Desertification of Tamil Nadu: Private Wells & Paddy

To understand the scale of Tamil Nadu’s water woes, let’s understand what the demand is and how much water there is to divvy up. The demand estimate by the various sectors are,



This 1,894 TMC is well beyond total assessed water resources in the state which is 1,587 TMC. In other words, the demand is 19.3% over and above known supply. So even if there’s good/normal rainfall in Tamil Nadu, the demand exceeds supply. Partly because we discharge fresh water into the sea in some cases and because we haven’t invested enough in processes to recharge aquifers. But even if all of that is done, it’s unlikely this deficit will vanish.

With agriculture/irrigation taking up 93% of the demand, that becomes the only segment that demands our attention. Sure the City of Chennai and its bourgeoisie waste a lot of water or appear to when measured on per capita consumption of domestic water compared to their rural counterparts. But that’s inconsequential in the overall scheme of things. Water scarcity in Chennai does not cause desertification. While Tamil Nadu’s unsustainable sectoral allocation will.

To understand where this 93% water largely gets used, let’s look at Tamil Nadu’s land use pattern. Tamil Nadu’s land area that is sown is 38.3% of its total surface area. That to those of us who aren’t familiar with the data, sounds like a staggeringly high number. Let’s understand where these farmlands are, and to what extent.


With the exception of Chennai, every district has a significant portion of its land sown. For some of the districts, like those in the Cauvery Delta, it’s more than 50% of their total surface area. And with multiple schemes that have been announced, there has even been a tiny growth in this share. As a point of comparison, one world’s largest and most productive agricultural state, California, has 27% of its surface area as cropland. And that state is now contemplating reducing that to conserve water.

The state does seem to have too much of its land under cultivation; it is a lower riparian state of a contentious water treaty and has an annual rainfall far less than states to the west of Western Ghats. An important question then becomes, what are the kind of crops that are grown in Tamil Nadu? What’s their water usage and how are they distributed.



Paddy crops occupy 32.3% of the total area sown in Tamil Nadu!

A state that’s water deficient has about a 38.3% of its overall land cropped in some way and 32.3% of that as one of the most hydrophilic crops known to man: Paddy. That’s 12.3% of the total surface area of Tamil Nadu! In absolute terms, over 1.9 Million Hectares. Of just Rice. That needs standing water.

Now, let’s look at where Rice is grown in the various parts of Tamil Nadu so we can correlate with our earlier findings on ground water level drops.


As one’d expect the Cauvery Delta districts have paddy in over 60% of their sown land. There are other districts which also reach over 60% for paddy. But, as the previous chart showed us, the Delta districts also have the maximum total area under cultivation. For instance, Kancheepuram and Sivagangai – two districts that aren’t in the Delta – have about 20 to 30% of their overall land area sown for any crop. And 70% of that, while still above state wide average, is about 14% – 21% of their total land area.

The Delta districts of Thanjavur, Thiruvarur and Nagapattinam have 60 to 70% of their total land area sown – for all crops. And of this, again have 60-70% under paddy. That means about 40-50% of their total surface area is occupied by water guzzling paddy crops!

The reason paddy or any other hydrophilic crop is an issue in Tamil Nadu is: the state maxed out on surface water irrigation sometime in the 1960s. That capacity has remained stagnant; as a result, the share of private tube and bore wells have dramatically increased. The current share of such wells forms well over 50% of irrigation sources.



Is it the case that these open/tube/bore well are primarily used for paddy? Let’s take a look at where the private wells are and how the various types of wells are distributed.



Thanjavur stands out as a district with a large number of private wells and a significant number of them being bore wells that suck water out at rates that are difficult to replenish.  While Namakkal and Erode basically have come to a situation where marginal farmers who cannot afford a bore well can’t farm.

Coastal districts of northern Tamil Nadu, historically a region irrigated by tanks, now have most wells among regions. The risk there, one’d imagine, is water turning saline more than a drop in ground water levels.

The current classification of ground water by blocks by Government of Tamil Nadu is already alarming.


The shift from rice to another crop is something that is inevitable in the short term. And in the long term, this state cannot afford to have 38% of its area cropped. The proposed amendments that were recently withdrawn – one where farmland can be acquired without consent – may be a necessity soon in Tamil Nadu for a very different reason. One where the government tells the farmer: the society cannot afford the luxury of you farming.

Data Sources:

1.  Season and Crop Report, Tamil Nadu for 2011-12. A scanned version is available here.

2.  Tamil Nadu Water Supply and Drainage Board gave the demand estimate.