Promising ways to catch and store rainwater
I keep thinking that a major reason why there is no sense of urgency among Filipinos in addressing climate change is the smug thought that we are in a climatically hot and wet country, which is further fed with copious rainfall by regular typhoons. But I would like to disabuse our mind of such notion because, among Southeast Asian countries and Japan, the Philippines actually ranks second from the lowest in terms of per capita water availability a year, with only 1,907 cubic meters per person, based on a study by the World Bank on the Philippine Environment Monitor early in the millennium.
While water-related government agencies are being urged to address water scarcity and the high cost of agricultural products, I would like to offer practical advice on where to focus our attention so that we can collect and store water more cheaply and quickly at the sub-watershed and household levels.
One promising alternative is setting up what are called small water impounding projects (SWIPs). SWIPs that are built in small sub-watersheds are cheaper and faster to construct, plus they directly provide local government units with water and other benefits, and closely involve the local community in their development efforts. As communities are mobilized at the more manageable level of sub-watersheds that abound in our mainly mountainous country, this approach can even be a practical way of rehabilitating our more than 130 impaired critical watersheds.
The SWIP is a structure constructed across a narrow depression or valley to hold back water and develop a reservoir that will store rainfall and runoff during the rainy season for immediate or future use. Its specific functions include: crop irrigation, flood control; groundwater recharge; aquaculture; domestic water use, water for livestock, and recreation/ecotourism. A study by the Forest Management Bureau in 2015 puts the cost of a SWIP construction at only around P300,000.
A joint study by the Department of Public Works and Highways and the Department of Agriculture in 2001 of 25 SWIPs in northern Luzon also showed that, compared to non-SWIP farms, SWIP areas had significantly higher palay yields during both rainy and dry seasons. The study also pointed out that the key to the success of a SWIP project includes the early participation of beneficiary farmers in planning decisions from the formation and design stages, and nurturing the farmers’ sense of project ownership.
The government should lose no time in shifting its focus to this promising project. Amid the threat of more frequent droughts hitting the country during El Niño events and the consequent short notice given by the National Water Resources Board to households on cuts to their water supply, it is also about time that we focus our attention at the household level, and on the neglected practice of rainwater harvesting commonly observed in arid regions of the world.
I am referring to rainwater collection that captures water from the roofs of houses through the use of a gutter that conducts the water into either a rain barrel or into a cistern placed either above or below the ground. In the Iloilo province where I come from, towns without piped water commonly use a tall cylindrical tank for catching and storing rainwater for general household use. We call the tanks “allebe,” a corruption of the Spanish word “aljibe”—meaning cistern.
A study by S.F. Heron in 2018 observes that a typical household in cities can reduce its consumption of treated water from mains by between 30 and 50 percent through rainwater harvesting. We should lose no time in actively promoting long-ignored practices as we face the challenges of climate change.
Meliton B. Juanico is a retired professor of geography at the College of Social Sciences and Philosophy at the University of the Philippines Diliman, and is a practicing licensed environmental planner.
