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Wastewater use in Wastewater use in irrigated irrigated agriculture: agriculture: closing the rural-closing the rural-urban-rural water urban-rural water looploopPresented at Departmental Seminar Series (Soil, Water & Environmental Science), University of Arizona, 19 February 2007
Wastewater Use Wastewater Use in Irrigated in Irrigated Agriculture:Agriculture:
Closing the Rural-Urban-Closing the Rural-Urban-Rural Water LoopRural Water Loop
Christopher ScottChristopher ScottUdall Center for Studies in Public Policy, andUdall Center for Studies in Public Policy, and
Dept. Geography & Regional DevelopmentDept. Geography & Regional DevelopmentUniversity of ArizonaUniversity of Arizona
Scarcity & Competition Scarcity & Competition for Waterfor Water Declining allocations of water to
agriculture Rapid urban growth a global
phenomenon Water productivity in agriculture
rising (“more crop per drop”) Agriculture increasingly adapting to
the use of poorer quality water for irrigation
Sobering DemographicsSobering Demographics
880 million additional population by 2015, virtually all in developing countries.
After 2015, all worldwide growth in population will take place in developing country cities.
Urban ExplosionUrban Explosion India will soon cross the 50-50 urban-
rural population threshold… 750 million urban Indians by 2050.
China is actively planning for cities each with more than 100 million population.
Africa’s urban population growth rates among the highest in the world.
Latin America has been predominantly urban for generations.
Urban Water Supply Urban Water Supply GrowthGrowth
Millennium Development Goals face resource constraints (water, Millennium Development Goals face resource constraints (water, investment). Progress towards sanitation goals lagging behind water investment). Progress towards sanitation goals lagging behind water supply; therefore, supply; therefore, wastewater management is critical.wastewater management is critical.
DefinitionsDefinitions
Wastewater = partially treated or untreated urban sewage
Effluent = treated to secondary or tertiary levels (with or without disinfection)
Rural-Urban-Rural Water Rural-Urban-Rural Water LoopLoop Transfer of water from agriculture to
cities Physically, often entails inter-basin transfers Water rights, property regime, economic issues
Urban use, quality degradation & depletion Salinity load, even with (because of?) treatment Public health risk (consumers and producers)
Agricultural end use of wastewater/ effluent Adapt to quality (nutrients, salinity) Adapt to timing (uniform throughout year)
Rural-Urban-Rural Loop Rural-Urban-Rural Loop TypologyTypologyRural source
Urban use Rural end use
Production irrigated ag.
Multiple (w/ urban sprawl on ag.). Wastewater
WW mixed source for in-formal urban & periurb. ag. e.g. Hyderabad, India - Musi
Small-scale “rural” water
Multiple use. Wastewater
WW primary source for production irrigated ag.e.g. Mexico City - Mezquital
Production irrigated ag.
Multiple use.Effluent
Same ag. users as source water (i.e., water swap with treatment). e.g. Monterrey, Mex. – Bajo Rio San Juan
Hyderabad, IndiaHyderabad, India
Sampling Transects
III – rural (25 – 40 km)
II – periurban (10 – 25 km)
I – urban (0 – 10 km)
Hyderabad Water Hyderabad Water FootprintFootprint
Hyderabad Water Supply/ Hyderabad Water Supply/ DemandDemand
Hyderabad Water Supplies and Demands
Osman Sagar Himayat SagarGround Water
Singur
Manjira
Krishna river
Godavari
extra needed (demand - total supply)
0
10
20
30
40
50
60
70
80
90
100
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
2020
2025
2030
time (years)
Milli
on C
ubic
Met
ers
per M
onth
Wastewater Wastewater BiogeochemistryBiogeochemistry Microbial attenuation and infection Coliform die-off Nematode (hookworm) egg deposition
Heavy metals attenuation (& uptake?) Deposition, re-suspension
Nutrient attenuation – plant uptake, eutrophicn.
Dissolved solids concentration, deposition Irrigation diversion, evaporation, return flow
Hyderabad +40 Km
Coliforms in WastewaterColiforms in WastewaterDec. 03 – Jan. 05 (red squares = mean value)Dec. 03 – Jan. 05 (red squares = mean value)
0
1
2
3
4
5
6
7
8
9
0 5 10 15 20 25 30 35 40
Distance downstream from Hyderabad (km)
LO
G E
.col
i (CFU
100
ml-1
)
Nematode Eggs in Nematode Eggs in WastewaterWastewater
0
20
40
60
80
100
120
140
I II IIISample Point
Ova
litre-
1
Hookworm
Ascaris
Trichuris
Nematode Prevalence in Nematode Prevalence in FarmersFarmers
0
10
20
30
40
50
60
70
I (n=240) II (n=354) III (n=413)Sample point
Pre
vale
nce
(%)
HookwormAscarisTrichuris
Sediment SamplingSediment Sampling
Mean egg load per 1 kg of sediment: 410,000 (SD: 240,000)
Heavy Metals in Heavy Metals in SedimentSediment
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-10 -5 0 5 10 15 20 25 30 35
Distance Downstream from Amberpet Bridge (km)
No
rmal
ized
Met
al C
on
cen
trat
ion
(--
-)
Copper Zinc Cadmium Lead
Amberpet NagoleHigh Court Pirzadiguda Mutialguda Koremalla Pillaipalli
Source: Gerwe, Caroline. An Assessment of Heavy Metals Contamination in the Wastewater-Irrigated Area of the Musi River
Dissolved NitrogenDissolved Nitrogen
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35 40
Distance downstream from Hyderabad (km)
Disso
lved
nitro
gen
conc
entrat
ion
(mg
l-1)
Dissolved OxygenDissolved Oxygen
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0 5 10 15 20 25 30 35 40
Distance downstream from Hyderabad (km)
DO
con
cent
ration
(m
g l-1
)
Total Dissolved SolidsTotal Dissolved Solids
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 5 10 15 20 25 30 35 40
Distance downstream from Hyderabad (km)
Salin
ity
conc
entrat
ion
(dS
m-1)
TDS Seasonal VariationTDS Seasonal Variation
800
1000
1200
1400
1600
1800
2000
2200
0 10 20 30 40Distance from Hyderabad (km)
TD
S (
mg
l-1)
Maximum, April Minimum, August Annual mean
City Rural Threshold sensitivity for rice = 2010 mgl-1
TDS Conceptual ModelTDS Conceptual Model
Hyderabad
Urban drainage
Rural drainage
Irrigated fields
W ater quality sampling points
Irrigation divers ion
Urban dra inage
Rura l dra inage
Return flows
Q in,C in
Q i,C i
Qd,Cd
Qout,Cout
Qu,Cu
Qr,Cr
E
E
I II III IV V VI VIIIVII
E E E E E
E Evaporation
Qbd,CbdQbu,Cbu
Irrigation Adapts to Irrigation Adapts to Constant FlowConstant Flow
0
10
20
30
40
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flo
w (
Mm
3)
Irrigation abstractions Flow at Amberpet
Mexico City Water Mexico City Water FootprintFootprint
26%
Mexico City Wastewater Mexico City Wastewater Sources/FateSources/Fate
Source/Fate Flow (m3/s)
Comments
Wastewater generated in Mexico City
45 194 l/s/cap. At 70% return rate, water supply is 260 l/s/cap.
Primary treatment for irrigating parks/green areas within Mexico City
10 Could irrigate upto 10,000 ha of land, but may be used to maintain wetlands and “floating gardens.”
Primary and secondary treatment for Texcoco Lake Reclamation
1.0 ~ 1.5 Reclamation of sodic soils, reforestation, and Nabor Carillo Lake.
Tertiary treatment for animals and/or groundwater injection, Texcoco Lake
0.05 Sedimentation, flocculation, filtration (sand, activated carbon), chlorination.
Untreated wastewater 34 Discharged to Tula Irrigation District (Hidalgo State) through a network of tunnels, one > 60 km.
Tula Irrigation DistrictTula Irrigation District
Nutrient Uptake, Salt Nutrient Uptake, Salt ConcentrationConcentrationHead-Tail Water Quality Trends, Tula Irrigation District 003, Mexico
0
200
400
600
800
1000
1200
1400
1600
1800
Head Middle Tail
EC
(m
icro
mho
s)
0
2
4
6
8
10
12
Nut
rient
s, 0
.1*B
OD
(m
g/L)
EC
Nitrogen (dry)
Nitrogen (rains)
0.1*BOD (rains)
0.1*BOD (dry)
Phosphates (rains)
Phosphates (dry)
Monterrey-Bajo RMonterrey-Bajo Ríío San o San Juan SwapJuan Swap
Tamaulipas
McAllen, Texas
Marte R. Gómez Reservoir
El Cuchillo Reservoir
Falcon Reservoir
Bajo Río San Juan Irrigation District
47%
El CuchilloEl Cuchillo Constructed in 1993 Supplies 5 m3/s to Monterrey (to
be increased toMarte R. Gomez vs. El Cuchillo Reservoir Storage (1993-2004)
y = 0.5015x + 31.7
0
100
200
300
400
500
600
700
0 200 400 600 800 1000 1200
El Cuchillo (MCM)
Mar
te R
. Gom
ez (M
CM
) 10 m3/s) MR
Gómez reservoir impacts
Negotiated SettlementNegotiated Settlement
9 Oct. 1989 – Monterrey, federal and Nuevo León governments agree to finance and construct El Cuchillo dam
6 Sept. 1990 –Tamaulipas, federal and Nuevo León governments agree to “rationalize” water use, preserve multiple uses of BRSJ irrigation water
Effluent – the Bargaining Effluent – the Bargaining ChipChip Federal CNA allocates 189 MCM (6
m3/s) of effluent from Monterrey to BRSJ irrigators
Nuevo León assumes responsibility and cost of treatment in compliance with federal water quality standards
Rehabilitation of the Anzaldúas-Rhode pumping station on the Río Bravo
Relocation of downstream Tamaulipas urban water demand from MR Gómez reservoir (Rhode canal)
BRSJ Irrigation Water BRSJ Irrigation Water ProductivityProductivityYear Total Production Total Gross Total Net Gross Water Net Water
Volume Used Volume Used Productivity Productivity
(Ton) (Thousand m3) (Thousand m3) (Ton/Thousand m3) (Ton/Thousand m3)
95-96 202,131.86 263,331.00 146,743.00 0.77 1.38 96-97 101,029.00 146,811.00 78,927.00 0.69 1.28
97 - 98 175,891.00 222,875.00 128,059.00 0.79 1.37 98 - 99 84,614.00 114,272.00 64,089.00 0.74 1.32 99 - 00 90,555.00 110,100.00 64,201.00 0.82 1.41 00 - 01 6,609.00 160,499.00 83,283.00 0.04 0.08 01 - 02 250,578.00 383,171.00 219,372.00 0.65 1.14
02 - 03 281,786.20 395,429.90 213,457.40 0.71 1.32
03 - 04 394,543.58 217,267.50 110,089.20 1.82 3.58
BRSJ Irrigation EfficiencyBRSJ Irrigation EfficiencyIrrigation District 026 Bajo Rio San Juan
0
100
200
300
400
500
600
1989-1
990
1990-1
991
1991-1
992
1992-1
993
1993-1
994
1994-1
995
1995-1
996
1996-1
997
1997-1
998
1998-1
999
1999-2
000
2000-2
001
2001-2
002
2002-2
003
2003-2
004
2004-2
005
Irrigation Season
Res
ervo
ir W
ater
Del
iver
y (M
CM
)
(10,000)
10,000
30,000
50,000
70,000
90,000
110,000
130,000
150,000
Irri
gate
d A
rea
(ha)
Reservoir Water Release
Irrigated Area
But, growing upstream demand and capture of wastewater; will But, growing upstream demand and capture of wastewater; will need to pipe it 100+ km.need to pipe it 100+ km.
Wastewater Use: Wastewater Use: ConclusionsConclusionsUrban growth + high tertiary treatment costs = increasing agricultural reuse
Promote beneficial agricultural reuse
Mitigate health and environmental risk
Risk MitigationRisk Mitigation Secondary treatment (biosolids handling
enforcement is essential) Application method to limit irrigators’
exposure Market wash water and handling Crop restrictions – non-edible and fodder.
Limit fresh produce irrigation, e.g.:
Treatment for Treatment for ComplianceCompliance WHO - 103 faecal coliforms/100 ml
Cost of treating raw sewage used for direct irrigation to meet WHO standard is approx US$125 per case of infection (of hepatitis, rotavirus, cholera, or typhoid) prevented (Fattal, Shuval, Laempert, 2004).
USEPA – zero incremental risk Incremental cost of further treating
wastewater from WHO to USEPA standard approx. US$450,000 per case of infection prevented (Fattal, Shuval, Laempert, 2004).
Policy ImplicationsPolicy Implications Planned reuse offers no easy solutions Key to success are:
coherent legal and institutional framework coordination of multiple government agencies flexible application of the ‘polluter pays’
principle extension to farmers of appropriate practices
for wastewater use public awareness campaigns to build social
acceptability for reuse
Wastewater Use in Wastewater Use in Irrigated AgricultureIrrigated Agriculture http://www.cabi.org/bk_BookDis
play.asp?PID=1785 http://www.idrc.ca/en/ev-31595-
201-1-DO_TOPIC.html Introduction: management
challenges Typology and global assessment Livelihoods the key driver WHO health guidelines Cost of guidelines compliance
Case Studies in the BookCase Studies in the Book
Kenya Ghana Vietnam Pakistan Senegal India
Bolivia Mexico Jordan Tunisia
Formal programs of planned reuse with treatment
Thank you.Thank you.Christopher Scott
cascott@email.arizona.edu
626-4393Acknowledgements: Stephanie Buechler, UA Bureau of Applied Research in Anthropology Pay Drechsel, International Water Management Institute, Ghana Jeroen Ensink, London School of Hygiene and Tropical Medicine Naser Faruqui, International Development Research Centre Francisco Flores, Cornell University Jesús R. Gastélum, UA Dept. of Civil EngineeringLiqa Raschid, International Water Management Institute Daan van Rooijen, International Water Management Institute, Ghana
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