Transcript Dia 1 - Spate Irrigation

1.3
SPATE IRRIGATION IN PAKISTAN
History of spate irrigation in Pakistan
Some bunds in Balochistan are more than 5000 years old
The construction of spurs and bunds in the Bolan river
(Balochistan) during dry period was one of first opportunities
to control surface flows and resulted in strong population increase
In 2600 BC
Source: French Archeological Mission
Spate irrigation - globally
Country
Algeria
Eritrea
Libya
Morocco
Pakistan
Somalia
Sudan
Tunisia
Yemen
Year of
Irrigation
Total Irrigated
Area (ha)
Spate Irrigated
Area(ha)
1992
1993
1987/1997
1989
1990
1984
1997/1987
1991
1987/1997
555,500
28,124
470,000
1,258,200
15,729,448
200,000
1,946,000
385,000
485,000
110,000
15,630
53,000
165,000
1,402,448
150,000
280,000
30,000
193,000
Spate Irrigation as
% of Total
Irrigation
19.8
55.6
11.3
13.1
8.9
75.0
14.4
7.8
39.8
Source: FAO Aquastat; Hadera 2001; Kohler 1999
Pakistan has the single largest area under spate irrigation
The area is 9% of the total irrigated area
Even so – it is completely ignored
Spate irrigation in Pakistan – where?
Major area
NWFP
DI Khan, Tank, Laki Marwat, Bannu,
Karak
Punjab
DG Khan, Rajanpur, Mianwali
Sindh
Dadu, Larkana, Jamshoro, Thatta,
Karachi
Balochistan
Kacchi, Sibi, Jal Magsi, Kharan, Qila
Saifullah, Musakhel, Barkhan, Lorelai,
Las Bela
HILL TORRENT AREAS
DI KHAN
TANK
TAUNSA AREA
DG KHAN
KACCHI PLAINS
KACCHI PLAINS MIDDLE SECTION
as elsewhere based on earthen bunds
distance from river as important as head tail
huge fields
many braiding stream (flat gradient)
Type of spate irrigation systems:
(1) large systems along the Kohi Suleiman,
Kirthar Range and in Kacchi Plains
Type of spate irrigation (2)
smaller systems –
coastal Las Bela, interior Balochistan, smaller
rivers from Koh-i-Sulaiman and Kirthar Range
Type of spate irrigation
(3) mini systems – mountain systems
General typology
Spate irrigation in Pakistan:
- World’s largest area under spate irrigation: 1.4 M ha!
- Equivalent to 9% of canal irrigated area
- Completely neglected
- Very low productivity compared to other countries
- Major poverty pocket in the country
- Important environmental functions
- Some areas short range from mountain to Indus
Special characteristics
- Based on large earthen bunds and deflectors
- Overstretched area – command area compared to floods is
large – many areas only irrigation < 1 in 5 years
- Few floods (<5), elsewhere more floods
- Large fields
- Mainly flat and sandy areas
Interventions
- Based on failed civil engineering concepts not appropriate to
spate system – high failure rate (65%)
- Lost its dynamism – no new development
- Role of local government in management was positive but is
weakened
- Spate irrigation seen as nuisance (flood damage) not as
potential
Potentials
Potential is large:
Water management:
- Revive and resource local management by communities and
local government
- Rationalize area under spate irrigation
- Ensure affordable availability of bulldozers in public or private
sector
- Stay away from inappropriate civil engineering solutions, such
as weirs and flood storage dams. Instead – attenuate and
regulate flood patterns
- Appropriate civil engineering solutions are: flow dividers,
fixing flood canal inlets, bed stabilizers, improved/
strengthened earthen bunds (gabion sections, abutments),
guide bunds, controlled field inlets and overflow structures
- Improve drinking water supply – improved shallow ponds and
subsurface dams
- Combine spate irrigation with groundwater use and recharge
Potentials
Potential is large:
Agronomy and livestock:
- Improved soil moisture conservation (mulching,
ploughing, improved equipment)
- Improve yield of major crops such as sorghum by
better varieties and better soil moisture conservation –
in Eritrea yield of sorghum is 8 times more!!
- Better marketing and processing of promising minor
crops (guar, sesame for instance)
- Improve prospects for local vegetables and medicinal
plants
- Spate irrigated forestry (gum arabica)
- Improve local livestock varieties (Bagh Nari)
- Improved fodder for livestock
Potentials
Potential is large, if managed well:
Environment
- Stabilizes the area, avoid desertification
- Recharge of groundwater
- Local wetlands and lakes
- High biodiversity, indigeneous plants
- Low external input (organic) farming