Isotopic and Hydrochemical Signatures in Characterizing Pollutants Movement in Overexploited Groundwater Aquifers of Delhi State
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Isotopic and Hydrochemical Signatures in Characterizing Pollutants Movement in Overexploited Groundwater Aquifers of Delhi State S.K. Tyagi, P.S. Datta, S. Kulshreshtha and R.K.Sharma Nuclear Research Laboratory Indian Agricultural Research Institute New Delhi-110012 APRAISAL OF THE INVETIGATED AREA Alipur Geographical Location: Block 28°24’17”- 28°53’00” N 76°50’24”- 77°20’37” E Kanjhawala Shahdara Block Block Geographical Area: 1483 Sq. Km. City Climatic Conditions: Semi-arid Block Najafgarh Y Geological Formation: Alluvial a Block R m Deposits of Quaternary period iv una e r Average Rainfall: 711 mm Mehrauli Mostly occurs between Map of Block June to September Delhi State 14000000 Population growth 12000000 of Delhi Population 10000000 projection 8000000 for 2008 is 6000000 18.2 million Population Map of 4000000 India 2000000 0 1951 1961 1971 1981 1991 2001 Year LANDUSELANDUSE CHANGESCHANGES ININ DELHIDELHI STATESTATE Sprawling Urbanization 1960 Red: Rural Area, Blue: Urban Area 1999 Urban Area Agricultural Land CONCERN OF RESOURCES MANAGERS Rapid changes in landuse pattern. Indiscriminate land disposal of wastes. Land-groundwater interaction. Land use induced changes in groundwater withdrawal, flow regime, recharge and conntamination characteristics. Search for availability of adequate quantity of good quality groundwater, in the limited surface water available conditions. Protection of land and water resources from depletion and degradation. GROUNDWATER ISSUES OF CONCERN Disproportionate use of groundwater. Lowering of groundwater levels. Decline in productivity of wells. Increasing pumping costs, more energy requirement. Intermixing of contaminated water with fresh water. Expanding areal extent of groundwater pollution. Indiscriminate disposal of domestic and industrial wastes. Contamination of groundwater in and around the land fill sites. Decline in water table in different blocks of Delhi Southern, South-western and Western parts are most affected GPS Model of Topography of Delhi region Alipur Block 265 260 255 Mehrauli 250 Altitude Block 245 (m) 240 235 Altitude 230 (m) Kanjhawla 225 Block 220 215 e 210 ud t i t 205 a L 200 195 Najafgarh tude ongi Block L Peri-Urban areas being located at relatively higher elevation Generate significant surface runoff, resulting depression focused recharge conditions. Isotopic composition (δ18O, ‰) in groundwater of Delhi Pre-M Post-M 28.85 2005 28.85 2005 Alipur Block Alipur Block 28.75 28.75 Kanjhawala Block Shahdara • • Block • • • Kanjhawala Block• Shahdara Block 28.65 • City Block 28.65 • Najafgarh Block • City Block • • Najafgarh• Block Y Y a a m m u u 28.55 n 28.55 n a a R R • i • v iv Mehrauli Block e e r r Mehrauli Block 28.45 28.45 0Km 11Km 22Km Canal 0Km 11Km 22Km Canal Drain Drain 28.35 28.35 76.8 76.9 77 77.1 77.2 77.3 77.4 76.8 76.9 77 77.1 77.2 77.3 77.4 Groundwater in Pre-monsoon 2005 and 2004 is isotopically similar, indicating depression focused recharge from isotopically enriched rainfall. Post-monsoon 2005 is relatively depleted, suggesting dilution effect due to lateral flow from surrounding areas High Chloride (mg/l) Plumes Dynamics in Groundwater of Delhi Region Chloride Contours 2003 28.85 2005 • •• 500 1000 28.75 • Alipur Block• Kanjhawala Block Shahdara • Block 28.65 • ••City Block • Najafgarh Block • • Y • a m u 28.55 n a • R • i v Mehrauli Block e r Drain Canal 28.45 STP ● 0Km 11Km 22Km ● Recharge zone LFS Recharge zone 28.35 76.8 76.9 77 77.1 77.2 77.3 77.4 Groundwater is moderately to highly saline suggests rainfall recharge is limited. Lateral extension of high salinity plumes towards the central urban parts along specific flowpaths reflects that the withdrawal is not in balance with recharge. High Nitrate (mg/l) Plumes Dynamics in Groundwater of Delhi Region 2003 2004 • • • • 50 100 •• •••• • • • • • • • • • • • • • • • • • • • • • • Canal Drain Canal Drain wide range of Nitrate values are observed in the groundwater of Delhi region. Northern, western and south western parts are more affected by nitrate pollution. Spreading of high nitrate locations indicate multiple sources of contamination. Scatter diagram of Nitrate and Chloride content in groundwater in Delhi Area 800 N=77 (PreM 2004) 700 Nitrate:Chloride=1:1 Point sources 600 500 Mitraon Dhansa 400 Alipur Block 300 Kanjhawala Block Ghuman Hera Najafgarh Block 200 Mehrauli Block Shahdara Block Nitrate Content (mg/l) 100 City Block 0 0 1000 2000 3000 4000 5000 Chloride Content (mg/l) Straight line relationship suggests the contribution from domestic sewage. Other anthropogenic sources like landfills, sewage irrigation, chemical fertilizers and surface water runoff are the other sources of contamination to the groundwater system Relationship between Chloride content with δ18O and sodium content in groundwater in Delhi State 8000 Alipur Block N=88, 2005 Pre-M 7000 Sanoth Kanjhawala Block Najafgarh Block Dhansa Relationships between groundwater Cl 6000 Mehrauli Block Malik Pur 18 Point Shahdara Block and O indicate mixing processes 5000 along specific flow pathways, due to sources City Block changes in hydraulic heads, induced 4000 by indiscriminate pumping. In some 3000 parts significant variation in groundwater Cl with no change in 18O values suggests 2000 salinity increase contributed by vertical 1000 infiltration of Cl containing chemicals in (mg/l) Content Chloride soil with rainwater or irrigation water. 0 -9 -7 -5 -3 -1 1 2000 1 N=85 ( 2004) 18 = 1800 e δ O (‰) id Dhansa 1600 r lo h 1400 :C m Ghuman Hera 1200 iu d Highly correlated linear trend between o 1000 S Alipur Block Na and Cl indicates mixing of two :1 800 Kanjhawala Block groundwater bodies with different end 600 Najafgarh Block member compositions (i.e. Fresh and 400 Mehrauli Block saline). Most of the groundwater Shahdara Block Sodium Content (mg/l) 200 City Block samples lie below the equiline, 0 suggesting influence of anthropogenic 0 1000 2000 3000 4000 5000 activities. Chloride Content (mg/l) Chemical Composition of Groundwater in Delhi Area Alipur Block Kanjhawala Block Trilinear diagrams indicate Sant Nirankari • Kolony different groundwater Darya Pur compositions, viz, Ca-Mg- Tikri Khurd HCO3, Ca-Na-HCO3, Na-Ca- HCO3-Cl, Mg-Na-HCO3, Na-Cl- HCO3 and Na-Cl etc. • Calcium bicarbonate water is • derived from rainfall recharge. Najafgarh Block Mehrauli Block Ca-Na-HCO3 water more likely derived from recharge of rainfall that carried saline water mixing along with. Abundance of (Ca+Mg) in groundwaters can be attributed to mainly Jona Pur carbonate weathering. Mandi Multi-Component Model of Groundwater Intermixing Alipur Block Kanjhawla Block 2004 2004 Sanoth Bakarwala N=22 N=11 The groundwater samples with mixed cation- bicarbonate and mixed cation-bicarbonate- chloride, found in surface Tikri Ghat (YR) Muhammad Pur Mundka water or shallow groundwater, represent mixture of various waters. In contrast mixed cation bicarbonate with depleted isotopic signature were Najafgarh Block Mehrauli Block found both in shallow and 2004 relatively deep (60 ft or 2004 N=14 more). The deeper mixed N=17 Dhansa Maandi cation bicarbonate water might have evolved by chemical interactions with aquifer sediments. Ayanagar Kapashera CONCLUDING REMARKS Peri-Urban areas being located at relatively higher elevation generate significant surface runoff. Infiltration of isotopically enriched surface runoff collected in low elevated areas, sewage irrigated areas, and landfills, along with pollutants in wastes, contributes to pollution. Groundwater is moderately to highly saline, and salinity is in decreasing order in different blocks as Najafgarh > Nangloi > Alipur > Shahdara > Mehrauli. Potential recharge zones confined to some small pockets in northern parts adjacent to the western Yamuna Canal, and river and in the southern parts in Chattarpur Basin. Lateral extension of high salinity plumes takes place towards the central parts along specific flowpaths. High Nitrate plumes in groundwater from western parts have a tendency to move towards southern and southeastern parts along specific pathways, induced by groundwater abstraction.. Continued....... CONCLUDING REMARKS Continued........ Intensive exploitation induced inter mixing of polluted groundwater with fresh water takes place within the block as well among the blocks. Groundwater in north-western, western parts and areas near to landfill sites are highly contaminated. In many parts of the area groundwater is not even fit for irrigation purposes, and more vulnerable to nitrate pollution. Mapping the complexity of the groundwater situation, integration of isotopic methods with modeling, GIS and Remote Sensing can help to obtain detailed insight to protect the groundwater resource from its depletion and deterioration. This initiative clearly indicates the need for programmes on local community awareness and participation, to evolve policy guidelines to restrict indiscriminate waste disposal and control of groundwater withdrawal/pollution to conserve the resource base. Acknowledgement Indian Agricultural Research Institute, New Delhi Indian Council of Agricultural Research, New Delhi Ministry of Agriculture, Govt. of India Special Thanks to Institute of Global Environmental Strategies (IGES) Organizing committee of 3rd WEPA International Forum .