Water capture and storage for irrigation has been an ongoing theme of research in Columbia’s earth and environmental engineering department, but Professor Upmanu Lall has recently taken things a step further. With funding from the Pulitzer family, Lall challenged a group of students in his senior engineering course to design a low-cost system of water capture and storage for irrigation in Koraro, Ethiopia, one of the Earth Institute’s Millennium Villages.
The challenge is not an idle one. Ethiopia is at a critical crossroads, with a burgeoning population, a severely depressed national economy, insufficient agricultural production and a minimal number of developed energy sources. Hydroclimatic year-to-year variability has long hindered the country’s growth and prosperity. Eighty-five percent of the people lives in rural areas, and most of them practice subsistence farming. A heavy reliance on agriculture, combined with a susceptibility to frequent climate extremes, has left it in a precarious position, striving not only to stay on par, but to prevent vast numbers of people from falling deeper into poverty. One devastating year can nullify the gains of several successful growing seasons.
Northern Ethiopia, especially the region of eastern Tigray, where Koraro is located, is notoriously dry. Yet local farmers continue to work the land. Irrigation is practically nonexistent, as the capital costs for infrastructure far surpass farmers’ means. Water storage through small-scale ponds designed to capture rainwater runoff is becoming more commonplace. However, this source alleviates only short-term dry spells (weeks to months) and isn’t sufficient for dry seasons or drought conditions. The ponds also create ideal breeding grounds for mosquitoes, increasing the risk of malaria transmission.
For the students in Lall’s class, one of the major challenges in providing a better irrigation system is to develop alternative means for capturing rainwater runoff, as soils are highly permeable. The team has designed a system to retard the runoff in higher elevation gullies through rock dams, allowing the water to infiltrate and recharge the upper aquifer. The goal is to provide water to agricultural areas at lower elevations through simple pipe networks, minimizing evaporation. So far, the work looks promising, though additional analysis and field visits are necessary before implementation.
A short audio slideshow describing this project in Koraro is available below or by visiting the International Research Institute for Climate and Society (IRI).