P1252109248mBlVQ - PowerPoint PPT Presentation

Title: P1252109248mBlVQ


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Berlin - Wednesday, 16.07.2003
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Ecosystem Analysis and Integrated Ground Water
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Dr. H. Kehl
Todays Topic of Conversation and Discussion
Conflicts Between Modern and Traditional
Irrigation Methods as a Result of Population
Growth and misspended investments in Arid Areas".
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As we all know Irrigation is essential for
food production ... especially in semi-arid and
arid zones with above average population
growth. FAO
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Dr. H. Kehl
At present one-sixth of the agricultural land
in the world is irrigated and provides more
than one-third of global food production.
source FAO
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Dr. H. Kehl
The food requirements of an ever-increasing
world population higher necessitate agricultural
production, a large share of which comes from
irrigated lands, especially true in arid zones.
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Dr. H. Kehl
At approximately 80 to 87 of all the available
freshwater supply is used for agriculture and
food production. Therefore, only 13 to 20 is
available for domestic and industrial
requirements.
source FAO
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Dr. H. Kehl
The efficiency of water in agricultural
production is, however, low. Only 40 to 60 of
the water is effectively used by crop, the
remainder of the water is lost in the system, in
the farm or on the field, either
through evaporation, through runoff to the
drainage system, or by percolation into the
groundwater.
source FAO, UN-WWDR 2003
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Dr. H. Kehl
What does it mean efficiency?
In general, the term is used to quantify the
relative output obtainable from a given input
(e.g. investment or water).
The Term on-farm application efficiency or
field application efficiency generally refers
to the fraction of the water volume applied to a
farm or a field that is consumed by a crop,
relative to the amount applied.
In actual practice, however, the water reported
to be consumed in the field consists of actual
EVAPOTRANSPIRATION incl. Interception - but
without percolation!.
The Term Crop Water Use Efficiency (WUE) is a
physiological index and should be used. The
relevant measure is the response of crop to
irrigation as total biomass produced
(above-ground dry matter!) per unit mass of water
taken.
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Dr. H. Kehl
What does it mean efficiency?
There is much evidence that, in a given climate,
the growth of many crops is directly related to
the amount of water they transpire, AND to the
ratio of biomass below and above
surface. Therefore, deep rooting crops will have
a lower WUE.
source FAO, UN-WWDR 2003
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Dr. H. Kehl
Poor management of irrigation water is one of
the principal reasons for this low water use
efficiency in irrigation. A range of
environmental problems are linked to ineffective
water use, such as waterlogging, leaching of
agro-chemicals and consequent ground water
pollution, as well as soil and ground water
salinization resulting from inappropriate
applications.
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Dr. H. Kehl
Studies on the economies of Sub-Saharan Africa
(SSA) have generally neglected the link between
economic growth and environmental quality.
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Dr. H. Kehl
The key to SSA future is to achieve long-term
sustainable growth and not to implement and
focus on showcase white elephant type expensive
technologies (e.g. high-tech irrigation
systems) developed under differing climatic,
socio-economic conditions of HDCs (Highly
Developed Countries). Frequently, that was a
costly fallacy!
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Dr. H. Kehl
The quite recently launched Human Development
Report (HDR-UNDP, July 8th 2003) emphasized in
particular the self-responsibility and
self-determination of LDCs, especially their
farmers with their knowledge of adapted
irrigation systems as a key issue for successful
developments in the future.
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Dr. H. Kehl
Complementary assistance comes from the FAO
Key decision makers have tended to favour
high-visibility projects with impressive
works e.g. large Dam Projects, large-scale
Center-Pivot sprinkler systems, large group well
constructions for ground water utilization ,
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Dr. H. Kehl
while neglecting the more modest needs
of indigenous farm units, as well as the issues
of reconstruction of traditional irrigation
systems, of modification, of training and
maintenance that are of interest to lower-lever
personel without decision-making power.
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Dr. H. Kehl
Lessons learned from several Case Studies, UNDP-,
UN-WWD- and FAO Reports and keys to success
Essential Elements to move towards integrated
water resources management relate to
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Dr. H. Kehl
Lessons learned from several Case Studies, UNDP-,
UN-WWD- and FAO Reports and keys to success
Essential Elements to move towards integrated
water resources management relate to
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Dr. H. Kehl
You wish to know something more about advanced
techniques of Rain Water Harvesting for Crop
Production?
Please, visit the FAO Training Course in the
Internet! The most complete and detailed
How-To Manual available. Strongly recommended
? !
URL http//www.fao.org/ag/agl/aglw/wharv/whtoc/sl
d001.htm
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Modern vs. Traditional Water Harvesting and
Irrigation Methods
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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Rain water harvesting with micro/macro catchment
  areas and flood water harvesting (since thousands
  of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Hand-dug wells (e.g. Qanats and horizontal wells,
  since thousands of years)

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Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Runoff Collection Cisterns (Near East, North
  Africa, since thousands of years)

Indian Cistern
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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Roof Top Rain Water Harvesting (Near East, North
  Africa, India, etc. since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Semi-Arid Areas
Only a selection

• Runoff agriculture (involves rain water
  harvesting, since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Runoff Collection (e.g. also good to built up
  artificial ground water bodies, S-Medit. area).

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Canal irrigation (e.g. Iraq, since thousands of
  years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Semi-Arid Areas
Only a selection

• Canal irrigation with Archimedes Screw (e.g.
  Iraq, Egypt, since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Pits and open wells (e.g. India, Central Africa,
  since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• ZAY pitting holes (since thousands of years)

source FAO copied witout permision!
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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Arid Areas
Only a selection

• Porous clay jars (Near East, North Africa, India,
  etc. since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Wed Areas
Only a selection

• Furrow irrigation (SE-Asia, Central Africa,
  India, etc. since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Semi-Arid Areas
Only a selection

• Flood and basin irrigation (SE-Asia, Central
  Africa, India, etc. since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting -
Flood Water
Only a selection

• Flood water harvesting (SE-Asia, Egypt in ancient
  time, India, etc. since thousands of years)

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Dr. H. Kehl
Traditional Irrigation and Water Harvesting in
Wet Areas
Only a selection

• Drip irrigation with bamboo pipes (SE-Asia,
  India, etc. since thousands of years)

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Dr. H. Kehl
Modern Irrigation Methods in Semi-Arid and
Semi-Arid Zones
Only a selection

• Fog catcher (for harvesting dew - Chile, Ecuador
  - at present experiments)

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Dr. H. Kehl
Modern Irrigation Methods in Semi-Arid and Arid
Zones
Only a selection

• Sprinkler irrigation (e.g. portable, solid,
  travelling sprinklers, center pivot systems -
  high pressure / low pressure, etc. utilizing
  clean (!) ground or surface water).

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Dr. H. Kehl
Modern Irrigation Methods in Semi-Arid to Wet
Zones
Only a selection

• Surface Irrigation, Auto Flood and Flood (e.g.
  wild flooding, contour flooding, borders,
  channel, basin, etc.).

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Dr. H. Kehl
Modern Irrigation Methods in Semi-Arid and
Semi-Arid Zones
Only a selection

• Localized Irrigation (e.g. drip resp. trickle,
  subsurface drip, bubblers, micro-sprinklers
  etc.).

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Dr. H. Kehl
Modern Irrigation Methods in Semi-Arid and Arid
Zones
Only a selection

• Localized Irrigation (e.g. drip resp. trickle,
  subsurface drip, bubblers, micro-sprinklers
  etc.).

B)
Water Use Efficiency (WUE) is about 97
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Dr. H. Kehl
Modern Irrigation Methods in Semi-Arid and Arid
Zones
Only a selection

• Localized Irrigation (e.g. drip resp. trickle,
  subsurface drip, bubblers, micro-sprinklers
  etc.).

C)
Water Use Efficiency (WUE) is about 97
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Dr. H. Kehl
Soil Water Availability for Plants - some Basics
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Dr. H. Kehl
Effects of Traditional Modern Irrigation
Methods
Only a selection

• The problem of Salinization occurs with nearly
  any type of irrigation in arid zones. Especially
  with sprinkler irrigation and loamy soils.

• Soil structure and soil texture also have an
  impact on and thus on water management
  efficiency water losses from evaporation or
  runoff are either reduced or increased when soil
  structure is modified.

• Soils developed under arid and semi-arid
  conditions can be changed irreversible by
  irrigation, solely the soil structure is more
  fragile than anywhere.

• Generally, on a long-term basis, large-scale
  sprinkler irrigation is a delicate tool that can
  endanger the farming system's sustainability
  (long-term profitability) instead of increasing
  it

• Potentially, it can shrink the biodiversity,
  cause irreversible soil property changes, can dry
  out underground and surface water resources, and
  last but not least, it can be too expensive for
  forthcoming generations.

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Dr. H. Kehl
The General Pre-Condition for Arid Areas
SALINIZATION Land Degradation Productivity is
Diminished
Salinization are most commonly associated with
excessive water application, rather than with too
little!
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Dr. H. Kehl
The General Pre-Condition for Arid Areas
SALINIZATION Land Degradation Productivity is
Diminished

• Salinization may occur with nearly any type of
  irrigation!

EGYPT
The High Assuan Dam made year-round irrigation
possible (and necessary!!) and prevented the
annual floods, which led to increased
salinization in the land irrigated by the canal
system. Therefore, leaching and drainage takes
additional water (Dregne, 1983 El Baz, 1988
Goossens et al., 1994 Mainguet, 1994).
Large areas around the Egyptian Oasis Kharga and
Dahkla became unproductive through irrigation
mismangement with fossil water. Additionally,
although best available irrigation technologies
have been implemented in the Wadi Natrun area
(N-Egypt) repeated cycles of groundwater led to
toxic brackish water tables.
Source (partly, and modified) ICS-France 2003
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Dr. H. Kehl
The General Pre-Condition for Arid Areas
SALINIZATION Land Degradation Productivity is
Diminished

• Salinization may occur with nearly any type of
  irrigation!

Iraq
In Iraq, there is a historical record of
salinization caused by canal irrigation between
2.400 and 1.700 B.D., and this problem has
recurred at intervals through the present
(Dregne, 1983).
About 11.48 million hectares (ha) of land is
cultivable. However, FAO estimates for 1998
reveal that only 5.5 million ha is put under
cultivation due to soil salinity, fallow
practices and the unstable political situation.
64 of the cultivated land was irrigated.
Agricultural water withdrawals accounted for 52
of total renewable water resources.
Source (partly, and modified) UNESCO 2003
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Dr. H. Kehl
General Pre-Conditions and Limitations for Arid
Areas
Limited Ground Water Resources

• RISK The overutilization of limited (fossil)
  ground water resources ...

• As it has been mentioned yesterday, between 1980
  and 1995, Saudi Arabia consumed 75 of the proven
  reserves of fossil ground water in its major
  aquifers to irrigate wheat crops. FTGW, 1997

• Libya (Great Man-Made River) and Egypt (New
  Valley resp. Toshka Agribusiness Mega-Project)
  both, are on the way to use up their huge - but
  limited (!) - non-renewable fossil ground water
  reserves.

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Dr. H. Kehl
General Pre-Conditions and Limitations for Arid
Areas
Limited Surface Water Resources

• RISK Evaporation losses of limited surface water
  through dams ...

• E.g.
• The water loss from Lake Nasser in the South of
  Egypt
• is one of the national problems ... the
  evaporated water range between 10 to 16 billion
  m³/y which represent
• 20 to 30 of the Egyptian income from Nile
  water .
• Mosalam Shaltout El Housry, 1996

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Dr. H. Kehl
Just enough is best!
"It is the universal fallacy of humans to assume
that if a little of something is good, then more
must be better. In irrigation (as indeed in many
other activities), just enough is best." (Prof.
Daniel Hillel in FAO Publ. 1997).
As we have seen, agriculture is the highest fresh
water consumer, especially in arid zones with
LDCs. Therefore future agricultural extension
policy must focus predominantly and early enough
on Impact Assessment AND long-term Economic
Evaluation of water harvesting techniques in arid
zones.
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Dr. H. Kehl
AND New is not always better. Water from
"improved wells" is often only marginally better
in quality than water from traditional sources
and it generally demands a costly or risky change
in management techniques.
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Dr. H. Kehl
AND Monitoring is important to determine the
nature and extent of change to see if technical
results match expectations and to tell whether
new management methods are actually adopted.
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Dr. H. Kehl
IDRC (International Development Research Center)
- supported research has explored the use of
non-governmental social auditors. These
community leaders identify interests and
arguments that might not otherwise be heard. They
also stimulate debate and discussion within and
between communities.
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Dr. H. Kehl
Population, Lifestyle, Culture, Governance,
Policies
Re-Adaptation to the Environment
The Tripartite Inter-Relationship
WATER THE KEY RESOURCE
IMPACTS SERVICES
Land Climate Hydrology Ecosystems Biota
Agriculture Households Industry Transport Services
adapted from Gallopin Raskin 2002
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Dr. H. Kehl
Consequences for arid areas with low annual
precipitation amounts and potentially high
evaporation

• Any given environment can spend only a limited
  service for a limited population. It is embodied
  by the carrying capacity of its ecosystems,
  manifested and indicated by long-term adapted
  plants and animals through a long-lasting
  evolution. It is therefore, and once more,
  essential to understand and monitor these
  ecosystems.

• The given natural vegetation of arid and
  semi-arid zones indicate its possible durability
  and simultaneously its utilization (and possible
  impact!) by human beeings and their economy.
  

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Dr. H. Kehl
Consequences for arid areas with low annual
precipitation amounts and potentially high
evaporation

• If the only renewable and most essential water
  source is RAIN, it is also essential to prevent
  it from - every - non-productive evaporation.

• Therefore rain water has to be carefully
  harvested and protected below the soil surface.
  The same is true for flood water which should be
  guided to sites with favourable (infiltratable)
  soil conditions for crops.

• Generally, a set of different and advanced
  techniques suitable for small-scale water
  management should be applied.

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Dr. H. Kehl
Consequences for arid areas with low annual
precipitation amounts and potentially high
evaporation

• If ground water discharge is necessary during the
  dry season a recharge during the wet season is a
  precondition for a long-term sustainability of
  the given ecosystem.

• And last but not least, affortable and
  sustainable agriculture in arid areas needs a
  high intensity of labour, as it has been since
  ancient times. It is adequate for
  self-sufficiency and can provide additional food
  for local markets.

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Dr. H. Kehl
Questions and Discussion of Today
1
What kind of co-operation between dicision-makers
and affected low-level people (especially
village-level institutions) is possible and what
has been realized? What are the main problems?
2
What criteria and options for appropriate
irrigation methods have been choosen and
implemented in your - different - countries to
ensure a sustainable ecosystem management? What
are the ecological effects on native vegetation
of large-scale and small-scale irrigation
projects?
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