Question $4$

$($a$)$ With reference to hydrographs, define "baseflow" and the catchment characteristics that may affect its magnitude. Explain why baseflow is normally removed when undertaking rainfall$/$runoff analysis.

$(5$ marks$)$

$($b$)$ Define the principles of proportionality and superposition used to derive unit hydrographs. What are the main assumptions in these two principles?

$(6$ marks$)$

$($c$)$ The rainfall hyetograph resulting from a storm lasting for eight hours is shown in Table Q$4\mathrm{.}1.$ The $10$ mm $,2$ hr unit hydrograph for the catchment is shown in Table Q$4\mathrm{.}2.$ If losses were $4m\frac{m}{h}r,$ determine the hydrograph of the quick response runoff.

$(14$ marks$)$

Table Q$4\mathrm{.}1$: Rainfall hyetograph

$\backslash$table$[[$Time $($hr$),0-2,2-4,4-6,6-8$