Water harvesting involves the capture and storage of runoff rainwater, so that it can be channeled onto targeted land areas when needed, thereby improving agricultural productivity. The potential of water harvesting is a function of land slope, rainfall frequency and cropping potential. Maps, based on Geographical Information Systems (GIS) and models, can give a clear picture of areas where rainwater can be effectively harvested at the community level.
Mapping Eritrea
The International Center for Agricultural Research in the Dry Areas ICARDA and its partners used a GIS model, adapted to data-poor environments, to produce a ‘suitability map’ of Eritrea’s Zoba Debub area (see page 21). The map enabled them to assess the potential of different macro- and micro-catchment water harvesting techniques and indicated that 70% of the area is suitable for at least one of the approaches.
Based on these findings, water harvesting was introduced and tested in two of the eight high-potential watersheds studied (Tselema in the north east and Hazemo in the south east). Partners are currently seeking funds to scale up water harvesting in all the locations studied.
Water harvesting reservoirs in Ethiopia
In Ethiopia’s northern Amhara region, torrential daily rainstorms cause immense surface water runoff and soil erosion from July to September, while water is scarce from December to June, making off-season crop production only possible by diverting river water. Water harvesting techniques can help farmers capture and store water, and deliver it to crops at critical moments in the growing cycle.
ICARDA, working in collaboration with the Amhara Region Agricultural Research Institute (ARARI), is investigating options to provide individual farm households with water harvesting ponds that can capture about 75 cubic meters of water. Such ponds can provide drip irrigation for high-value crops such as garlic, onion and shallot during the dry season, and supplemental irrigation for wheat during dry spells at the end of rainy season.
Currently, such ponds cost between US$600-US$800 (including installation). If longer credit terms were made available and if costs were reduced through market mechanisms, large-scale uptake of these ponds by the resource-poor farmers in the region would be a possibility.
In the UK, rainwater harvesting has already progressed to full house systems, including potable water supply.
Although we have a relatively high annual rainfall, we still have massive water supply issues, particularly in the South East of England and rainwater harvesting has to be the way forward to ensure a sustainable future for all countries.
It is necessary to increase crop production especially with climate change
It is necessary to assess people in the dry areas who are vulnerable to climate change and climate change risks.
Ahmed, thanks for your comments. You might find more materials of interest to you: http://ccafs.cgiar.org/
as well as http://www.icarda.org/