Water availability & sustainable crops

[rtkaushik]

I take an acre to be about 4000 sq.metres. 1 mm of rainfall on this equals 4000 litres of water...4KL. If I take Anantapur in AP as an example, with its annual rainfall of 400 to 700mm of rain, I get an average of 1 to 2 mm of rainfall per day.
Taking 1.5mm as the average, my water usage per acre should not exceed 6000 litres per day. So, if I want to grow banana here, i should not plant more than 500 plants in an acre, assuming 11L/plant on an average. This will ensure that the water table does not deteriorate.
Is my thinking right ? And this logic holds irrespective of drip or trench irrigation?

 

[kirti s]

Dear Mam,

Average rain fall is some thing over period by looking to yr rainfall it is difficult to grow banana as it needs lot of water. yr caluclation is wrong as once rain most of water will be lossed fallowing ways.
1.Runoff.
2.Infiltraton.
3.evoprotion.

Regrds

Kirti s

 

[aromedindia]

water availability

If such assumtions hold true there will be no need of creating irrigation infrastructure in the country and any crop ,irrespective of water need, can be grown any where in the country.
Thanks
aromedindia@gmail.com
9451504200/9424633501

 

[rtkaushik]

Aromedindia
The intention of my post/query was to elicit opinions about how crop planning is done on a piece of land for a particular water budget available. I was curious to know whether water availability/ budgeting is done before crops are chosen. Sustainable farming ultimately has to be within the water available...is what I thought.

Taking the example of urban settlement like Bangalore, the water needs of a person is 160L per day, which means, at 2mm per day of rainfall, 80 sq.m is needed for a person. So per acre of land, 50 people can build their houses i.e. 12-13 families can live off an acre, in Bangalore. Whereas, about 18 sites of 1200 sq.ft is the norm per acre with the rest going to roads, parks and community areas. So we end up with 30-35 families living in an acre in middle-class areas and in posher areas with larger sites, it is about 8 families.

At 740 sq.km, and 800 mm of rainfall, the population it can take is about 92 lakhs. The problem of water hence is due to excess runoff on the roads and from rooftops. Once the percolation increases due to rainwater harvesting, things should be easier.

So...was wondering whether anybody has thoughts on % of percolation and all that