1. Preliminary Remarks 96 2. Gauges and Regulators 103 3. Gauge Readings and Discharges 106 4. Registers of Irrigation and Outlets 113 5. Distribution of Supply 118 6. Extensions and Remodellings 127 7. Remodelling of Outlets 131 8. Miscellaneous Items 137 CHAPTER IV THE PUNJAB TRIPLE CANAL PROJECT 1. General Description 144 2. Areas and Discharges 147 3. Remarks 156 CHAPTER V PROPOSED IMPROVEMENTS IN IRRIGATION CANALS 1. Preliminary Remarks 158 2. Reduction of Losses in the Channels 159 3. Modules 162 APPENDICES A. Divide Wall on Lower Chenab Canal 169 B. Specification for Maintenance of Channels 171 C. Specification for Maintenance of Masonry Works 174 D. Watching and Protecting Banks and Embankments 175 E. Specification for Bushing 178 F. Escapes 180 G. Gauges 183 H. Gibb’s Module 186 K. Kennedy’s Gauge Outlet 193 INDEX 196 PREFACE When _River and Canal Engineering_ was written it was decided to omit Irrigation works and to deal with them separately because the subject interests chiefly specialists. The present book deals with the principles which govern the design and management of Irrigation works, and it discusses the Canals of Northern India--the largest and best in the world--in detail. Some years ago a number of rules for designing distributaries were framed, at the request of the Punjab Government, by the late Colonel S. L. Jacob, C.I.E., R.E., and comments on these rules were obtained from many experienced engineers and recorded. The author has had the advantage of reading all these opinions. Generally the weight of opinion on any point agrees with what most experienced engineers would suggest, and direct conflicts of opinion scarcely occur. Important papers have been printed by the Punjab Irrigation Branch on Losses of Water and the Design of Distributaries, on the great Triple Canal Project, on Gibb’s Module, on Kennedy’s Gauge Outlet, and on the Lining of Watercourses. These papers are not always accessible to engineers, and the chief points of interest in them are not, in most cases, discernible at a glance. Such points have been extracted and are given in this book. E. S. B. CHELTENHAM, _May_ 20_th_, 1913. IRRIGATION WORKS. CHAPTER I. INTRODUCTION