LABORATORY AND FIELD MANUALON

IRRIGATION ENGINEERING

— Ground Water Manual a Water Resources

— Greenhouse Engineering R.A. Aldrich

Technical Publication USDI

— Handbook on Pressurized Irrigation Techniques 2nd Ed A. Phocaides

— Irrigation Resources S.B. Verma

— Krishi Jagat: JET Evam Krishi Paryavekshak Pariksha Upoagi (Hindi) M.L. Jat

— Pesticide Application Equipment for Use in Agriculture (Vol. 1) G.A. Matthews

— Principles of Agricultural Meteorology B.M. Mote

— Quinoa (Chenopodium Quinoa Willd) Dharm Singh

— Rainfed Farming Development in Central India G.P. Verma

— Rainwater Management Theory and Practice M.L. Jat

— Remote Sensing and GIS Applications: A Starter Guide D.C. Joshi

— Remote Sensing: Principles and Applications 2nd Ed A.N. Patel

— Soil Conservation 3rd Ed N.W. Hudson

— Soil Conservation Technical Handbook D.H. Hicks

— Spice Crops Production Technology P.C. Das

— Theory, Construction and Calculation Agricultural Machines (Vol. 1) E.S. Boson

— Theory, Construction and Calculation Agricultural Machines (Vol. 2) E.S. Boson

— Trikle Irrigation Design David Karmeli

— Water Measurement Manual 3rd Ed USDI

— Food Crops: Evolution, Diversity and Advances D.A. Patil

— Farm Mechanization for Production Dhirendra Khare

— Dryland Technology 2nd Ed M.L. Jat

— Drought Proofing and Water Resource Management T.S. Chouhan

— Drought Mitigation and Management Suresh Kumar

— Drainage Engineering: Principles and Practices S.K. Gupta

— Drainage Engineering J.N. Luthin

— Chemistry of the Soil 2nd Ed F.E. Bear

— Beverages: Processing and Technology Deepak Mudgil

— Basic Statistics 2nd Ed P.K. Mohanty

— Agricultural Drainage Engineering H.V. Parmar

— A Manual on Conservation of Soil and Water USDA

— A Handbook of Laboratory Solutions M.H. Gabb

— Fundamentals of Agriculture 2nd Ed. (Vol. 1-2) (set) R.L. Arya

Related Books

Titles Authors

LABORATORY AND FIELD MANUALON

IRRIGATION ENGINEERING

R. J. PatelAssistant Professor

© 2020, Author & Publisher

ISBN: 978-93-89184-21-1eISBN: 978-93-89184-23-5

Printed in India

All rights reserved. No part of this publication or the information contained herein may be reproduced, adapted, abridged, translated, stored in a retrieval system, computer system, photographic or other systems or transmitted in any form or by any means, electronic, mechanical, optical, digital, by photocopying, recording or otherwise, without written prior permission from the publisher. Any breach will attract legal action and prosecution without further notice.

This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the editors and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The editors and publisher have attempted to trace and acknowledge the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission and acknowledgement to publish in this form have not been obtained. If any copyright material has not been acknowledged please write and let us know so that we may rectify it.

Trademark Notice: Publications or corporate names may be trademarks, and are usedonly for identification and explanation in bonafide intent without intent to infringe.

Disclaimer: While every effort has been made to avoid errors and omissions, this publication is being sold and marketed on the understanding and presumption that neither the editors (or authors) nor the publishers nor the printers would be liable in any manner whatsoever, to any person either for an error or for an omission in this publication, or for any action to be taken on the basis of this work. Any inadvertent discrepancy noted may be brought to the attention of the publisher, for rectifying it in future editions, if published.

Published by SCIENTIFIC PUBLISHERS (INDIA) 5 A, New Pali Road, P.O. Box 91 Jodhpur 342 001 (INDIA) E-mail: info@scientificpub.com Website: www.scientificpub.com

Dr. H. D. Rank Professor and Head Soil and Water Engineering Department College of Agricultural Engineering and Technology Junagadh Agricultural University Junagadh - 362001 (GUJARAT) Phone : +91 0285 2672081-90 (Ext 478) : +91 0285 2670068 Fax No. : +91 0285 2671018 Email : swe@jau.in

FOREWORD

With the increasing population, the demand of water for domestic and other sectors is escalating and the efficient use of irrigation water would play a significant role in meeting the ever growing demand for food, fuel, fodder, etc. in the country. Any mismanagement of the precious irrigation water is leading to low irrigation efficiency and degradation of our highly productive lands due to salinization and water logging. Hence, it is the need of hour to take up scientific methodology of irrigation water management based on individual farm needs.

Therefore, a comprehensive knowledge of available soil moisture and its constants, scheduling of irrigation and evaluation of various irrigation methods with proper techniques is crucial. This manual on irrigation engineering is an attempt to fulfill this urgent need as it covers all major aspects of irrigation water management. This manual would be of immense help for the students of under-graduate and post-graduate students as well as scientific community and field functionaries.

I congratulate Dr. R. J. Patel for bringing out this important document. The efforts made by him for compilation of information of the crucial aspect of ‘Irrigation Engineering’ are commendable.

H. D. Rank

PREFACE

The irrigation water is considered as the essential input for crop production. In India, over exploitation of natural water resources has caused a menace for the future human generations. The depletion of underground water table in high productivity areas and under utilization of the water resources in rain fed areas of the country, poor irrigation efficiency and high seepage losses from conveyance system, poor land development and mismanagement of the irrigation water resources has acquired alarming proportions. As the share of water for agriculture in future is going to reduce, there will be tremendous pressure to produce more per drop of water in order to meet the food and other requirements of burgeoning population of the country. The existing irrigation water resources are not utilized judiciously and their mismanagement has lead to problems like low production efficiency, salinization, water logging and degradation of land. To manage these problems and increase the production efficiency of irrigation, it is pertinent to adopt judicious methods of irrigation water use, by efficient on-farm irrigation management based on scientific approach. Therefore, a comprehensive knowledge of available soil moisture and its constants, scheduling and quality of irrigation water and proper drainage techniques is crucial. This manual on irrigation engineering is an attempt to fulfil this urgent need as it covers all major aspects of irrigation water management. Although, manual is meant primarily for the students of agricultural universities, yet it will provide valuable basic information and guide to the scientific community and field functionaries.

I am very grateful to honourable Vice-Chancellor Dr. A. R. Pathak for motivating to bring out this publication. I am highly thankful to Dr. N. K. Gontia, Principal and Dean, College of Agricultural Engineering and Technology, Junagadh Agricultural University, Junagadh for his ever encouraging attitude. I am also obliged to Dr. H. D. Rank, Professor and Head, Soil and Water Engineering Department for his precious advice and all possible

(viii)  Laboratory and Field Manual on Irrigation Engineering

help. My sincere thanks are due to Dr. H. R. Vadar for his valuable suggestions and all possible help in proof reading and finalizing the manuscript. I am also appreciative to Dr. H. V. Parmar, Prof. P. B. Vekariya, Prof. H. H. Mashru, Dr. J. M. Modhvadia, Prof. K. C. Patel, Dr. G. V. Prajapati, Prof. P. A. Pandya, P. J. Bagada, H. N. Dalsaniya, J. H. Kelaiya and D. K. Dwivedi for their kind help.

I am deeply indebted to the authors of various books, pamphlets and manuals for getting useful information for inclusion in this manuscript. R. J. Patel

CONTENTS

1. Measurement of Soil Moisture Content 1–46 1.1 Determination of soil moisture content using gravimetric

method 2

1.2 Determination of the soil moisture using tensiometer. 3

1.3 Determination of soil moisture content by electrical resistance block (Gypsum block) 7

1.4 Determination of soil moisture content using pycnometer method 10

1.5 Determination of soil moisture content using sand bath method. 12

1.6 Determination of soil moisture content using alcohol method 14

1.7 Determination of soil moisture content using calcium carbide method 16

1.8 Determination of soil moisture content using torsion balance method 17

1.9 Determination of soil moisture content using dielectric method 19

1.10 Determination of soil moisture content using heat dissipation sensor 20

1.11 Determination of soil moisture content using Frequency Domain Reflectometry 21

1.12 Determination of soil moisture content using Time Domain Reflectometry 24

1.13 Determination of soil moisture content by Amplitude Domain Reflectometry 26

(x)  Laboratory and Field Manual on Irrigation Engineering

1.14 Determination of soil moisture content using phase transmission 26

1.15 Determination of soil moisture content using neutron probe 28

1.16 Determination of soil moisture content using soil psychrometer 36

1.17 Determination of soil moisture content using Time Domain Transmission (TDT) 38

1.18 Determination of soil moisture content using capacitance probe 38

1.19 Determination of soil moisture content using Gamma-ray absorption method 39

1.20 Determination of soil moisture content using microwave method 41

1.21 Determination of soil moisture content using nuclear magnetic resonance method 43

1.22 Determination of soil moisture content using nuclear soil moisture characteristic curve 45

1.23 Determination of soil moisture content using optical methods 46

2. Measurement of Irrigation Water 47–80 2.1 Measurement of irrigation water by volumetric

measurement method 48

2.2 Measurement of irrigation water by velocity area method 50

2.3 Measurement of irrigation water by current meter (velocity area) method 52

2.4 Measurement of irrigation water by pipe method 56

2.5 Measurement of irrigation water by orifices 59

2.6 Measurement of irrigation water by venturimeter. 60

2.7 Measurement of irrigation water by water meter method 63

2.8 Measurement of irrigation water by weirs. 68

Contents (xi)

2.9 Measurement of irrigation water by flumes. 71

2.10 Measurement of irrigation water by tracer methods 76

3. Measurement of Infiltration Characteristics of Soil 81–86

4. Determination of Dry Bulk Density, Field Capacity and Permanent Wilting Point 87–96 4.1 Dry bulk density 87

4.2 Determination of field capacity 90

4.3 Determination of permanent wilting point 92

5. Land Grading Methods 97–110

6. Design of Underground Pipeline System 111–120

7. Estimation of Evapotranspiration 121–174 7.1 Computation of evaporation 123

7.2 Computation of transpiration 140

7.3 Measurement of evapotranspiration 145

7.4 Estimation of evapotranspiration 151

8. Estimation of Irrigation Efficiencies 175–184 9. Infiltration by Inflow-Outflow Method 185–186 10. Evaluation of Surface Irrigation Methods 87–206 10.1 Evaluation of border irrigation method 188

10.2 Evaluation of furrow irrigation method 192

10.3 Evaluation of check basin irrigation method 198

Chapter 1

Measurement of Soil Moisture Content

Soil is a heterogeneous mass and consists of three phases, viz., solid, liquid and gaseous phase. Soil is a porous medium, and serves as a water reservoir or bank. Water is retained by a soil particle in the form of a thin film around it, and in the numerous small pores of the soil matrix with forces, such as surface tension capillarity, cohesion and adhesion.

Importance of Soil Water• Soil water serves as a solvent and carrier of food nutrients

for plant growth.

• Yield of crop is more often determined by the amount of water available rather than the deficiency of other food nutrients.

• Soil water regulates soil temperature.

• Soil forming processes and weathering depend on water.

• Microorganisms require water for their metabolic activities.

• Soil water helps in chemical and biological activities of soil.

Soil is the source of water for the plants, which is always present in a dynamic state. A soil profile holds water on its surface in a form of thin film with a certain force. Pore space, which is the space in between soil particles, contains both air and water in varying proportions. Soil moisture is expressed as percentage on oven dry basis either on weight basis, volume basis or depth basis. Moisture percentage is generally expressed on weight basis, unless stated otherwise. Determination of soil moisture content is needed to help in the estimation of i) available water in the root

2  Laboratory and Field Manual on Irrigation Engineering

zone, ii) scheduling of irrigation, iii) soil water potential and iv) changes in physical and chemical properties of soil due to changes in water content.

1.1 DetermInatIon of SoIl moISture content uS-Ing gravImetrIc methoD

Objective: To determine the moisture content of a soil sample in the laboratory using gravimetric method.

Definition: The water content, also called moisture content is defined as the ratio of weight of water to the weight of solids.

Apparatus: Soil auger, moisture boxes, weighing balance, drying oven with thermostat.

Procedure:1. Weigh the moisture box along with lid (W

3).

2. Collect the soil sample from the desired soil depth withthe help of auger and record the weight of moist soil andcontainer along with lid (W

1).

3. Allow the soil sample to dry in the oven for 24 hours ata constant temperature of 105 °C to attain a constant dryweight.

4. Weigh the dried soil sample along with the container and lidafter cooling (W

2).

5. Repeat the above procedure at least for five soil samplescollected from various depth of soil profile.

Observations:1. Sample No. = ____________

2. Weight of moist soil and container along with lid W1 g =

____________

3. Weight of dry soil and container along with lid W2 g =

____________

4. Weight of container along with lid W3 g = ____________

Calculations:1. Weight of moist soil sample = (W

1 – W

3) g = ____________

2. Weight of dried soil sample = (W2 – W

3) g = ____________