FAO IRRIGATION AND DRAINAGE PAPER 61
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 2002
by
Kenneth K. Tanji
Hydrology Program
Department of Land, Air and Water Resources
University of California
Davis, United States of America
Neeltje C. Kielen
Water Resources, Development and Management Service
FAO Land and Water Development Division
Reprinted 2003
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ISBN 92-5-104839-8
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© FAO 2002
Part I. Framework and technical guidelines
Need for drainage of irrigated lands
Need for water conservation and reuse
Towards drainage water management
Scope of this publicationChapter 2. Defining the problem and seeking solutions
System approach in drainage water management
Defining the problem
Seeking solutions
Spatial issues
The use of models in recommending solutions and anticipated resultsPrinciples of rootzone hydrosalinity models
Salt balance in the rootzoneDefinition of drainage water management and tasks involved
Driving forces behind drainage water management
Physical drainage water management optionsConservation measures
Reuse measures
Treatment measures
Disposal measuresNon-physical drainage water management options
Emission levels
Ambient levels
Salinity permits
Charges on inputs
Subsidies on practices
Charging/subsidizing outputs
Combined measuresSelection and evaluation of drainage water management options
BenchmarkingChapter 4. Water quality concerns in drainage water management
Introduction
Drainage water quality
Factors affecting drainage water qualityGeology and hydrology
Soils
Climate
Cropping patterns
Use of agricultural inputs
Irrigation and drainage management
Drainage techniques and designCharacteristics of drainage water quality
Salts and major ions
Toxic trace elements
Agropollutants
SedimentsWater quality concerns for water uses
Crop production
Living aquatic resources, fisheries and aquaculture
Livestock production
Concerns for human healthNeed for water conservation measures
Hydrologic balance
Irrigation performance indicators
Source reduction through sound irrigation managementReasonable losses
Management options for on-farm source reduction
Options for source reduction at scheme level
Impact of source reduction on long-term rootzone salinity
Maintaining a favourable salt balance under source reduction
Calculation example impact of source reduction on salinity of rootzone
Impact of source reduction on salt storage within the cropping season
Calculation example of impact of source reduction on salt balance of the rootzone
Impact of source reduction on salinity of drainage water
Calculation example of source reduction and the impact on drainage water generation and salinityShallow water table management
Controlled subsurface drainage
Considerations in shallow water table management
Capillary rise
Maintaining a favourable salt balance under shallow water table management
Calculation example of the impact of shallow water table management on salinity buildup and leaching requirementHydrologic, soil and biologic considerations
Selection of lands to retire
Management of retired landsChapter 6. Drainage water reuse
Introduction
Relevant factors
Considerations on the extent of reuse
Maintaining favourable salt and ion balances and soil conditionsMaintaining a favourable salt balance
Maintaining favourable soil structure
Maintaining favourable levels of ions and trace elementsReuse in conventional crop production
Direct use
Conjunctive use - blending
Conjunctive use - cyclic useCrop substitution and reuse for irrigation of salt tolerant crops
Crop substitution
Reuse for irrigation of salt tolerant plants and halophytesChapter 7. Drainage water disposal
Requirements for safe disposal
Disposal conditions
Disposal in freshwater bodies
Disposal into evaporation pondsEvaporation ponds in Pakistan
Evaporation ponds in California, the United States of America
Evaporation ponds in Australia
Design considerations for evaporation pondsChapter 8. Treatment of drainage effluent
Need for drainage water treatment
Treatment optionsFlow-through artificial wetlands
Evaluation and selection of treatment options
Drainage water management in the Aral sea basin
Drainage water reuse and disposal: a case study from the Nile Delta, Egypt
Drainage water reuse and disposal in northwest India
Drainage water reuse and disposal: a case study on Pakistan
Drainage water reuse and disposal: a case study on the western side of the San Joaquin Valley, California, the United States of America
Annex 1. Crop salt tolerance data
Annex 3. Drinking-water quality guidelines for parameters of concern in agricultural drainage water
Annex 5. Capillary rise and data set for soil hydraulic functions
Annex 6. Trees and shrubs for saltland, salinity ratings and species lists