Water table going down in the post-monsoon days termed bad sign
27 wells were identified in 1976 to measure the table Drought in Somwarpet taluk has adversely altered the water table in that region Presence of the Harangi reservoir gives hope to Somwarpet
Madikeri: There has been a gradual decline in the water table in Kodagu district in the last eight years.
The district average concerning water table in the last eight years, which was measured from the surface at 9.55 metres from November to April (pre-monsoon period), fell to 9.31 metres between May and October (post-monsoon period), according to H.H. Sharief, Senior Geologist, Department of Mines and Geology, here.
As many as 27 open wells were identified in 1976 in the three taluks of the district to measure the water table in the district every month, which continues to even this day.
Ten wells were identified in Virajpet taluk, nine in Madikeri taluk and eight in Somwarpet taluk.
Measurement is taken between 25th and 30th of every month and recorded.
Mr. Sharief said the water table between 1998 and 2003, had gone down. In Madikeri taluk, water was available at a depth of 3.56 metres but it had gone down to 5.85 metres in the last five years.
In Virajpet taluk water table had gone down from 9.15 metres to 14.07 meters. In Somwarpet, it was 15 metres from 10.44 metres.
In Madikeri taluk, water table in the last eight years, on an average, was available at a depth of 4.77 metres in the post-monsoon period. It was down to 5.22 metres in the pre-monsoon period.
Madikeri taluk gets the highest rainfall compared to the other two taluks. In spite of the heavy run-off of the rainwater in Madikeri taluk, the water table was good because of the heavy rainfall.
During 2005-06, the post-monsoon measurement in this taluk, comprising May, June and July, was in the range of eight metres and excess.
Formation of silt
But it had improved to around four metres in August, September and October. Again, in February, March and April, water table in Madikeri taluk had gone down.
The earth layer in Madikeri taluk was found to be at a depth of nearly 70 metres.
In the event of sinking borewells, more casing pipes would be needed in this taluk, Mr. Sharief said.
In Virajpet taluk, the water table had gone down considerably. Water yield in the borewells was found to be low because of silt formation.
Water table in open wells was found to be low in the first three months in the post monsoon period from May to July, recording 12 to 13 metres and excess.
It improved considerably in the next three months in the post-monsoon months of August, September and October with measurements of 11.07, 10.21 and 9.87 metres respectively.
In three months of pre-monsoon period during the same year, from February to April, the level had sunk to 12.93 metres, 12.28 metres and 13.39 metres respectively.
The situation appears to be worst in Somwarpet taluk, where the wells chosen for the sample study had dried up completely, in the post-monsoon and pre-monsoon periods during 2001-02 and 2002-03. The same situation had come up between January and April, Mr. Shareif said.
Drought in many parts of the taluk adversely altered the water table.
To a question, Mr. Sharief said that unless steps were taken to conserve groundwater, things could go from bad to worse in Kodagu district.
Rainwater harvesting could be one of the effective methods to arrest the declining water table in Kodagu.
The Harangi reservoir command areas were potential water sources for Somwarpet taluk, Mr. Sharief said.