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Thiruvellore District Profile

  • Thiruvallur district is the northern most coastal district of Tamil Nadu.
  • The district is bounded by the Bay of Bengal in the East, Vellore district of Tamil Nadu and Chittoor district of Andhra Pradesh on the West, Nellore district of Andhra Pradesh on the North and on the South by Kancheepuram district.
  • It lies between 12º 55'N to 13º 34'N Latitude, 79º 17'E to 80º 21'E Longitude and has an areal extent of 3550 sq.km.

Physiography and Drainage

  • Thiruvallur district Varies from featureless pediplain to residual and structural hills.
  • The Thiruthani and R.K.Pet hills form part of the important landmarks. The Coastal tract is marked by beach ridges with a general slope towards the east.
  • The Araniar, Kosasthalaiyar, Adayar and Coovum are important rivers draining the district.
  • The Araniar originating in Andra Pradesh flows between Ponneri and Thiruvallur taluks and joins the Bay of Bengal near Pulicat.
  • The Coovum has its origin in the Surplus water from the Coovum tank in Sriperumbudur taluk and feeds the Chembarampakkam tank through a Channel.
  • The Poondi reservoir and Red hills are important tanks. The Pulicat tank is considered to be an important lagoon.

Rainfall:

The average annual rainfall and the 5 years rainfall collected from IMD, Chennai is as follows:

Actual Rainfall in mm Normal Rainfall in mm
2017 2018 2019 2020 2021
1198.0 733.4 1174.2 1229.0 1809.6 985

Geology:

Rock Type Geological Formation
Sedimentary Rock 80%
Hard Rock 20%
Charnockite, Gneiss, Conglomerate, Sandstone, Shale, Laterite, Alluvium and Marine deposits

Ground Water Level:

The Ground Water levels from the 35 number of observation wells of TWAD have been analysed for Post-Monsoon and Pre-Monsoon. 5 years average Ground water level in m Below Ground Level for pre and post monsoon is as follows:

Jan
2017

May
2017

Jan
2018

May
2018

Jan
2019

May
2019

Jan
2020

May
2020

Jan
2021

May
2021

5 Years
Pre Monsoon
Average

5Years
Post Monsoon
Average

8.5

13.9

8.9

21.7

9.5

12.3

8.5

15.3

5.9

14.7

13.1 7.3

Sustainability:

With a view to enhance the Sustainability of the drinking water sources, recharge structures are being implemented by TWAD Board under various State and Central Government assistances.

The Recharge Structures implemented so far in district is as under.

Categorization of Firkas:

The status of Categorization of firkas as of March 2020 for the District in is shown below.

Categorisation based on Extraction (as on 2020) No. of Firkas Firkas
Over Exploited (>100%) 7 Avadi, Poonamallee, R.K.Pet, Thiruninravur, Tirumullaivoiyal, Vayalanallur, Vellanur
Critical (90%-100%) 2 Tiruttani, Vengathur
Semi Critical (70%-90%) 17 Balapuram, Cherukkanoor, Erumbi, Kanagammachattram, Kannigaipair, Manavor, Mappedu, Morai,
Nemam, Pallipattu, Poondi, Poonimangadu, Puzhal, Thirumazhisai, Tirur, Uthukkottai, Velliyur
Safe (<70%) 20 Ammanambakkam, Arani, Elavur, Gnayiru, Gummidipoondi, Kadambathur, Kattur, Kolur, Madharpakkam,
Pandur, Pennalurpett, Periyapalayam, Ponneri, Poovalambedu, Pothattur Pettai, Sholavaram,
Thirupalaivanam, Thiruvallur, Thiruvalangadu, Velakapuram
Others (Poor & Saline) 1 Minjur
Total 47  

Rural Habitations

Total No. of Rural Habitations: 3842

Partially covered 64 (10-39 lpcd )
Fully covered 3778(40 lpcd and above)