WATER FOR HUMANITY APPROPRIATE TECHNOLOGY:
Rainwater Harvesting: El Albarrata y Tapas
by Steven G. Herbert
For millennia, those who live in regions characterized by distinct wet and dry seasons have faced the challenge of how to manage the abundance of water at one time of year and the scarcity of it at another. One common solution has been to create situations where large quantities of water can be captured and contained during the rainy season which can be rationed to last through the dry season. In ancient times, large bowl-shaped areas were dug by hand. In modern times, catchment ponds are dug with excavation machinery. Clay might be used in either case to minimize the lose of water through the ground below.
A modern albarrata in Ecuador's province of Manabi.
On my first trip to Ecuador in 2007, I had the opportunity to see both types, ancient and modern, for the first time. There, a rain harvesting pond is called an albarrata. It purposely has no inlet or outlet. However, a variety of albarrata which is constructed to allow seasonal floodwaters to enter at one end is called a tapas. In other words, a tapas can capture water that not only falls as rain, but also surface floodwaters. This technology has been a blessing in making water available year round, even in times when there might otherwise be drought conditions. However, this system has also had certain drawbacks. One is that static water becomes more and more stagnant as the dry season wears on, with increasing risks of contamination. Water filtration technology becomes more important to be coupled with retention ponds in those times. Another problem as these ponds can become silted in over time, thus requiring maintenance removing silt from time to time.
An example of an albarrata which has become stagnant.
While I was in the dry coastal province of Manabi, we made a detour to visit the community of Santa Rosa. Here we found a tapas, but the problem was that it was a dry one. It normally functioned well, filling up with rain and floodwaters which carried the community through until the rains returned. However, when the government built a road through here, the tapas was cut off from its source of replenishing rains and went dry, leaving the community without water. The solution was simple, though they lacked the funds to build a culvert across the road. Fortuitously, I had been given some funds by the Uniting Church of Christ of Amherst, NH, for just such an emergency should I encounter it. The culvert was built in time to capture some of that season’s rains and provided some relief.
The dry tapas in the village of Santa Rosa, Ecuador
On my return visit in the following year, I arrived to see it with my own eyes, and also observe that concrete wing walls had been built on the receiving end. The men were working on clearing the channel on the other end when we arrived. Expressing their sincere gratitude for the help given them before, they explained they needed next to build concrete wing walls on the other end and line the channel with rocks to better stabilize it. I was thankful in turn for having with me further funds from the same church group and was able to provide the funds (which were managed by Heifer Project) to complete the project. To feel like this was truly a complete success, however, I continue to encourage progress in Ecuador to build a factory to manufacture the ceramic water filters.
Members of the community of Santa Rosa, Ecuador, standing over the culvert and wing walls they built to direct waters into a tapas.