Quality of groundwater for irrigation in tehsil Taxila of district RawalpindI, Punjab

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1 Soil & Environ. 29(2): , Online ISSN: Print ISSN: Quality of groundwater for irrigation in tehsil Taxila of district RawalpindI, Punjab A. Waheed 1, R. Khalid 1, T. Mahmood 1, M.T. Siddique 2* and A.S. Javed 1 1 Soil Fertility Survey and Soil Testing Institute, Rawalpindi 2 PMAS-Arid Agriculture University Rawalpindi Abstract A study was undertaken to categorize suitability of groundwater for irrigation purpose in Taxila area of Rawalpindi district. A total of 628 water samples were collected from nine union councils in Taxila, analyzed and categorized according to the suitability criteria of water quality evaluation. Sixty six percent water samples were fit, 21 % were marginally fit and 13 % were found unfit for irrigation purposes. In majority of the union councils, water was fit for irrigation except Thatta Khalil and Khurram Paracha where > 20 % of water samples were unfit. About 17 % water samples were unfit due to higher electrical conductivity (EC). Residual sodium carbonate (RSC) and sodium adsorption ratio (SAR) were higher in few water samples, while > 90 % water samples had RSC and SAR within prescribed safe permissible limits. The dominant cations were Ca ++ + Mg ++ and Na + with mean values of 7.6 and 3.3 me L -1 - whereas, HCO 3 and Cl - were dominant anion with mean values of 4.2 and 3.0 me L -1, respectively. The analytical data indicated that these waters had higher EC. However, the quality of available groundwater in the tehsil is suitable for raising trees and orchards. Guidelines of water for irrigation purpose should be based on the soil textural class for its maximum utilizationr and to avoid any potential harmful effects on soil health. Keywords: Water analysis, Groundwater quality, Rawalpindi district Introduction crop yield is also governed by the type of soil, climate and The Pothwar plateau consists of an area of more than one million hectares. The plateau generally has flat to gently undulating surface, locally broken by gullies and low hills/ ranges. Rawalpindi district is an important part of Pothwar plateau (latitude 32º 10 to 34º 9 N and longitude 71º 10 to 73º 55 E) consisting of five tehsils. Taxila is one of them situated near Margalla Hills. Rawalpindi district lies in high to medium rainfall zone, rainfall varies from 500 to 1000 mm per annum. About 70 % of annual precipitation is received in the summer months of July and August (Nizami et al., 2004). The farmers have to rely on irrigation through tubewells for growing vegetables and other ornamental crops due to seasonal and erratic rains. It is estimated from the groundwater survey of the country that with assured and dependable supply from private tubewells, farmers have changed the cropping pattern towards high value crops like vegetables and fruits. For successful crop production on sustainable basis, the quality of groundwater is of main concern. The common quality characteristics considered are electrical conductivity (EC), sodium adsorption ration (SAR) and residual sodium carbonate (RSC) (Idris and Shafiq, 1999). The concentration and composition of dissolved constituents in water determine its quality for irrigation use. It is difficult to define the critical limits of EC, RSC and SAR because the effect of different qualities of water on soil health and * mt_siddique1@yahoo.co.uk 2010, Soil Science Society of Pakistan ( management practices (Singh et al., 1992). However, water with EC values below 0.75 ds m -1 are satisfactory for irrigation, although salt sensitive crops may be adversely affected by the use of irrigation waters having conductivity values in the range ds m -1 (U.S. Salinity Lab. Staff, 1954). The quality of groundwater is highly variable in various parts of the country both vertically and horizontally from complete fresh to extremely saline. In Rawalpindi district due to deeply incised nature of main rivers, groundwater over most of the areas are derived from precipitation. Ali et al. (2009) reported that quality of available ground water in most (76.6%) of the villages of Lahore district was not suitable for sustainable crop production and soil health. According to Soil Fertility Survey and Soil Testing Institute, Rawalpindi ( ), 73% of water samples analyzed, were fit for irrigation during Khalid et al. (2003) reported that in Rawalpindi district, 71% of water samples were fit, 9% marginally fit and 20% were unfit for irrigation. The 48% of water samples were unfit for irrigation in Gujrat district of Punjab (Pervaiz et al., 2003). Kashif et al., (2009) investigated quality and heavy metal occurrence in Hudiara drain water and its accumulation in vegetable crops in Lahore region. The water of Hudiara drain was found fit for irrigation purpose but not fit in relation to heavy metal contents. The objective of present study was to assess the

2 168 Waheed, Khalid, Mahmood, Siddique and Javed quality of groundwater in the Taxila tehsil of Rawalpindi district for its suitability to irrigation. Materials and Methods During the study a total of 628 tubewell/well water samples were collected from 9 union council of tehsil Taxila, district Rawalpindi. Tubewells selection was made randomly in all tehsils. The samples were taken in polythene bottles after thirty minutes of tubewell operation. The depth of tubewells/wells ranged from 30 to 200 feets. The tubewells water is being used for raising vegetables, ornamental plants, forests trees and nurseries. The water samples were analyzed at Soil Fertility Survey and Soil Testing Institute, Rawalpindi for electrical conductivity (EC), cations (Ca +2 + Mg +2, Na + ) and anions (CO 3-2, HCO 3 -, Cl - ) by the methods described by Page et al. (1982) and U.S. Salinity Lab. Staff (1954). Residual sodium carbonates (RSC) and sodium adsorption ratio (SAR) were determined by following formulas of U.S. Salinity Lab. Staff (1954). RSC (meq L -1 ) = (CO HCO - 3 ) - (Ca ++ + Mg + ) SAR = Na + / Ca ++ + Mg + /2 The criteria used for evaluation of irrigation water was proposed by Malik et al. (1984) and is given in Table 1. Table1: The criteria for suitability of irrigation water. Parameter Fit Marginally fit Unfit E C (ds m -1 ) > 1.25 RSC (me L -1 ) < > 2.25 SAR [(mmol L -1 ) 1/2 ] < > 10 Results The analytical data regarding cations, anions, EC, SAR and RSC of tubewell water in tehsil Taxila are presented in following paragraph. Ionic concentration Ca +2 + Mg +2 were the dominant cations, ranging from 2.0 to 57.0 me L -1 with mean value of 7.6 me L -1 followed by Na + with mean value of 3.3 me L -1 (Table 2). Among the - anions, HCO 3 was the dominant anion ranging from me L -1 with mean value of 4.2 me L -1 followed by Cl - with mean value of 3.0 me L -1. However, CO -2 3 were present in few water samples. Electrical conductivity (EC) status The classification of water samples on the basis of EC (Table 3) indicated that EC of 76 % water samples were within safe limits (<1.00 ds m -1 ) whereas, 11% samples were unfit and 14% were marginally fit for irrigation. The EC of all water samples ranged from ds m -1 with a mean value of 0.95 ds m -1. Residual sodium carbonates (RSC) status Table 4 showed the classification of water samples on the basis of RSC. The RSC ranged from me L -1 with mean value of Out of 628 water samples, the RSC of 587 water samples was within safe limits (<1.25 me L -1 ). Only 14 water samples (2%) were unfit and 27 (4%) were marginally fit due to higher RSC. Sodium adsorption ratio (SAR) status The SAR values of water in most of the union councils (Table 5) were within safe limit (< 6). The SAR ranged from [(mmol L -1 ) 1/2 ] with mean value of 1.7 (Table 2). With respect to their distribution, 610 (97%) water samples were within safe limits and only one water sample of Thatta Khalil union council was unfit due to high SAR. Commutative effect of EC, RSC, SAR on water quality Classification of water on the basis of commutative effect of three parameters (EC, RSC, SAR) is presented in Table 6 and Figure 1. It indicated that out of 628 water samples, 416 (66%) were fit, 129 (21%) were marginally fit and 83 (13%) were unfit for irrigation according to the suitability criteria (Table 1). Table 2: The minimum, maximum, and mean values of cations, anions, electrical conductivity (EC), sodium adsorption ration (SAR) and residual sodium carbonate (RSC) Ca +2 +Mg +2 Na CO 3 HCO 3 Cl - EC RSC SAR me L -1 ds m -1 me L -1 (mmol L -1 ) 1/2 Min Max Mean SD

3 Ground water quality for irrigation 169 Water quality in union councils of tehsil Taxila Jalala union council had maximum 48 (91%) water under safe limits followed by Usman Khattar (87%). Out of 53 samples analyzed from Jalal union council, none was unfit for irrigation. Whereas, maximum number (8) of unfit water samples (32%) were recorded in Khurram Pracha followed by 39 (21%) in Thatta Khalil union councils. In remaining union councils, more than 50 % samples were fit for irrigation. Table 3: Classification of water samples on the basis of electrical conductivity (EC: ds m -1 ) Thatta Khalil Taxila Losar Sharfoo Cantt Area Jalala Usman Khattar Gari Sikandar Wah Village Khurram Paracha Total % age Table 4: Classification of water samples on the basis of residual sodium carbonate (RSC: me L -1 ) Thatta Khalil Taxila Losar Sharfoo Cantt Area Jalala Usman Khattar Gari Sikandar Wah Village Khurram Paracha Total % age Table 5: Classification of water samples on the basis of sodium adsorption ration [SAR (mmol L -1 ) 1/2 ] Thatta Khalil Taxila Losar Sharfoo Cantt Area Jalala Usman Khattar Gari Sikandar Wah Village Khurram Paracha Total % age

4 170 Waheed, Khalid, Mahmood, Siddique and Javed Table 6: Classification of irrigation water using commutative guidelines for electrical conductively (EC), residual sodium carbonate (RSC) and sodium adsorption ratio [SAR (mmol L -1 ) 1/2 ] Union Councils No of water samples Fit Marginally fit Unfit Thatta Khalil (50) ψ 54 (29) 39 (21) Taxila (58) 37 (25) 24 (17) Losar Sharfoo (80) 8 (13) 4 (7) Cantt Area (86) 4 (9) 4 (7) Jalala (91) 5 (9) 0 (0) Usman Khattar (87) 3 (8) 2 (5) Gari Sikandar (75) 8 (25) 0 (0) Wah Village (82) 3 (11) 2 (7) Khurram Paracha (40) 7 (28) 8 (32) Total % age ψ ( ) give the % share in each category along with number of water samples No. of Water Samples Union councils of Taxila Fit Marginall y fit Figure1: Classification of Irrigation water in Taxila tehsil Discussion and Recommendations It was observed that most of the water samples were unfit due to higher electrical conductivity indicating no sodicity problem in these waters. This might be due to more rainfall area and coarse textured soils; the minerals and dissolved salts has been leached to lower profile over a period of time. The soils of Rawalpindi district are medium textured and have well-developed profile containing lime concentration at lower depths (Nizami et al., 2004). Unlike the rivers of Punjab plains, the riverbeds lie far below the general level of land, which prevents infiltration of river flow to general water table (Soil Survey of Pakistan, 1967). The presence of lime in soil parent material, deep water table and less infiltration of river flow to ground water table might increase the EC and resultantly water becomes unfit for irrigation purposes. However, the effect of different qualities of water on soil health and crop yield is also governed by the type of soil, climate and management practices (Singh et al., 1992). It is therefore, important to point out that waters having EC up to 1.25 ds m -1 may be used to raise most of the crops on light textured soils without affecting soil quality (Pervaiz et al., 2003). Chaudhry and Rana (1975) reported that water having < 7.5 SAR and 1.25 me L -1 RSC did not create problems to soils and crops. Irrigation water having EC < 3.0 ds m -1, SAR < 10 (mmol L -1 ) 1/2 and RSC < 2.50 me L -1 is safe for coarse textured soils with out creating any potential hazard (WWF, 2007). In general, waters of EC values below 0.75 ds m -1 are satisfactory for irrigation and the use of these waters will not create any problem except some salt sensitive crops. However, the use of unfit water due to high EC will cause salinization. To avoid salinzation, it was proposed to increase/decrease the depth of bore to find good quality water (Yonus, 1977). The farmers can use marginal and unfit water for salt tolerant crops (wheat, sorghum and barley) and fruit (Guava) trees etc. It is also recommended that on degraded soils, the poor quality irrigation water may be used to grow Eucalyptus and Acacia for timber and fuel, and Atriplex spp. for grazing purposes. However, quality of irrigation water in most of the union councils of Taxila is still suitable for raising crops and orchards. References Ali, M.S., S. Mahmood, M.N. Chaudhary and M. Sadiq Irrigation quality of ground water of twenty villages in Lahore district. Soil and Environment 28(1): Chaudhry, H.G. and G. M. Rana Effect of tubewell irrigation on the SCARP-I, CMC Pub. No. 27, WAPDA, Lahore.

5 Ground water quality for irrigation 171 Idris, M. and M. Shafiq Irrigation quality of groundwater in Quetta division of Balochistan. Pakistan Journal of Soil Science 16: Kashif, S.R., M. Akram, M. Yaseen and S. Ali Studies on heavy metals status and their uptake by vegetable by in adjoining areas of Hudiara drain in Lahore. Soil and Environment 28(1): Khalid, R., T. Mahmood, Z. Abbas, M.D. Dilshad and M.I. Lone Ground water quality of irrigation water in Rawalpindi district. Pakistan Journal of Soil Science 22: Malik, D.M., M.A Khan and T.A. Chaudhry Analysis manual for soils plants and water. Soil Fertility Survey and Soil Testing Institute, Lahore. 74p. Nizami, M.I., M. Shafiq, A. Rashid and A. Aslam The soils and their agricultural development potential in Pothwar. WRRI and NARC, Islamabad, Pakistan. p: 5-7. Page, A.L., R.H. Miller and D.R. Keeney Methods of Soil Analysis Part II, 2 nd Ed. American Society of Agronomy. No. 9. Madison, Wisconsin, USA. Pervaiz, Z., S.S.H. Kazmi and K.H Gill Characterization of ground water in Gujrat district. Pakistan Journal of Soil Science 22: Singh, R.B., P.S. Minhas and R.K. Gupta Effect of high salinity and SAR waters on salinization, sodication and yield of pearl-millet and wheat. Agricultural Water Management 21: Soil Fertility Survey and Soil Testing Institute Annual Report Soil Fertility Survey and Soil Testing Institute, Rawalpindi. p: 6-7. Soil Survey of Pakistan Reconnaissance Soil Survey Report, Rawalpindi district. Soil Survey of Pakistan, Lahore. p: 11. U.S. Salinity Laboratory Staff Diagnosis and Improvement of Saline and Alkali Soils. USDA Hand book 60, Washington, D.C., USA. WWF National surface water classification criteria and irrigation water quality guidelines for Pakistan. Hudiara drain project phase II funded by UNDP under GEF small grants programme. Yonus, M.M Water quality in Indus plain. Keynote paper. p In: Proceeding Seminar on Water Management for Agriculture, November 15-7, 1977, Lahore, Pakistan.