District Atlas
Tamil Nadu
Where the Atlas began: the Cauvery delta's canal country and the over-exploited west, read district by district.
Thanjavur
District|TN|Cauvery Delta
The rice bowl: 80% of irrigation is canal water released at Mettur, so the district's water year is decided upstream.
Open districtTiruchirappalli
District|TN|Mettur Reservoir to Noyyal confluence
Thanjavur's inverse: 60% of irrigation is from wells, so its water security is a groundwater question.
Open districtSalem
District|TN|Tirumanimuttar
Holds Mettur, the delta's canal head, and irrigates almost none of its own farmland from it: 13 of 14 taluks draw more groundwater than recharges.
Open districtTirupathur
District|TN
The Palar tannery belt without a canal: every taluk is over-exploited and all irrigation is from wells.
Open districtErode
District|TN|Lower Bhavani
Canal country on the Bhavani: 39% of irrigation is canal water and 49% open wells, and Nambiyur taluk pumps 171% of its recharge.
Open districtNamakkal
District|TN|Mettur Reservoir to Noyyal confluence
Cauvery bank with almost no canal: 72% of irrigation is open wells, and 5 of 8 taluks are over-exploited, Rasipuram at 150% of its recharge.
Open districtKarur
District|TN|Amaravathi
Where the Amaravathi meets the Cauvery: 4 of 7 taluks are over-exploited and the other 3 critical, and 84% of irrigation is from wells.
Open districtTiruppur
District|TN|Noyyal
The Noyyal's dyeing belt: 22% of irrigation is canal water and 77% wells, and Palladam taluk pumps 121% of its recharge.
Open districtVellore
District|TN
The Palar's fort town with no canal and no tank irrigation: 5 of 6 taluks are over-exploited, K.V. Kuppam at 151% of its recharge, and every hectare is watered from wells.
Open districtRanipet
District|TN
The Palar below Vellore with no canal: 96% of irrigation is from wells and 4% from tanks, Arcot taluk is over-exploited at 113% of its recharge and Walajapet is critical.
Open districtDindigul
District|TN
Under the Palani hills: 7 of 10 taluks are over-exploited, Gujiliamparai at 159% of its recharge, and 73% of irrigation is from open wells.
Open districtTiruvallur
District|TN
The district north of Chennai has no canal irrigation: 80% of its irrigated land is on tube and bore wells and 11.5% on tanks, 6 of 9 taluks read safe and Avadi is the highest at 83% of its recharge.
Open districtKrishnagiri
District|TN
Hosur's district on the Thenpennai: 3 of 8 taluks are over-exploited, Uthangarai at 149% of its recharge, Hosur taluk is critical at 90%, and 89% of irrigation is from wells.
Open districtWhat the disaster plan says about floods
The state's own disaster management plan, quoted with its page. The Atlas classifies nothing itself; each district page carries the plan's statement for that district.
Fourteen coastal districts named highly vulnerable; inland flood exposure is stated separately and is not classified per district.
“The 14 coastal Districts, viz., Chennai, Kancheepuram, Tiruvallur, Cuddalore, Villupuram, Thanjavur, Tiruvarur, Nagapattinam, Myladuthirai, Pudukottai, Ramanathapuram, Thoothukudi, Tirunelveli and Kanniyakumari are highly vulnerable and affected frequently by the trough and depression formed in the Bay of Bengal and Indian Ocean during South-West and North-East monsoon periods.”
The remaining columns of the district signal ledger (groundwater by taluka, polluted river stretches, drought declarations) land here one at a time, each as its source, mapping and licence are pinned down; the page never invents a column it cannot source.