How it works?
Dug well is a traditional method of availing water for thousands of years in the state. It is a shallow hole dug down in to the water table. The diameter of the well varies from One meter to 8 meters depends upon the terrain and practice of people in obtaining water from the vicinity of their homesteads. Depth to the shallow aquifers varies from 2 meters to 15 meters below ground level which again varies from place to place.
Indeed, Wells are the most popular water sources widely used in Kerala for domestic purposes. Most of the families depend on private water sources, which are usually open wells. Many of these wells dry up by early March and remain so till the monsoons, which are in May - June.
Before introduction of public water supply systems by modern governments, open dug wells were the main source of drinking and domestic water supply in Kerala. This means more than 95% of the water needs of households were met from the open dug wells. Whereas this has reduced drastically ignoring wells for pipe water supply systems. As per the 2001 India Census data, 72% of the households in Kerala were depending upon open dug wells and it reduced to 62% in 2011 Census data figures. This is alarming and causes concern for the water security systems in the state.
The methods of well recharging
Supporting Scientific Principle
The Theory of Ghyben- Herzberg Relation supports the recharge of coastal water bodies by rainwater harvesting. As per Ghyben Herzberg Relation, when fresh ground water table of the coastal area dips down one feet, the access of saline ingress to the coastal water bodies is forty times high. It is the based on density of coastal ground water and sea saline water.
Technology We Use
|Technology choice||Specification||Indicative Cost-Range in US$|
|Open well (Drinking)|
|1. Roof top harvest with Sand filter||PVC Gutters pipes are fixed to collect water from roof and water is diverted to the filter using a PVC pipe. The filter consists of sand, metal and charcoal||US$ 100.00|
|2. Roof top harvest with ordinary Nylon filter||Water is harvested from the roof and is diverted to the well through a Nylon or cloth filter using a PVC pipe.||US$ 75.00|
The technology adopted for the Mazhapolima programme is mainly the roof water harvesting for open well recharging. Households in Kerala mainly depend upon homestead open dug wells than the inefficient public water supply systems. However, ground water depletion in general calls forth large scale replenishment of unconfined aquifers from where open dug wells make avail water in Kerala. The pictures below shown how the roof water is collected from the roof top and filtered before injecting down to dug wells. While doing so a fresh water zone is formed at the source of dug wells as shown in the diagrammatic representation of roof water harvesting.An open surface well from Methala Grama Panchayat in Kodungalloor block as shown below. The water quality and its appearance are so poor that it cannot even be used for bathing animals. Such wells in the coastal areas with poor water quality can be improved and recovered by backwashing it with rainwater.
A Case Study From Midland Lateritic
Thettayil Rappai (61) and Elsy (52) family lives in Kuttoor near St.Annes School of Kolazhy Grama Panchayat. Rappai is a local contractor for RCC roof construction and Elsy is a homemaker. This location is about 6 Km away from Thrissur Municipal Corporation. This area comes under midland lateritic zones as per the Geomorphology. Kolazhy Grama Panchayat ward no.11 where they live in, is a water scarce area in the summer. The soil condition is red loamy top soil and lateritic below 5 feet. People opt for homestead dug wells from the unconfined aquifers seen below 10 to 15 feet from the ground level. Average depth of the wells here is 9 meters from the ground level. Rappai and Elsy couples live in the present place for the past 27 years with 11 cents (0.11 Acres) of land. And they have their open well dug since 26 years soon after their settlement. This well was non-perennial / seasonal till during the summer of 2010. They require 750 liters of daily water needs for their four member family and pump up water from the Fig.. Rappai shows how to Open the Valve of First Flush well to their over head tank of 750 liters. The family requires approximately 25 liters of water from drinking and remaining 725 liters for domestic purposes. During summer, they meet their water demand from Tanker water supply in the nearby area and it cost them Rs. 500/- (about US$ 8.25) for 6000 liters of water. Tanker water will be poured to open dug well since they do not have the storage system.
Normally this helps them for about 10 days. And when it gets dry either they go to their neighbor or call the water tanker again. This was the practice for the last 27 years. Mazhapolima which is a ground water recharge programme through roof water harvesting was implemented in 98 houses in the Kolazhy local government, Ward no.11 which is the driest among all other Wards. Thettayil Rappai and Elsy couples got this scheme benefit from the Kolazhy local government. Mazhapolima system will have half round PVC pipes of 6 inches as rain gutters that collect roof rain water. And the roof rain water thus collected is directed to the open dug well near to their houses premises using 2 inch pipes with its accessories. Beneficiaries are supposed to clean the well and roof and also to install a filter system, as per the direction from the local government to consider it as their contribution. This system has a first flush unit to drain out the unclean water from the roof from the first spell of rains. Mazhapolima installation them about Indian Rs.3000/- (US$ 50). The Rappai and Elsy couples learnt about the benefits of the scheme from the classes held at Kolazhy local government and at the beneficiary meeting jointly organized by this local government and Mazhapolima Monitoring and Coordination Unit alias District Rainwater Harvesting Mission. And therefore, the family did not have any hesitation to direct the roof water to the open dug well. The RCC roof area of the house is 950 sq.ft which can harvest nearly 225000 liters of rainwater as per the matrix of Central Ground Water Board of India with 3000 mm average rainfall of Kerala. (2.5 Lakh liters of rainwater from 1000 sq.ft roof or 1.2 lakhs from 1 Cent of land). The Mazhapolima well recharge unit was installed during March 2010 and started to collect summer showers which helped their dug well to supply enough water for summer. Elsy says they had even the water for 4 feet during the last summer which was complete dry during the summers of past 26 years. Also they had to spend Rs.500/- (US$ 8.25) for 15 days earlier which they have saved during this summer.
The threats they had to face were the defecation of cats over the roof. And therefore they preferred the roof water to direct just near to the well where a coconut tree exists. As a part of the agriculture operation, farmers take 1. 7 meter breadth of coconut tree ground basin to percolate the rainwater under the tree. This naturally goes down to the aquifers of the well without any filtering systems. Many scheme beneficiaries under Mazhapolima programme prefers thus to allow the roof water spread near the premises of open dug wells which is less risky they say. Now the couples are happy and over joy about the water bounty for summer. They relieve that no longer they need to approach their neighbor for water or to call water tankers. Joyful Elsy is vociferous to talk about message she learnt from Mazhapolima well recharging method wherever she goes.