Thottappally Desilting Note

 Removal of Mineral Sand from Thottapally spillway channel & Pozhy Mouth
 
Obstructions at Thottapally Pozhy Mouth
 
In every year during monsoon season the water level of the rivers Achavonkovil, Pamba and Manimala rises inordinately causing heavy flood in the low laying area of Kuttanad region. To safe guard the lives and properties of these in habitations in Kuttanad region, the excess flood water should be drained out to the sea through Thottapally spillway.

 

In August 2018, severe floods affected the state of Kerala, due to unusually high rainfall during the monsoon season. It was the worst flooding in Kerala in nearly a century. All 14 districts of the state were placed on red alert. According to the Kerala government, one-sixth of the total population of Kerala had been directly affected by the floods and related incidents. The Indian government had declared it a Level 3 Calamity, or "calamity of a severe nature. It is the worst flood in Kerala after the great flood of 99 that happened in 1924. Achenkovil River,Manimala,Pampa,Puthanar and Thalavadiyar   overflowed and flood water reached to the roof level of nearby inhabitants. Even though the Sand bar formed in the mouth of Thottapally spillway was opened (for a width of 200 metres) well before the flood, the Kuttanad regions were fully submerged leading to huge losses to the State.
 
The thottappally estuary is closed for most part of the year and needs to be opened before the onset of monsoon. The actual  design capacity of Thottappally spillway is 1800 Cubic meter per second but it gets reduced to 600 Cubic meter per second due to reduced width of pozhi. Due to formation of sand bars and plantation of Casuarina tree in the pozhi , the width was reduced from 380m to 150 m.
 
This shortage of width at mouth decreases the efficiency of draining out the flood waters into the sea. Based on the observation that the trees were impeding  the  flow  of  floodwaters  from  Kuttanad, District  administration  cut around 550 casuarina trees to widen the estuary to ensure the smooth flow of water during the rainy season.  The present work is removal of obstructions of approximately 410 metres towards downstream of Thottapally spillway channel near PozhyMouth. The removed sand is being transported to KMML unit at Chavara.
 
The quantity of sand deposited downstream of Thottappally spillway which can be removed was assessed to be around 220031 cubic metres covering an area of 85612.5 Sqm.
  • Agreement No.47/SE/ISC/2019-20 dated11/10/2019
  • Site handed over on 29/02/2020
  • Contractor :M/s Kerala Minerals and MetalsLtd.
  • Estimated Quantity: 220031 cum; (Initially)
  • Expected date of completion- 20/07/2020 (Initially)
  • Sand   is   being   transported   to  KMML   Chavara   based   on   the Acknowledgement receipt issued by the Irrigation Department
  • As per the direction of the Executive Engineer, Irrigation Division Alappuzha,vide LetterNo.D1-1280/18 dated 18/05/2020,  in  light  of the early onset of monsoon; cutting open the sand bar from pozhy mouth for the year 2020-21 was entrusted to KMML and the Mineral Sand so excavated to be removed from site as per the work Agreement No.47/SE/ISC/2019-20  dated  11/10/2019. As per the request from KMML the Excavators for the aforesaid work was arranged with the aid of Irrigation Department based on the rates finalized with KMML.
Initial Estimated Quantity to be removed : 2,20,031.25 cum
Initial Proposed Date of completion : 31/07/2020
Additional Estimated Quantity to be removed to attain a width of 360m at pozhy mouth22,800 cum
Proposed date of Achieving 300m at Pozhy Mouth : 22/07/2020
Total Qty to be removed to attain a width of 360m at pozhy mouth : 2,42,831.25 m3
Proposed Date for achieving target: 28/07/2020

The work has been completed on 23.07.2020

 
Officers Incharge

 

 
Syam Gopal
 
Mob: 9495747237
Special Officer - Suprendenting Engineer
Arun K Jacob
Mob : 9447175074
Executive Engineer
Sajeev Kumar
Mob : 9446989495
Assistant Executive Engineer
Sreekumar K S
Mob : 9446491454
Assistant Engineer

 

            
 
 
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Last updated :30:10/2020  11:03:43