Skip to main content

GATE 2014, PSUs- irrigation Engineering - one liners - part 11

Hello there,

Here is the 11th part of our notes for the preparation of the GATE and PSUs exams.

  • Fertility of a soil is adversely affected, when the pH value is more than 11.
  • Optimum depth of kor watering for rice crop is nearly 19 cm.
  • Average delta of rice crop is nearly 120 cm.
  • The duty of a crop is 432 hectares/cumec, when base period of the crop is 100 days. Delta for the crop will be 200.
  • Water consumed in irrigation, when compared with the total water used for all purposes in our country, is about 90%.
  • Water consumed for producing one tonne of wheat and one tonne of rice will be of order 2000 tonnes and 4000 tonnes.
  • Lime concrete lining is used when velocity of flow is below 2 m/sec, irrigation channel with capacity upto 200 cumec and where economy is required.
  • Thickness of concrete lining, for discharge upto 200 cumec varies from 10 to 15 cm.
  • Force considered for the analysis of an elementary profile of a gravity dam under empty reservoir condition is self weight.
  • Uplift pressure on a dam can be controlled by pressure grouting in foundation, constructing drainage channels between dam and its foundation and by constructing cut-off under upstream face.
  • In a gravity dam total force due to wave pressure acts at a height of 0.375.hw above the still water level.
  • Horizontal acceleration due to earthquake results in hydro-dynamic pressure and inertia force in the body of the dam.
  • Vertical acceleration due to earthquake results in increase in the effective weight of the dam and also decrease in the effective weight of the dam.
  • In the elementary profile of a dam having empty reservoir condition, vertical stress at heels and toe are respectively given by 2W/B and 0.
  • In gravity dam, main overturning force is water pressure.
  • For economical design of a gravity dam, shear friction factor should be 0.65.
  • In Ogee shaped spillway, discharge is proportional to H^(3/2).
  • Garrets diagrams are based on Kennedy's theory.
  • Discharge co-efficient of an Ogee-shaped spillway is 3.7.
Thanks for visit!

Popular posts from this blog

Comparison of Kennedy's and Lacey's Theories


Here is a brief comparison of Kennedy's theory and Lacey's theory for the design of channels for canal etc.

The concept of silt transportation is same in both the cases, both agree that the silt is carried by the vertical eddies generated due to friction of the flowing water against rough surface of canal. Kennedy considered a trapezoidal channel section and, therefore, he neglected eddies generated from the sides. For this reason, Kennedy's critical velocity formula was derived only in terms of depth of flow(y).  Lacey considered that an irrigation channel achieves a cup-shaped section(semi-ellipse) and that entire wetted perimeter of the channel contributes to the generation of silt supporting eddies. He, thus, used hydraulic mean radius(R) as a variable in his regime velocity formulas instead of depth(y).Kennedy stated all the channels to be in state of regime provided they did not silt or scour. But Lacey differentiated between two regime conditions, i.e. initia…

GATE, PSUs - Hydraulics, Irrigation, water resource Engg. notes - part 7

Hello there,
How have you been? Here is the 7th part of our notes for preparation of GATE and other examinations related to Civil Engineering.

As compared to gravity dams, earthen dams requires less skilled labor.The most suitable material for the central impervious core of a zoned embankment type dam is clay mixed with fine sand.Seepage through embankments in the earthen dam is controlled by drain trenches.Seepage through foundation in an earthen dam is controlled by providing impervious cut-off.The flow of water after spilling over the weir crest in chute spillway and side channel spillway respectively are at right angle and parallel to weir crest.The discharge passing over an Ogee spillway is given by CLH^(3/2) where, L is the effective length of spillway crest and H is the total head over the spillway crest including velocity head.Co-efficient of discharge of an Ogee spillway depends on depth of approach and upstream slop and also on downstream apron interference and downstream su…

GATE questions from Hydrology - GATE PSUs preparation -part 10

Here are few statements from Hydrology which has made their place in GATE Civil Engineering(CE). The bold letter represents the answer which are absent in actual question.

A linear reservoir is one in which storage varies linearly with outflow rate.When there is an increase in the atmospheric pressure, the water level in a well penetrating in a confined aquifer does not undergo any change.During a 6-hour storm, rainfall intensity was 0.8 cm/hour on a catchment of area 8.6 km^2. The measured runoff volume during this period was 2,56,000 m^3. The total rainfall that was lost due to infiltration, evaporation, and transpiration (in cm/hour) is 0.304.Vertical hydraulic conductivity of the top soil at certain is 0.2 cm/hr. A storm of intensity 0.5 cm/hr occurs over the soil for an indefinite period. Assuming surface drainage to be adequate, infiltration rate after the storm has lasted for a very long time, shall be 0.2 cm/hr.While applying Rational formula for computing design discharge, …