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close this bookAbstracts on Sustainable Agriculture (GTZ; 1992; 423 pages)
Open this folder and view contentsAbstracts On Traditional Land-Use Systems
Open this folder and view contentsAbstracts on farming systems research and development
Open this folder and view contentsAbstracts on integrated systems
Open this folder and view contentsAbstracts on cropping system
Open this folder and view contentsAbstracts on agroecology
Open this folder and view contentsAbstracts on agrometeorology
Open this folder and view contentsAbstracts on agroforestry
Open this folder and view contentsAbstracts on homegardens
Open this folder and view contentsAbstracts on seed production
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close this folderAbstracts on water management
View the documentAcknowledgements
View the document1. Water management.
View the document2. Crop diversification in irrigated agriculture: water management constraints.
View the document3. Steam corridors in watershed management
View the document4. Water harvesting.
View the document5. An economic analysis of irrigation systems.
View the document6. Production of annual crops on microcatchments.
View the document7. Problems and lessons from irrigation projects in less developed countries of Africa.
View the document8. Irrigation organization and management.
View the document9. Soil water balance in the Sudano-Sahelian zone: summary proceedings of an international workshop. (bilan hydrique en zone Soudano-Sahelienne: comptes rendus d'un Atelier international)
View the document10. Vanishing land and water.
View the document11. Water use by legumes and its effect on soil water status.
View the document12. Environmental impact assessment for sustainable development: chittaurgarh irrigation project in outer Himalayas.
View the document13. Production and water use of several food and fodder crops under irrigation in the desert area of southwestern Peru.
View the document14. Evaluation of the on-farm water management project in the Dominican republic.
Open this folder and view contentsAbstracts on soil fertility
Open this folder and view contentsAbstracts on erosion and desertification control
Open this folder and view contentsAbstracts on potential crops for marginal lands
 

4. Water harvesting.

In: Proc. of the FAO Expert Consultations on the Role of Forestry in Combating Desertification, Saltillo, Mexico, 1985; FAO Conservation Guide No. 21, 1989; ISBN92-5-102802-8

The earliest evidence of the use of water harvesting are the well publicized systems used by the people of the Negev Desert perhaps 4000 years ago. Hillsides were cleared of vegetation and smoothed in order to provide as much run off as possible; the water was then channeled in contour ditches to agricultural fields and/or to cisterns. By the time the Roman Empire extended into the region, this method of farming encompassed more than 250,000 hectares.

Water harvesting is a technique of developing surface water resources that can be used in dry regions to provide water for livestock, for domestic use, and for agroforestry and small scale subsistence farming.

Water harvesting systems may be defined as methods whereby precipitation can be collected and stored until it is beneficially used. The system includes a catchment area, usually prepared in some manner to improve run off efficiency and a storage facility for the harvested water, unless the water is to be immediately concentrated in the soil profile of a smaller area for growing drought-hardy plants. A water distribution scheme is also required for the systems devoted to subsistence farming for irrigation during dry periods.

A successful system must be:

 

- Technically sound, properly designed and maintained.
- Economically feasible for the resources of the user.
- Capable of being integrated into the social traditions and abilities of the users.

Water harvesting offers methods of effectively developing the scarce water resources of arid regions. As contrasted to the development of groundwater, which is usually a finite water resource in arid zone, the method allows use of the renewable rainfall which occurs, even though in limited amounts. It is also a relatively inexpensive method of water supply that can be adapted to the resources and needs of the rural poor.

It is necessarily small scale, and as such it can provide stability and improve the quality of life in small rural communities and that of small land holders who are several stages removed from the benefits of large scale development projects. It involves some risk, dependent upon the vagaries of climate. New skills, though simple, are required, maintenance is a constant necessity, and good design is imperative.

There is no universally "best" system of water harvesting. However, there will be some type of system that can be designed to best fit within the constraints of a given location. Each site has unique characteristics that will influence the design of the most optimum system. All factors, technical, social, physical and economic must be considered.

During the past two decades, there have been many water harvesting systems constructed and evaluated at a number of different places in the world. Some of the systems have been outstanding successes, while others were complete failures. Some of the systems failed, despite extensive effort, because of poor design or the materials used. Other systems failed despite good design and proper materials because social factors were not integrated into the systems. These systems failed because of poor communication and lack of commitment by the local people both in planning and financing the projects.

Sufficient knowledge and experience has been accumulated to put into operation water harvesting projects throughout the arid lands of the world. Empirical information and documentation is needed from successes as well as failures on which to build a more exact technology.

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Water management

Case study, USA, irrigation systems, costs and benefits, cotton production

LETEY, J. et al.

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