Green Water Management Handbook - World Agroforestry Centre

229 Pages·2008·12.56 MB·English

Green Water Management Handbook
Rainwater harvesting for agricultural production and ecological sustainability
ICRAF Technical Manuals series
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experience. -- Nairobi , Kenya : World Agroforestry Centre (ICRAF) ICRAF technical manual No. 1,
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pour les pépinières communautaires. -- Nairobi , Kenya : World Agroforestry Centre (ICRAF) ICRAF
Manuel Technique No. 2, 95p.. [B14473] ICRAF
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les pépinières de recherche. -- Nairobi , Kenya : World Agroforestry Centre (ICRAF) ICRAF Manuel
Technique no. 3, 93p.. [B14474] ICRAFP
4. Wightman, K.E.; Cornelius, J.P.; Ugarte-Guerra, L.J. 2006. Plantemos madera : manual sobre el
establecimiento, manejoy aprovechamiento de plantaciones maderables para productores de la
Amazonía peruana. -- Lima , Peru : World Agroforestry Centre – Amazon Regional Programme,
ICRAF Technical Manual no.4, 204p.. [B14518] 630*26 WIG ICRAF
5. Maimbo M. Malesu, Joseph K. Sang, Alex R. Oduor, Orodi J. Odhiambo & Meshack Nyabenge.
Rainwater harvesting innovations in response to water scarcity: The Lare experience. Nairobi,
Kenya: Regional Land Management Unit (RELMA-in-ICRAF), Netherlands Ministry of Foreign Affairs
and Swedish International Development Cooperation Agency (Sida). ICRAF Manuel Technique No.
5, 41p + xii includes bibliography. ISBN: 92 9059 197 8
6. Bekele-Tesema, Azene. 2006. Useful Trees and Shubs of Ethiopia. Identification, Propagation
and Management for 17 Agroclimatic Zones. Nairobi, Kenya : World Agroforestry Centre (ICRAF)
– Eastern Africa Regional Programme. ICRAF Technical Manual No. 6, 551p. ISBN 92-9059-2125
7. Maimbo Malesu, Elizabeth Khaka, Bancy Mati, Alex Oduor, Tanguy De Bock, Meshack Nyabenge
and Vincent Oduor. 2007. Mapping the Potential of Rainwater Harvesting Technologies in Africa:
A GIS overview and atlas of development domains for the continent and nine selected countries.
Nairobi, Kenya : World Agroforestry Centre (ICRAF) – Eastern Africa Regional Programme. ICRAF
Technical Manual No. 7, 130p. ISBN 92 9059 2117.
Green Water Management Handbook
Rainwater harvesting for agricultural production and ecological sustainability
Edited by:
Maimbo M. Malesu
Alex R, Oduor
Orodi J. Odhiambo
Contributors:
Maimbo M. Malesu
Alex R. Oduor
Orodi J. Odhiambo
Ephraim M. Senkondo
Ayub Shaka
Peter Okoth
Anna Mutinda
Joyce S. Musiwa
John Mutua
Published by
SearNet Secretariat, The World Agroforestry Centre, ICRAF House, United Nations
Avenue, Gigiri. P.O. Box 30677 – 0000, Nairobi, Kenya.
2007 Netherlands Ministry of Foreign Affairs and Swedish International Development
Cooperation Agency (Sida).
Editor of Water Management Series of Publications,
Alex R. Oduor, Programme Officer
World Agroforestry Centre, Eastern Africa Region
Editor of ICRAF Global Series
George Obanyi, Editor
World Agroforestry Centre, Eastern Africa Region.
Design and Layout & Computer Graphics
Logitech Ltd
P.O. Box 1003 00100
Nairobi, Kenya
Computer Graphics
Pixiniti Studios
P.O. Box 1004 00100
Nairobi, Kenya
Cataloguing in publication data
Maimbo M. Malesu, Alex R. Oduor and Orodi J. Odhiambo (Eds). 2007. Green water
management handbook: Rainwater harvesting for agricultural production and ecological sustainability.
Technical Manual No. 8 Nairobi, Kenya: World Agroforestry Centre (ICRAF),
Netherlands Ministry of Foreign Affairs. 219 p. + x p; includes bibliography.
ISBN: 978 92 9059 219 8
The contents of this book may be reproduced without special permission. However,
acknowledgement of the source is requested. Views expressed in the Water Management
series of publications are those of the authors and do not necessarily reflect the views of
World Agroforestry Centre (ICRAF).
Printed by:
Colour Print Ltd
P.O. Box 44466
Nairobi, Kenya
Table of contents
Chapter 1: Introduction ..................................................................................................1
1.1 General overview ................................................................................................1
1.2 Water resources in Africa ...................................................................................4
1.3 Uses of water .......................................................................................................6
1.4 Green water resources for sustainable production .......................................11
1.5 Challenges and opportunities ..........................................................................14
1.6 Potential and prospects for green water .........................................................18
Chapter 2: The Climate of Africa ................................................................................23
2.1 Characteristics ..................................................................................................23
2.2 Rainfall regimes ................................................................................................24
2.3 Factors that influence rainfall over Africa........................................................27
2.4 Vulnerability of Africa to variations in climate .................................................36
2.5 Rainfall trends in Africa ...................................................................................39
2.6 Climate change and its effect in Africa ...........................................................40
2.7 Climate variability and change: coping strategies ..........................................46
Chapter 3: Classification of agricultural RWH systems ...........................................52
3.1 Overview ............................................................................................................52
3.2 Classification of rainwater harvesting systems ...............................................54
3.3 Survey and site selection .................................................................................62
Chapter 4: Technical issues and technological options ...........................................65
4.1 Crop production and rainwater management systems ..................................65
Chapter 5: Conservation tillage ..................................................................................90
5.1 Introduction .......................................................................................................90
5.2 Benefits ..............................................................................................................91
5.3 Linking conservation farming to rainwater harvesting ...................................93
5.4 CFU’s components and process .....................................................................94
5.5 Conservation farming as a rainwater harvesting technique for sustainable
agriculture in semi arid Zambia: A case study ....................................................101
Chapter 6: Rainwater management for livestock production ..............................108
6.1 Overview ..........................................................................................................108
6.2 Challenges and opportunities ........................................................................109
6.3 Classification of livestock production systems .............................................111
6.4 Livestock production and supply in Africa .....................................................112
6.5 Livestock water use and livestock water productivity...................................113
Chapter 7: Rainwater management for environmental sustainability ................124
7.1 Overview ..........................................................................................................124
7.2 The challenges ................................................................................................124
7.3 Opportunities to minimize environmental degradation ................................126
7.4 Technological options for ecological and ecosystem sustainability ............129
7.5 Water management practices for ecological sustainability .........................142
Chapter 8: Economics of Rainwater Harvesting ....................................................153
8.1 Introduction .....................................................................................................153
8.2 Economic evaluation of rainwater harvesting ...............................................155
8.3 Planning and appraising rainwater harvesting projects ...............................158
8.4 Case studies ...................................................................................................161
8.5 Conclusions and recommendations ..............................................................167
Chapter 9: Extension Methodology ..........................................................................168
9.1 Introduction .....................................................................................................168
9.2 Extension strategy ...........................................................................................168
Chapter 10: Sustainable use of water resources ....................................................172
10.1 Introduction ...................................................................................................172
10.2 Conditions for sustainability ........................................................................174
Chapter 11: Gender issues in rainwater management .........................................183
11.1 Issues that marginalize women ...................................................................183
11.2 Gender disparities in irrigated agriculture ..................................................184
11.3 Gender-related irrigation design and management factors ......................186
Chapter 12: Policy and legislation...........................................................................187
12.1 Review of Kenya Government policy documents ........................................187
12.2 Review of policy documents in Tanzania ....................................................197
12.3 Review of policy documents in Uganda ......................................................203
Chapter 13: Monitoring and evaluation ..................................................................207
13.1 An overview of the role indicators play in the M&E process ......................208
13.2 Some nuts and bolts of establishing an M&E system ...............................213
13.3 Key lessons ...................................................................................................216
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List of Synonyms
ACZ Agro-climatic zone
AfDB African Development Bank
AMCOW African Ministerial Council on Water
AWTF African Water Task Force
ASAL Arid and Semi-Arid Lands
CAADP Comprehensive Africa Agriculture Programme
ECA Economic Commission for Africa
ET Evapotranspiration
FAO Food and Agricultural Organization of the United Nations
GIS Geographical Information System
GPS Geographic Positioning System
GWP Global Water Partnership
GWP/AP Global Water Partnership-Associated Programme
ICRAF International Centre for Research in Agroforestry / World Agroforestry Centre
IWRM Integrated Water Resource Management
MDG Millennium Development Goals
NEPAD New Partnership for Africa’s Development
NGO Non Governmental Organization
RELMA Regional Land Management Unit
RWH Rainwater Harvesting
SEARNET South and East Africa Rainwater harvesting Network
UNEP United Nations Environmental Programme
WSSD World Summit for Sustainable Development
SOTER Soil Terrain Database
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Preface
The water cycle is partitioned into blue and green flows. Green water constitutes 65%
of the total precipitation at global scale and blue water the rest. Green water is used in
forests, grasslands, wetlands and croplands, while blue water sustains ecosystems.
Owing to the visibility of blue water as it flows into surface and underground reservoirs
as runoff or base flow respectively, most governments and policy institutions have focused
on it for planning purposes while neglecting the green water fluxes. This has created
an impression of water scarcity, especially in Africa. For instance, the United Nations
Economic Commission for Africa (UNECA) projects that 14 countries in Africa will
suffer from water stress and scarcity by the year 2025.
Already, the competition for the scarce water resource is intense in many places, with
river basins not having enough to meet all demands. Lack of water is a major constraint
to food production. According to the Comprehensive Assessment report, it takes up 70%
of freshwater.
However, inclusion of the green water potential in the hydrologic equation changes the
picture. A study by World Agroforestry and UNEP on mapping of water harvesting
potential for Africa and nine selected countries shows that the continent receives
around 24,000 km3 of rainwater, 75% of which can be used to support the livelihoods
of millions, mainly through production of food, tree and livestock products. Africa is
thus not physically water scarce. The problem is more of an economic nature owing
to inadequate capacity and investments in infrastructure to manage water, including its
storage. This inadequacy has reduced access to available water, jeopardizing efforts to
improve food production.
This handbook highlights the principles and technologies that can be used to harness
the huge untapped potential of rainwater. Instead of a stereotyped view focusing only
on rivers and groundwater, the book directs readers in recognizing rain as the ultimate
source of water for food production and other uses in rural economies across Africa.
viii
The book gives attention to climatological aspect of rainfall as a key component in the
design of water harvesting technologies. The handbook looks at factors that influence
rainfall and the effect of climate change. Also covered are technical options for rainwater
management for crops, livestock and environmental systems. Other topics include
economic evaluation of rainwater and sustainability of water resources. There is also a
section dedicated to extension approaches, gender and policy considerations.
Finally, the handbook is based on practical experiences of work gained by members
of the Southern and Eastern Africa Rainwater Network (SearNet, www.searnet.org),
many of who contributed content for the various chapters. The participatory approach
to developing this book makes it a useful reference for trainers and others interested in
the practical application of water harvesting technologies in the field.
Dr. Dennis Garrity
Director General
World Agroforestry Centre
ix
Acknowledgement
This document is inspired by the desire of SearNet members to be custodians of reference
material for green water management which they can use in building the capacity of
rainwater harvesting practitioners in the East and Southern Africa sub-continent. A
workshop organized in July 2003 deliberated on the contents and potential authorship of
the handbook. Although it took five years to finally accomplish preparation of the draft,
the Secretariat kept pace in upraising the document with up-to-date technological status
of rainwater harvesting for agriculture.
In lieu of the above, the Secretariat is grateful to all the participants of the Machakos
workshop in Kenya, who contributed immensely in developing the outline for this
handbook. The authors also wish to recognize institutions or persons who delivered
photographs, case studies, comments and advice that were crucial in enriching the
handbook.
Compilation of this handbook wouldn’t have been possible were it not for the endeavour
put in by Naomi Njeri, the Programme Assistant of the Global Water Partnership
Associated Programme.
Finally, lots of gratitude go to the Netherlands Ministry of Foreign Affairs for facilitating
the printing and distribution of this publication which forms a key reference material for
the upscaling programmes and projects across Africa.
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