Two centimeters $(2\mathrm{.}00$ cm$)$ of runoff result from a storm on a drainage area of $100$ km $2.$

Convert this amount to cubic meters $($m$3).$

Final answer: $2$ x $106$ m$3$

$2.$ A vertical$-$walled reservoir has a surface area of $500,000$ m$2.$ An inflow of $1\mathrm{.}0$ m$3/$s into

the reservoir occurs. How many hours will it take to raise the reservoir level by $30$ cm$?$

Final answer: $41\mathrm{.}6$ hrs

$3.$ If the mean annual runoff of a drainage basin of $10,000$ km$2$ is $140$ m$3/$s$,$ and the average

annual precipitation is $105$ cm$,$ estimate the ET losses for the area in $1$ year. List all

assumptions in your calculations. How reliable do you think this estimate is$?$

Final answer: $61$ cm$/$yr

$4.$ The evaporation rate from the surface of a lake with a surface area of $14\mathrm{.}77$ km$2$ is $12\mathrm{.}33$

hectare$-$m$/$day$.$ Estimate the depth change in the lake $($in cm$)$ during a $1-$year period if

the net inflow to the lake is $0\mathrm{.}708$ m$3/$s$.$ Is the depth increasing or decreasing?

Note: $1$ hectare $=10,000$ m$2$

Final answer: $1\mathrm{.}54$ m $($decreasing$)$

$5.$ The storage in a reach of a river is $20,000$ m$3$ at a given time. Determine the storage $1$ hr

later if the average rates of inflow and outflow during the hour are $20$ m $3/$s and $18$ m$3/$s$,$

respectively.

Final answer: $27,200$ m$3$