RAIN HARVESTING AS WATER CRISIS INTERVENTION

RAIN HARVESTING AS WATER CRISIS INTERVENTION

Erle Frayne D. Argonza

Crispin Maslog of the Philippines, who previously worked for the International Rice Research Institute, cogitates about the practice of rain harvesting as a viable water crisis intervention measure. I couldn’t agree more with this noblesse gentleman from environmentalist circles in Southeast Asia.

I still recall all too well in the early 80s, when I began my career as a development worker, how a municipal government decided to convert a mountainous part of the town of Solana into a water catchment. Being a rice producer, the town of Solana, of Cagayan Province, has more than ample water supply at that time coming from the freshly started irrigation projects. Yet the presence of irrigation facilities didn’t stop the mayor of the town [name now escapes my memory] to conceptualize, along with his able staff, such a project.

The catchment had multiple purposes, with irrigation or water for crop production only among the common usages. It can also be used for bath, washing stuff, and even as potable water for drinking. I honestly highly appreciated the project, and was directed to opine that all rural towns in the Philippines for that matter should construct their equivalent of water catchments.

Well, the good news is that the Congress of the Philippine republic legislated a law that enforced the construction of water catchments in all of the local villages of the country. The bad news is that the law wasn’t implemented as originally conceptualized.

Below is the interesting reportage on the subject by Crispin Maslog.

[Manila, 02 June 2013]

Source: http://www.scidev.net/en/agriculture-and-environment/water/opinions/asia-pacific-analysis-rain-harvesting-can-avert-crisis.html

Asia–Pacific Analysis: Rain harvesting can avert crisis

Crispin Maslog

29 May 2013 | EN

To ensure South-East Asias's growing population has enough water to drink, we need to collect more rain, says Crispin Maslog.

The world's next major crisis will be a lack of water for home use, including drinking water, many scientists predict. Humans can survive around 40 days without food, but much less than that without water to drink.
The scarcity of water for domestic use is becoming a critical problem, especially in rural parts of developing countries. Surface water in rivers, streams or lakes, and groundwater, are increasingly becoming contaminated with pollutants from factories, households, farms and mines. Wells dug deeper to extract groundwater are drying up. [1]

·                       Water scarcity is becoming a critical problem, but rainwater can provide a solution

·                       Rain is stored in jars in Thailand and on roofs in Singapore

·                       But only governments can drive consistent, centralised efforts to collect rainwater

To meet the water demands of an exploding population, it is time to look up to the sky for the solution: harvesting rainwater as it falls.

As well as for drinking, rainwater serves various needs. It can be used domestically, for example to wash clothes, flush toilets and to water plants, and in the community, for instance in firefighting or to clean public places such as markets, and for agriculture.

If properly done, "rainwater harvesting appears to be one of the most promising alternatives for supplying freshwater in the face of increasing water scarcity and escalating demand", according to the UN Environment Programme. [2] Water catchments, whether it is just small ponds or large dams, can also be used for flood control.

Updating an ancient practice

Harvesting rain for domestic use has age-old roots. Ancient Romans used their villa courtyards to collect rainwater that was then stored in large underground cisterns.

Rainwater harvesting in Asia can be traced back to about the ninth century, when the small-scale collection of rain from roofs and simple dams began in rural parts of South and South-East Asia.

Today, rainwater harvesting is commonly practised in parts of East Africa, central Australia and Central America, as well as in Japan, Mexico, Singapore and Thailand, among others.

Countries in South-East Asia and the Pacific enjoy abundant rainfall spread fairly evenly throughout the year, albeit with peaks during the monsoon season that normally occurs between July and December. Annual rainfall in the region typically ranges between 1,500 and 2,500 millimetres, although mountain areas have in excess of 4,000 millimetres. [3] Such massive downpours often cause flooding in lowland areas.

The monsoon season is obviously the peak time for water harvesting. It makes sense for the region to consider widespread, systematic harvesting of rainwater for domestic, agricultural and industrial uses.

Varying practices

Modern rainwater harvesting practices in the region vary from country to country. 

In Singapore, which has limited land and where most people live in high-rise buildings, rooftop rainwater harvesting is widely practised. Collected water is kept in separate roof cisterns for non-potable uses. The country's Changi Airport has a large rainwater harvesting system that collects rain from the runways and the surrounding green areas in two reservoirs. The water is used mainly for firefighting drills and toilet flushing. [4]

For Thailand, which has the lowest per capita volume of freshwater in Asia, rainwater harvesting provides a major alternative supply. 'Rain jars' — vessels of up to 3,000 litres that catch water from roofs — have always been part of its culture. In rural northeastern Thailand, "a home was not a home unless it had one huge rainwater jar", according to Thai writer Cezar Tigno. [5]

The Philippine Congress passed a law in 1989 that required each of the country's 42,000 villages to build rainwater collectors or ponds mainly for aquaculture use as well as to minimise the risk of flooding, to provide water for areas on the banks with vegetation and small parks, and to recharge badly depleted groundwater. [6]

However, more than two decades later, because of the lack of implementation by local governments, only a handful of these collectors have been constructed.

Directly harnessing rainwater

There appear to be four ways to bring about rainwater harvesting: introduce legislation requiring every new home to include a harvesting system before a building permit is approved; create laws requiring villages to build communal ponds; draw up legislation requiring every industrial plant or complex to build a harvesting system to meet its water needs; or to build proper drainage, water recycling or underground reservoir systems for cities. Most engineers think that this centralised system is more viable than the three other fragmented approaches.

So governments must lead the way. The mystery is why governments in South-East Asia and the Pacific have not gone all out in tapping this abundant natural water supply. To harness rainwater, what is needed is consistent public policy and political will.

Crispin Maslog is a Manila-based consultant for the Asian Institute of Journalism and Communication. A former journalist, professor and environmental activist, he worked for the Press Foundation of Asia and the International Rice Research Institute.

This article has been produced by SciDev.Net's South-East Asia & Pacific desk.

References

[1] Luong, T.V. Harvesting the rain: A construction manual for cement rainwater jars and tanks (UNICEF East Asia and Pacific Regional Office, 2002)

[2] UN Environment Programme Sourcebook of Alternative Technologiesfor Freshwater Augmentation in Some Countries in Asia (UNEP, 1998)

[3] Sehgal, J.D. Roof-Top Harvesting of Rainwater: A Sustainable Water Resource in S.E. Asia (4th International Conference on Sustainable Water Environment: Innovative Technologies and Energy Efficient Solutions, 2008)

[4] UN Environment Programme Examples of Rainwater Harvesting and UtilisationAround the World (UNEP, retrieved 24 May 2013)

[5] Tigno, C. Thailand: Promoting Rainwater Harvesting,Preserving Rain Water Jar Culture (Scribd, 2007)

[6] Oposa T., Jr. Implement 1989 rainwater collection law (Philippine Daily Inquirer, 2009)