A Case Study On Sea Water Ingress Into Ground Water By Chemical Analysis

Transcription

1 International Jornal of Engineering Technology, Management and Applied Sciences A Case Stdy On Sea Water Ingress Into Grond Water By Chemical Analysis Dr.K.R.Prasad Professor, Dept of Civil Engineering, VRSiddhartha Engineering College Vijayawada, A.P, India T.Ramaiah Chowdary Professor, Dept of Civil Engineering, VRSiddhartha Engineering College Vijayawada, A.P, India Abstract Sea water intrsion can potentially render large portions of delta nstable. In the present stdy an attempt is made to identify the ingress of sea water into grond water in Krishna delta of Andhra Pradesh, India. Samples were collected from the selected villages of the delta. From the reslts of chemical analysis, the village wise data base has been generated. The vales obtained for different chemical parameters are compared with the standard vales given by ISI and ICMR. The stdy revealed that the fresh water crisis is more in Krishna Eastern delta rather than in Krishna Western delta. The stdy also helped in identifying the areas of ingress of sea water into grond water which in trn need proper attention. Keywords sea water intrsion, grond water samples, chemical analysis, water qality, Krishna delta INTRODUCTION Deltaic regions are the most densely poplated as they provide best conditions for prodctivity. These regions face the problem of sea water intrsion into grond water becase of their proximity to the coast. Ingress of sea water into fresh water aqifers takes place de to natral process or hman activities. The bondary between sea water and fresh water is a zone of conflence between the two (Cstodio et. al., 1987). Sea water intrsion can be identified on the basis of chemical compositions like chlorides and total dissolved solids (TDS) present in the grond water. The intrsion is one of the major cases for deterioration of grond water qality in deltaic regions. It cases agricltre, health and environmental problems for sers of grond water. Hence the knowledge on qality of grond water is of tmost importance in the delta. The need of the hor is to determine the degree and extent of sea water intrsion in deltaic region. This is of paramont importance in the context of Indian scenario becase of the long coast line and increasing water demands. The possible sorces of sea water intrsion are presence of salt domes in geologic formations, sea water present in the aqifers from past geologic times retrn flow from irrigation, increase in nmber of bore wells for varios prposes etc., (Reilly and Goodman, 1985). The degree and extent of sea water intrsion may vary widely within the delta and is affected by hydro geological settings. The objective of the present stdy is to identify the ingress of sea water into grond water in selected villages of Krishna delta, Andhra Pradesh, India. II. PROFILE OF THE STUDY AREA The Krishna delta is formed by the major river Krishna close to the Bay of Bengal in East coast of India. The river flows across the delta. The Krishna Western delta is on right side and Krishna Eastern delta is on left side to the river. The delta is geographically bonded by North latitde and East longitde extending from Bapatla in the West to Kaikalr in the East with its apex at Vijayawada. The aerial extent is abot 46 sq. kms. Covering parts of Krishna and Gntr districts of Andhra Pradesh, India. The major townships in the delta are Vijayawada, Gntr, Tenali and Machilipatnam. The relief of the delta is nearly 19m. The delta experiences tropical semi-arid type of climate with mean annal temperatre at 28 C. The mean annal precipitation varies from 12mm to 13mm. Abot 63% of total rainfall is received from Soth West monsoon and 28% is received from North East monsoon. Geologically the delta is predominantly occpied by allvim formations. The major types of soils in the delta are black soils, coastal sands and soils with stratified layers. 6

2 International Jornal of Engineering Technology, Management and Applied Sciences Fig. 1S Location of Stdy Area and Sampling Locations The total poplation of the delta as per 21 censs is 29, 34, and 978. Abot 7% of the poplation in the delta is dependent on agricltre. The delta is known for good yields of agricltral prodction. The major crops grown in the area are Paddy and Sgarcane. The secondary crops like black gram, green gram, grondnts and frits are grown in dry and pland areas of the delta. 75% of the poplation of the stdy area is dependent on grond water for meeting varios needs like domestic, agricltral and indstrial. The demand for grond water is rapidly increasing in the deltaic region becase of increasing poplation and increase in the gross area nder agricltre. The crrent annal grond water draft in Krishna Eastern delta is MCM and 99.5 MCM in Krishna Western delta. Over the years the transformation of fresh grond water to saline water is taking place in the delta at a faster rate de to intensive increase of sea water intrsion. III. MATERIALS AND METHODS To identify the ingress of sea water into grond water, random sampling was carried ot in the villages of the delta within the reach of 4-75 km from the coast line and where 9% of the poplation is dependent on grond water. 5 samples are collected in polythene bottles from working dg wells, hand pmps and bore wells dring Janary 27. The sampling locations are shown in Fig.1 Chemical examination is carried ot in the laboratory to find ot the degree and extent of sea water ingress. The water samples collected are analysed for Chlorides, Calcim, Total Hardness, Magnesim, P H, Alkalinity and Total Dissolved Solids (TDS). Chlorides are analysed sing precipitation method. Calcim is determined by EDTA micrometric method. Total hardness is estimated by EDTA method. Magnesim is estimated as the difference between total hardness and calcim hardness. P H vale of the sample is measred directly by P H meter. Alkalinity and TDS are analysed by volmetric analysis and weight loss method. Test procedres for the analysis of the above parameters are adopted from APHA, IV. RESULTS AND DISCUSSIONS Proper development, tilization and management of grond water resorces can be achieved only when the chemical composition of the grond water is flly known. The chemical composition of the water will affect the qality of water, irrigation pattern, crop yields, indstrial needs and environment. To know the qality of water, the parameter wise database for the samples taken from the stdy area is generated by chemical analysis. The permissible limits for Chlorides, Calcim, Total hardness, Magnesim P H, Alkalinity and TDS as per ISI and ICMR are 1mg/l, 2mg/l, 6mg/l, 1mg/l, , 6mg/l and 15mg/l respectively. Concentrations of chlorides and TDS in grond water samples are the commonly sed indicators of sea water intrsion into grond water (Van Dam, 1999). In the present stdy the analyzed vales of water qality parameters of the stdy area are compared with the respective permissible limits.the analysis for the samples taken in villages of Krishna district is as follows: Table 1 show that the lowest vale (123mg/l) of chlorides is observed for the village Kanr (32). The highest vale of 629.4mg/l is fond for sample no.1 taken in the village Machilipatnam. As the village is sitated near the sea coast, sea water intrsion is most common. Bt the villages like Movva (16, 29.93km), Palankipad (17, 28.5km), Kaza (18, 2.km) and Thadanki (22, 4.79km) are experiencing higher concentrations of chlorides. Sample srvey condcted in some of these villages revealed certain important observations. Palankipad (17) experiences higher concentration of chloride de to pward leakage from the nderlying shallow artesian aqifer. In kaza (18), the villagers are dependent on one srviving well, which implies that excess pmping of water from the well is nder exection. In Thadanki (22), salt domes are present in the geological formations beneath the grond. It is observed that the villagers of Kaza (18) as well as Thadanki (22) are sffering from harmfl effects like kidney stone formation de to consmption of grond water 7

3 International Jornal of Engineering Technology, Management and Applied Sciences containing high chloride concentrations. It is also feared that the disease may englf the villages in near ftre becase of the faster rate of sea water intrsion. Ot of 32 samples analysed, concentrations of chlorides in six samples (2- Kodr, 4-Nagayalanka, 9-Pamarr, 26-Chinaogirala, 31-Penamalr and 32-Kanr) are less than the permissible vale. All the other 26 samples analyzed exceeded the permissible limit. All the samples analyzed for calcim content are fond to have lower concentrations and are far below the permissible vale i.e. 2mg/l. Table 1 Concentrations of Chlorides in samples taken from villages of Krishna district No the village 1. Machilipat nam (6.9 km) 2. Kodr (7.23 km) 3. Avanigadd a (21.38 km) 4. Nagayalan ka (13.16 km) 5. Gdlavaller (22.7 km) 6. Gdivada (32.24 km) 7. Pedaparp di (35.86km) 8. Pedana (7.56 km) 9. Pamar (31.25 km) 1. Pedamadda li (32.25 km) 11. Gdr (11.55 km) 12. Mopidevi (2. km) 13. Challapalli (21.38 km) 14. Ghantasala (25.33 km) 15. Endakdr (14.14 km) 16. Movva (29.93 km) Chlori des No the village Palankipad (28.5 km) Kaza (2. km) Nidomol (2.72 km) Pamidim kkala (37.83 km) Mantada (4.13 km) Thadanki (4.79 km) Medr 6 (41. km) Marrivada (38.82 km) Vyyr (42.77 km) Chinaogira 1 la (43.9 km) Kalavapa mla (52.8 km) Thotlavall r (49.67 km) Kankipad (57.9 km) Velpr 8 (36.19 km) Penamalr (57.57 km) 32. Kanr (66.12 km) Chlori des

4 International Jornal of Engineering Technology, Management and Applied Sciences Note: The figres given in the parenthesis of the second colmn of the table 1 are the distances of the villages from the coast line. The total hardness (Fig.1) is fond to be maximm (198mg/l) for sample no.17 of village Palankipad. It is fond that the villagers of Palankipad are experiencing adverse effects on domestic sage of water. Whereas the minimm vale of 52mg/l is fond in sample no.26 of village Chinaogirala. Ot of 32 samples analysed, it is fond that the total hardness is within the prescribed permissible limit (i.e.6mg/l) for 29 samples. Only three samples (15-Endakdr, 17-Palankipad and 18-Kaza) exceeded the permissible limit. The least vale (42.38mg/l) of Magnesim is observed in sample no.26 of Chinaogirala village (Fig.2). The maximm concentration of mg/l is fond in sample no.17 of Palankipad village. Except in seven samples ( 2- Kodr, 6-Gdivada, 26-Chinaogirala, 27-Kalavapamla, 28-Thotlavallr, 31-Penamalr, 32-Kanr), the Magnesim concentrations in other 25 samples exceeded the permissible limit. The P H vales are reasonably well within the prescribed limits except for samples 6 and 28 taken in Gdivada and Thotlavallr villages. From Fig.3, it may be observed that 27 samples are well within the permissible limit of alkalinity. The concentration of alkalinity in the other 5 samples (12-Mopidevi, 15-Endakdr, 16-Movva, 17-Palankipad, and 31-Penamalr) exceeded the prescribed limit. Maximm concentration of 948.9mg/l is fond in sample no.17 of village Palankipad. TDS concentrations are fond to have exceeded the permissible limit in 27 samples. This can be observed from Fig.4. Only 5 samples (2-Kodr, 4-Nagayalanka, 9- Pamarr, 26-Chinaogirala, 32-Kanr) are fond to be within the permissible limit of TDS i.e. 15mg/l. The maximm concentration (1879.5mg/l) is fond in sample no.1 of Machilipatnam village. Medical srvey is condcted in some villages having higher concentrations of TD The srvey revealed that higher concentrations are casing disease prodcing bacteria. This in trn is affecting the hman health as well as livestock and aqacltre. From the analysis it can be inferred that the village Kankipad (29) which is abot 58km from the coastline is prone to sea water intrsion. This is evident from the presence of concentrations of chlorides and TDS in the respective sample. Ths it can be stated that the extent of sea water intrsion is abot 58km from the coastline. Persal of the reslts show that the most sensitive villages that need proper attention are Machilipatnam (1), Pedana (8), Endakdr (15), Movva (16), Palankipad (17), Kaza (18) and Thadanki (22). The analysis for the samples taken in villages of Gntr district is as follows: The chloride concentrations for 18 samples analyzed varied between 98.31mg/l (48-Chebrol) to mg/l (42- Nizampatnam). This is evident from Table-2. The concentrations of chlorides exceeded the permissible limit in 7 samples (33-Kazipalem, 36-Bapatla, 4-Patchalatadiporr, 41-Retr, 42-Nizampatnam, 43-Gntr, -Peddapalli). The concentrations in the other 11 samples are fond to be well within the permissible limit i.e. 1mg/l. Calcim content in all the samples analyzed are fond to be well within the prescribed limit i.e. 2mg/l. 9

5 Total Hardness Magnesim International Jornal of Engineering Technology, Management and Applied Sciences Table 2 Concentrations of Chlorides in samples taken from varios villages of Gntr district N village * Chlorid es N village * Chlorides o o 33 Kazipalem Nizampat nam 34 Kakman Gntr Prathipad Yajili Bapatla Peddapalli Alr Alakapra m 38 Ponnr Karlapale m Narakodr Chebrol Patchalata Pesaralan diporr ka 41 Retr Nidbrol (* Sample village nmbers and distances from the coast line: km, km, km, km, km, km, -41.1km km, km, km, km, km, -1.12km, km, km, km, km, km.) From Fig.5, it may be observed that the maximm vale (85.4mg/l) of total hardness is fond in sample no.43 of Gntr. Whereas the minimm vale (66.66mg/l) is fond in sample no.37 of Alr. Ot of 18 samples analyzed, hardness concentrations in 5 samples (4-Patchalatadiporr, 41-Retr, 42-Nizampatnam, 43-Gntr, -Peddapalli) exceeded the permissible limit Fig.5 Concentration of Total Hardness Fig.6 Concentration of Magnesim Magnesim concentration exceeded the permissible limit in 9 samples (33-Kazipalem, 36-Bapatla, -Narakodr, 4-Patchalatadiporr, 41-Retr, 42-Nizampatnam, 43-Gntr, -Peddapalli, and 46-Alakapram). This is evident from Fig.6. The concentrations in the other nine samples are within the permissible limit i.e. 1mg/l. The concentrations of P H of the analyzed samples varied from 7.2 to 8.5. All the analyzed samples are well within the permissible limit of P H. From Fig.7, it may be observed that the maximm concentration (91.55mg/l) of alkalinity is fond in sample no.43 of Gntr. The minimm vale of 97.4mg/l is fond in sample no. 48 of Chebrol. The concentrations of alkalinity exceeded the permissible limit in abot 5 samples (33-Kazipalem, 41-Retr, 42-Nizampatnam, 43-Gntr, - Peddapalli). 1

6 Alkalinity TDS International Jornal of Engineering Technology, Management and Applied Sciences TDS concentrations in the samples varied between 664mg/l (44-Yajili) to 7689mg/l (42-Nizampatnam). From Fig.8, it may be observed that abot 9 samples (33-Kazipalem, Fig.7 Concentration of Alkalinity Fig.8 Concentration of TDS 35-Prathipad, 36-Bapatla, -Narakodr, 4-Patchalatadiporr, 41-Retr, 42- Nizampatnam, 43-Gntr, - Peddapalli) are fond to have exceeded the permissible limit of TDS i.e. 15mg/l. The analysis of the samples taken in villages of Gntr district revealed that the effect of sea water intrsion is not that predominant in villages sitated at abot 7-75km from the coastline. This is evident from the absence of higher concentrations of Chlorides and TDS in village like Alakapram (46) (74.38km). The extent of sea water intrsion in the district is abot 5km from the coastline. This is evident from the presence of higher concentrations of Chlorides and TDS in Gntr (43) (49.58km). To know the reasons for higher concentrations of Chlorides and TDS, sample srvey is condcted in the villages Bapatla (36), Nizampatnam (42) and Gntr (43). The villagers of Bapatla stated that sgarcane is the heart of their agricltre. The srvey revealed that there is excess exploitation of water from bore wells to meet the agricltral demands. In Nizampatnam, aqacltre bsiness is on great demand. Over exploitation of grond water for domestic prposes is observed in Gntr. It is noticed that the villagers of these three villages are experiencing high blood pressre on consmption of grond water. Carefl examination of the reslts show that the most sensitive villages that need proper attention are Kazipalem (33), Bapatla (36), Patchalatadiporr (4), Retr (41), Nizampatnam (42), Gntr (43) and Peddapalli (). V. SUMMARY AND CONCLUSIONS The se of chemical analysis for identification of sea water ingress in 5 sampled villages of the stdy area is promising and yielded knowledge based information. The chemical compositions of sea water ingress indicators namely chlorides and TDS varied widely ranging from mg/l, mg/l in the Krishna Eastern Delta and mg/l, mg/l in the Krishna Western Delta. The stdies revealed that the fresh grond water crisis is more in villages of Krishna Eastern (KE) delta rather than in Krishna Western (KW) delta. The most sensitive villages that need proper attention are - 1, 8, 15, 16, 17, 18 and 22 in KE delta and 33, 36, 4, 41, 42, 43 and in KW delta. No proper trends were fond between chlorides, TDS concentrations and distances from coastline. However the stdies may form the basis for an in-depth research regarding periodic monitoring of water qality especially with respect to salinity and total hardness in the delta. Awareness on the conseqences of sea water intrsion, protective and corrective measres of qality of grond water mst be created among the villagers of the delta. Precations shold be taken to redce/eliminate sea water intrsion to a maximm possible extent by adopting modification of pmping pattern, artificial recharge, hydralic barriers, injection barrier, pmping-injection barrier, physical barrier etc., The approach followed in the stdy is considered a valable attempt becase it cold help in nderstanding the degree and extent of sea water intrsion in the delta. Acknowledgment The researchers deeply acknowledge the Management of VR Siddhartha College of Engineering, Vijayawada, Andhra Pradesh for their spport and encoragement given for carrying ot this stdy. References [1] APHA, Standard Methods for the Examination of Water and Waste Water, American Pblic Health Association, Washington DC, 16 th edition, pp [2] Cstodia, E., G. A. Brggemen and V. Cotecchia, Grond Water Problems in Coastal Areas. Stdies and Reports in Hydrology. Vol. 35, UNESCO, Paris. 11

7 International Jornal of Engineering Technology, Management and Applied Sciences [3] Reilly, T.E., and A. Goodman, Qantitative Analysis of Saltwater Freshwater Relationships in Grond water Systems A Historical Perspective. J. Hydrology, Vol. 8, pp [4] Van Dam, J. C Exploitation, Restoration and Management. In Bear, Jacob and Others, Eds., Seawater Intrsion in Coastal Aqifers-Concepts, Methods and Practices, Dordrecht, the Netherlands, Klwer Academic Pblishers, pp