Ouestion $1(10$ marks$)$

a$)$ A river reach had a flood wave passing through it$.$ At a given instant the storage

of water in the reach was estimated as $50{10}^3{m}^3.$ At that time, the inflow into

the reach is $15\frac{m^3}{s}$ and the outflow is $20\frac{m^3}{s}.$ After two hours, the inflow and

the outflow are $20\frac{m^3}{s}$ and $22\frac{m^3}{s},$ respectively. Determine the change in

storage during two hours period and the storage volume after two hours.

$(5$ marks$)$

b$)$ A catchment having an area of $3,000k{m}^2$ received rainfall of $1,500mm$ in

one year. The average rate of flow measured in a river draining the

catchment was $35m^{3}s-1$ for that year.

i$.$ Calculate the total river runoff that occurred in the year $($in m$3)?$

ii$.$ Calculate the runoff coefficient?

iii. How much water is lost due to the combined effects of evaporation,

transpiration, and infiltration? $($Expressed in meters$).$