concentration in ground- bonate ions showed good correlation with nickel water could be linked to anthropogenic sources. and sulphate ions showed good correlation with Lalwani et al.(2004) had a similar observation and nitrate, while chloride ions do not show promi- opined that the arsenic contamination in ground- nent correlation with any trace element and mod- water of Delhi could be from the arsenic present erate correlation with nitrate. In this context, it in garbage of open landfill sites rich in chemi- can be inferred that originally the groundwater cals. Dubey et al.(2012) confirmed anthropogenic facies in the area was chloride type, the process source for arsenic contamination in groundwater of dilution by influx of drain water into ground- of Delhi. water system could have led to the changes in the The correlation matrix could be an effective groundwater facies originally from chloride type tool to understand the relationship among different towards bicarbonate type. Thus, it can be said

Figure 9. Hill–Piper plot for the groundwater quality data. 52 Shashank Shekhar and Aditya Sarkar that the anthropogenic contamination of ground- of groundwater system in vulnerable stretches by water system by the drain water and the trace ele- wastewater flowing through the drain. It has been ment in the drain water simultaneously changed established that originally the groundwater in the the groundwater facies. aquifers had evolved to chloride facies, where the total dissolved solutes in groundwater was con- tributed mainly by geogenic sources. The ground- water recharge to shallow aquifers along the drain 5. Discussion caused dilution of the chloride facies water leading to re-evolution of the groundwater facies towards Hydrogeological characteristics of the catchment of bicarbonate type. In this process, the groundwa- the Najafgarh drain system and aquifer parame- ter quality was degraded by anthropogenic con- ters of the formation along the Najafgarh drain taminants from wastewater flowing through the establish vulnerability of groundwater to contam- drain. Thus, recharge through drain water led to ination by wastewater flowing through the drain. influx of trace element/heavy metals in ground- It has also been indicated by isotopic study (Datta water. This establishes the fact that anthro- et al. 1996) that there is seepage recharge from pogenic contamination of the groundwater simul- surface water courses in Delhi. In case of the taneously leads to changes in the hydrochemical Najafgarh drain, mixing of seepage recharge from facies of the groundwater. The influx of contami- the drain with water coming from adjacent high- nants into groundwater system through network of lands has been reported (Kumar et al. 2011). subsidiary drains is also evident from the pattern of The Najafgarh drain water was reported to con- spatial variation in the concentration of the tain considerable concentration of heavy metal con- groundwater contaminants. Hence, the study on taminants such as iron, lead, manganese, copper anthropogenic contamination of groundwater sys- and nickel (Sharma et al. 2004). Hence, it is quite tem should be coupled with hydrochemical facies possible that along with seepage recharge from the analysis for comprehensive assessment of ground- drain, the heavy metal contaminates the ground- water quality. water as well. However, a recent study by Lorenzen et al.(2011), based on bank filtration technique, proposed groundwater extraction from the aquifer near the drain for drinking purposes. The shal- Acknowledgements low aquifer in this area is contaminated in differ- ent stretches. Thus, any groundwater development Author (AS) thanks the Council of Scientific and for emergency requirement should be preceded by Industrial Research for financial grant through a microlevel groundwater quality study. The ground- junior research fellowship. It is duly acknowledged water pumping in such areas must be staggered in that the groundwater sampling was done by the space and time to control saline water upconing first author when he was working as a Scientist (Rao et al. 2006, 2007). at Central Ground Water Board and the samples A system simulation and numerical modelling were analysed at CGWB Laboratory, Chandigarh. study can suggest optimal pumping from the The data for publication was taken from CGWB aquifer under different possible scenarios. The Report by Shekhar (2008). The authors are grateful model can incorporate possibilities of contami- to anonymous reviewers for their meticulous review nant transport from sampling locations where con- of the manuscript, which helped in improving the taminants have been reported. It is also sug- manuscript. gested that the sewage treatment level can be esti- mated so that the drain bank filtrated water into aquifer attains portable drinking water standards. This can be enforced on the concerned authorities Appendix A undertaking sewage treatment projects along the drain. Table showing the location of sampling sta- tions and the concentration of different chemical parameters. Cd – Cadmium, Cr – Chromium, Cu – Copper, Fe – Iron, Mn – Manganese, 6. Conclusion Ni – Nickel, Pb – Lead, Zn – Zinc, As – Arsenic, EC – Electrical conductivity, Cl – Chloride, The study gives a detailed insight into hydrogeol- SO4 – Sulphate, NO3 – Nitrate, F – Fluoride, ogy of the area adjacent to the Najafgarh drain Ca – Calcium, Mg – Magnesium, Na – Sodium, and groundwater quality in shallow aquifers along K – Potassium, HCO3 – Bicarbonate, N.A. – Not the Najafgarh drain. It establishes contamination analysed/data not available. Assessment of groundwater quality in shallow aquifers 53 3 FCaMgNaKHCO 3 NO 4 . 1.2.3. Rawta4. Shikarpur road5. Shikarpur-26. Nanakheri7. Isapur Khera 0.0058. Dhulsiras 0.029 0.007 0.0119. Chhawla 0.009 0.032 3.381 0.041 Kutub Vihar 0.003 0.004 0.114 0.017 0.005 Dwarka Sec.19 3.885 0.013 0 1 0.042 0.017 0.007 0.003 0.002 0.007 3.072 0 0.02 0.017 0.076 0 0.02 0.026 0.009 0.003 0.073 0 0 0.046 0.101 0.046 0.01 1.7 0 0.003 0 0.001 0.025 0 1.7 2.259 0.014 0.005 0.04 0.182 0.029 0.032 2.3 0 0 0.045 0.2 2250 0 0 0 N.A 489 0.096 0 0.02 N.A 0.04 0 125 0 N.A 0 0.025 4 N.A 75 N.A 0 N.A 2780 0.04 0.11 N.A N.A 774 2.23 1 0 0.133 N.A 21 0 N.A 95 0 2340 N.A N.A 300 88 N.A. 0 2120 N.A 55 N.A 1620 50 511 N.A 410 N.A N.A 362 0.84 N.A 230 N.A 10 N.A 48 83 50 N.A N.A N.A 8 N.A 467 1.47 121 N.A N.A 13 13 390 N.A N.A 0.3 0.3 N.A 45 N.A 3 79 N.A N.A 53 510 N.A N.A 82 317 26 N.A N.A 6 315 N.A N.A 315 4 N.A 995 5 249 437 10.11.12. Dwarka Sec.16 STP13. Dharampura 0.00614. Dwarka Sec.16 J Flat 0.02515. Nand Vihar 0 0.00316. Ghasipura 0.024 017. Deep Enclave 0.001 0.218. Vikash 1.333 Nagar19. Ranhola 0.015 0.016 0.005 0.211 0 0.00820. Nathan 0.043 Vihar 0 0.003 0.009 221. Chander 0.035 Vihar 0 0.007 0.005 1.722. Nihal 0 Vihar 0.001 0.003 0.03123. 0.224 Karampura 1.055 0.4 0.005 0.068 0.009 0.001 024. Shashtri 0.421 Nagar 7.4 0.004 0.01 0.014 0 1.4 0.02425. Roop 0 0 0.056 0 Nagar 0.002 0.048 0.35826. Timarpur 0.001 0 0.113 0 0.011 0.004 0.1 0.014 1.006 Nehru 0 0.031 0.007 0 Vihar 0.382 0 D-9 0.04 N.A 0.01 1100 Nehru 0.006 0.023 0.011 Vihar 1.3 0.164 0 C-280 223 N.A 0.6 4.879 0.005 0 0 0 0.02 0.003 0.8 0.053 N.A 1.7 0.496 0.008 105 0 0.004 0.014 0.003 5 0.0015 0.03 0 N.A 0 0.006 0.051 0.006 0.0009 10 0.04 0.06 1.667 1470 0.546 0.047 N.A 4980 3.11 0.005 0.001 1325 0.031 287 0.003 0.016 0.095 1180 0.001 N.A 1548 1.3 0 0.5 3.218 223 0.08 0 0 0.022 0.06 0.0019 0.0019 113 1.615 N.A 370 100 1.2 0 53 50 0.154 2250 2430 0.149 0.7 N.A 0.092 50 149 0.4 0.001 425 277 0.04 0 0.004 0.0013 0.012 1080 N.A 52 0.2 0 0.43 0.0026 3850 0.02 0 0.04 223 2190 9 155 N.A 65 8 290 6000 135 872 475 0.14 0.08 0.074 0.134 90 75 1297 107 238 60 51 0.02 430 6 0.015 1.2 0.0028 95 0.047 1140 0.0008 570 25 0.71 2120 2.23 0.181 0.0001 37 237 116 29 1100 1255 41 111 18 188 31 234 13 0.0003 2530 142 184 1.78 0.66 0.21 200 260 32 305 0.36 200 755 62 76 75 106 115 53 25 196 26 14 12 113 385 175 85 127 0.2 440 475 107 63 28 127 32 261 458 351 575 4 1100 7.14 2 5 0.05 100 275 2.93 1.25 29 650 4 82 4 459 68 71 5 6 458 1007 679 36 21 267 48 96 0.45 198 354 460 150 40 150 425 2 7 39 7 3 747 73 344 466 488 2 259 Sl. no. Locality Cd Cr Cu Fe Mn Ni Pb Zn As EC Cl SO 54 Shashank Shekhar and Aditya Sarkar

References Rao S V N, Kumar S, Shekhar S and Chakraborti D 2006 Optimum pumping from skimming wells; J. Hydrol. Eng. Bajpai 2011 Hydrogeological studies in the National Cap- 11 464–471. ital Territory of Delhi with reference to land use pat- Rao S V N, Kumar S, Shekhar S, Sinha S K and Manju S tern and effective groundwater management; Proc. Indian 2007 Optimum pumping from skimming wells from the Nat. Sci. Acad. 77(1) 31–49. Yamuna river flood plain in north India; Hydrogeol. J. 15 Banerjee A D K 2003 Heavy metal levels and solid phase 1157–1167. speciation in street dust of Delhi, India; Environ. Pollut. Sarkar A 2011 The hydrochemical facies variation in ground- 123 95–105. water along Najafgarh drain in National Capital Ter- BIS 1991 Indian Standard Specifications for drinking water; ritory, Delhi vis-`a-vis trace element concentration in B.S.10500. groundwater; M.Sc. dissertation, Department of Geology, CGWB 2006 Hydrogeologic Framework of NCT Delhi; University of Delhi, Delhi 7. Report, Central Ground Water Board, Delhi, Ministry of Sharma B, Kumar M and Ramanathan A L 2004 Impact Water Resources, Government of India. of surface water on the groundwater quality in and Datta P S, Bhattacharya S K and Tyagi S K 1996 18O stud- around Najafgarh drain, Delhi; In: Freshwater manage- ies on recharge of phreatic aquifers and groundwater flow ment (eds) Ramesh R and Ramachandran S (Delhi: paths of mixing in the Delhi area; J. Hydrol. 176 25–36. Capital Publications Co.), pp. 70–86. Dubey C S, Mishra B K, Shukla D P, Singh R P, Tajbakhsh Shekhar S 2004 Integrated groundwater management study M and Sakhare P 2012 Anthropogenic arsenic menace of south-west district with special reference to fresh/saline in Delhi Yamuna Flood Plains; Environ. Earth Sci. 65 water interface; Report, Central Ground Water Board, 131–139. Delhi, Ministry of Water Resources, Government of India. Goel Y K 1990 Infiltration study in Pappan Kalan area, Shekhar S 2006 An approximate projection of availability New Delhi, Report, Government of India, Central Ground of the fresh groundwater resources in south-west district Water Board, Ministry of Water Resources, North- of NCT Delhi, India – A case study; Hydrogeol. J. 14 western Region, Chandigarh. 1330–1338. INTACH 2003 Installation of tube wells and treatment of Shekhar S 2008 Integrated groundwater management study water along Najafgarh drain; Detailed Project Report in New Delhi, central, west, north-east, east and south (sponsored by Delhi Jal Board), Indian National Trust for districts, NCT Delhi with special reference to surface Art and Cultural Heritage (INTACH), 71, Lodhi Estate, water–groundwater interaction along the Najafgarh drain; New Delhi 110003. Report, Central Ground Water Board, Ministry of Water Jindal M C 1975 The groundwater conditions around Resources, Delhi. Najafgarh Jhil in parts of Delhi and Haryana State; Shekhar S, Singh S B and Romani S 2005 The controls to the Report, Government of India, Central Ground Water variation in depth to fresh/saline interface in the ground- Board, Ministry of Water Resources, North-western water of south-west District, NCT Delhi – A case study; Region, Chandigarh. J. Geol. Soc. India 66 17–20. Kumar M, Ramanathan A L, Rao M S and Kumar B 2006 Shekhar S, Mohiddin S K and Singh P N 2006 Vari- Identification and evaluation of hydrochemical processes ation in concentration of fluoride in the groundwater in the groundwater environment of Delhi, India; Environ. of south-west district, NCT Delhi – A case study; In: Geol. J. 50 1025–1039. Assessment of groundwater resources and management Kumar M, Ramanathan A L, Rao M S and Kumar B 2011 (eds) Ramanathan A L, Bhattacharya P, Keshari A K, Identification of aquifer-recharge zones and sources in an Bundschuh J, Chandrashekharan D and S K Singh urban development area (Delhi, India), by correlating iso- (New Delhi: I K International), pp. 370–376. topic tracers with hydrological features; Hydrogeol. J. 19 Shekhar S, Purohit R and Kaushik Y B 2009 Groundwa- 463–474. ter management in NCT Delhi; Technical paper included Lalwani S, Dogra T D, Bhardwaj D N, Sharma R K, Murty in the special session on Groundwater in the 5th Asian O P and Vij A 2004 Study on Arsenic level in groundwater Regional Conference of INCID, December 9–11, 2009 of Delhi using hydride generator accessory coupled with held at Vigyan Bhawan, New Delhi, available online at atomic absorption spectrometer; Ind. J. Clin. Biochem. http://www.cgwb.gov.in/documents/papers/INCID.html. 19(2) 135–140. Singh R B 1999 Impacts of urban growth on surface water Lorenzen G, Sprenger C, Taute T, Pekdeger A, Mittal A and and groundwater quality; Proc. IUGG 99 Symposium Massmann G 2011 Assessment of potential for bank filtra- HS5, Birmingham, July 1999, IAHS 259 227–231. tion in water stressed megacity (Delhi, India); Environ. WAPCOS 1999 Prefeasibility study for construction of a Earth Sci. 61 1419–1434. parallel channel to intercept the flows from Nallas out Moturi M C Z, Rawat M and Subramanium V 2004 Distri- falling into river Yamuna between and bution and fractionation of heavy metals in solid waste , draft final prefeasibility report for Irriga- from selected sites in the industrial belt of Delhi, India; tion and Flood Control Department, Government of NCT Environ. Monit. Assess. 95 183–199. Delhi, Report, Water and Power Consultancy Services NEERI 2002 Environmental management plan for rejuvena- (India) Limited, A Government of India Undertaking, 9, tion of river Yamuna; Report (sponsored by Delhi Devel- Community Centre, Saket, New Delhi 17. opment Authority), National Environmental Engineering WHO 2011 Guidelines for drinking water quality (4th edn), Research Institute (NEERI), Nagpur 440020. World Health Organization.

MS received 23 September 2011; revised 6 July 2012; accepted 16 July 2012