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7/29/2019 Introduction to Water Harvesting
1/25
Water Harvesting
for Improved
Agricultural
Production
Unit 1Introduction
What is water harvesting ?
What are the benefits of water harvesting ?
What are the limitations of water harvesting ?
For which areas is water harvesting suitable ?
Where was water harvesting used traditionally ?
Where is water harvesting used at present ?
Introduction
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
1.to be directly conveyed to a
cropping area and stored in the soil
profile for immediate uptake by thecrops (i.e. runoff farming systems) or
2.to be stored in a water reservoir for
future productive uses
domestic consumption
livestock watering
irrigation
aquaculture
What is water harvesting?
Run-on area
= cropping area
or storage mediaRunoff area
= catchment area
The principle
A process of collecting runoff from a catchment area
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Water Harvesting
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Unit 1Introduction
To secure water supply in dry areas where other water
resources (surface water or ground water) are not
available or are uneconomical to develop, in order to:
increase the productivity of arable and grazing land which suffers frominadequate rainfall
increase yields of rainfed farming
minimize the risk of crop failure in drought- prone areas
combat desertification by afforestation, fruit tree planting or agroforestry supply drinking water for animals
supply domestic water
The main goals of water harvesting
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Water Harvesting
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Unit 1IntroductionWater Harvesting
Storage in thesoil profile
Annual crops/ trees / pasture
Run-on area
Irrigatedcrops
Runoff area
(catchment)
water
water
water
Storagemedia
Storagemedia
The principle of water harvesting
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
The principle of water harvesting
Macrocatchment
Floodwater harvesting
Microcatchment
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
Roof tops
Courtyards, streets, public squares
Catchment area
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
Small ground surfaces
untreated
treated
Catchment area
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
Slopes
untreated
treated
Catchment area
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
Large, untreated catchment areas which feed
seasonal water courses
Catchment area
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
Roof tops
Courtyards,
streets, public
squares
Catchment areas
Slopes
untreated
treated
Large
catchment areas
feeding seasonal
courses
Small groundsurfaces
untreated treated
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Unit 1Introduction
Underground storage
Soil
Sediments
Storage media
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Unit 1Introduction
Underground storage
Cisterns
Storage media
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Unit 1Introduction
Storage above ground
Tanks and jars
Storage media
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AgriculturalProduction
Unit 1Introduction
Storage above ground
Ponds
Storage media
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Water Harvesting
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AgriculturalProduction
Unit 1Introduction
Storage above ground
Reservoirs
Storage media
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Unit 1Introduction
Underground storage
Soil
Sediments
Cisterns
Storage media
Storage
above
ground
Tanksand jars
Ponds
Reservoirs
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Unit 1Introduction
What are the benefits of water harvesting ?
WATERHARVESTING
Water conservation(tapping unused water)
Soil conservation(for macrocatchments
on cropping area only) =less soil erosion
Higher productivity(higher yieldsand less risk)
Pastureimprovement =more livestock[= moredesertification ?]
Improvedre-/afforestation =less desertification
Crop production inareas where it isnormally not feasible
Groundwaterrecharge = morewater available
Suppression of salinityin soil = moreproductive land
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Unit 1Introduction
What are the limitations of water harvesting?
Climatic risks still exist
No guarantee for high yields
Methods scientifically not well established
Very often limited experience of extension service
Possible conflicts between people upstream and downstream
Possible harm to fauna and flora
Larger schemes and structures are difficult to implement (need
acceptance by people, political backing and financial support)
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Unit 1Introduction
Arid, semi-arid and semi-humid areas
Where water demand of crops is higher than supply because of
low rainfall and / or
uneven seasonal distribution of rainfall and / or
high temperatures (high evapotranspiration)
Where rainfall exceeds 150 mm /year, if rain falls in
the cool season
Where rainfall exceeds 200 mm /year, if rain falls in the hot seasonand if no storage in ponds or reservoirs is provided
For which areas is water harvesting suitable?
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Unit 1Introduction
Where was water harvesting
used traditionally?
Asia
Jordan (since 7000 BC)
Mesopotamia (4500 BC)
Palestine (2000 BC-1200 AD)
Yemen (since 1000 BC)
Pakistan
India
Sri Lanka
China
America
Arizona and New Mexico(1000 AD)
Africa Tunisia: `Meskats, Mgoud
and Jessours
Somalia: `Caag and `Gawansystems
Sudan: `Haffire, `Teras etc.
Burkina Faso: Pits
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Examples:
Morocco
Algeria Egypt
Chad
Mali
Niger
Sudan
Ethiopia
Somalia
Kenya
Tanzania
Zambia
Where is water harvesting usedat present in Africa ?
WH welldocumented
WH mostprobablyapplied
Othercountries
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Some examples:
Niger, Ader Doutchi Maggia area (Haussa): rock bunds,
stalks and earth for water diversion in fields
Burkina Faso (Mossi): rock bunds and stone terraces
Mali : stone constructions, macrocatchments
Chad, Ouaddai area: small check dams
Burkina Faso: pitting (Zay), rock bunds
Kenya, Turkana and Baringo area: many types
Many more traditional water harvesting systems exist
In sub-Saharan Africa, water harvesting is
still far below its potential!
Where is water harvesting used
in sub-Saharan Africa?
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Othercountries
WH mostprobablyapplied
WH welldocumented
Where is water harvesting used
at present in Asia? (I)
Yemen
Saudi Arabia
Iran
India
China
Pakistan
AfghanistanSyria
Jordan
Oman
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Unit 1Introduction
Where is water harvesting used
at present in Asia ? (II)
China
Thailand
VietnamLaos
MyanmarIndia
CambodiaPhilippines
WH mostprobablyapplied
WH welldocumented
Othercountries
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AgriculturalProduction
Unit 1Introduction
Water harvesting
Is the collection and concentration of runoff water
Can produce crops in areas with insufficient rain
Can improve pasture and crop yield
Is suited for arid, semi-arid and semi-humid regions
Has positive side effects on: water and soil conservation
Consists of a runoff area and a run-on area
The water is stored in the soil, in cisterns or reservoirs
Has been used traditionally in many (semi-) arid areas of the world
Its use is still far below its potential!
Summary
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