Isohyetal Method

Q. The area between the two isohyetes 45 cm and 55 cm is $100{\text{km}}^2$ and that between 55 cm and 65 cm is $150{\text{km}}^2$. What is the average depth of annual precipitation over the basin of $250{\text{km}}^2$

1. 50 cm
2. 52 cm
3. 56 cm
4. 60 cm

Q. An accurate estimate of average rainfall in a particular catchment area can be obtained by

1. arithmetic mean method
2. isohyetal method
3. normal ratio method
4. Thiessen method

Q. An isohyet is a line joining points of

1. equal temperature
2. equal humidity
3. equal rainfall depth
4. equal evaporation

Q. The area enclosed by the adjacent isohyets of a catchment basin are

Isohyets (in cm)	30-40	40-50	50-60	60-70	70-80
Area (in $k{m}^2$)	150	250	300	200	100

The average depth of annual rainfall in the basin would be________mm.

1. 0.535
2. 5.35
3. 53.5
4. 535

Q. Mean precipitation over an area is best obtained from gauged amounts by

1. arithmetic mean method
2. Thiessen method
3. linearly interpolated isohyetal method
4. orographically weighted isohyetal method

Q. The equivalent uniform rainfall depth of the catchment as shown in figure is _____ mm.

1. 103.85

Q. For a large catchment, contours joining points of equal monthly rainfall values were plotted.
The plot is known as:

1. Isohyetal map
2. Mass curve
3. Isobar map
4. Thiessen polygon