[amp_mcq option1=”Both A and R are true and R is the correct explanation of A” option2=”Both A and R are true but R is not the correct explanation of A” option3=”A is true but R is false” option4=”A is false but R is true” correct=”option1″]
The correct answer is: A. Both A and R are true and R is the correct explanation of A.
The rainfall gradient is the rate of change of rainfall with respect to distance. In hilly areas, the rainfall gradient is steep, which means that the rainfall can vary greatly over a short distance. This is because the hills create a barrier to the flow of air, which causes the air to rise and cool. As the air rises, it expands and cools, which causes the water vapor in the air to condense and form clouds. The clouds then release the water as rain or snow.
In order to estimate the rainfall over a catchment, it is necessary to have a number of raingauges distributed over the area. The number of raingauges required per unit area is greater for hilly areas than for flat areas because of the steep rainfall gradient. This is because the rainfall can vary greatly over a short distance in hilly areas, so it is necessary to have more raingauges to get an accurate estimate of the total rainfall.
The reason why R is the correct explanation of A is because the steep rainfall gradient in hilly areas causes the rainfall to vary greatly over a short distance. This means that it is necessary to have more raingauges to get an accurate estimate of the total rainfall.