Reviving an age-old practice | Daily News

Rainwater harvesting

Reviving an age-old practice

Dr. Tanuja Ariyananda, Chief Executive Officer, Lanka Rain Water Harvesting Forum (LRWHF)
Dr. Tanuja Ariyananda, Chief Executive Officer, Lanka Rain Water Harvesting Forum (LRWHF)

For centuries, rainfall has been a source of wealth, food, water, energy and it is the ultimate source of life itself. It has given us hydropower providing us with electricity and blesses the agricultural community with a harvest providing us with food. It drives and sustains the circle of life, by giving life to trees and these trees in turn give us oxygen, oxygen that we need to breathe. Oxygen which is necessary to create rain. Rain prevents climate change by providing us with trees that suck in the carbon dioxide, lowering the temperature. Rainfall is the giver of water which is vital to life.

The Daily News spoke to Chief Executive Officer of the Lanka Rain Water Harvesting Forum (LRWHF), Dr. Tanuja Ariyananda on rainwater harvesting and the water harvesting project which is now nearing completion.

Dr. Ariyananda spoke of the great King Parakramabahu who in ancient Sri Lanka made the very first proclamation on rainwater harvesting when he said that not a single drop of rainwater should run into the sea without being utilised for human consumption.

“As an organisation, we are promoting the concept of rainwater harvesting for domestic purposes. At the moment, we are on a project to promote rainwater harvesting for the drought and flood-prone areas. We have selected Kilinochchi in the North, Badulla and Moneragala in the Uva Province, and we are also focusing on the Batticaloa district. Our aim is to provide safe drinking water to the communities affected by disaster,” said Dr. Ariyananda.

LRWHF has introduced the rainwater harvesting system where rainwater is collected from the roof and then sent to a tank. The system has been introduced to 390 houses, 48 schools and 10 clinics and rural hospitals. LRWHF has identified the most severely affected drought and flood-prone areas.

“Rainwater is pure drinking water and it is clean water. We are also building the capacity of government officials, NGOs and researchers on these technologies. We have carried out a series of training programmes in these districts. There are also pockets in these areas where people are prone to chronic kidney problems. We are targeting those areas as well. In the Batticaloa district, especially through our partners, pipes are installed for beneficiaries, where the Water Board hasn’t yet done so. It is a three-year project supported by USAID,” Dr. Ariyananda said.

LRWHF has covered 17,000 beneficiaries through its rainwater harvesting projects. The idea is also to make children more aware of the changing weather patterns, because drought and floods are due to changes in the weather patterns.

“We have installed weather stations in some schools, and children have been trained how to operate and maintain these weather stations. They are mobile weather stations, giving frequent information on rainfall, wind, wind direction, pressure and temperature. The children take note of these parameters on a daily basis. A person can view information on weather in those locations on a website. We are a small 23-year-old organisation, but we have reached out to many communities with our technology. In addition to having storage rainwater systems, we are recharging the groundwater through rainwater. In places where there are large capacity tanks, the overflow of the tank is directed to the wells or directly from the roof into the wells. We want to increase the quality and quantity of the wells,” explained Dr. Ariyananda.

She further stressed that if you maintain the system well, you will have pure drinking water. “Rainwater harvesting in Sri Lanka is important because of the changes in climate. We have a very long drought period with no rain, and a very short rain period. During the rainy season, it is very important to collect water and use it during the dry season. In this way, you address the drought. During the floods, if you can store as much as possible, then you reduce the amount that flows into the roads and into the landscape,” she said.

“There are around 70,000 people in the Northern, Central, Uva and Southern Provinces with chronic kidney disease. But the cause of the disease is not known yet. Amongst various other explanations for the cause, some suspect the type of water to be the cause. So, we are providing those households with clean drinking water. Some people say that their condition has improved as a result. However, this has not been clinically proven yet,” Dr. Ariyananda said.

The data from the weather stations in schools can be sent to the mobile phone and is also available on the website, which predicts the weather forecast for the next 10 days. People can therefore be more prepared when a drought or flood is predicted. However, not all schools have weather stations. Only around four are operating. The mobile stations are run on solar power.

“USAID has been supporting us from 2016. The schoolchildren are enthusiastic about the project and the subject as well. All the communities that we have projects with are very involved as well. In each village where we have installed rainwater harvesting systems, people are made aware of the benefits of rainwater harvesting. After the system is installed, we teach them how to operate and maintain it. Rainwater harvesting is a simple technology used from time immemorial,” Dr. Ariyananda said.

She said the irrigation marvels of our ancient monarchs are living embodiments of this technique which still continue to feed acres of agricultural land. “What we are trying to do is to revisit this age-old practice at a time when climate change is unprecedented and replicate the concept to the modern setting.”

In terms of storage facility and capacity, 8,000-litre capacity storage tanks are promoted for domestic use, while 10,000 to 16,000-litre capacity tanks are promoted for hospitals and 30,000-litre capacity for schools.


The science of rainwater harvesting

First, the rainwater on the roof needs to flow through the gutters, and then through a pipe to the ground. After sufficient water flows through the gutter cleaning it, it is assumed that the gutter is cleaned. Once the pipe fills to the brim, the end of the pipe that connects to the ground is closed with a valve. With water unable to enter the pipe, it is diverted through another pipe, which takes it into the storage tank. However, before the water passes into the storage tank, a filter separates the debris, resulting in clean water in the tank. 

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