Spate irrigation
Encyclopedia
Spate irrigation uses seasonal floods of rivers, streams, ponds and lakes to fill water storage canals. If irrigation
is the manipulation of water for use in growing crops, Spate irrigation is perhaps the most ancient method devised. Records of basic spate irrigation engineering can be traced back beyond recorded history and include the Ancient Egyptian diversion of the Nile River for storage at times of heavy rainfall for use in the dryer times of the year.
In spate irrigation, water is diverted from normally dry river beds when the river is in spate
. The flood water is then diverted to the fields. This may be done by free intakes, by diversion spurs or by bunds, that are build across the river bed. The flood
water, typically lasting a few hours or a few days, is channeled through a network of primary, secondary and sometimes tertiary flood channels. Command areas may range from anything between a few hectares to over 25,000 hectares.
Spate water management is substantially unique to arid and semi-arid regions, typically in underdeveloped countries in the Middle East
, North Africa
, West Asia, East Africa
and parts of Latin America
.
Spate irrigation systems require huge management efforts to control and optimize the flow of water. Because fast-moving water is capable of moving very large amounts of sediment
, the heights of river banks and the composition of their beds can change rapidly. Diverting the flow of a powerful force which is capable of moving rock
s, soil
s and other materials used to divert the path of the water can prove difficult.
The number of public programs to support spate irrigation have been relatively limited. One reason has been the difficulty to justify investments in civil engineering
works on systems, dominated with low value farming. The second reason has been that it has been hard to identify successful interventions in spate systems, because spate systems are often hydraulically and socially generally very complex.
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
is the manipulation of water for use in growing crops, Spate irrigation is perhaps the most ancient method devised. Records of basic spate irrigation engineering can be traced back beyond recorded history and include the Ancient Egyptian diversion of the Nile River for storage at times of heavy rainfall for use in the dryer times of the year.
In spate irrigation, water is diverted from normally dry river beds when the river is in spate
Spate
Spate is a surname, and may refer to:* Clive Spate , British game show contestant* Oskar Spate , geographerSpate may also refer to a flood.-See also:* Pate * Spade * Spat...
. The flood water is then diverted to the fields. This may be done by free intakes, by diversion spurs or by bunds, that are build across the river bed. The flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
water, typically lasting a few hours or a few days, is channeled through a network of primary, secondary and sometimes tertiary flood channels. Command areas may range from anything between a few hectares to over 25,000 hectares.
Spate water management is substantially unique to arid and semi-arid regions, typically in underdeveloped countries in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
, North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
, West Asia, East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
and parts of Latin America
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
.
Spate irrigation systems require huge management efforts to control and optimize the flow of water. Because fast-moving water is capable of moving very large amounts of sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
, the heights of river banks and the composition of their beds can change rapidly. Diverting the flow of a powerful force which is capable of moving rock
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
s, soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
s and other materials used to divert the path of the water can prove difficult.
The number of public programs to support spate irrigation have been relatively limited. One reason has been the difficulty to justify investments in civil engineering
Civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
works on systems, dominated with low value farming. The second reason has been that it has been hard to identify successful interventions in spate systems, because spate systems are often hydraulically and socially generally very complex.
See also
- Rod KohRod KohRod Koh or Rod Kohi is a form of irrigation system in Pakistan. Rod means channel and Koh means mountain in Persian). The Rod Kohi system based on Kulyat Riwajat governed the irrigation system ever since the Pashtun tribes had moved into Damaan...
Spate irrigation in Pakistan - Irrigation of alluvial fans#Khuzdar
- Surface irrigationSurface irrigationSurface irrigation is defined as the group of application techniques where water is applied and distributed over the soil surface by gravity. It is by far the most common form of irrigation throughout the world and has been practiced in many areas virtually unchanged for thousands of years.Surface...