Water harvesting (AGL/MISC/17/91)













Table of Contents


 

A Manual for the Design and Construction of Water Harvesting Schemes for Plant Production

by

Will Critchley - Conservation Agronomist Centre for Development Cooperation Services Free University, Amsterdam

and

Klaus Siegert - Water Resources Engineer Land and Water Development Division FAO, Rome

with contributions from:

C. Chapman, FAO Project Manager M. Finkel, Agricultural Engineer, Yoqneam, Israel

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS - Rome, 1991

This electronic document has been scanned using optical character recognition (OCR) software and careful manual recorrection. Even if the quality of digitalisation is high, the FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.


Table of Contents


Preface

Acknowledgement

1. Introduction

1.1 The basis of water harvesting: History and perspectives

1.1.1 Historical perspectives
1.1.2 Recent developments
1.1.3 Future directions

1.2 Definitions and classification
1.3 Basic categories of water harvesting systems for plant production

1.3.1 Microcatchments (rainwater harvesting)
1.3.2 External catchment systems (rainwater harvesting)
1.3.3 Floodwater farming (floodwater harvesting)

1.4 Overview of main WH systems

2. Water and soil requirements

2.1 Water requirements of crops

2.1.1 Introduction
2.1.2 General estimates
2.1.3 Factors influencing crop water requirements
2.1.4 Calculation of crop water requirements

2.2 Water requirements of trees, rangeland and fodder

2.2.1 Multipurpose trees
2.2.2 Fruit trees
2.2.3 Water requirements of rangeland and fodder

2.3 Soil requirements for water harvesting

2.3.1 Introduction
2.3.2 Texture
2.3.3 Structure
2.3.4 Depth
2.3.5 Fertility
2.3.6 Salinity/sodicity
2.3.7 Infiltration rate
2.3.8 Available water capacity (AWC)
2.3.9 Constructional characteristics

3. Rainfall-runoff analysis

3.1 Introduction
3.2 Rainfall characteristics
3.3 Variability of annual rainfall
3.4 Probability analysis
3.5 Rainfall-runoff relationship

3.5.1 The surface runoff process
3.5.2 Factors affecting runoff
3.5.3 Runoff coefficients

3.6 Determination of runoff coefficients
3.7 Assessment of annual or seasonal runoff
3.8 Runoff plots

4. Design model for catchment: Cultivated area ratio

4.1 Introduction
4.2 Crop production systems
4.3 Examples on how to calculate the ratio C: Ca
4.4 Systems for trees
4.4 Systems for rangeland and fodder

5. Water harvesting techniques

5.1 Site and technique selection

5.1.1 People's priorities
5.1.2 Basic technical criteria

5.2 Negarim microcatchments

5.2.1 Background
5.2.2 Technical details
5.2.3 Layout and construction
5.2.4 Maintenance
5.2.5 Husbandry
5.2.6 Socio-economic considerations

5.3 Contour bunds for trees

5.3.1 Background
5.3.2 Technical details
5.3.3 Layout and construction
5.3.4 Maintenance
5.3.5 Husbandry
5.3.6 Socio-economic factors

5.4 Semi-circular bunds

5.4.1 Background
5.4.2 Technical details
5.4.3 Layout, and construction
5.4.4 Maintenance
5.4.5 Husbandry
5.4.6 Socio-economic Factors

5.5 Contour ridges for crops

5.5.1 Background
5.5.2 Technical details
5.5.3 Layout and construction
5.5.4 Maintenance
5.5.5 Husbandry
5.5.6 Socio-economic factors

5.6 Trapezoidal bunds

5.6.1 Background
5.6.2 Technical Details
5.6.3 Layout and construction
5.6.4 Maintenance
5.6.5 Husbandry
5.6.6 Socio-economic factors

5.7 Contour stone bunds

5.7.1 Background
5.7.2 Technical details
5.7.3 Layout and construction
5.7.4 Maintenance
5.7:5 Husbandry
5.7.6 Socio-economic factors

5.8 Permeable rock dams

5.8.1 Background
5.8.2 Technical Details
5.8.3 Layout and construction
5.8.4 Maintenance
5.8.5 Husbandry
5.8.6 Socio-economic factors

5.9 Water spreading bunds

5.9.1 Background
5.9.2 Technical Details
5.9.3 Layout and construction
5.9.4 Maintenance
5.9.5 Husbandry
5.9.6 Socio-economic Factors

6. Husbandry

6.1 Introduction
6.2 Crops

6.2.1 General
6.2.2 Crop choice
6.2.3 Fertility
6.2.4 Other husbandry factors

6.3 Trees

6.3.1 General
6.3.2 Choice of species
6.3.3 Husbandry

6.4 Rangeland and fodder

7. Socio-economic factors and project management

7.1 Introduction
7.2 Socio-economic factors

7.2.1 People's priorities
7.2.2 Participation
7.2.3 Adoption of systems
7.2.4 Area differences
7.2.5 Gender and equity
7.2.6 Land tenure
7.2.7 Village land use management

7.3 Project management

7.3.1 The project and the people
7.3.2 Project approach
7.3.3 Machinery or hand labour
7.3.4 Flexibility of approach
7.3.5 Subsidies and incentives
7.3.6 Monitoring, evaluation and reporting

Appendix - Simple surveying techniques

A.1 Use of the line level for surveying

Introduction
Laying out a contour
Laying out a graded contour
Measuring the slope of the land
Important points to remember

A.2 Use of the water tube level for surveying

Introduction
Laying out a contour
Important Points to Remember

Annotated bibliography