An accurate estimate of average rainfall in aparticular catchment area can be obtained bya)arithmetic mean methodb)isohyetal methodc)normal ratio methodd)THIESSEN methodCorrect answer is option 'B'. Can you explain this answer?

Question

Answer

Explanation:
The isohyetal method is used to estimate the average rainfall in a particular catchment area. This method involves the following steps:

1. Dividing the catchment area into sub-areas: The catchment area is divided into sub-areas based on the topography, rainfall patterns, and other factors that can affect the rainfall distribution.

2. Collecting rainfall data: Rainfall data is collected from rain gauges located within each sub-area. The data is recorded at regular intervals, such as daily or hourly.

3. Plotting isohyetal lines: Isohyetal lines are plotted on a map of the catchment area based on the rainfall data collected from the rain gauges. These lines connect points of equal rainfall intensity. The distance between the lines represents the change in rainfall intensity.

4. Calculating average rainfall: The average rainfall for the catchment area is calculated by dividing the total rainfall for the area by the area's size. This calculation is done separately for each sub-area, and the results are combined to obtain the overall average rainfall for the catchment area.

Advantages of the isohyetal method:
- It takes into account the variations in rainfall intensity across a catchment area.
- It is relatively simple to apply and requires only basic rainfall data.

Limitations of the isohyetal method:
- It assumes that rainfall intensity is constant between the rain gauges, which may not be true in reality.
- It may not be suitable for catchment areas with complex topography or other factors that can affect rainfall distribution.

Answer

B
isohytal method is used for large no of stations

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