Application of Qual2k Model for Prediction of Water Quality in a Selected Stretch of Pamba River
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International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 6, June 2017, pp. 75–84, Article ID: IJCIET_08_06_009 Available online at http://iaeme.com/Home/issue/IJCIET?Volume=8&Issue=6 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed APPLICATION OF QUAL2K MODEL FOR PREDICTION OF WATER QUALITY IN A SELECTED STRETCH OF PAMBA RIVER Ashwani S Research Scholar, Manipal Institute of Technology, Manipal University, Karnataka, India Vivek B Scientist, Centre for Water Resources Development and Management (CWRDM), Kunnamangalam, Kozhikode, India Shilpa Ratnoji Associate Professor, Department of Civil Engineering, Manipal Institute of Technology, Karnataka, India Jayakumar P Scientist, Centre for Water Resources Development and Management (CWRDM), Kunnamangalam, Kozhikode, India Jainet P J Scientist, Centre for Water Resources Development and Management (CWRDM), Kunnamangalam, Kozhikode, India ABSTRACT Pamba River acts as a source for drinking, irrigation and is subjected to pollution loads. The application of QUAL2K model for a stretch of 20.63km of the river for prediction of water quality at Cherukole where a WSS is proposed is studied here. The effect of point source from dairy farm at Cherukole is analysed. Samplings done during the monsoon and post monsoon showed how the water quality changed along the entire stretch of the river. Post monsoon and pilgrimage season data was used for calibration and validation of the model. The results show that the values predicted by the model are in good agreement with the measured values in majority of the stations, and that the water quality at the proposed location of WSS is within standards. Key words: Pamba River, QUAL2K, River pollution, Water Quality Prediction. Cite this Article: Ashwani S, Vivek B, Shilpa Ratnoji, Jayakumar P and Jainet P J. Application of Qual2K Model for Prediction of Water Quality in a Selected Stretch of Pamba River. International Journal of Civil Engineering and Technology, 8(6), 2017, pp. 75–84. http://iaeme.com/Home/issue/IJCIET?Volume=8&Issue=6 http://iaeme.com/Home/journal/IJCIET 75 [email protected] Ashwani S, Vivek B, Shilpa Ratnoji, Jayakumar P and Jainet P J 1. INTRODUCTION Water is one of the basic necessities and is facing increasing demand due to population growth, industrialization and urbanization. The quality of the available water is getting depleted day by day due to, discharge of urban and industrial sewage, agricultural runoff etc. India has 14 major and 55 minor riverine systems and is often referred to as “land of rivers”. Human life is dependent on rivers for irrigation, potable water, transportation, generation of electricity etc. In addition, these rivers are worshipped as goddesses by the people of several regions of India. According to studies carried out by National Environmental Engineering Research Institute (NEERI), 70 percent of river water in India is polluted, mainly by wastes of domestic origin. The main consequence of river pollution is depletion of dissolved oxygen (DO) levels. If it falls below 2mg/l the survival of fishes will be affected and is considered to be one of the most important parameter, Other than that carbonaceous biochemical oxygen demand (CBOD), total nitrogen (TN), total phosphorous (TP), temperature and pH also determines quality of water. In order to achieve the designated standards of water quality, appropriate waste management measures have to be adopted so that capacity of the stream is not exceeded in the entire river[1].The complex relationships between waste loads from different sources and the resulting water quality is best described with the help of mathematical models. The selection of a model to predict the behaviour of system is based on the number of parameters it can model and the level of accuracy achieved [2].The prediction of water quality of a stretch of river Pamba has been done using the enhanced version of QUAL2K model which was developed by the United States Environmental Protection Agency (US EPA). The conservative and non-conservative parameters considered in the study are BOD, TN, TP, TSS and Alkalinity. Many water quality models were developed over the past years for various types of water bodies.QUAL2E water quality model developed during the earlier stages had many limitations. To overcome those limitations, QUAL2K was developed by Park and Lee in 2002[3]. The modifications in QUAL2K includes the expansion of computational structures and addition of new constituent interactions like algal BOD, de-nitrification and DO change caused by fixed plants. This model can simulate up to 16 water quality parameters along a river and its tributaries. The first step involves the segmentation of the river into a number of sub reaches. The assumptions required for proper running of the model are (a) the advective transport is based on the mean flow, (b) the water quality indicators are completely mixed over the cross-section and (c) the dispersive transport is correlated with the concentration gradient. Many studies have been carried out using different versions of QUAL2E series which includes QUAL2K and the modernized version known as QUAL2Kw. QUAL2K was applied for water quality modeling in the Bagmati River which concluded that, the model represented the field data almost accurately. Various water quality management options such as pollution loads modification and affixing of weirs for local oxygenation were adopted to enhance DO levels, The results showed that, local oxygenation is effective in raising DO levels[4]. Furthermore QUAL2K was used to determine the water environmental capacity of Hongqi River (China).The results obtained revealed that the simulated results correlated precisely with the measured data [5]. QUAL2K was used to model the polluted segment of Ndaguru River and to evaluate the performance of the model using correlation coefficient (R2) and standard error (SE) [6]. QUAL2K model was used for simulating the various water quality parameters of River Yamuna characterized by increased waste loading from sewers and drains. The results obtained proved the ability of QUAL2K for effective simulation of water quality [7].The impact of wastewater discharge on water quality of Zayandeh-rood River was studied by the application of QUAL2K with DO and BOD as the parameter of concern. The results showed that the model is perfectly reliable in modelling streams when http://iaeme.com/Home/journal/IJCIET 76 [email protected] Application of Qual2K Model for Prediction of Water Quality in a Selected Stretch of Pamba River complex data are not available [5]. In most of the studies carried out in the application of QUAL2K model, it was observed that the model represents the field data quite well and guarantees the use of QUAL2K for future river water quality options [8]. 2. PROBLEM DEFINITION Currently there are 18 Water Supply Schemes (WSS) both ongoing and proposed with Pamba as a source. It also serves as a source of water for irrigation schemes. The water quality is of serious concern especially in the mid-stretches because majority of the WSS are concentrated in this region. Wastewater flow to the river is mainly from towns located on the bank of the river, point sources from hospitals, small scale industries, institutions and pollution caused by the pilgrims during the pilgrimage season. The region generally experiences scarcity for water and Pamba is the only source by which even the basic necessities are met by the local inhabitants. Therefore it becomes a necessity to predict the water quality at ‘Cherukole’ where a new WSS is proposed. Prior studies have shown that outbreaks of water borne diseases occur as a result of severe pollution caused during the pilgrimage season. Absence of efficient sewage collection and treatment facilities at the pilgrim center of Sabarimala adds to the pollution load in the river. It is estimated that daily average sewage generated at Sabarimala is about 3.5 MLD which is discharged without sufficient treatment into the river. Coliform count in the river was reported as 40,000 to 46,000/100ml during pilgrimage seasons. Apart from this, the river is considered to be sacred and various religious rituals were done on the banks of river. 3. MATERIALS AND METHODS 3.1. Study Area The river Pamba has a length of 176 kms, and a catchment area of 2235 sq. km. It originates from Pulachimalai in the Western Ghats. Major portion of the river flows through Pathanamthitta and Alappuzha districts of Kerala and finally discharges to Vembanad Lake which is a Ramsar site. The river has five major tributaries namely Kakki, Arudi, Kakkad, Kal and Pambiyar. Many portions of the river becomes dry during summer seasons. The study area covers a stretch of 12.63 kms of Pamba River. Four sampling sites Viz: Athikkayam (AK), Mukkam (MK), Madammon (MM) and Ranni (RN) were selected for the study. Apart from this, at Cherukole a station 8.2 kms from the last sampling station mentioned earlier, where a WSS is proposed is also chosen and selected water quality parameters at the station were predicted using the water quality model QUAL2K. Fig. 1 shows the sampling sites for water quality monitoring chosen along with the river stretch. http://iaeme.com/Home/journal/IJCIET 77 [email protected] Ashwani S, Vivek B, Shilpa Ratnoji, Jayakumar P and Jainet P J Figure 1 Map showing the study area in Pamba Basin 4. METHODOLOGY 4.1. Reach Segmentation The stretch of the river between Athikkayam to Cherukole has been segmented into 22 number of reaches of unequal lengths. Athikkayam was taken as the upstream boundary condition. The option of internal calculation was selected for the downstream boundary condition.Fig.2 shows the study area with the location of predicted and sampling stations along with the point source. Fig.3 shows the segmentation of the stretch with the location of point sources discharged to the river along with monitoring stations.