If the intensity of rainfall is more than the infiltration capacity of soil, then the infiltration rate will be
Cyclonic precipitation is caused by lifting of an air mass due to
Precipitation is general term for all forms of moisture emanating from the clouds and falling to the ground. Types of precipitation 1. Cyclonic precipitation: - lifting of air masses converging into low Pressure area or cyclone. 2. Convective precipitation: - Temperature difference may result from unequal heating at the surface, unequal cooling at the top of the air layer. 3. Orographic precipitation: - Due to natural topographical barriers such as mountains.
Which of the following is a non-recording raingauge
Raingauge:- A device for collecting and measuring the amount of rain which falls. 1. Non recording raingauge: - a) Simon’s raingauge 2. Recording raingauge: - a) Weighing bucket raingauge b) Tipping bucket raingauge c) Float type raingauge
A raingauge should be preferably be fixed
Selection the site for a raingauge station. 1. The site where a raingauge is setup should be an open place. 2. Distance between the raingauge and nearest object should be at least twice the height of the object. 3. The raingauge should never be situated on the side or top of a hill if the suitable site on the level ground can be found. 4. In The Hills situated where wind does not cause eddies. 5. Protect the gauge from cattle etc.
If allowable percentage error in the estimate of basic rainfall is E and coefficient of variation of rainfall is C, then the optimum number of raingauge is given by
Which of the following types of raingauge is used for measuring rain in remote hilly inaccessible areas
Rate of evaporation from a water surface increases if i) difference of vapour pressure between water and air is increased ii) velocity of wind is decreased iii) concentration of soluble solids in water is decreased. The correct answer is
Factors affecting the evaporation are 1. Temperature: - ↑ 2. Surface area: - ↑ 3. Density: - ↓ 4. Wind velocity: - ↑
A 70% index of wetness means
Under the same conditions, which of the following shapes of water surface will give the highest rate of evaporation
Assertion A: To estimate the rainfall over a catchment, the number of raingauge required per unit area is large for hilly areas Reason R: Rainfall gradient system Select your correct answer according to the coding system given below
World Meteorological Organisation (WMO) follows: For plain areas of the basin 1 rain-gauge for every 500 km2 . For hilly areas of the basin: 1 rain-gauge for every 150 km2
When surface of transpiration is submerged under water, then potential evapotranspiration is
Evaporation:- The water from the surface of ocean, rivers, lakes and also from moist soil evaporates. Transpiration:-Is the process of water being lost from the leaves of the plants. Evapotranspiration= Evaporation + Transpiration Potential evapotranspiration (PET):- Is defined as the amount of evaporation that would occur if a sufficient water source were available.
coefficient of variation
The coefficient of variation represents the ratio of the standard deviation to the mean. It is a useful for comparing the degree of variation from one data series to another.
Unit of runoff in M.K.S. System is
Runoffwould be expressed in the same units as stream flow, cubic meter per second
The runoff Increases with
Runoff → The part of the water cycle that flows over land. 1. Amount of Rainfall:- The amount of rainfall directly affects the amount of runoff. As expected, if more rainfall hits the ground, more rainfall will turn into runoff. 2. Permeability: - The ability of the ground surface to absorb water will affect how much surface runoff occurs. The less water the ground can absorb, the more runoff on the surface there will be. 3. Vegetation: - Vegetation needs water to survive, and a plant's root system is designed to absorb water from the soil. There is less runoff in highly vegetated areas. 4. Slope: - The steeper a surface is, the faster it will flow down the slope. A flat surface will allow the water time to absorb
The area between the isohyets 45 cm and 55 cm is 100 square km and between 55 cm and 65 cm is 150 square km. The average depth of annual precipitation over the basin of 250 square km will be
Isohyet :- A line on a map or chart connecting areas of equal rainfall. Isohyteal method = (P1A1+P2A2)/total area = [ 100(45+55)/2+150(55+65)/2 ]/(100+150) = 56 cm
A current metre is used to measure the
Current meter → Instrument for measuring the velocity of flow of a fluid (Water) in a stream.
If it rains between 2 p.m. And 3 p.m. And the entire basin are just starts contributing water at 3:00 p.m. To the outlet, then time of concentration will be
Time of Concentration:- Time taken by rain water that falls at the farthest point to reach the outlet of a catchment
The rainfall on five successive days were measured as 100 mm, 80 mm, 60 mm, 40 mm and 20 mm respectively. If the infiltration index or the storm loss rate for the catchment area is earlier estimated is 50 mm/day, the total surface runoff will be
Addition of more than phie index is equal to total surface runoff. Here phie index is 50 then more than phie is (100-50)+(80-50)+(60-50) = 90 mm
The normal annual precipitation at stations X, A, B and C are 700 mm, 1000 mm, 900 mm and 800 mm respectively. If the storm precipitation at three station A, B and C were 100 mm, 90 mm and 80 mm respectively, then the storm precipitation for station X will be
P/700 = 1/3(100/1000+90/900+80/800) = P = 70 mm
The best unit duration of storm for a unit hydrograph
Unit hydrograph is a direct runoff hydrograph resulting from one unit (one inch or one cm) of constant intensity uniform rainfall occurring over the entire watershed/basin/catchment. The concept of unit hydrograph is based on linear systems theory and follow the principles of superposition and proportionality. Experience has shown that the best unit duration is about onefourth of the basin lag, the time from the centre of mass of rainfall to the peak of the hydrograph
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