IMPROVING WATER AND LAND MANAGEMENT … IMPROVING WATER AND LAND MANAGEMENT FOR EFFICIENT WATER USE...
Transcript of IMPROVING WATER AND LAND MANAGEMENT … IMPROVING WATER AND LAND MANAGEMENT FOR EFFICIENT WATER USE...
1
IMPROVING WATER AND LAND MANAGEMENT FOR EFFICIENT WATER USE IN IRRIGATED AGRICULTURE
Luis S. Pereira
Vice-president Hon., ICIDPresident, CIGR
Technical University of Lisbon
The 19th ICID Congress, Beijing, Sept. 2005
Q52.1: On-farm water and soil management;Q52.2: Performance evaluation and integrated
management of irrigation and drainage systems;
Q52.3: Conjunctive use of water to optimize food production;
Q52.4: Policy options for water saving in irrigation;Q52.5: Management transfer and participatory
irrigation and drainage management;
Q52.6: Application of information technology in irrigation and drainage management.
Q52. IMPROVING WATER AND LAND MANAGEMENTFOR INCREASING EFFICIENCY IN IRRIGATED AGRICULTURE
Tozeur
For millennia, civilisations developed in water scarce environments. The respective cultural skills are an essential heritage of those nations and peoples, and the humanity as well.
However, progress in XX century questioned the traditional know-how, which has been often replaced by modern technologies and management imported from different environments and cultures.
A water economic culture is now following a technical one, imposed when the large irrigation schemes were built. Both are generally imported from different cultural and instituttional environments.
Management faces therefore difficult challenges due to the fact that irrigators have a perception of problems, practices and objectives different from the non-farmer managers.
A turn in viewing traditional irrigation is starting in the non-technical media
But we need to help providing our know-how accepting farmers cultures and perception
Oasis of Turpan, Xinjiang
Pressures about water use in irrigation are coming from a ever growing urban society that understands less and less the rural world and, mainly, the peasants. Most common include:
“decrease water consumption” - when it should be said “control water demand”
Farmers may not have access to other and better technologies, and may do not know how to improve those they are using after centuries
2
Zairi et al., 2003
Reducing the demand for supplemental irrigation of cereals may be feasible if to decreasing Gross Margins per unit land (GM/ha)correspond increased GM per unit water. The farmer incomes then reduces but, when water is lacking, thatincome is higher than reducing the cropped area.
0
1000
2000
3000
4000
5000
240 320 400 480 560 640 720 800 880
Season irrigation (mm)
GM
(U
SD
/ ha)
(6) (8) (10) (12) (14) (16) (18) (20) (22)
Number of irrigations
r average ( ), high ( ) and very high ( ) demand conditions Zairi et al., 2003
However for crops having a high demand for water such as summer crops, including if they have a favourable ratio between yield price and water cost, e.g. tomato in Tunisia, when GM/ha decreases due to less water application
GM/ha
0.0
0.2
0.4
0.6
0.8
240 320 400 480 560 640 720 800 880
Season irrigation (mm)
GM
(U
SD
/ m3 )
(6) (8) (10) (12) (14) (16) (18) (20) (22)
Number of irriga tions
GM/m3
the GM/m3 do not increase. It is then questionable to adopt deficit irrigation
More knowledge about water-yield-revenues is required before adocating deficit irrigation for demand reduction
“pay the full costs of water”, but, …
what about yield prices and farmers revenues?
Paddies in the Po Valley, courtesy by M. Greppi
what about the externalities of irrigation such as aquifer recharge and flood control?
Impacts of water prices on water demand (and irrigated cropped area) at system level
Traditional irrigation, Duero Modern irrigation, Guadalquivir
Impacts of water prices on water demand, cropping pattern and income at farm level, Alentejo, Portugal
If water is to be paid in full as an economic good the demand will decrease together with the irrigated area and farm income Pinheiro and Saraiva, 2002
Japan. Inst. Irrig. Drain., 2003Mitsubishi Res. Inst., 2001
If multifunctions of irrigated agriculture are recognized, the water is “fully” valued and farmers will pay what is socially and economically acceptable
3
“improve irrigation efficiency”, but
New developed oasis near Tozeur, Tunisia
farmers generally know they need to apply water in excess to leach salts, to store water in the soil when deliveries are not reliable, or to overcome the distribution uniformity of the system
Mantovani, 1993
The depth of applied water D depends upon the technologies available. Improving them to achieve an high uniformity UC that provides for making D close to Dopt relates to the relationship between the price of the yield commodity (PY) and the cost of the water (PW)
“more crop per drop”, or “increase water productivity”. However, this may be achieved by improving agronomic practices not decreasing water use
Qingtongxia, Ningxia
Moreover, a peasant farmer, having 0.5 ha/family, do not understand the water productivity concept: he needs to increase land not water productivity, because it relates to the revenue he may get from his land
Maximing Yields or maximizing WP follow different objectives which relate to the socio economic farming conditions
Molden at al., 2003
There is a contradiction between water and land productivity that is solved differently by
a water manager Max(WP)a farmer Max(LP)
English et al., 2002
A key issue is to know the relationship between “applied water” and “costs” and “revenues”, maily these ones!
4
The farm’s socio economic conditions dictate options that may be different of those of water managers
Max net income for commercial farming Is below max Yield
(near max WP)
Max total income for small (family) farmers
Is near max Yield (far from max WP)
Where this water goes? To irrigation only?
Tank irrigation in Sigirya, Sri Lanka
May be it is worthwhile to adopt new water use concepts
WATER USE = Diverted for any purpose
CONSUMED FRACTION
NON-CONSUMED FRACTION
REUSABLENON-
REUSABLE
Degraded Quality
Preserved Quality
WATER USE
CONSUMED FRACTION
NON-CONSUMEDFRACTION
REUSABLENON-
REUSABLE
Degraded Quality
Preserved Quality
Beneficial
Non-beneficial
LOSSES
Non-beneficial (waste) Non-beneficial
Pathways to improve water use Pathways to improve water use
Maximize beneficial uses
Minimize non-beneficial uses
Control, avoid water losses
WATER USE
CONSUMED FRACTION
NON-CONSUMEDFRACTION
REUSABLENON-
REUSABLE
Degraded Quality
Preserved Quality
LOSSES
Beneficial
Non-beneficial
Waste
WATER USE
CONSUMED FRACTION
NON-CONSUMEDFRACTION
REUSABLENON-
REUSABLE
Degraded Quality
Preserved Quality
LOSSES
Beneficial
Non-beneficial
Waste
Identify the water pathways
A new approach looking the Basin and not the irrigated fields alone has been developed by IWMI along these lines
5
WATER DIVERSION
Agriculture Domestic Industry Environmentand other
Effective rain
Transpiration Soil evapor
Seepage +runoff
Conveyance + distribution
Application tocropped field
Percolation +runoff
Non-crop ET
YIELD
reuse
Classical transport & distribution efficiency
Classical application efficiency
WATER DIVERSION
Agricultureand landscape
Effective rain
Transpiration Soil evapor
Seepage +runoff
Conveyance + distribution
Application tocropped field
Percolation +runoff
Non-crop ET
YIELD
reuseTotal WP Irrig WP
WUE
Farm WP
WATER DIVERSIONAGRICULTURE
Reservoir
System
Field
YIELD
Crop ET
Leaching
BWU
Seepage + runoff
Non-crop ET
Evaporation
Percolation +runoff
N-BWU
WATER DIVERSIONAGRICULTURE
Reservoir
System
Field
YIELD
Crop ET
Leaching
BWU
Seepage + runoff
Non-crop ET
Evaporation
Percolation +runoff
N-BWU
WATER DIVERSIONAGRICULTURE
Reservoir
System
Field
YIELD
WATER DIVERSIONAGRICULTURE
Reservoir
System
Field
YIELD
Crop ET
Leaching
BWU
Crop ET
Leaching
BWU
Seepage + runoff
Non-crop ET
Evaporation
Percolation +runoff
N-BWU
Seepage + runoff
Non-crop ET
Evaporation
Percolation +runoff
N-BWU
NCF CF CF NCNRF NCRF
WATER DIVERSION
Agriculture(and landscape) Urban Industry Environment
and other
Reuse
Non-consumNon-reusable
Non-consumReusable
Consumpuse
treatment
Crop ET
Non-beneficial use
NetworkSeepage + runoff
Field Runoff + percol
Reusable
Wild ET Leaching
Non-reuse
Losses Wastes Beneficial use
LossesWastes
Beneficial + non-benef. use
Cons.use
Pathways to improve water use Pathways to improve water use
WATER USE
CONSUMED FRACTION
NON-CONSUMEDFRACTION
REUSABLENON-
REUSABLE
Degraded Quality
Preserved Quality
LOSSES
Beneficial
Non-beneficial
Waste
WATER USE
CONSUMED FRACTION
NON-CONSUMEDFRACTION
REUSABLENON-
REUSABLE
Degraded Quality
Preserved Quality
LOSSES
Beneficial
Non-beneficial
Waste
Identify the water pathways
Maximized beneficial uses
Minimized non-beneficial uses
Controlled, avoided water losses Efficient water use
High water productivity
6
On farm water management for efficient water use
Objective Technology Reduce demand Water saving
Water conservation Higher yields per unit of water Higher farmer income
• Select low demand crop varieties/crop patterns
• Adopt deficit irrigation • Improve irrigation systems uniformity and management
• Reuse water spills and runoff• Soil management/surface mulch
• Adopt best farming practices • Avoid crop stress at critical periods
• Select cash crops • Adopt appropriate irrigation technologies
Modern sprinklers may produce excellent performances in set systems, ...
if design is adequate and the selected system is appropriate for the local environmental constraints and farming conditions
The same applies to moving gun sprinklers under non-windy conditions ...
... and to the modern sprinklers in moving laterals. They produce excellent performances with low energy when design and management fit the environmental constraints
When micro-irrigation – drip, SDI, micro-sprinkling -are well designed and managed, performances can be excellent, but …
these are not achievable without appropriate support to farmers
Excellent performances may be achieved with surface irrigation when land levelling and irrigation technologies are appropriate
The challenge is to pay adequate attention and provide incentives to support farmers in improving their systems
Adopting zigzag furrowing, shortening the basin strips and using a PE pipe and valved tubing available in the market, this farmer reduced the demand from about 1500 to near 1000 mm. But DU still is very low because land is unlevelled!
7
With poor nozzling design, without assistance, what can this farmer do to get an uniform crop?
Near a tower, a well developed crop
In betwwen the towers, a less developed crop
The reality is far from ideal: without techical assistance, this farmer was unable to adequately use drip irrigation – he was using more water and expecting less yield than for his surface irrigated field, ...
...but Services in his region were just advising to move from surface to drip
1st case: basin irrigation in the Yellow River Basin
Huinong Irrigation System
This is an arid region, with very cold winter and rain generally < 200 mmMain crops are wheat and maize, often intercropped, and rice
Crop Irrigationsafterplanting
Seasonirrigation(mm)
Deeppercolation(mm)
GWc(mm)
ETcadj(mm)
ETc(mm)
Intercrop 6 630 386 471 810 816
Wheat 4 422 213 297 546 554
Maize 5 521 266 383 747 780
Present: excess water diversion causes high watertable and salinity, making inadequate the typical irrigation schedules
Pre-conditions for farm water savings and increased productivity:
1st: cut to about half the diversions from the river
2nd: rehabilitate the drainage system (without great investments)
3rd: reduce percolation (to the level required for leaching, upland crops)
Irrigation number
q (l s-1 m-1)
D (mm)
Zreq (mm)
Ea (%)
DUlq (%)
Percolation(mm)
1st 1.0 - 1.4 107 - 109 92 77.8 - 85.9 61.4 - 90.9 15 - 24 2nd 0.7 - 1.3 90 - 136 30 22.0 - 33.5 56.8 - 95.6 64 - 106 3rd 0.4 - 0.9 94 - 114 51 44.8 - 54.4 82.9 – 87.3 43 - 63 4th and 5th 1.2 105 - 157 50 25.6 - 35.2 84.4 - 92.7 12 - 77 6th 0.7 - 0.9 97 - 141 14 9.9 - 14.4 99.3 - 94.3 83 - 127
Present Irrigation Performances
Uniformity DU is acceptable to very good Efficiencies Ea are very low because
•Irrigations after the first are applied when there is too much water in the soil (lack of watertable control)•Applied depths are much above required•Percolation very high
8
Irrigation depths may be optimized according to pre-defined objectives. If yields are to be improved the total water application may have to increase but percolation is controlled.
Season irrigation volumes
0100200300400500600700
Intercrop wheat maize
Vol
umes
(mm
)
Deep percolation
0100200300400500600700
Intercrop wheat maize
Vol
umes
(mm
)
Present Improved Salt control Salt control with water savings
Zero level basins are required if such results are intended
1 2 3 4 5 6 78
9
ET+PercolationActual
0
50
100
150
200
250
Depth (mm)
GIRFARM(mm)GIDSUPPLY(mm)
Foreseen
Actual
0
500
1000
1500
2000
2500
3000
3500
Irrigation (mm)
Adopting low paddy water depths, improved delivery and irrigation scheduling, demand reduces by 50% and yields increase by 10%
Improved Irrigation Performancesimproved schedulecontrolled water tablezero levellinghigher inflow rates
field length of 48m
Irrigationnumber
q(l s-1 m-1)
D(mm)
Zlq(mm)
Ea(%)
DUlq(%)
Percolation(mm)
1st 1 130 112.0 84.3 75 20.43 113 106.9 97.0 93 3.2
2nd 1 123 110.3 89.5 85 12.93 113 108.3 97.4 95 2.9
3rd 1 119 108.2 92.1 88 9.33 111 106.7 98.5 95 1.5
4th 1 119 109.7 92.3 93 9.03 113 109.0 97.5 97 2.7
5th 1 120 110.5 91.4 92 10.23 112 108.5 97.4 96 2.8
Present
Drain+sched
40% Imp farm
50% Imp syst
Imp deliv+farm
no rice
High improv
V. High imp.
Max imp.
GM/Vol_DelivGM/Vol_Farm
0
0.5
1
1.5
2
2.5
Yuan/m3
Gross margin per unit water use, Huinong
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
0 1 2 3 4 5 6 7 8 9 10 Time implementation
Util
ity
farm gross margin delivery cost water use delivery
and to utilities show that more stringent improvements (after level 4) have relatively reduced impacts
0
5
10
15
20
0 1 2 3 4 5 6 7 8 9 10
Time implementation (years)
Wat
er v
olum
es (1
0
3 m 3 /h
a/ye
ar) Total water use, TWU
Non-beneficial WU, farm Non-beneficial WU, delivery
Using a DSS mulyicriteria model applied to the system to analyse the foreseen improvements. results relative to water use
Improved 4
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
decade
wat
er v
olum
e (1
000
m3/
year
)
farm demandfarm consumptive usesimulated demand
Present
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
decade
wat
er v
olum
e (1
000
m3/
year
)
farm demandfarm consumptive usesimulated demand
Combined Improvements in delivery conditions, drainage, farm irrigation scheduling and basin irrigation systems lead to reduce the demand
at system and farm levels, and to increase the consumptive use
system demand
system demand
Present conditions
Improved to level 4
9
Improvements at farm – land levelling, inflow rates, irrigation scheduling – reduce the non-consumed and non-reusable fraction (percolation),
and the non-consumable but reusable fraction (runoff), mainly relative to paddies
Improved 4
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
decade
wat
er v
olum
e (1
000
m3/
year
)
farm demandfarm consumptive usefarm percolationfarm runoff
Present
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
decade
wat
er v
olum
e (1
000
m3/
year
)farm demandfarm consumptive usefarm percolation farm runoff
Present conditions
Improved to level 4
Fergana Valley2nd case: 2nd case: furrow furrow irrigation in irrigation in the Aral Sea the Aral Sea BasinBasin
Arid climate where excessive water use produced enormous changes in Aral Sea and river ecosystems
Main crops are wheat and cotton, furrow irrigation
2.39 2.36 1.79 1.78 1.791.78 1.21
Ea
Ea (adj tco)DU
DU (adj tco)0
10
20
30
40
50
60
70
80
90
100
Inflow rate (l/s)
Best performances are for alternate furrow irrigation
Efficiencies (Ea) are low except for alternate furrow irrigation due to excessive time of application. Uniformities (DU) are good/very good
Furrow irrigation with continuous flow to alternate or every furrow
Reducing cutoff times the irrigation depth D reduces, Ea improve, and DU decreases
0
10
20
30
40
50
60
70
80
90
100
%
2.4/1.2 2.4/1.2 2.4 2.4 3.0/1.5 3.0/1.5 2.4/1.2 2.4/1.2 2.4 2.4 3.0/1.5 3.0/1.5Inflow rate (l/s)
EaDU
Comparing continuous and surge flow, the later tends to provide for better performances
0
1
2
3
4
5
6
7
8
9
treatmentsEC ES AC AS Average
103 m3/ha or kg/ha D Yield
Water use is less for alternate furrows (A) than for every furrow irrigation (E) and also decrease from continuous to surge flow
However, the highest land/farm productivity is for continuous flow in every furrow
EC ES AC AS Average
ECES
ACAS
WP (irrig) kg/m3
WCF(field)
BWUF(field)
Ya/Ymax
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Every furrow continuous flow provides for maximizing yields (Ya/Ymax) but to minimal water use ratios. Opposite, alternate surge irrigation do not achieve maximal yields but highest WP(irrig) and highest beneficial water use fraction
However, if prices of production factors are high and those of commodities are low the farmer option is to maximise Ya/Ymax
10
Using a DSS in a GIS environment to evaluate alternative improvements operating
Satellite image
Fields layer
Irrigation network layer
Application to Fergana, Uzbekistan
Present
Cutoff-Ev
Sched-Ev
Sched-Alt
Def-Ev
Def-Alt
Surge-Ev
Surge-Alt
Sur-Def-Ev
Sur-Def-Alt
EconomicsUniformWater saving0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Glo
bal U
tility
Comparing alternative improvements through multi-criteria analysis, for the actual farming conditions in Fergana, the bestaletrnatives are the present one – no changes - or Sched + AC: The price of products do not compensate for improving farm irrigation. Surge flow has not enough economic return
Concluding: Knowledge and technologies exist that allow to make a more efficient the use of water in irrigation
These should mean capability to transfer into practice and to improve the existing irrigation, both at farm and system levels.However, knowledge and technologies progress much faster than technology transfer in case of small family and peasants farms
Technologies are easily available when manufacturers have an easy market, as it is for a variety of irrigation scheduling equipment adopted by commercial farms and for sprinkler and micro-irrigation equipment, the so-called “modern irrigation”. But when the markets have no quality exigences and control, the farmers may be purchasing less good equipment, poorly designed and demanding too much energy. In case of surface irrigation such market is generally not existing and surface irrigation becomes synonimous of “old fashion”
Knowledge and technologies that exist to provide for a more efficient use of water in irrigation need that appropriate quality control of equipments and management tools be enforced to support farmers in modernizing the systems
The constraints imposed to farmers, which they know well, need to be recognized, such as
inappropriate delivery conditions high costs of production factors, of irrigation equipments, low prices of commodities, low incomeslack of technical assistance and poor systems design
Using indicators need to be carefully done and taking into consideration the irrigator constraints, not to be used to describe environmental and managerial objectives
Incentives that compensate for the upgrading costs, society responsibilities, recognition of cultural skills, farmers decision making and not only PIM, need innovative approaches.