Due to Northeast monsoon failure, Tamil Nadu government has declared 24 districts as drought-affected. Moreover, 38 blocks in seven districts have also been declared drought-affected.
Out of the 12,524 village panchayats located in 385 blocks, 143 panchayat unions, 2,883 village panchayats and 14,333 habitations would be affected during March while the number would go up in April and May. In April, 222 panchayat unions, 4337 village panchayats and 20,212 habitations would be affected. Similarly, during May, 252 panchayat unions, 5,426 village panchayats and 25,993 habitations would be affected.
The storage level in the reservoirs which provide water to Chennai, is also depleting. Against the full capacity of 12,722 mcft, only 2,441 mcft was available as of January 28. The storage during the same period during January 2018 was 5,352 mcft.
The districts which have been declared drought-affected (Hydrological Drought) are: Chennai (serviced by CMWSSB), Dharmapuri, Krishnagiri, Karur, Salem, Vellore, Tiruchirapalli, Perambalur, Tiruvallur, Namakkal, Virudhunagar, Kancheepuram, Madurai, Dindigul, Erode, Pudukottai, Sivagangai, Thanjavur, Viluppuram, Tiruvannamalai, Ariyalur, Nagapattinam, Cuddalore and Ramanathapuram.
The government also declared the 38 blocks of Tirunelveli (6), Tiruppur (9), Kanyakumari (6), Thoothukudi (6), Theni (5) Coimbatore (5) and The Nilgiris (1) districts as affected by Hydrological Drought.
During the Northeast monsoon 2018, 38 blocks in the above seven districts, the percentage deviation with reference to the season’s normal rainfall was ‘deficient’ and ‘large deficient’. As a result, with the surface water and groundwater resources fast depleting, the district/blocks are already experiencing drinking water problems and would be affected further due to hydrological drought in the ensuing summer.
Of the 24 districts, 17 have recorded deficit rainfall ranging from -59 to -19 per cent. In the remaining seven districts, though the Northeast monsoon rainfall in 2018 was normal, the annual rainfall was in deficit.
In the rest of the seven districts, though the rainfall aggregate at district level matches normal rainfall (with deficit less than 19 per cent), the distribution was not uniform across the district.
Rainfall plays a critical role in Tamil Nadu for meeting its drinking water and irrigation needs.
The long-term annual average rainfall is 920.9mm and rainfall received during winter, summer, Southwest and Northeast monsoon seasons, account for 3 per cent, 14 per cent, 35 per cent and 48 per cent respectively. The rainfall is received in two major seasons.
The Southwest monsoon (June to September) accounts for 35 per cent of the total rainfall and Northeast monsoon accounts for 48 per cent of the rainfall.