Drain for Gain: Making Water Management Worth its Salt
Subsurface Drainage Practices in Irrigated Agriculture in Semi-arid and Arid Regions
Salinity affects 10 to 16% of all irrigated lands while the annual rate of land loss due to waterlogging and salinity is about 0.5 million hectares per year. In this dissertation, the role of subsurface drainage to reduce these problems in irrigated agriculture in arid and semi-arid regions has been analysed and challenges for improving subsurface drainage practices have been formulated.
Although the installed subsurface drainage systems are in general technically sound and cost-effective, drainage development lags behind irrigation development and consequently a substantial part of the irrigated areas suffers from waterlogging and salinity. This is mainly because the subsurface drainage systems are designed and implemented by government, with the users, the small farmers, having little responsibility and having little input. In the adopted top-down approach the location-specific conditions and farmers’ preferences are hardly taken into consideration. Furthermore, the emphasis has been on the technical aspects (the physical infrastructure), while the organizational aspects (institutional infrastructure) have been largely neglected.
To reverse the negative trend in salt build-up and waterlogging in irrigated lands in semi-arid and arid regions, a number of challenges for enhancing the role of subsurface drainage have been formulated: (i) balancing top-down against bottom-up, (ii) from standardization to flexibility and (iii) focus on capacity development.
Table of Contents
1 1.1 Rationale of the study
1 1.2 Scope of the study
1.6 Benefits of the research
1.7 Outline of this thesis
2 Subsurface drainage practices in Egypt
2.1 History of irrigation and drainage in Egypt
2.2 Organization of the drainage sector
2.3 Planning of drainage projects
2.4 Design principles
2.5 Installation practices
2.6 Disposal of the drainage effluent
2.7 A modified layout of the subsurface drainage system for rice areas
2.8 Controlled drainage and farmers participation
2.9 Verification of drainage design criteria in the Nile Delta
2.10 Water balance study in a drained area
3 Subsurface drainage practices in India
3.1 History of irrigation and drainage in India
3.2 Organization of the drainage sector
3.3 Design principles
3.4 Installation practices
3.5 Disposal of the drainage effluent
3.6 Lessons learned in famers’ fields
3.7 Water balance study in a drained area
3.8 Participatory approach
3.9 Participatory modelling to cope with off-site externalities of drainage
4 Subsurface drainage practices in Pakistan
4.1 History of irrigation and drainage in Pakistan
4.2 Organization of the drainage sector
4.3 Need for subsurface drainage
4.4 Design principles
4.5 Installation practices
4.6 Participatory drainage development
4.7 Operation and maintenance
4.8 Disposal of the drainage effluent
5 Improving subsurface drainage practices
5.1 From manual installation to large-scale implementation
5.1.2 Installation equipment
5.1.3 Drain pipe materials
5.1.4 Envelope materials
5.1.5 Quality control
5.1.7 Capacity Building
5.2 The added value of research on drainage in irrigated agriculture
5.2.2 Identification of the need for subsurface drainage
5.2.4 Planning and design
5.2.6 Operation and maintenance
6 Capacity development to improve subsurface drainage practices
6.1 An integrated approach for capacity development in drainage
6.1.2 Materials and methods
6.1.3 Training and dissemination of knowledge through publications
6.1.4 Capacity development to improve subsurface drainage practices
6.1.5 Capacity development to combat waterlogging and salinity
6.1.6 Capacity development to increase farmers’ participation
6.1.7 Capacity development for wise use of tropical peatlands
6.2 Participatory research on the effectiveness of drainage
6.2.2 Participatory research approach
6.2.3 Pre-drainage investigations
6.2.4 Monitoring programme
6.2.4 Model simulations
6.2.5 Conclusion and recommendations
7 Synthesis: subsurface drainage practices in irrigated agriculture
7.1 Is subsurface drainage an acceptable option?
7.1.1 Are subsurface drainage systems technically sound?
7.1.2 Are the subsurface drainage systems cost-effective?
7.1.3 Is subsurface drainage a socially accepted practice?
7.2 How can the integration of irrigation and drainage be improved?
7.3 What are the main challenges in making subsurface drainage work?
7.4 Improving subsurface drainage practices: the way forward
7.4.1 The state of the art in subsurface drainage
7.4.2 Institutional and policy challenges
7.4.3 Increased stakeholder participation
7.4.4 Drainage system requirements
7.4.5 Capacity development
8 The way forward: enhancing the role of subsurface drainage
Abbreviations and acronyms
List of symbols
Henk Ritzema received his MSc degree from the Department of Civil Engineering at Delft University of Technology in 1980. After graduation, he worked for the Food and Agriculture Organization of the UN and the Dutch Civil Service. In 1989 he joined the International Institute for Land Reclamation (formerly ILRI, now Alterra), Wageningen. In 2008 he joined the Irrigation and Water Engineering Group at Wageningen University.