QUESTION $7$

A buttress dam wall must be designed for storage and erosion control on a farm in the Free State. To do the design, the design peak discharge$/$ runoff must be determined for a $1$: $50-$year flood. Determine the peak discharge by making use of the Rational method and the data listed in Table $1.$

The following information is available:

$-$ Catchment area:

$\backslash [$

$28\backslash$mathrm$\{$~km$\}^\{2\}$

$\backslash ]$

$-$ MAP:

$\backslash [$

$580\backslash$mathrm$\{$~mm$\}$

$\backslash ]$

$-$ Length of main water course:

$\backslash [$

$8\mathrm{.}50\backslash$mathrm$\{$~km$\}$

$\backslash ]$

$-$ Height of most remote point above outlet:$320$ m

$-$ H$0\mathrm{.}85$L:

$\backslash [$

$135\backslash$mathrm$\{$~m$\}$

$\backslash ]$

$-$ H$0\mathrm{.}10$L:

$-$ Return period factor $\backslash ((\backslash$mathrm$\{$Ft$\})\backslash )$ :

Assume overland flow as $150$ m and $\backslash ($ r$=0\mathrm{.}4\backslash )($average grassland$).$

Table $1$: Catchment compilation

TOTAL MARKS: $100$ END OF EXAMINATION