Foreword
Acknowledgements
List of Boxes
List of Figures
List of Tables
List of Acronyms and symbols
Part I. Framework and Technical Guidelines
1. Introduction
Need for drainage of irrigated lands
Need for water conservation and reuse
Towards drainage water management
Scope of this publication
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 rocommending solutions and anticipated results
Model characteristics
Regional models
Rootzone hydrosalinity models
Principles of rootzone hydrosalinity models
Salt balance in the rootzone
3. Framework to selecting, Evaluating and Assessing the Impact of Drainage water Management Measures
Definition of drainage water management and tasks involved
Driving forces behind drainage water management
Physical drainage water management options
Conservation measures
Reuse measures
Treatment measures
Disposal measures
Non-physical drainage water management options
Emission levels
Ambient levels
Salinity Permits
Charges on inputs
Subsidies on practies
Charging/subsidizing outputs
Combined measures
Selection and evaluation of drainage water management options
Benchmarking
4. Water Quality Concerns in Drainage water Management
Introduction
Drainage water quality
Factors affecting drainage water quality
Geology and hydrology
Soils
Climate
Cropping Patterns
Use of Agricultural inputs
Irigation and drainage management
Drainage techniques and design
Characteristics of darinage water quality
Salts and Major ions
Toxic trace elements
Agropollutants
Sediments
Water quality concerns for water uses
Crop production
Living aquatic resources, fisheries and aquaculture
Livestock production
Concerns for human health
5. Water Conservation
Need for water conservation measures
Hydrologic balance
Irrigation performance indicators
Source reductioni through sound irrigation management
Reasonable 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 salinity
Shallow 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 requirement
Land retirement
Hydrologic, soil and biodogic considerations
Selection of lands to retire
Management of retired lands
6. Drainage water reuse
Introduction
Relevant factors
Consideration on the extent of reuse
Maintaining favourable salt and ion balances and soil conditions
Maintaining a favourable salt balance
Maintaining favourable soil structure
Maintaining favourable levels of ions and trace elements
Reause in conventional crop production
Direct use
Conjunctive use – Bleding
Conjunctive use – cyclic use
Crop substitution and reuse for irrigation of salt tolerant crops
Crop substitution
Reuse for irrigation of salt tolerant plants and halophytes
Reuse in IFDM systems
Reclamation of salt-affected land
7. Drainage water disposal
Requirements for safe disposal
Disposal conditions
Disposal in freshwater bodies
Disposal into evaporation ponds
Evaporation ponds in pakistan
Evaporation ponds in California, the United States of America
Evaporation ponds in Australia
Design considerations for evaporation ponds
Injection into deep aquifers
8. Treatment of drainage Effluent
Need for drainage water treatment
Treatment options
Desaliniation
Trace element treatment
Flow-through artificial wetlands
Evaluation and selection of treatment options
Part II- Summaries of case studies from Central Asia, Egypt, India, Pakistan and The United States of America
Summeries of case studies
References
Annexes
1. Crop salt Tolerance Data
2. Water quality guidelines for livestock and poultry production for parameters of concern in agricultural drainage water
3. Drinking-water quality guidelilnes for parameters of concern in Agricultural drainage water
4. Impact of Irrigation and drainage management of water and salt balance in the absence of capillary rise
5. Capillary rise and data set for soil Hydraulic functions
6. Trees and Shrubs for Saltland, Salinity Ratings and Species Lists