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Salient Details of Tamil Nadu State:

Tamil Nadu

Tamil Nadu state has a geographical area of 1,30,058 sq.km and is situated between North Latitudes 080 00’ and 13o30’ and East Longitudes 76o15’ and 80o 18’. The State is bounded by Bay of Bengal in the east, Indian Ocean in the south, Western Ghats in the west and the States of Karnataka and Andhra Pradesh in the north.

For administrative purpose, the State is divided in to 32 Districts, 209 Taluks and 385 Blocks. The State has 10Corporations, 150 Municipalities, 559 Town Panchayats, 12,620 Panchayat Villages and 93,699 Habitations

Physiographically, Tamil Nadu State is divided into Four units viz.,

    Coastal Plains

    Eastern Ghats

    Central Plateau

    Western Ghats

The coastal Plains stretch over a distance of about 998 kms extending from Pulicat Lake to Cape comerin.

Tamil Nadu is predominantly a shield area with 73% of the area covered under hard crystalline formations while the remaining 27% comprises of unconsolidated sedimentary formations. As far as ground water resource is concerned scarcity is the major problem in hard rock environment while salinity is the problem in sedimentary areas.


Tamil Nadu is a state with limited water resources and the rainfall in the state is seasonal. The annual average rainfall in the state is 960 mm. Approximately 33 % of this is from the southwest monsoon and 48 % from the northeast monsoon.

The annual rainfall distribution is as follows:

Season Month Average rainfall mm Percentage
Winter rains Jan – Feb 47 4.82 %
Summer rains May 138 14.12 %
Southwest monsoon Jun – Sept 322 32.96 %
Northeast monsoon Oct - Dec 470-970 48.10 %

 Surface water Potential:

The total surface water potential of the river basins of Tamil Nadu is assessed as 24160 MCM (853 TMC).

The details of the break up of the potential are as under:

    39000 tanks with a storage capacity: 347 TMC

    79 reservoirs with a storage capacity: 243 TMC

    Contribution from the other States: 261 TMC

    Other Storages: 2 TMC

The average Run off (surplus flow) to the sea from the 17 Basins of Tamil Nadu State is computed as 177.12 TMC.

 Groundwater Potential:

Categorisation of Firkas No. of Firkas
Over-Exploited (>100%) 358
Critical (90-100%) 105
Semi-critical (70-90%) 212
Safe (<70%) 429
Saline Blocks 35
Total 1139

 Coverage of Rural Habitations

In Tamil Nadu as on 1.4.2017 there are 1,00,018 habitations, of which 7,674 habitations are partially covered habitations and 92,344 are fully covered

Rural Habitations are covered through Individual Power Pump Schemes and Combined Water Supply Schemes

 Water Supply Status in Urban Towns

Civic statusGoodAveragePoorTotal
Corporations (excluding Chennai) 7 2 2 11
Municipalities 52 70 2 124
Town Panchayats (Erstwhile RTP &UTP) 477 43 8 528
Total 536 115 12 663

  Districtwise Water Supply Status in Urban Towns  Open

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