$($b$)$ A town has flooded due to an extreme weather event raising the water levels in the river to $10$ m$.$O$.$D$.$ Using quasi$-$steady flow analysis, determine how long it will take flood waters to recede to normal levels considering the following information:

vel

level

Figure Q$2$b

Table Q$2$b

Make reasonable assumptions in the case of missing or incomplete information.

Comment on the sources of error which may affect your estimate and possible alternative techniques to solve the problem.