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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
 

6. Production of annual crops on microcatchments.

In: Rainfall Collection for Agriculture in Arid and Semiarid Regions;

Publ. of CAB, UK; ISBN 0-85198-486-X, 1981, pp. 39-42

Water harvesting for agriculture is an ancient art with proven usefulness for producing food in arid and semiarid regions of the world.

Water is often the limiting natural resource in these regions. The greatest potential for augmenting available water supplies rests in the collection and conservation of precipitation. An estimated 95% of precipitation in arid and semiarid regions of the world is lost to evaporation. A small reduction in these evaporation losses would substantially increase the quantity of water available to agricultural, industrial, and municipal concerns. Agriculture is by far the largest consumer of water, and therefore, conservation in agriculture or substitution of harvested water for traditional water sources in crop production would release large quantities of water to other sectors of society.

Although natural precipitation in an area may be inadequate to raise a crop, enough water can be collected from an entire region for ample crop yields on a portion of the region. Water harvesting enables a greater percentage of precipitation to be put to beneficial use in a water efficient agricultural system.

Some of the simplest water-harvesting systems collect 20% to 40% of the precipitation for later beneficial uses, while a more elaborate system can collect more than 90%.

A number of water-harvesting systems have been developed to suit given regions, crops, and rainfall patterns. Desert-strip-farming experiments to grow two crops per year began in 1978 at the University of Arizona Page Trowbridge Experiment Farm (Page Ranch). Desert-strip-farming is similar to conservation bench-terrace farming and conventional dryland-strip farming in which crops are planted along contours. An important difference, however, is that the fallow areas are used as catchments. The catchment area is often cleared of vegetation shaped, smoothed, compacted, and even treated with sealants to increase runoff efficiency. Furthermore, the adjacent cultivated area, which is formed by leveling a swath along the contour, has a small dike on the downhill side to trap runoff water. Another difference is that unlike dryland-strip farming, where the ratio of fallow to crop is usually 1:1, desert-strip-farming is based on % ratio that varies with the environmental conditions of each specific site. Other variations among systems derive from different methods of treating catchments and storing water.

An important concept in understanding water-harvesting systems is the ratio of catchment area to cultivated area (CCAR). The CCAR depends upon the runoff efficiency of the catchment area, the crop moisture requirements, and the expected quantity and temporal distribution of precipitation. Moisture requirements are determined from consumptive use data for the particular crop and are adjusted to the date of planting and associated considerations.

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Water management

Africa, developing countries, Transkei, Ciskei, irrigation projects, case studies, management, human factors, agricultural production, institutional constraints, socio-economy, culture, tradition, inputs, research needs

BEMBRIDGE, T.J.

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