NEED FOR MASSIVE DESILTING OF RESERVOIRS IN INDIA
TO OVERCOME GLOBAL WARMING CHALLENGE
One part of India or the other undergoes severe drought or heavy flood conditions every year.
Following such trend, Tamil Nadu is presently undergoing one of the worst drought conditions in the recent years. The severity of the drought is well reflected by the reported suicide of more than one hundred farmers in the state in the last few weeks, unable to bear the distress conditions in the farming operations. Such farmer suicides have also taken place in other states like Maharashtra and Andhra Pradesh in recent time due to failure of monsoon and consequent drought conditions.
Impact of global warming on weather :
While the monsoon conditions in the recent years are showing high fluctuations, it appears that such trend will continue and may even become worse in the coming years.
This is mainly due to global warming that has resulted in increase of global mean temperature by one degree centigrade between the year 1880 and 2010 . Between the year 2010 and 2015, the global temperature further increased by 0.15 degree centigrade. If the global temperature would increase by 1.5 degree centigrade from the base year of 1880, there will be huge change in the weather pattern. It would be a matter of very high concern if the global temperature would increase by 2 deg. centigrade from the base year 1880.
Need for appropriate strategies and forward planning :
As the wind direction would change due to rising global temperature, there could be excess rain fall at one time and deficit rainfall at another time, with both the conditions being unpredictable. Further, increased global warming may lead to rise in sea water level and also melting of the ice in Himalayas, leading to heavy flood conditions.
Several world governments are now examining the appropriate strategies to face the consequences of change in the weather pattern in the coming years, due to steadily increasing global temperature.
There is no indication so far that Government of India has given any serious thought to work out the strategies to tackle the consequences of unpredictable and adverse monsoon conditions , that may happen in the years ahead due to rise in global temperature.
Need to store and conserve water :
There have been many discussions during the last several decades in various forums about linking the rivers all over India, to ensure that no region would suffer from water scarcity at any time. However, such discussions have not led anywhere, due to the practical difficulties in linking the rivers, huge investments needed and the fact that such scheme would involve several decades for implementation.
In such uncertain scenario, only option left is to store and conserve water in tanks and reservoirs all over India as much as possible, when there would be excess rainfall.
India’s reservoirs :
India has more than 91 major reservoirs including all artificial lakes with large capacity. Indira Sagar Dam reservoir is a largest one in India followed by Nagarjuna Sagar. Other larger reservoirs include Shivsagar Lake, Berijam Lake , Fateh Sagar Lake, Upper Lake, Vihar Lake, Modak Sagar, Kanva Reservoir, Nizam Sagar, Aliyar Reservoir, Stanley Reservoir , Gobind Ballabh Pant Sagar.
Apart from the large reservoirs, there are thousands of village tanks and ponds all over the country, which are the sources of water storage and supply for the local people.
As per the available information, storage capacity of about 253 billion cubic metre are available in India. However, this may be much more, if small village tanks and ponds all over India would also be taken into account.
But, due to lack of desilting operations and inadequate maintenance over the years , the present actual storage capacity in the reservoirs, ponds and tanks in the country are, obviously , much less than the potential storage level.
Dip in the water level in recent time
The total capacity of the 91 major reservoirs in the country is around 157.799 billion cubic metre.
According to Water Resources Ministry, Government of India, water level in 91 major reservoirs in the country has dipped to 48% of the total capacity in February, 2017, as only 74 .977 billion cubic metres ( bcm) water was available in these reservoirs for the week ending on February,9, 2017 .
The states which have recorded less storage vis a vis the corresponding period last year are Himachal Pradesh, Tripura, Uttarakhand, Andhra Pradesh and Tamil Nadu.
Case study of Tamil Nadu
The present fluctuation in monsoon conditions and consequent drought conditions in Tamil Nadu indicate the likely trend for the future.
Fortunes of large area of agricultural land in Tamil Nadu depend on monsoon and release of Cauvery water from Karnataka to meet the water needs. However, Karnataka is also facing serious drought conditions due to failure of monsoon and lack of adequate rain fall in the Cauvery water basin.
Tamil Nadu’s water availability scenario is now facing uncertainty and could face huge stress in the coming years.
In the past several years, between 1991 and 2015 , around 1165 tmc of water has gone in the sea via the Kollidam river in Tamil Nadu due to excess rain fall. It is estimated that in a bountiful monsoon year ,around 170 tmc of water are being let into the sea. In the one year 2005 alone , which was a bountiful monsoon year, around 349 tmc of water has gone into the sea due to lack of storage capacity.
Fortunately, due to the proactive measures of several rulers over the last centuries, Tamil Nadu is endowed with 79 reservoirs with total storage capacity of around 243 tmc and 39000 tanks of total capacity 347tmc. Such tanks and reservoirs can be well utilised to store and conserve water , that would be available during the bountiful monsoon period, that can be utilised during the drought period.
However , tanks and reservoirs in Tamil Nadu have not been desilted adequately during the last several years, resulting in the loss of storage capacity to a considerable extent.
For example, the total storage capacity of Veeranam lake near Cuddalore is supposed to be 1465 million cubic feet. However, due to inadequate desilting operations in the past , the present storage capacity is estimated to be only around 906 million cubic feet.
Even in the case of Mettur dam, it is suspected by many that the present storage capacity is much less compared to the original level due to accumulation of silt over the years and lack of desilting operations.
In the past, several crores of rupees have been spent by the Tamil Nadu government in conducting desilting operations in several lakes and reservoirs.
However, the results have been poor and disappointing due to inefficient level of desilting operations carried out. For example, in the case of Veeranam lake , in 2005, around Rs.356 cr. was allotted for strengthening the bunds of Veeranam lake and desilting operations. However, again in 2012, the state government allotted Rs. 40 cr. for desilting operations. The desilted mud is supposed to be used for raising and strengthening the bund .
However, the local farmers who are in the know of things, say that the desilting operations have been carelessly and incompletely carried out.
Laudable efforts of Telangana government :
The Telangana government’s flagship programme “Mission Kakatiya” to desilt , revive and restore minor irrigation tanks, ponds and lakes is receiving lot of praise. Official estimate is that so far ten crore cubic metre of silt has been removed , creating 3.77 thousand million cubic metre of water storage in the revived tanks and ponds from around 8272 tanks.
Some three crore tractor loads of silt have been removed and farmers have used their own tractors to take the silt to their fields. It is well known that silts have the micronutrients, which are valuable agri inputs and may reduce the level of fertilizer need to a considerable extent.
The budget for Telangana government for 2016-17 for desilting operations is Rs. 2500 cr. and it plans to spend Rs. 11500 cr. over the next five years.
Make the desilting operations a people’s movement :
Government of India has recognized the ground reality of global warming and the fact that change in weather conditions and uncertain monsoon behaviour would become the order of the day in the future. The government has said on several occasions that India’s huge water storage capacity have to be well utilised efficiently , as an appropriate strategy to meet the challenge of global warming and consequent monsoon fluctuation and drought conditions. However, appropriate action plans are yet to be evolved and implemented to the extent necessary.
Several state governments say that they lack funds for carrying out desilting operations in the various tanks and the lakes to the required level . This may be true to some extent.
In such a case, why not government of India and state governments consider taking a decision to allow any individuals or groups to collect the silt from the tanks and the lakes and take them away free of charge and use it for whatever purpose they desire ?
This can be done as per the guidelines to be worked out by the government and for a stipulated period.
As the river sand are in great demand for construction purposes and the silt can be used as agri input for farming operations all over India ,there is bound to be huge enthusiasm and response from cross section of individuals and groups to collect the sand and the silt.
This approach will have the benefit of executing the much needed desilting operation in short time and save the expenses for government of India and state governments in conducting the desilting operations themselves, apart from creating huge employment opportunities at skilled and semi skilled level.
Of course, the huge and visible benefit would be towards creating large capacity for water storage in the states, that would help to a considerable extent in overcoming the stress conditions due to water scarcity during the period when monsoon may fail to arrive at appropriate time.