In this blog I will be discussing on how to prepare for Irrigation Engineering. This subject contains very few & small chapters and most of the questions asked can be easily answered if you focus on these chapters.
A rough breakup of questions of various chapters in last 30 years in GATE is as follows:
|Sl No||Topic||No. of Questions|
|1 mark||2 marks||5 marks|
|1||Water Requirement of Crops||8||15||2|
|2||Gravity Dams and Spillways||3||1||1|
|4||Design of Unlined & Lined Canals||4||–||4|
|5||Cross Drainage Works & Canal Regulation Works||–||1||–|
If we check the last 5 years GATE papers, we can see that Hydrology and Irrigation Engineering together carry 6-9 marks.
Time Required for Preparation (for Irrigation)
7 days (if you have 8-10 months of preparation) with 4 hours daily
3-4 days (if you have 4-5 months of preparation) with 7-8 hours daily
In this blog I will be dealing with Irrigation and hydraulic structures (Hydrology is discussed in a separate BLOG-7). Try to maintain a formula sheet as there will many empirical formulas also. The textbook(s) to be referred are mentioned in BLOG-3 which you can utilize.
WATER REQUIREMENT OF CROPS (2 DAYS) : This is the most important topic from which a numerical question (even NAT type) is frequently asked in many forms.
GRAVITY DAMS AND SPILLWAYS (1 DAY) : Design of dam is itself a very big topic. But concepts important for GATE are forces acting on gravity dams, modes of failures (crushing, overturning, tension and sliding) & their factors of safety, principle stresses. Practice 2-3 numerical questions in full length related to these topics.
DIVERSION HEADWORKS (1 DAY) : Different types of diversion head works (weirs in detail), Creep theories (Bligh’s, Lanes), Khosla’s theory are important. Practice numerical questions related to creep coefficients, uplift pressure heads.
DESIGN OF UNLINED & LINED CANALS (1-2 DAYS) : This is another very important topic, both from theoretical and numerical point of view. Kennedy’s theory and Lacey’s theory are important; understand the basic difference/comparison (true, initial & final regime) b/w the two from theoretical point of view. They both use their own set of formulas for design, which are complicated but, unfortunately, you have to remember. Formula sheet! Practice 2 numericals for each theory.
In lined canals, just understand mechanics of sediment transport (tractive τo=γRS), Shield’s formula for non-scouring/no erosion of side banks (critical τc=γd/11) & stability of bed (τo<τc OR d>11RS). You can practice these numericals while giving test-series directly.
CROSS DRAINAGE WORKS & CANAL REGULATION WORKS (1 DAY) : In depth study of these chapters are not needed, read once. However give importance to canal modules.