A $4,000-$km$2$ watershed receives $102$ cm of precipitation in one year. The average flow of the river draining the watershed is $34\mathrm{.}2$ m$3/$s$.$ Infiltration is estimated to be $5\mathrm{.}5\backslash$times $107$ cm$/$s and evapotranspiration is estimated to be $40$ cm$/$y$.$ Determine the change in storage in the watershed over one year. The ratio of runoff to precipitation $($both in cm$)$ is termed the runoff coefficient. Compute the runoff coefficient for this watershed.