Owing to inadequate rainfall last year, groundwater levels have fallen drastically
The South West monsoon that began in the second week of June is yet to bring results for areas in the plains in Coimbatore district and under the Noyyal irrigation system.
Because of the inadequate rainfall of 422.105 mm during 2012, groundwater level went down beyond 600 ft in many of the areas in and around Coimbatore city.
Noyyal river that begins as Kanchi Maanadhi near Thondamuthur runs through Coimbatore district for 65 km and it was designed then in such a way that it benefited as many as 36 tanks, helping in recharging groundwater aquifer and in irrigation of over 13,500 acres.
As far as Coimbatore District was concerned, the average rainfall expected during the South West monsoon was 167 mm during the period June to September.
If the rainfall was more than 2.5 mm across the district, then it is treated as ‘rain day’ and during June there had been only six ‘rain days’ in the district.
Expectation is for an average of 60 mm rain during July. Total rainfall during the year 2013 was 77.58 during the winter months of January and February.
Summer showers during March, April and May brought in 83.65 mm while the first month of South West Monsoon has brought in 42.76 mm.
However, the rainfall was more in hill areas benefiting the catchments of various reservoirs and poor rainfall in the plains resulted in Noyyal system not reaping the desired benefits.
Of the 36 tanks in the 65 km journey of Noyyal, the benefits had reached only up to 19 km i.e., filling up only five major the tanks till the Chithiraichavadi check-dam.
Ukkulam has 90 per cent storage now, Pudukulam and Kolrampathy have 60 per cent, Narasampathy 35 per cent and Krishnampathy has 25 per cent storage.
The remaining tanks in the region are waiting for further rain to improve the storage levels.
While therewas heavy rainfall and appreciable improvement in some of the reservoirs under the Parambikulam — Aliyar Project (PAP) in Pollachi region, Pilloor also surplussed but Siruvani storage has reached only 871 ft (dead storage level is 863 ft and full reservoir level of 878.5 ft (at mean sea level).
As far as Coimbatore district was concerned, the highest of 941 mm rainfall was in 2005, followed by 905 mm in 2011, 730 mm in 2010 and 705 mm in 2007 and 703 mm in 2006.
Sources in the Water Resource Organisation (WRO) of PWD said that only in the event of heavy downpour or more than moderate showers during July, August and September, there could be some benefit for the remaining 31 tanks.
In Nilgiris district
Rainfall continued in the Nilgiris and in the last 24 hours that ended at 8.30 a.m. on Thursday, the district recorded a total rainfall of 348.00 mm and average rainfall of 20.47 mm.
The highest amount of 69 mm was reported from Avalanche and the lowest of one mm was reported from Kinnakorai and Kotagiri.
Rainfall in mm in other places are: Coonoor 1.20, G. Bazar 38.20, K Bridge 8.60, Ketti 9, Naduvattam 50, Udhagamandalam 6, Kallatty 3, Glenmorgan 25, Upper Bhavani 50, Emerald 20, Geddai 4 and Devala 62.
In Coimbatore district
Rainfall continued to improve storage in the reservoirs in the district on Wednesday as well and in the last 24 hours that ended at 8.30 a.m. on Thursday, district recorded a total rainfall of 203.20 mm and average rainfall stood at 16.93.
Rainfall in mm in other places:
Pollachi 10, TNAU 0.20, Cincona 65, Chinnakallar 28, Valparai PAP 46, Valparai taluk office 52, Coimbatore South 2, Sholayar 94, Parambikulam 87, Thoonakadavu 18, Peruvaripallam 21, Aliyar dam 10.6, Thirumurthi dam 4, Amaravathi dam 3, Upper Nirar 28, Lower Nirar 29, Upper Aliyar 3, VLP camp 46, Makkinampatti 6.6, Manakadavu 27.8.
Storage in reservoirs in ft and full reservoir level in brackets:
Sholayar 162.80 (160), Parambikulam 22.85 (72), Aliyar dam 75.30 (120), Thirumurthi dam 3.84 (60) and Amaravathi dam 40.84 (90). Water that surpluses from Sholayar and the continuing rainfall is expected to further improve the storage.