A border irrigation system is on a clay soil with a $1$:$150$ gradient. The dimensions of the individual border are $200m$ long $2m$ wide border Assume the resistance to flow from the crop to be high $(n$ value $=0\mathrm{.}15).$

a$.$ What should the stream size and cut off time be in order to uniformly apply a Gross Application of $20mm?$

$(4$ marks$)$

b$.$ If you later learn that the maximum flow that can be supplied from the water source is $80m^3*h{r}^{-1},$ what options do you have to achieve an application that is close to the Gross Application target of $20mm,$ while maintaining a Distribution Uniformity of $80\%$ or higher?