Quality of Groundwater for Irrigation in Tehsil Taxila of District Rawalpindi, Punjab
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Soil & Environ. 29(2): 167-171, 2010 www.se.org.pk Online ISSN: 2075-1141 Print ISSN: 2074-9546 Quality of groundwater for irrigation in tehsil Taxila of district RawalpindI, Punjab A. Waheed1, R. Khalid1, T. Mahmood1, M.T. Siddique2* and A.S. Javed1 1Soil Fertility Survey and Soil Testing Institute, Rawalpindi 2PMAS-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 -1 - - -1 of 7.6 and 3.3 me L whereas, HCO3 and Cl were dominant anion with mean values of 4.2 and 3.0 me L , 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 management practices (Singh et al., 1992). However, water The Pothwar plateau consists of an area of more than with EC values below 0.75 dS m-1 are satisfactory for one million hectares. The plateau generally has flat to irrigation, although salt sensitive crops may be adversely gently undulating surface, locally broken by gullies and low affected by the use of irrigation waters having conductivity hills/ ranges. Rawalpindi district is an important part of values in the range 0.25-0.75 dS m-1 (U.S. Salinity Lab. Pothwar plateau (latitude 32º 10 to 34º 9 N and longitude Staff, 1954). The quality of groundwater is highly variable 71º 10 to 73º 55 E) consisting of five tehsils. Taxila is one in various parts of the country both vertically and of them situated near Margalla Hills. Rawalpindi district horizontally from complete fresh to extremely saline. In lies in high to medium rainfall zone, rainfall varies from Rawalpindi district due to deeply incised nature of main 500 to 1000 mm per annum. About 70 % of annual rivers, groundwater over most of the areas are derived from precipitation is received in the summer months of July and precipitation. Ali et al. (2009) reported that quality of August (Nizami et al., 2004). The farmers have to rely on available ground water in most (76.6%) of the villages of irrigation through tubewells for growing vegetables and Lahore district was not suitable for sustainable crop other ornamental crops due to seasonal and erratic rains. It production and soil health. According to Soil Fertility is estimated from the groundwater survey of the country Survey and Soil Testing Institute, Rawalpindi (2006-07), that with assured and dependable supply from private 73% of water samples analyzed, were fit for irrigation tubewells, farmers have changed the cropping pattern during 2006-07. Khalid et al. (2003) reported that in towards high value crops like vegetables and fruits. Rawalpindi district, 71% of water samples were fit, 9% For successful crop production on sustainable basis, the marginally fit and 20% were unfit for irrigation. The 48% quality of groundwater is of main concern. The common of water samples were unfit for irrigation in Gujrat district quality characteristics considered are electrical conductivity of Punjab (Pervaiz et al., 2003). Kashif et al., (2009) (EC), sodium adsorption ration (SAR) and residual sodium investigated quality and heavy metal occurrence in Hudiara carbonate (RSC) (Idris and Shafiq, 1999). The drain water and its accumulation in vegetable crops in concentration and composition of dissolved constituents in Lahore region. The water of Hudiara drain was found fit for water determine its quality for irrigation use. It is difficult irrigation purpose but not fit in relation to heavy metal to define the critical limits of EC, RSC and SAR because contents. The objective of present study was to assess the the effect of different qualities of water on soil health and *Email: [email protected] © 2010, Soil Science Society of Pakistan (http://www.sss-pakistan.org) 168 Waheed, Khalid, Mahmood, Siddique and Javed - quality of groundwater in the Taxila tehsil of Rawalpindi anions, HCO3 was the dominant anion ranging from 0.1- district for its suitability to irrigation. 12.9 me L-1 with mean value of 4.2 me L-1 followed by Cl- -1 -2 Materials and Methods with mean value of 3.0 me L . However, CO3 were present in few water samples. 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 Electrical conductivity (EC) status randomly in all tehsils. The samples were taken in polythene bottles after thirty minutes of tubewell operation. The classification of water samples on the basis of EC The depth of tubewells/wells ranged from 30 to 200 feets. (Table 3) indicated that EC of 76 % water samples were The tubewells water is being used for raising vegetables, within safe limits (<1.00 dS m-1) whereas, 11% samples ornamental plants, forests trees and nurseries. The water were unfit and 14% were marginally fit for irrigation. The samples were analyzed at Soil Fertility Survey and Soil EC of all water samples ranged from 0.20-4.60 dS m-1 with Testing Institute, Rawalpindi for electrical conductivity a mean value of 0.95 dS m-1. +2 +2 + -2 - (EC), cations (Ca + Mg , Na ) and anions (CO3 , HCO3 , Residual sodium carbonates (RSC) status Cl-) by the methods described by Page et al. (1982) and U.S. Salinity Lab. Staff (1954). Residual sodium carbonates Table 4 showed the classification of water samples on (RSC) and sodium adsorption ratio (SAR) were the basis of RSC. The RSC ranged from 0.2-8.0 me L-1 with determined by following formulas of U.S. Salinity Lab. mean value of 0.60. Out of 628 water samples, the RSC of Staff (1954). 587 water samples was within safe limits (<1.25 me L-1). Only 14 water samples (2%) were unfit and 27 (4%) were RSC (meq L-1) = (CO -2 + HCO -) - (Ca++ + Mg+) 3 3 marginally fit due to higher RSC. SAR = Na+ / √ Ca++ + Mg+ /2 The criteria used for evaluation of irrigation water was Sodium adsorption ratio (SAR) status proposed by Malik et al. (1984) and is given in Table 1. The SAR values of water in most of the union councils Table1: The criteria for suitability of irrigation water. (Table 5) were within safe limit (< 6). The SAR ranged from 0.0-11.7 10 [(mmol L-1)1/2] with mean value of 1.7 Parameter Fit Marginally fit Unfit (Table 2). With respect to their distribution, 610 (97%) E C (dS m-1) 1.0 1.0 – 1.25 > 1.25 water samples were within safe limits and only one water RSC (me L-1) <1.25 1.25 – 2.25 > 2.25 sample of Thatta Khalil union council was unfit due to high SAR [(mmol L-1)1/2] < 6 6- 10 > 10 SAR. Results Commutative effect of EC, RSC, SAR on water quality The analytical data regarding cations, anions, EC, SAR and RSC of tubewell water in tehsil Taxila are presented in Classification of water on the basis of commutative following paragraph. effect of three parameters (EC, RSC, SAR) is presented in Table 6 and Figure 1. It indicated that out of 628 water Ionic concentration samples, 416 (66%) were fit, 129 (21%) were marginally fit Ca+2 + Mg+2 were the dominant cations, ranging from and 83 (13%) were unfit for irrigation according to the 2.0 to 57.0 me L-1 with mean value of 7.6 me L-1 followed suitability criteria (Table 1). by Na+ with mean value of 3.3 me L-1 (Table 2). Among the Table 2: The minimum, maximum, and mean values of cations, anions, electrical conductivity (EC), sodium adsorption ration (SAR) and residual sodium carbonate (RSC) +2 +2 + -2 - - Ca +Mg Na CO3 HCO3 Cl EC RSC SAR -1 -1 -1 -1 1/2 me L dS m me L (mmol L ) Min 2.0 0.0 0.0 0.1 0.8 0.20 0.0 0.0 Max 57.0 30.0 6.0 12.9 18.0 4.60 2.8 11.7 Mean 7.6 3.3 0.6 4.2 3.0 0.95 0.6 1.7 SD 6.10 3.50 0.76 1.81 2.61 0.68 4.86 1.46 Ground water quality for irrigation 169 Water quality in union councils of tehsil unfit for irrigation. Whereas, maximum number (8) of unfit Taxila water samples (32%) were recorded in Khurram Pracha Jalala union council had maximum 48 (91%) water followed by 39 (21%) in Thatta Khalil union councils. In under safe limits followed by Usman Khattar (87%).