Agro-Ecology and Irrigation Technology
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Agro-Ecology andIrrigatio n Technology Comparative Research on Farmer-Managed Irrigation Systems inth e Mid-Hills of Nepal Umesh Nath Parqjuli Promotor: Linden Vincent, hoogleraar in de irrigatie en waterbouwkunde Copromotor: Dr. Prachanda Pradhan, hoogleraar in de bestuurskunde, Tribhuvan University, Nepal Umesh Nath Parajuli Agro-Ecology and Irrigation Technology Comparative Research on Farmer-Managed Irrigation Systems inth e Mid-Hills of Nepal Proefschrift ter verkrijging van de graad van doctor op gezag van de rector magnificus van de Wageningen Universiteit, dr. CM. Karssen, in het openbaar te verdedigen op maandag 27 September 1999 des namiddags te 13.30 uur in de Aula ) ISBN 90-5808-078-1 Copyright © 1999b y Umesh Nath Parajuli All rights reserved. No part of this publication may be reproduced in any form, by print or photoprint, microfilm or any other means, without written permission of the holder of the copyright. Cover design by Mr.Erns t vanClee f Printed by Grafish Service Centrum, Wageningen Cover photo: An indigenous proportioning weir, locally named as barahamukhe dhara meaning weir with twelve notches, in the Sankhar Irrigation System. Cover sketch: The schematic layout of the Sankhar Irrigation System with proportioning weirs and their water shares. BIBUOTHF.:-:K LANDBOUWUNIV\LVS-IT. WAGENTNGGN CONTENTS Preface and acknowledgements vi List of tables viii List of figures viii List of photos x List of appendices x Glossary of local terms used in this thesis x List of units of measurement used in this thesis xi List of acronyms used in this thesis xii 1 Introduction 1 1.1 Problem definition 1 1.2 Focus of the research 3 1.3 Theoretical approach 4 1.3.1 Ecology and irrigation 4 1.3.2 Conceptualizing technology 5 1.3.3 Agro-ecology and technology 6 1.3.4 Design-management interaction 8 1.3.5 Technology, management functions and objectives, and management domains 9 Operational (management) objectives-10; Managementdomains-\\ 1.3.6 Summary of theoretical approach 12 1.4 Research questions 13 1.5 Methodology 14 1.5.1 Site selection criteria 14 1.5.2 Organization of research 16 1.5.3 Intensive data collection 16 Landsurveying andwater measurements-17; Structured and non-structured interviews-l&; Observation-lS; Problems andlimitations ofirrigation system research in Nepal-l& 1.6 Outline of the thesis 19 2 TheAgro-Ecologica l Differentiation ofIrrigatio nSystem s inth eMid-hill so fNepa l 21 2.1 An overview of the country 21 2.1.1 Physiography 21 Terai-22; Siwaliks-23; Hills-23; High Himalayas-24 2.1.2 Climate 24 2.1.3 Farming systems and principal crops 25 2.2 An overview of irrigation development in Nepal and present government policy 26 2.3 Irrigation systems and their classifications 28 2.3.1 Classification of irrigated land and respective irrigation systems 29 Foothill terraces (khola khet)and foothill irrigation systems-29; Slope-hill terraces (Tar) andslope-hill irrigation systems-32; River-valley terraces and river-valley irrigation systems-34 2.4 Water allocation and distribution 37 2.4.1 Principles of water allocation 37 2.4.2 Water distribution 37 2.4.3 Water division structures 38 Open-close-38; Adhoc adjustments^; Fixedproportion-^ 2.5 Summary 40 3 Design Considerations of Proportioning Weirs 43 3.1 The indigenous proportioning weir 43 3.2 Hydraulic characteristics of a proportioning weir 44 3.2.1 Hydraulic flexibility 44 3.2.2 Basic hydraulics of the weir 45 Coefficientof velocity-46; Coefficientof discharge-46 3.2.3 Flow constriction 46 3.3 Sankhar Irrigation System 47 3.4 Flow measurements and constraints 49 3.4.1 Flow measurements 49 3.4.2 Difficulties in flow measurements in the field 50 3.4.3 Accuracy of the flow measurement in the field 51 3.5 Farmers' considerations of hydraulics in the design of proportioning weirs ...52 3.5.1 Length of the approach canal and the width and the height of the weir..55 Length ofan approach canal-56; Weirheight above the canalbed-56 3.5.2 Operational consequences of raising the weir 57 3.6 Flow constriction 57 3.7 Design of notch width 63 3.7.1 Hydraulic considerations 63 3.7.2 Operational/topographical considerations 63 3.7.3 Notch width per unit of water share (unit notch width) 65 3.8 Summary and conclusions 66 4 Julphe Irrigation System 69 4.1 Agro-ecological and social settings 69 4.1.1 Landscape 70 4.1.2 Land use 71 4.1.3 Farming system 71 4.1.4 Landholding and land tenure 73 4.1.5 The village and its residents 74 4.2 Historical development 75 4.2.1 Development of the physical system 75 Modification in the distribution system-lS 4.3 The physical system 79 4.3.1 Water source 79 MMO^1 , 2.^ Propositions 1. The more the island of knowledge expands in the area of ignorance, the larger its boundary to the unknown. L.S.Rodberg and V.F.Weisskop f sited by Firey (1960) 2. It is not possible for any human being to take a step forward without putting one foot firmly on the ground. Similarly, a society which tries to move ahead without keeping itself firmly rooted in its owntradition ,tend s to fall. Mahadevi Verma,cite d by Agrawal,A . andNarain , S. (1997) 3. The naturalness of natural rights to access and use of water as a resource rests on a belief that, all people, because they are people, whatever be their moral, legal, social or civil status, have a natural right towate r since water asa resourc e isanothe r way of describing the right to life. Upendra Baxi, cited byKhadka , S.S. (1996) 4. Great things aredon ewhe n men andmountain s meet;thi s isnot doneb yjostlin g inth e street. Gnomic Verses, William Blake (1757-1827). 5. So innatura l science, it isth e compositething ,th ethin ga s awhol ewhic h primarily concernsus , notjus t the materials of it,whic h areno t found apartfrom th ethin g itself. Aristotle, cited byAltier i etal. (1987 ) 6. Farmer managed irrigation systems follow the principle of proportional distribution of opportunities, benefits and risks. Thisthesi s 7. Farmer managed irrigation systems are socio-technical systems adapted to local environment. Their infrastructure do not entirely follow the standard engineering design. Besides technical considerations, the infrastructure are shaped by a number of other social, managerial and environmental factors. This thesis 8. Irrigation isa man-mad e ecological system, in whichwate r istransferre d into a location with the help of a certain technology to increase agricultural production. This thesis 9. Farmers are knowledgeable by experience. Their design of hydraulic structures conforms to the modem theory ofhydrauli c science. This thesis 10. An integration of indigenous and modern technology isessentia l in the development of irrigated agriculture to minimize the environmental degradation and unsustainable mining of natural resources. 11. Smiling faces and a cooperative attitude are the common quality of hill farmers in Nepal. They believe inth e philosophy of 'atithi debobhaba\ meaning 'guests are god'. 4.3.2 Intake 80 4.3.3 Main canal 82 4.3.4 Distribution canals 83 4.4 Water distribution structures 85 4.4.1 The proportioning weir 85 Weirheight above thecanal bed-S6; Design ofnotch width-%1; Accuracy in flow division-Si 4.5 System operation 90 4.5.1 Organizational and institutional arrangements 90 Irrigation organization-90 4.5.2 System maintenance 93 Basis ofresource mobilization-95 4.5.3 Water acquisition 96 4.5.4 Water allocation 98 Watertrading-9& 4.5.5 Water distribution 99 Water distribution for paddytransplantation at the upperend-101; Water distribution for paddy transplantation at the lower end-102; Water distributionafter the completionof paddy transplantation-103; Night irrigation andaccess tofemale-headed households-105; Water distribution through proportioning weirs-105; Operational principles across fully and partiallyproportionate areas-l1 0 4.6 Conclusions 112 5 Bachcha Irrigation System 115 5.1 Agro-ecological and social settings 115 5.1.1 Landscape 117 5.1.2 Land use 118 5.1.3 Farming system 118 5.1.4 Landholding and land tenure 120 5.1.5 The village and its residents 121 5.2 Historical development 122 5.2.1 Irrigation system 122 5.2.2 Irrigation organization 123 5.2.3 Agriculture 124 5.3 The physical system 125 5.3.1 Water source 125 5.3.2 Intakes 125 5.3.3 Main canal 126 5.3.4 Distribution canals 129 5.4 Water distribution structures 129 5.4.1 The proportioning weir 129 Location-130; Design and construction of proportioning weir-131; Proportioning weirs in the secondary canal-134; Notch width of proportioning weir-134 5.4.2 Fixed orifice inth e maincana l 134 5.4.3 Ungated turnouts inkhola khet 135 5.5 System operation 136 5.5.1 Organizational and institutional arrangements 136 5.5.2 Water acquisition 137 5.5.3 Water allocation 139 5.5.4 Water distribution 140 Water distribution byproportioning weirs-142; Timed rotation within sub- block-H5; Waterdistribution during winterand spring crops-147 5.6 Conclusions 148 6 Sankhar Irrigation System 151 6.1 Agro-ecological and social settings 151 6.1.1 Landscape 153 6.1.2 Land use 153 6.1.3 Farming system 153 6.1.4 Landholding and land tenure 155 6.1.5 The village and its residents 155 6.2 Historical development 155 6.3 The physical system 157 6.3.1 Water source 157 6.3.2 Intake 158 6.3.3 Main canal 159 6.3.4 Distribution canals 160 6.4 Water distribution structures 160 6.4.1 The proportioning weir 160 6.5 System operation 161 6.5.1 Organizational and institutional arrangements 161 6.5.2 System maintenance 162 6.5.3 Water acquisition 163 6.5.4 Water allocation 165 6.5.5 Water distribution 165 Water distribution during the monsoonseason-165;