Assessment of Water Quality of Goalichara: A Water Quality Index Based Approach

Transcription

1 Assessment of Water Qualty of Goalchara: A Water Qualty Index Based Approach 1* Sourav Ray, 2 S. H. Bar, 3 S. D. Shuvro 1* Department of Cvl and Envronmental Engneerng, Shahjalal Unversty of Scence and Technology, Sylhet, Bangladesh 2 Department of Cvl Engneerng, Leadng Unversty, Sylhet, Bangladesh 3 Department of Water Resources Engneerng, Bangladesh Unversty of Engneerng and Technology, Dhaka, Bangladesh * Correspondng author: sourav.ceesust@gmal.com ABSTRACT Ths study provdes the assessment of the present status of water qualty of Goalchara and downstream ponts of ths canal at the Surma Rver based on analyss of water sample collected from the chara and ts downstream ponts. The nvestgaton was based on laboratory tests on water samples obtaned from fve samplng ponts. The test parameters were ph value, turbdty, alkalnty, bochemcal oxygen demand, dssolved oxygen, total solds, total dssolved solds, and chlorde. The ndvdual water qualty ndex was calculated based on CCME WQI (Canadan Councl of Mnsters of the Envronment Water Qualty Index) formula for dfferent locatons at Goalchara. The ndex values found for agrculture purpose ranged from to 61.33, for aquatc lfe ranged from to 60.37, and for drnkng purpose ranged from to It was found that CCME WQI value for drnkng purposes, agrculture purpose, and aquatc lfe ndcate more or less margnal water qualty. Also, NS WQI (Natonal Santaton oundaton Water Qualty Index) was appled to the same locaton. The overall NS WQI value at dfferent samplng ponts of Goalchara was n the range 34 58, ndcates more or less bad water qualty n the canal. The study showed that dfferent parameters analyzed at the same locatons do not change sgnfcantly n dfferent seasons and the water qualty of ths chara s unsafe for human and aquatc lfe. Keywords: Water qualty, CCME ndex, NS ndex 1. INTRODUCTION Ground water and rver water are the man water sources of Bangladesh. However, n some hlly areas of Bangladesh small local canals transport water from upstream water bodes whch are the man water sources for peoples lvng nearby. The qualty of these surface water sources are often found napproprate for use, hence need to be justfed. However, surface water qualty assessment often becomes complex due to the presence of numerous ndcatng parameters. On the other hand, assessng water qualty on the bass of sngle statstcal analyss concernng ndvdual parameters remans cumbersome, hence not popular and dffcult to understand by mass people [1, 2]. Oppostely, Water Qualty Index (WQI) s an effectve tool that combnes composte nfluence of each parameter wth a sngle value ndcatng the overall qualty of water. Varous researchers developed numbers of WQI for varous regons after the concept was orgnally ntroduced by Horton [3]. or beng easly understandable and due to ts capacty of reducng the bulk of nformaton, the system gets ncreased mportance worldwde. Water Qualty Index ncreases the ablty of understandng of certan water qualty n a glmpse that s useful to the polcy makers, as well as users of the water resource [4]. Horton ntally ntroduced water qualty ndex (WQI) n Unted States by selectng 10 most commonly used water qualty varables [3]. Snce then t has been wdely appled and accepted n European, Afrcan and Asan countres [5 8]. Later, n 1970 Brown [9] proposed an approach based on weghts to ndvdual parameter. A general WQI approach [10] s based on the most common factors, whch are descrbed n the followng three steps: Parameter Selecton [11], Determnaton of Qualty uncton (curve) for Each Parameter Consdered as the Sub-Index and Sub-Indces Aggregaton wth Mathematcal Expresson [12]. However, snce ts frst applcaton there have been varety of modfcatons for water qualty ndex for varous purposes. Modfcaton for local (regonal) purposes s also often appled. 2. MATERIALS AND METHODS 2.1 Study Area Sylhet s a major cty n north-eastern Bangladesh located on the banks of the Surma Rver and surrounded by the Janta, Khas and Trpura hlls. The cty has nne local canals (called Chara) flowng through t. Among nne, two man canals are called Malnchara and Goalchara. These two man canals are combned wth the estuary of the Rver Surma at ther ends. It s observed that the Malnchara and Goalchara receve a consderable polluton load manly from domestc waste water ncludng human waste and food waste, but also ndustral waste water ncludng power staton, tea ndustres and food processng ndustres. The ultmate result of ths polluton s the deteroraton of Surma water qualty. Despte havng polluton load, the water of these two canals s the source of varous water demand of nearby people. Consderng the water uses mportance from these canals, assessment of water qualty for ths area s a demand of tme. The study of seasonal varaton n water qualty of natural canals as well as Surma Rver ndcated that polluton n dry season s much hgher than n wet season n Surma Rver [13]. 336

2 gure 1: Locaton map of Goalchara wth samplng ponts. 2.2 WATER QUALITY INDEX (WQI) Among varous modfcatons of WQI systems the followng two were used n ths study: Canadan Councl of Mnsters of the Envronment Water Qualty Index (CCME WQI) Ths consstent method was formulated by Canadan jursdctons to convey the water qualty nformaton for both management and the publc. A commttee, establshed under the jursdcton of Canadan Councl of Mnsters of the Envronment (CCME) has developed ths Water Qualty Index. Ths formula s proved useful for many water agences n varous countres wth slght modfcaton [14 16]. Besdes of determnng WQI for drnkng purpose, ths method support water qualty assessment for both aquatc lfe and agrcultural use n accordance wth specfc gudelnes. The parameters related wth varous measurements may vary from one staton to the other whle samplng protocol requres at least four parameters, sampled at least four tmes [17, 18]. The calculaton of ndex scores n CCME WQI method can be obtaned by usng the followng relaton: WQI 100 (1) Where three factors 1, 2, and 3 are defned as scope, frequency and ampltude respectvely. The factor of arses because each of the three ndvdual ndex factors can range as hgh as 100. Ths means that the vector length can reach as a maxmum. Dvson by brngs the vector length down to 100as a maxmum. A bref descrpton of calculaton of scope frequency and ampltude s gven below: actor 1: Scope 1 (Scope) represents the extent of water qualty gudelne non-complance over the tme perod of nterest. It has been adopted drectly from the Brtsh Columba Index: number of faled varables 1 ) 100 (2) total number of varables Where varables ndcate those water qualty varables wth objectves whch were tested durng the tme perod for the ndex calculaton. actor 2: requency 2 (requency) represents the percentage of ndvdual tests that do not meet objectves ( faled tests ): number of faled tests 2 ) 100. (3) total number of tests actor 3: Ampltude 3 (Ampltude) represents the amount by whch faled test values do not meet ther objectves. 3 s calculated n three steps. a. The number of tmes by whch an ndvdual concentraton s greater than (or less than, when the objectve s a mnmum) the objectve s termed an excurson and s expressed as follows. When the test value must not exceed the objectve: faled test value excurson ) -1. (4) objectve j or the cases n whch the test value must not fall below the objectve: 337

3 objectve j excurson ) -1. (5) faled test. value n WQI Q W 1 (8) b. The collectve amount by whch ndvdual tests are out of complance s calculated by summng the excursons of ndvdual tests from ther objectves and dvdng by the total number of tests (both of those meetng objectves and those not meetng objectves). Ths varable, referred to as the normalzed sum of excursons or nse, s calculated as: n excurson 1 nse (6) number of tests c. 3 s then calculated by an asymptotc functon that scales the normalzed sum of the excursons from objectves (nse) to yeld a range between 0 and 100. nse 3 (7) [14 16] nse 0.01 A moredetaled descrpton of computaton method and water qualty ratng as per dfferent Water Qualty Index methods can be found n the lterature [12] Natonal Santaton oundaton Water Qualty Index (NS WQI) A usual water qualty ndex method was developed by payng great rgor n selectng parameters by Brown et al., developng a common scale and assgnng weghts. The challenge was supported by the Natonal Santaton oundaton (NS) and therefore termed as NSWQI n order to calculate WQI of varous water bodes that are crtcally polluted. Total nne water qualty parameters such as temperature, ph, turbdty, fecal colform, dssolved oxygen, bochemcal oxygen demand, total phosphates, ntrates and total solds are used whle comparng water qualty for dfferent water bodes [9, 19]. Collected water qualty data are transferred to a weghtng curve chart, where a numercal value of Q s obtaned. A detal descrpton of the method can be found elsewhere [20]. The mathematcal expresson for NS WQI s as follows: Where, Q = sub-ndex for th number of water qualty parameter; W = weght assocated wth th number of water qualty parameter; n= number of water qualty parameters. To complete the determnaton of Water Qualty Indces, a number of water qualty parameters were tested. The test parameters were ph value, turbdty, alkalnty, bo oxygen demand, dssolved oxygen, total solds, total dssolved solds, and chlorde. 3. RESULTS AND DISCUSSION Water sample collected from fve dfferent locatons of Goalchara were tested to determne the Water Qualty Index (WQI). To calculate desred WQI, each parameter were multpled by weghtage factors accordng to ther relatve mportance n determnng qualty ndex as prescrbed n NS and CCME ndex. Results obtaned from analyss are gven n followng sectons. 3.1 The CCME WQI CCME Water Qualty Index for Goalchara was calculated n the context of drnkng purpose, aquatc lfe, and agrcultural use. CCME WQI s desrable n that sense that t compares observatons wth a benchmark nstead of comparng to a ratng curve [14]. Ths advantage of CCME ndex makes ths more representatve for evaluaton of drnkng water qualty. Whle calculatng WQI, average values calculated for dfferent seasons for each parameter were used. Table1 shows the classfcaton of water qualty ndex for water from Goalchara used for drnkng purpose, based on CCME WQI value. The CCME WQI value of 45 to 64 ndcates margnal water qualty. The water qualty ndex of S 1, S 2, S 3, S 4, and S 5 was found wthn to 50.19, representng water of margnal qualty. Table 1: CCME water qualty ndex for drnkng water from Goalchara Staton Perod CCME WQI Remarks S The CCME WQI Value s n between 45 to 64. So the water qualty s S S S S The CCME WQI Value s n between 45 to 64. So the water qualty s The CCME WQI Value s n between 45 to 64. So the water qualty s The CCME WQI Value s n between 45 to 64. So the water qualty s The CCME WQI Value s n between 45 to 64. So the water qualty s 338

4 Calculaton of CCME ndex for aquatc lfe was done usng the alkalnty, DO, BOD 5, TS, TDS, and chlorde. Whle ph, turbdty, alkalnty, DO, BOD 5, TS, TDS and chlorde were used for the calculaton of CCME ndex for agrcultural use. All the results ndcate below margnal water qualty for aquatc lfe and agrculture purpose n Goalchara. Results for the CCME ndex for aquatc lfe and agrcultural use are gven n gure 2. Deterorated water qualty from Goalchara n CCME ndex shows no usablty of ths water for drnkng purposes, but the water may be used for agrcultural purposes. However, below margnal standard s not recommended f the alternatve supply s avalable. 3.2 NS WQI for Overall Water Qualty Water qualty ndex at fve dfferent locatons at Goalchara (S 1, S 2, S 3, S 4, and S 5 ) was estmated usng the formula proposed by NS WQI. It s ndcated n the Table 2 that almost all samples were found to be margnal n qualty. Ths may be due to the presence of varous non-pont source pollutants. Moreover, the area s densely populated around the water body. gure 2: CCME WQI for aquatc lfe and agrcultural use. Table 2: Water qualty ndex for four dfferent seasons n Goalchara November-2012 ebruary-2013 May-2013 June-2013 Staton NS WQI Remarks NS WQI Remarks NS WQI Remarks NS WQI Remarks S1 58 ar 49 Bad 41 Bad 42 Bad S2 49 Bad 50 ar 38 Bad 45 Bad S3 41 Bad 47 Bad 40 Bad 43 Bad S4 35 Bad 39 Bad 34 Bad 44 Bad S5 45 Bad 41 Bad 41 Bad 47 Bad 4. CONCLUSION The results from data analyss show that the water s unft for drnkng purposes wthout any form of treatment and the water s undoubtedly undesrable for aquatc lfe and agrculture. Several mportant water qualty parameters lke ph, turbdty, alkanty and DO value were found to be unusual for Goalchara. However, BOD, TDS, TS, and chlorde were found more or less tolerable for aquatc lfe. Clear evdence s that usablty of water for drnkng purpose decreased at the vcnty of the Surma Rver. Ths may be due to the gradual organc polluton load from the nearby areas. In the recent years, ths area has been rapdly habtuated by local tea gardener s causng ncremental waste dsposal n Goalchara. It s evdent that, snce the current trend of polluton s lkely to contnue, the water qualty n the Surma Rver s lkely to get worse n the comng years, especally n the dry season. REERENCES [1] I. S. Akoteyon, A. O. Omotayo, O. Soladoye, and H. O. Olaoye, Determnaton of water qualty ndex and sutablty of urban rver for muncpal water supply n Lagos-Ngera, Eur J Sc Res, vol. 54, no. 2, pp , [2] D. Katyal, Water Qualty Indces Used for Surface Water Vulnerablty Assessment, Int. J. Envron. Sc., vol. 2, no. 1, [3] R. K. Horton, An ndex number system for ratng water qualty, J. Water Pollut. Control ed., vol. 37, no. 3, pp , [4] M. Nasran, A new water qualty ndex for envronmental contamnaton contrbuted by mneral processng: A case study of Amang (Tn Talng) processng actvty, J. Appl. Sc., vol. 7, no. 20, pp ,

5 [5] C. Itcescu, L. P. Georgescu, and C. M. Topa, Assessng the Danube water qualty ndex n the cty of Galat, Romana, Carpathan J. Earth Envron. Sc., vol. 8, no. 4, pp , [6] I. Lewn, S. Jusk, K. Szoszkewcz, I. Czernawska-Kusza, and A. E. \Lawnczak, Applcaton of the new multmetrc MMI_PL ndex for bologcal water qualty assessment n reference and human-mpacted streams (Poland, the Slovak Republc), Lmnol.-Ecol. Manag. Inland Waters, vol. 49, pp , [7] D. Sarala Thambavan and T. S. R. Uma Mageswar, Water qualty ndces as ndcators for potable water, Desalnaton Water Treat., vol. 52, no , pp , [8] S. Venkatramanan, S. Y. Chung, S. Y. Lee, and N. Park, Assessment of rver water qualty va envronmentrc multvarate statstcal tools and water qualty ndex: a case study of Nakdong Rver basn, Korea, Carpathan J. Earth Envron. Sc., vol. 9, pp , [9] R. M. Brown, N. I. McClelland, R. A. Dennger, and R. G. Tozer, A WATER QUALITY INDEX- DO WE DARE, Water Sew. Works, vol. 117, no. 10, pp , [10] N. ernández, A. Ramírez, and. Solano, PHYSICO-CHEMICAL WATER QUALITY INDICES-A COMPARATIVE REVIEW, BISTUA Rev. ac. Cenc. BASICAS, vol. 2, no. 1, [11] D. A. Dunnette, A geographcally varable water qualty ndex used n Oregon, J. Water Pollut. Control ed., pp , [12] S. Tyag, B. Sharma, P. Sngh, and R. Dobhal, Water qualty assessment n terms of water qualty ndex, Am. J. Water Resour., vol. 1, no. 3, pp , [13] M. Ahmed, A. A. M. Ahmed, and R. K. Mazumder, Deteroraton of water qualty of Surma Rver nfluenced by Natural Canals Passng through Sylhet Cty of Bangladesh, proceedngs of Intl, n Conf. on Env. Aspects of Bangladesh (Sept. 4) pp, 2010, pp [14] Canadan Councl of Mnsters of the Envronment, Canadan water qualty gudelnes for the protecton of aquatc lfe: CCME Water Qualty Index 1.0, Techncal Report, In: Canadan envronmental qualty gudelnes, 1999, Canadan Councl of Mnsters of the Envronment, Wnnpeg, Techncal, [15] A. A. Khan, R. Paterson, and H. Khan, Modfcaton and applcaton of the CCME WQI for the communcaton of drnkng water qualty data n newfoundland and labrador, n 38th, Central Symposum on Water Qualty Research, Canadan Assocaton on Water Qualty (ebruary 10 11, 2003), 2003, vol [16] A. Lumb, D. Hallwell, and T. Sharma, Applcaton of CCME Water Qualty Index to montor water qualty: A case study of the Mackenze Rver basn, Canada, Envron. Mont. Assess., vol. 113, no. 1 3, pp , [17] N. C. Kankal, M. M. Indurkar, S. K. Gudadhe, and S. R. Wate, Water qualty ndex of surface water bodes of Gujarat, Inda, Asan J Exp Sc, vol. 26, no. 1, pp , [18] A. A. Khan, A. Tobn, R. Paterson, H. Khan, and R. Warren, Applcaton of CCME procedures for dervng ste-specfc water qualty gudelnes for the CCME Water Qualty Index, Water Qual. Res. J. Can., vol. 40, no. 4, pp , [19] D. Kumar and B. J. Alappat, NS-Water Qualty Index: Does It Represent the Experts Opnon?, Pract. Perod. Hazard. Toxc Radoact. Waste Manag., vol. 13, no. 1, pp , [20] Abbas, Tasneem, and Shahd A. Abbas. Water qualty ndces. Elsever,