{"id":1936,"date":"2024-07-17T15:01:09","date_gmt":"2024-07-17T09:31:09","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=1936"},"modified":"2025-07-16T15:14:10","modified_gmt":"2025-07-16T09:44:10","slug":"irrigation-efficiencies","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies","title":{"rendered":"Irrigation Efficiencies"},"content":{"rendered":"<p>Efficiency is ratio of water output to water input. If losses will be more, then efficiency will be less. Various type of irrigation efficiencies are defined below:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1942 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/irrgation-efficiencies.jpg\" alt=\"IRRIGATION EFFICIENCIES\" width=\"952\" height=\"931\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/irrgation-efficiencies.jpg 952w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/irrgation-efficiencies-300x293.jpg 300w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/irrgation-efficiencies-768x751.jpg 768w\" sizes=\"auto, (max-width: 952px) 100vw, 952px\" \/><\/p>\n<h2>Irrigation Requirements of Crops<\/h2>\n<p>Irrigation requirement of crops is the quantity of water, exclusive of rainfall, required by a crop in a given time period for their normal growth under field condition. It includes evapotranspiration not met by the rainfall. It also includes surface run off and percolation losses (these losses are unavoidable losses). Irrigation requirement of crops can be categorized under the following categories:<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_79_1 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-light-blue ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies\/#Consumptive-Irrigation-Requirement-CIR\" >Consumptive Irrigation Requirement (CIR)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies\/#Net-Irrigation-Requirement-NIR\" >Net Irrigation Requirement (NIR)<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies\/#Field-Irrigation-Requirement-FIR\" >Field Irrigation Requirement (FIR)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies\/#Gross-Irrigation-Requirement-GIR\" >Gross Irrigation Requirement (GIR)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies\/#Bed-Formation-from-Practical-Aspect\" >Bed Formation from Practical Aspect<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/irrigation-engineering\/irrigation-efficiencies\/#Comparison-of-Laceys-and-Kennedys-Theories\" >Comparison of Lacey\u2019s and Kennedy\u2019s Theories<\/a><\/li><\/ul><\/nav><\/div>\n<h3><span class=\"ez-toc-section\" id=\"Consumptive-Irrigation-Requirement-CIR\"><\/span>Consumptive Irrigation Requirement (CIR)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Consumptive irrigation requirement (CIR) is the amount of irrigation water that is required to meet the evapotranspiration (consumptive use) needs of a crop during its full growth.<\/p>\n<p style=\"text-align: center;\">CIR = <em>C<\/em><sub>u<\/sub> \u2013 <em>R<\/em><em><sub>e<\/sub><\/em><\/p>\n<p style=\"text-align: left;\">where,<\/p>\n<p style=\"text-align: center;\"><em>C<\/em><em><sub>u<\/sub> <\/em>= Consumptive use of water<\/p>\n<p style=\"text-align: center;\"><em>R<\/em><em><sub>e<\/sub> <\/em>= Effective rainfall during growth period of crop<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Net-Irrigation-Requirement-NIR\"><\/span>Net Irrigation Requirement (NIR)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Net irrigation requirement (NIR) is the amount of irrigation water required to be delivered at the field to meet the evapotranspiration needs of crop as well as other needs like leaching, presowing requirements etc.<\/p>\n<p style=\"text-align: center;\">NIR = CIR + LR + PSR<\/p>\n<p style=\"text-align: left;\">where,<\/p>\n<p style=\"text-align: center;\">LR = Leaching requirement<\/p>\n<p style=\"text-align: center;\">PSR = Presowing requirement<\/p>\n<h4><span class=\"ez-toc-section\" id=\"Field-Irrigation-Requirement-FIR\"><\/span>Field Irrigation Requirement (FIR)<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>Field irrigation requirement is the amount of water required to meet the NIR plus the amount of water lost as surface runoff and deep percolation.<\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center;\">FIR =NIR\/n<sub>a<\/sub><\/p>\n<p style=\"text-align: left;\">where,<\/p>\n<p style=\"text-align: center;\">n<em><sub>a<\/sub><\/em><em>\u00a0<\/em>= Water application efficiency<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Gross-Irrigation-Requirement-GIR\"><\/span>Gross Irrigation Requirement (GIR)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Gross irrigation requirement is the amount of water required to meet the FIR plus the amount of irrigation water lost in conveyance through canal system by evaporation and seepage.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Bed-Formation-from-Practical-Aspect\"><\/span>Bed Formation from Practical Aspect<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Bed of channel can attain various shapes depending upon velocity of water or discharge. When the velocity of flow is very less, then there is movement of particles on channel. Depending upon the velocity, channel can be in any shape as discussed below:<\/p>\n<p>When velocity is gradually increased, then a stage comes when particles just start to move. It is known as threshold stage as discussed earlier. When velocity is further increased, bed develops ripples of saw-tooth type like in sand of any beach.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1946 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/saw-tooth-ripples.jpg\" alt=\" Saw tooth ripples\" width=\"451\" height=\"218\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/saw-tooth-ripples.jpg 451w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/saw-tooth-ripples-300x145.jpg 300w\" sizes=\"auto, (max-width: 451px) 100vw, 451px\" \/><\/p>\n<p>If the velocity starts increasing further, large periodic irregularities known as Dunes are developed on bed. During their first appearance, ripples are also superimposed on them.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1948 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/dunes-with-ripples.jpg\" alt=\"Dunes with ripples\" width=\"444\" height=\"219\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/dunes-with-ripples.jpg 444w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/dunes-with-ripples-300x148.jpg 300w\" sizes=\"auto, (max-width: 444px) 100vw, 444px\" \/><\/p>\n<p>Now, if velocity is further increased, then only dunes are left on bed without ripples. It is to be noted that flow remains sub-critical till this stage.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1949 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/dunes.jpg\" alt=\"Dunes\" width=\"433\" height=\"225\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/dunes.jpg 433w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/dunes-300x156.jpg 300w\" sizes=\"auto, (max-width: 433px) 100vw, 433px\" \/><\/p>\n<p>Further, increase in velocity, erases the dunes on bed leaving virtually a flat surface with sediment particle in motion.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1950 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/Flat-surface.jpg\" alt=\"Flat surface\" width=\"455\" height=\"244\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/Flat-surface.jpg 455w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/Flat-surface-300x161.jpg 300w\" sizes=\"auto, (max-width: 455px) 100vw, 455px\" \/><\/p>\n<p>In next stage, increase in velocity results in formation of sand waves along with surface waves.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1952 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/sand-waves-in-association-with-surface-waves.jpg\" alt=\"Sand waves in association with surface waves\" width=\"437\" height=\"232\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/sand-waves-in-association-with-surface-waves.jpg 437w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/sand-waves-in-association-with-surface-waves-300x159.jpg 300w\" sizes=\"auto, (max-width: 437px) 100vw, 437px\" \/><\/p>\n<p>Further increase in velocity makes the flow super-critical from sub-critical and Froude number exceeds unity.<br \/>\nSurface waves becomes so steep that they break intermittently and move upstream while sediment particles moves in downstream direction. These waves are then known as anti-dunes.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1954 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/07\/Antidunes.jpg\" alt=\"Antidunes\" width=\"488\" height=\"233\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/Antidunes.jpg 488w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/07\/Antidunes-300x143.jpg 300w\" sizes=\"auto, (max-width: 488px) 100vw, 488px\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Comparison-of-Laceys-and-Kennedys-Theories\"><\/span>Comparison of Lacey\u2019s and Kennedy\u2019s Theories<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<table class=\"table table-striped table-bordered table-condensed\" style=\"margin: 0 auto; width: 99%;\">\n<tbody>\n<tr>\n<th width=\"416\">Lacey&#8217;s theory<\/th>\n<th width=\"392\">Kennedy&#8217;s theory<\/th>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">1. Only one regime section for given discharge and silt factor.<\/td>\n<td style=\"text-align: center;\" width=\"392\">There can be as many sections for the given discharge.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">2. Did not leave silt grade as guess work but correlated silt factor <em>f <\/em>to diameter of silt and rugosity coefficient.<\/td>\n<td style=\"text-align: center;\" width=\"392\">Simply stated CVR varied according to the silt grade but did not give any method to measure CVR.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">3. Discarded arbitrary factors and gave general regime equation independent of rugosity coefficient, viz.<\/p>\n<p><em>V<\/em> = 10.8 <em>R<\/em> <sup>2\/3<\/sup><em>S<\/em><sup>1\/3<\/sup><\/td>\n<td style=\"text-align: center;\" width=\"392\">Gave no equation for regime velocity. Adoption of Kutter&#8217;s N and Chezy equation to work out mean velocity incorporated the limitations of those relations.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">4. Considered hydraulic mean depth <em>R <\/em>as relevant variable and derive velocity formula in terms of <em>R <\/em>:<\/td>\n<td style=\"text-align: center;\" width=\"392\">Considered depth as variable and gave critical velocity formula in terms of depth <em>D<\/em>.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\"><em>V<\/em> = 0.639 (<em>fR<\/em>)<sup>1\/2<\/sup><\/td>\n<td width=\"392\">\n<p style=\"text-align: center;\"><em>V<sub>0 <\/sub><\/em>= 0.55 <em>mD<\/em><sup>0.64<\/sup>.<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">5. Specified regime slope for the given discharge and silt factor<\/td>\n<td style=\"text-align: center;\" width=\"392\">Did not specify regime slope.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">6. Silt is kept in suspension by vertical components of eddies caused by friction against wetted perimeter.<\/td>\n<td style=\"text-align: center;\" width=\"392\">Eddies rise on account of roughness of bed and work up against depth. The eddies generated from sides are ignored.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">7. Considered channel section semi-elliptical.<\/td>\n<td style=\"text-align: center;\" width=\"392\">Considered channel section trapezoidal.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">8. Section is wider and shallower.<\/td>\n<td style=\"text-align: center;\" width=\"392\">Section is tighter and deeper.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">9. Considered that channels cannot be in true regime and classified them into initial and final regime.<\/td>\n<td style=\"text-align: center;\" width=\"392\">Considered all channels in regime when they neither silt nor scour.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: center;\" width=\"416\">10. Applicable to irrigation channels and rivers as well.<\/td>\n<td style=\"text-align: center;\" width=\"392\">Applicable to irrigation channels only.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: center;\"><a class=\"btn btn-danger\" role=\"button\" href=\"https:\/\/study.madeeasy.in\/ce\/irrigation-engineering\/intensity-of-irrigation-seasonal-and-annual\/\" target=\"_blank\" rel=\"noopener\">&lt;&lt; Previous<\/a> | <a class=\"btn btn-success\" role=\"button\" href=\"https:\/\/study.madeeasy.in\/ce\/irrigation-engineering\/canal-lining\/\" target=\"_blank\" rel=\"noopener\"> Next &gt;&gt;<\/a><br \/>\n<strong> Must Read: <\/strong> <a href=\"https:\/\/study.madeeasy.in\/subjects\/what-is-irrigation-engineering\/\" target=\"_blank\" rel=\"noopener\"><strong>What is Irrigation Engineering?<\/strong><\/a><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Efficiency is ratio of water output to water input. If losses will be more, then efficiency will be less. Various<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[510,2],"tags":[537,536,539,538,535,541,540,534],"class_list":["post-1936","post","type-post","status-publish","format-standard","hentry","category-irrigation-engineering","category-ce","tag-cir","tag-consumptive-irrigation-requirement","tag-gir","tag-gross-irrigation-requirement","tag-irrigation-requirements-of-crops","tag-kennedys-theory","tag-laceys-theory","tag-various-type-of-irrigation-efficiencies"],"_links":{"self":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/1936","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/comments?post=1936"}],"version-history":[{"count":0,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/1936\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/media?parent=1936"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/categories?post=1936"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/tags?post=1936"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}