A very wide river, with a bed slope of 10 cm/km and a Manning roughness coefficient of 0.032, conveys a specific discharge of 10  /s. A dam is constructed across the river so that the water depth...

A very wide river, with a bed slope of 10 cm/km and a Manning roughness coefficient of 0.032, conveys a specific discharge of 10
 /s. A dam is constructed across the river so that the water depth behind it becomes 14.0 m with a water surface elevation of 55.0 m measured from an arbitrary datum. Two villages A and B are to be built 20 km and 45 km upstream of the dam, respectively. Find the respective land elevation (relative to the datum) of the two villages so that they are not to be drowned. Use the standard step method.