What is interception? What is the limitation of using linear (Hortonian type) equation for its estimation? Does depression storage contribute to surface runoff?
A process by which rainfall is abstracted prior to reaching the ground. Wetting of surface vegetation is typically the primary form of interception.
Hortonian eq shows that there will be unlimited interception as precipitation increases – it can not be true. Depression storage does not contribute to surface runoff, it either infiltrates or evaporates following the rainfall.
What are the factors influencing infiltration in soil? Draw a net sketch to show the distribution of soil moisture during the downward movement of water
Surface cover – vegetation tend to have significantly higher infiltration capacity
How is sorptivity (S) of the Phillip’s equation is estimated?
For horizontal column of soil, soil suction is the only force drawing water into the dry soil, and Phillip’s eq reduces to F(t) = St^1/2
So we can solve the eq for S when the cumulative infiltration F can be measured for a duration of t
Draw a net sketch to show the distribution of soil moisture in Green-Ampt method. What is effective porosity?
effective porosity is the interconnected pore volume or void space in a rock that contributes to fluid flow or permeability in a reservoir.
What is called ponding time? What was the assumption in deriving all the 3 infiltration equations? Is it going to provide the same infiltration rate after 30 minutes if ponding times are 10 and 40 minutes, respectively? If not, why?
Ponding time tp is the elapsed time between the time rainfall begins and the time water begins to pond on to the soil surface
Assumption that water is ponded to a small depth on the soil surface and so all the water the soil can infiltrate is available at the surface