Study on Cauvery River at Erode
— by Satheesh Kumar T, July 2 2021 —
INTRODUCTION:
River Cauvery, also referred as Ponni, is an Indian river flowing through the statesofKarnataka and Tamil Nadu. It is the third largest afterGodavari and Krishna in south India and the largest in Tamil Nadu which on its course bisects the state into North and South. Originating in the foothills of Western Ghats at TalaCauvery, Kodagu in Karnataka, it flows generally south and east through Karnataka and Tamil Nadu and across the southern Deccan plateau through the southeastern lowlands, emptying into the Bay of Bengal through two principal mouths in Poompuhar, Tamil Nadu.
STUDY AREA:
The river enters Tamil Nadu through Dharmapuri district leading to the flat plains where it meanders. It drops into the Hogenakkal Falls just before it arrives in the town of Hogenakkal in Tamil Nadu. The three minor tributaries, Palar, Chinnar and Thoppar enter into the Cauvery on her course, above Stanley Reservoir in Mettur, where the dam has been constructed. It then flows further through the length of Erode district where the river Bhavani, running through the breadth of the district, merges with it. The confluence of the rivers Cauvery, Bhavani and Akash Ganga (mythological) is at the exact place of Bhavani, Tamil Nadu Kooduthurai or Tiriveni Sangamam, Northern part of Erode City. Here, we have to study the Cauvery river basins which are entering into the Erode District.
ACCORDING TO TNPCB:
Tamil Nadu Pollution Control Board (TNPCB) has constituted 6 Teams to carry out Sample collections for the polluted river stretches namely
1.Notchipallam Odai – 11°24’59.11N, 77°40’55.60″E
2.Sunnambu Odai – 11°23’39.26″N, 77°42’7.55″E
3.Pitachaikaranpallam Odai – 11°22’18.97″N, 77° 48’26.45E
4.Perumpallam Odai – 11°20’0.52″N, 77°45’13.38″E.
Five Numbers of drain samples discharged into River Cauvery werecollected by the Inspection team. Drain samples collected from afore-said location were analysed in TNPCB laboratory. The Report of analysis of the samples collected from the drains revealstoachieve the inland surface water standards prescribed by the Board.
ACCORDING TO TNPCB:
Tamil Nadu Pollution Control Board (TNPCB) has constituted 6 Teams to carry out Sample collections for the polluted river stretches namely
1.Notchipallam Odai – 11°24’59.11N, 77°40’55.60″E
2.Sunnambu Odai – 11°23’39.26″N, 77°42’7.55″E
3.Pitachaikaranpallam Odai – 11°22’18.97″N, 77° 48’26.45E
4.Perumpallam Odai – 11°20’0.52″N, 77°45’13.38″E.
Five Numbers of drain samples discharged into River Cauvery werecollected by the Inspection team. Drain samples collected from afore-said location were analysed in TNPCB laboratory. The Report of analysis of the samples collected from the drains revealstoachieve the inland surface water standards prescribed by the Board.
Analysis results of the samples collected from 5 No.of drains contributing to pollution load in River Cauvery :
RESULTS AND DISCUSSION:
1.BOD ( Biological Oxygen Demand):
BOD is determined by analyzing the difference in dissolved oxygen from a sample for five days. Because of this standardized time, BOD is often referred to as BOD-5. The dissolved oxygen readings are usually in parts per million (ppm). Higher BOD indicates more oxygen is required, which is less for oxygen-demanding species to feed on, and signifies lower watequality.
- COD:
A COD test can be used to easily quantify the amount of organics in water. The most common application of COD is in quantifying the amount of oxidizable pollutants found in surface water (e.g. lakes and rivers) or wastewater. chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution.
3.PH :
The pH of river water is the measure of how acidic or basic the water is on a scale of 0-14. It is a measure of hydrogen ion concentration. U.S. natural water falls between 6.5 and 8.5 on this scale with 7.0 being neutral. The optimum pH for river water is around 7.4.
TDS:
Average TDS values are: 7mg l-1 for rainwater, 118mg l-1 for river water and 34 400 mg l -1 for seawater. TDS values for groundwater vary too much for an average to be meaningful.
Total hardness:
Water hardness is the measurement of the amount of ions which have lost two electrons (divalent cations) dissolved in the tested water and is therefore, related to total dissolved solids. The more divalent cations dissolved in the water the “harder” the water. Generally the most common divalent cations are calcium and magnesium.
Conductivity:
Conductivity increases with increasing ion content, which means that in most cases it gives a good approximation of the TDS measurement using the conversion factor of 1 ppm = 2 uS/cm. Conductivity is temperature sensitive and is typically standardized to 25°C
Turbidity:
During periods of low flow (base flow), many rivers are a clear green color, and turbidities are low, usually less than 10 NTU. During a rainstorm, particles from the surrounding land are washed into the river making the water a muddy brown color, indicating water that has higher turbidity values.
TREATMENT AND SOLUTION:
| SL NO | NAME OF THE TEST | EQUATIONS | CHEMICALS USED | DESIRAB LE LIMIT | |
| 01 | pH Method followed: IS 3025(PART-11) : 1983 | Not applicable | Buffer solution prepared using pH tablets or powder of 4.7 and 9.2. | 6.5-8.5 | |
| 02. | Total hardness( as CACO3) Method followed: IS 3025(PART-21): 2009 | Total hardness= AX1000X c ml of sample taken | Buffer solution, EDTA solution. | 300mg/L | |
| 03. | Iron Method followed: Phenanthrolin method | Iron concentration = amount of ironX 1000 ml of sample taken | Phenanthrolinsolution,ammoniuma cetatebuffer, standard iron solution, hydroxylamine HCL solution. | 0.3mg/L | |
| 04. | Turbidity Method followed: Turbidity by | Not applicable | Hydrazine sulphate, Hexa methylene tetramine. | 10 NTU | |
| Nephlometer. | |||||
| 05. | COD Method followed: IS 3025(PART58):2006 | COD=      | Std.K2CR2O7 digestion Sulphuric acid reagent. Ferrion indicator. Std FAS solution. | NILL | |
| 06. | Dissolved oxygen Method followed: IS 3025(PART44):1993 | DO=  | Mangnous sulphate Conc.sulphuric acid Starch indicator solution Std.sodiumthiosulphate | 1.5mg/L | |
| 07. | Total dissolved solids Method followed: IS 3025(PART16):1984 | TDS= | ——– | 500ppm | |
| 08. | BOD Method followed: IS 3025(PART44):1993 | BOD=  | Phosphate buffer Magnesium chloride Calcium chloride Ferric chloride solution Distilled water | 3-5 mg/L | |
| 09. | Nitrates Method followed: Nitrates by PDA method | Nitrate conc=     | Phenol disulphonic acid Std.nitrate solution | 45mg/L |
CONCLUSION:
Erode City Municipal Corporation has completed the establishment of sewage treatment plant and the same was kept ideal for past one year, whereas the UGDSS works have to be completed so as to commission the STP. Hence, the Erode City Municipal Corporation shall expedite the completion of UGDSS in all 60 wards and commission the STP provided at
Vendipalayam Village early so as to stop the discharge of untreated sewage into River Cauvery through Odais and into Kalingarayan Canal through Kona Vaikkal. Thus, these are the treatment systems that are provided to clean the Cauvery river that are flowing through Erode District.
REFERENCE:
1. TNPCB
2. CPCB
4. PrsCauveryanalysis
Lakes of India 