Lok Sabha Question No. 1846 (UNSTARRED), answered on 2020-09-22
Subject: Dying Rivers in Kerala
Ministry: JAL SHAKTI
Asked by: Behanan Benny

## 1846. SHRI BENNY BEHANAN

Will the Minister of JAL SHAKT be pleased to state:

(a) whether it is a fact that many rivers are dying in Kerala due to various environmental f the details thereof along with the name of the rivers and reasons for its death;

(b) whethe r the Union Government has conducted any survey of the rivers and made suggestions Government and if so, the details thereof; and

(c) whether the Union Government has conducted a study on devastating floods and dying river if so, the details thereof?

## ANSWER

## THE MINISTER OF STATE FOR JAL SHAKTI & SOCIAL JUSTICE AND EMPOWERMENT (SHRI RATTAN LAL KATARIA )

(a) &(b) There are two types of rivers in the country; (1) perennial rivers and (2) Non - perennial rivers. In perennial rivers, water remains available throughout the year, while non - perennial rivers are rain fed rive in which water flows only during the rai nfall period. The flow in the rivers is dynamic and depen many parameters such as rainfall, its distribution and intensity in the catchment, catchmen and withdrawals / utilization of water in the basin.

Central Water Commission (CWC) monitors important rivers in the country. Considering average flow of last 20 years of terminal sites of important rivers, no appreciable increa trend in total water availability has been observed. Go vernm nt has taken water conservation initiati especially under Jal Shakti Abhiyan through the process of rain water harvesting and water

As per Central Pollution Control Board (CPCB) report of 2018 on polluted river stret them are found polluted in the state of Kerala bas d on BOD (Biochemical Oxygen Demand) levels. The detail of polluted river stretches is enclosed at Annexure - I

Discharge of untreated and partly treated sewage and industrial effluent along with solid  waste  are  the  major  reasons  for  pollution  in  rivers  in  the  State  of  Kerala.  It responsibility of the State Government to provide necessary sewerage infrastructure, treat discharge the sewage into water bodies & rivers. Sim ilarly, the State Government / ULBs are to prov facilities for proper collection; transportation and management of solid waste and prevent i rivers & water bodies etc.

## GOVERNMENT OF INDIA

## MINISTRY OF JAL SHAKTI,

## DEPARTMENT OF WATER RESOURCES, RIVER DEVELOPMENT & GANGA REJUVENATION

## LOK SABHA UNSTARRED QUESTION NO. 1846

ANSWERED ON 22.09.2020

## DYING RIVERS IN KERA LA

River cleaning is a continuous process and the Central Government is supplementing the State Governments and Union Territories in river rejuvenation through programmes like 'Namami Gange' and 'National River Conservation Plan'.

Water being a St ate subject, its management including conservation, augmentation and e management of rivers and revival of water bodies including rivers/flood plain management in is primarily State's responsibility.

Central Water Commission (CWC) has formulated a Model Flood Plain Zoning Bill way back 1975 which was circulated to all States for implementation. It aims at demarcating zones or be affected by floods of different magnitudes or frequencies and probability levels, specify ing the types of permissible  developments  in  these  zones,  so  that  whenever  floods  actually  occur,  the  dam minimized,  if  not  avoided.  Recently,  Ministry  of  Jal  Shakti  vide  DO  letter  No.  5/03/201 -FM/  dated 19.08.2020 has requested the State Govern ments that high priority may be accorded to the matter urgent action be taken for enactment of suitable legislation regarding Flood Plain Zoning.

The key findings od CWC, based on analysis of rainfall data of IMD, discharge data of sites and i nflow/outflow data of reservoir received from Government of Kerala, are at Annexure - II.

(c) Water Commission had constituted a Committee in September 2018 to carry out study on Kerala  Flood - 2018.  The  Committee  has  submitted  its  Report titled  'Kerala  Floods  and  Solutions'  in December 2018, which was sent to all concerned.

*****

Details of polluted stretches in Kerala as per CPCB report of 2018 as mentioned at part (a)& (b) of the Lok Sabha Unsatrred Question No. 1846 due for Answer on 22.09.2020 .

| River Name       | River Stretch                   | BOD (mg/l)   | Priority   |
|------------------|---------------------------------|--------------|------------|
| 1. Karamana      | Malekkdu to Thiruvallam         | 56.0         | I          |
| 2. Bharathapuzha | Along Patambi                   | 6.6          | VI         |
| 3. Kadambayar    | Manckakadavu to Brahmapuram     | 5.9 - 6.4    | VI         |
| 4. Keecheri      | Puliyannor to Kechery           | 6.4          | VI         |
| 5. Manimala      | Kalloopara to Thondra           | 6.3 - 6.4    | VI         |
| 6. Pamba         | Mannar to Thakazhy              | 3.3 - 7.8    | VI         |
| 7. Bhavani       | Along Elachivazhy               | 5.4          | V          |
| 8. Chitrapuzha   | Irumpanam to Karingachira       | 4.6          | V          |
| 9. Kadalundy     | Along Hajirappally/Hajiyarpally | 3.6          | V          |
| 10. Kallai       | Thekepuram to Arakkinar         | 4.5          | V          |
| 11. Karuvannur   | Along Karuvannur                | 3.5          | V          |
| 12. Kavvai       | Along Kavvai                    | 3.9          | V          |
| 13. Kuppam       | Thaliparamba to Velichangool3.1 | - 3.8        | V          |
| 14. Kuttiyady    | Along Kuttiyady                 | 5.0          | V          |
| 15. Mogral       | Along Mogral                    | 3.1          | V          |
| 16. Periyar      | Alwaye- Eloor to Kalamassery    | 3.2 - 5.1    | V          |
| 17. Peruvamba    | Along Peruvamba                 | 3.9          | V          |
| 18. Puzhackal    | Olarikkara to Puzhackal         | 3.8          | V          |
| 19. Ramapuram    | Along Ramapuram                 | 3.3          | V          |
| 20. Thirur       | Naduvilangadi to Thalakkadathur | 3.6          | V          |
| 21. Uppala       | Poyya to Mulinja                | 3.2          | V          |

## ANNEXURE - II

## Findings of CWC st udy as mentioned at part (a) & (b) of the Lok Sabha Unsatrred Question No. 1846 due for Answer on 22.09.2020.

i . Kerala terrain is a linear one with elevation varying from about - 2 m to 1500 m in a stretch of about 80 100  km  across  the  State.  The  Western  Ghats  terrain  has  steep  slopes,  while  the  rest rolling/plains. The time of concentration (the t ime required to travel the water from farthest point of catchment to the project catchment outlet) of most of the reservoirs in the region is about ii. During the August 2018 flood 13 out of 14 districts of the State were severel y affected from flood due to heavy rainfall. As per IMD, Kerala received about 2346.6 mm of rainfall during 1 June 2018 2018 against the normal rainfall of 1649.5 mm, which was 42% above the normal. During 1 Augu 19 August 2018 total rainfall occurred in Kerala was about 758.6 mm against the normal of 28 which was 164% above normal. iii. A one day rainfall of 398 mm, 305 mm, 255 mm, 254 mm, 211 214mm respectively was recorded at Nilambur in Mallapuram district, Mananthav ady in Wayanad district, Peermade, Munnar and Myladumpara in Idukki district and at Pallakad district respectively 2018. The severe rainfall in Wayanad district resulted in heavy flooding at Mananthavadi and 8- 10, August 2018. iv . As per analysis carried out by CWC, the rainfall of 15 - 17, August 2018 having eye of storm near Peermade between Pamba and Periyar sub - basins, was almost of the same order as tha rainfall of Devikulam, Kerala which occurred during 16 - 18, July 1924. A s per the historical records sev most  flooding  had  occurred  in  Kerala  during  the  year  1924.  The  average  cumulative  rainfa - 17, August 2018 is about 414 mm for entire Kerala. The consequent cumulative runoff of three entire Kerala (ar ea about 38,800 sq.km) is about 12 BCM (12,000 MCM) for a runoff coefficient of Further, total catchment area tapped by dams in Kerala excluding barrages is about 6610 sq runoff coefficient of 0.8 the runoff generated from the catchme nt tapped by the dams during the 3 day rainfall of 15 - 17, August 2018 has been estimated about 2.19 BCM, out of total runoff of 12 BCM Kerala. The total live storage of Kerala is about 5.8 BCM. Even with 20% of the live storage 14  August  2018,  the  available  flood  moderation  extent  would  have  been  only  1.16  BCM  ag estimated inflow of 2.19 BCM. It shows that in any case, it was essential to make releases vi. Out of 758.6 mm rainfall from 1 August 2018 to 1 9 August 2018, about 414 mm rainfall occurred in three days viz 15 - 17, August 2018, which created severe flooding in the State. Due to severe r 15- 17, August 2018, the gates of about 35 dams were also opened due to extremely large inflo f water the reservoirs. During August 2018, the reservoirs were either at FRL or only few feet belo During  15 - 17,  August  2018,  the  3 - day  rainfall  depths  realised  in  Periyar,  Pamba,  Chalakud Bharathapuzha sub - asins were 588 mm, 538 m m, 421 mm and 373 mm respectively and these depths a of the same order as that of 1924 rainfall. viii. As per CWC's Neeleswaram G&D site (Periyar sub - basin) records, the maximum discharge passed in Periyar river was 8800 cumec on 16 August 2018 at hrs and maximum water level attained was at EL 12.4 m. The earlier HFL was recorded on 27 July 11.105 m. The major storages in Periyar basin are Idukki (live storage 1.4 BCM) and Idamal BCM). The peak release on 16 August 2018 from I dukki was 1500 cumec against a peak inflow of 25 cumec achieving a flood moderation of 1032 cumec. The release from Idamalayar on 16 August 963 cumec against an inflow of 1164 cumec. The discharge in Periyar river at Neeleswaram G&D A ugust  2018  was  recorded  as  8600  cumec  and  release  from  Idukki  and  Idamalayar  were  1500 (inflow 1610 cumec) and 1272 cumec (inflow 1007 cumec). On analysis of data it has been fou releases from these dams were the controlled releases, as th e di charging capacity of these dams are 50 cumec (Idukki) and 3012 cumec (Idamalyar). ix. The maximum discharge in Pamba river at CWC site (Malakkara) was 2900 cumec on 16 August 2018 with corresponding water level at EL 9. earlier record ed HFL was 8.2 m.The majorreservoir in Pamba sub- basin is Kakki and release from thi

Contd…

reservoir was 488 cumec (15th of August), 899 cumec (16th of August), 443 cumec (17th of Au cumec (18th of August), 309 cumec (19th of August) against the spillway capacity of 1788 cumec. reservoir was at EL 980.91 m on 14 August 2018, against the FRL at EL 981.46 m. The maximum level attained on 19 August 2018 was 981.4 m. x. From the analysis it has been found tha Kerala neither added to the flood nor helped in reduction of flood, as most of the dams were or very close to FRL on 14 August 2018, due to more than normal rainfall in the months of 2018. It may be noted that, had the reservoir be en a few feet below FRL, the flooding conditions would not changed much, as the severe storm continued for 3 days and even for 4 days at majority and in any case it would have been necessary to release from the reservoirs after 1st day of the extreme rainfall. xi. Nevertheless, it is essential to review the rule curves of all the reservoir curves need to be meticulously drawn particularly for the reservoirs having the live stor more than 200 MCM in or der to create some dynamic flood cushion for moderating the floods o return periods particularly in the early period of monsoon. xii. The runoff generated from P Achenkovil and Meenachil rivers during 15 - 17, August 2018 rainfall was ab out 1.63 BCM against the 0.6 BCM carrying capacity of Vembanad lake. Further, the discharging capacity of 630 cumec of T spillway was the other major constraint for the disposal of runoff. Considering the lake car about 600 MCM and discharging capacity of 630 cumec of Thottappally spillway and about 170 present discharging capacity of Thaneermukkom barrage, it can be concluded that out of 1. runoff generated during the 15 - 17, August 2018 rainfall, only about 0.60 5 BCM runoff was possible to drain out of the Vembanad lake. The remaining runoff volume of about 1 BCM created the rise of the in the lake and nearby areas. This continuous rising of lake water may be one of the re change in the river hydrodynamics of Pamba, Manimala, Meenachil and Achenkovil river systems re higher water level for a particular discharge in these rivers. Considering the high rainf - 17, August 2018, the absence of appreciable storage reservoirs in the upstream in the above rivers along the shrinkage of carrying capacity of Vembanad Lake and reduction of the capacity of Thottapp worsened the flooding in the Kuttanad region and the backwaters flows to the low lying area per reaches  of  the  lake.  xiii.  The  worst  affected  districts  noticed  were  Wayanad  (Kabini  sub - basin),  Idukki (Periyar sub - basin), Ernakulam (Periyar and Chalakudi) sub - basins, Alleppey and Pathanamthitta (both Pamba sub- basin). xiv. In a nutshell, it can be concluded that August 2018 flood in Kerala was due to s storm occurrences during 8 - 9,  August 2018 and 15 - 17,  August 2018. The storm of 15 - 17, August 2018 resulted in heavy flooding in Periyar, Pamba, Chalakudi and Bharatpuzha sub - b sins of Kerala . The rainfall during 15 - 17,  August  2018  was  almost  comparable  to  the  historical  16 - 18,  July  1924  rainfall  of  Keral particularly in Periyar, Pamba, Chalakudi and Bharatpuzha sub - basins. xv. The release from reservoirs only minor role in flood augment ation as released volume from the reservoirs were almost similar volumes. In fact Idukki reservoir absorbed a flood volume of about 60 MCM during 15 - 17, August 2018. Even, with the 75 percent - filled reservoir conditions, the current flood could h ave not been mitigated as 1 -day rainfall in majority of the area was more than 200 mm and severe rainfall continued for 3

*****