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Inputs sought by the Lions Club Chairman about water management

 

*Dear Sir,
21st July, 2009*
**
*I am appointed as District Chairman "Water Management" by my Dist Governor
Lions Dist 324-C1 for the year 2009-10. I request you to clarify :*
*1) Provision of Drinking Water to villages based on Rain Water Harvesting
without  disturbing ground water* : With an average rainfall of 1000mm, a
hectare of land can receive as much as 10 million liters. Even if 50 to 80%
of rain water is  recovered with precautions taken to minimize percolation
and evaporation losses, it means 5 to 8 million liters, which can easily
take care of  the drinking water needs of a moderate village of  1370 to
2200 population at the rate of 10 liters per head per day round the year.
Instead of one plot of  ONE hectare, 10 plots of 1000 sq.m give better yield
because  percolation and evaporation losses are minimum.
The  rain water could be stored in  open storage tanks /  traditional ponds
with plastic lining at the bottom.
Spraying light  mineral oil as a thin film on the surface to minimize
evaporation.
*2) Construction of subsurface dykes along coastal cities* : Ground water
table usually runs parallel to surface and invariably drains precious water
into sea at the coast. If a suitable subsurface dyke is built parallel to
the coast a little away from the coast the flow could  be arrested and the
ground water pooled at the dyke can easily be tapped economically.
*2) Storm Water Harvesting* : It is a common sight most of our city roads
get filled with flood water even with little showers causing great
inconvenience to the citizens. If the water is pumped / drained rapidly to
pre constructed water bodies like tanks, ponds, lakes in and around the city
which can be used as drinking water after treatment. This can easily reduce
drinking water problem of the city. Excess water could be used for
recharging  aquifers through previously constructed injection wells
Ln P.Nukaiah 

I am appointed as District Chairman 'Water Management' by my Dist Governor Lions Dist 324-C1 for the year 2009-10.

I request you to clarify :

  • Provision of Drinking Water to villages based on Rain Water Harvesting without  disturbing ground water : With an average rainfall of 1000mm, a hectare of land can receive as much as 10 million liters. Even if 50 to 80% of rain water is  recovered with precautions taken to minimize percolation and evaporation losses, it means 5 to 8 million liters, which can easily take care of  the drinking water needs of a moderate village of  1370 to 2200 population at the rate of 10 liters per head per day round the year.
    • Instead of one plot of  ONE hectare, 10 plots of 1000 sq.m give better yield because  percolation and evaporation losses are minimum.
    • The  rain water could be stored in  open storage tanks /  traditional ponds with plastic lining at the bottom.
    • Spraying light  mineral oil as a thin film on the surface to minimize 
  • Construction of subsurface dykes along coastal cities : Ground water table usually runs parallel to surface and invariably drains precious water into sea at the coast. If a suitable subsurface dyke is built parallel to the coast a little away from the coast the flow could  be arrested and the ground water pooled at the dyke can easily be tapped economically.
  • Storm Water Harvesting : It is a common sight most of our city roads get filled with flood water even with little showers causing great inconvenience to the citizens. If the water is pumped / drained rapidly to pre constructed water bodies like tanks, ponds, lakes in and around the city which can be used as drinking water after treatment. This can easily reduce drinking water problem of the city. Excess water could be used for recharging  aquifers through previously constructed injection wells

Ln P.Nukaiah Chetty

http://www.watermanagementforall.com/

Tags:

3. Hello, I am a Hydrologist

Hello,

I am a Hydrologist working on various issues of soil & water conservation and watershed Managment. I would ike to put forward the following opinions-

1) In an aera of 1000mm rainfall, groundwater storage is certainly deficient and water may be allowed to percolate. However, care may be taken to reduce surface runoff.

2) Stored fresh water may be efficiently used in agriculture, thus helping in enhanced crop production and generating money.

3) Roof top water harvesting is the best solution for storm flood in cities. The harvested water may be stored in an underground tank, which may supplement water requirements of the residents. It is also advisable to promote keeping some part of the land surface unpaved for facilitating rainwater percolation.

Regards,

Benjamin Kaman

Assam

 

2. Dear Sri

Dear Sri Ranganathan,                                                                                 

Greetings and good wishes. I am glad that my website has elicited interest in you.

My clarifications are :

  • “1Q) Why are you trying to prevent percolation? Is the ground water saline or unfit in some way? In my opinion catching rainfall to re-charge ground water is the most suitable option. The sheer quantity of rain water would improve the ground water quality. It would be a good idea for you to get a realistic quotation for digging storage tanks for harvested rain water with plastic lining. You are likely to find the cost quite high and it may make the idea unviable. Spraying light mineral oil on the water will create a new problem of seperating water and oil. I am also not so sure if this is such a good idea to prevent evaporation.”
    • 1A) There is no question of preventing percolation. I agree with you that maximum amount of rainwater should be allowed to percolate to recharge ground water as far as possible.  Storm water often  floods  city roads for days together is not going to help ground water recharge because of concrete jungle in cities.  
    • What I want to impress is this storm water should be transferred fast to pre arranged water bodies for better reuse latter. Out of the normal 140 rainy days in a season,  rains normally occur only in about 50 to 100 hours. During these short span  of time frame the sewage component is very less and the storm water is fit for recycling and reuse. Rain water harvesting to augment village water supply is altogether a different issue  and dealt below.
    • For solving  village drinking water problem, I advocate rain water harvesting in an open level areas and this rain water has to be stored  in tanks with plastic lining to prevent percolation losses and spraying with suitable  mineral oil as thin film to minimize evaporation losses.  The practice of lining of irrigation canals with polethene sheet is common. Spraying non reactive mineral oil is also possible.
  • “2Q) Building dykes to keep fresh water from draining into the sea may also be a very expensive proposition, unless the quantity of fresh water saved is large enough to warrant such a measure and also if it is possible to use this water as a town water supply at a cost that will help fund the cost of construction dykes”
    • 2A)  I do not know how you   concluded  that construction of  a subsurface dyke (a  simple vertical masonry wall a  few feet below the ground surface) parallel to the sea coast in city limits,  to prevent ground water discharge into sea is very expensive.
    • For example, at Visakhapatnam (Andhra Pradesh), the terrain is steep sloping towards  sea coast and drinking  water is a problem.   So it might be feasible to construct suitable dyke.  Central Ground Water Board advocated this concept in their  website and you can see relevant  picture in my website.  Any way if the concept is good, feasibility  studies  and estimates could be undertaken before the actual construction.
  • “3Q) Harvesting roof top rain water extensively in any city would first of all substantially reduce the storm water volume. Unfortunately storm water drains in most cities and towns in our country also carry sewage. If this can be prevented, storm water can be harvested as proposed by you.”
    •  3A) Harvesting roof top Rain water has many advantages   like reduce dependence of city water Supply and  reduce Storm Water in the City. The excess water collected could be utilized for ground water recharge through an unused well.

You are again mixing up two different issues like Roof Top Harvesting and Recycling Storm Water.  The issue of sewage component in storm water is dealt above.

Regards

P.Nukaiah Chetty

1. Your ideas on rain water harvesting.

Dear Mr.Chetty,

I am a water management consultant based in Bangalore.I read your interesting ideas on 'holding on' to the water you have harvested.I am giving you my comments on your three  main points:

1) Why are you trying to prevent percolation? Is the ground water saline or unfit in some way? In my opinion catching rainfall to re-charge ground water is the most suitable option.The sheer quantity of rain water would improve the ground water quality.It would be a good idea for you to get a realistic quotation for digging storage tanks for harvested rain water with plastic lining.You are likely to find the cost quite high and it may make the idea unviable.Spraying light mineral oil on the water will create a new problem of seperating water and oil.I am also not so sure if this is such a good idea to prevent evaporation.

2) Building dykes to keep fresh water from draining into the sea may also be a very expensive proposition,unless the quantity of fresh water saved is large enough to warrant such a measure and also if it is possible to use this water as a town water supply at a cost that will help fund the cost of construction dykes.

3) Harvesting roof top rain water extensively in any city would first of all substantially reduce the storm water volume.Unfortunately storm water drains in most cities and towns in our country also carry sewage.If this can be prevented,storm water can be harvested as proposed by you.

Regards

S.S.Ranganathan

S.S.Ranganathan

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