Question

what will happen if excess rain falls on a region completely dried by a severe drought

Answer 1

Even if the region does not have rain/adequate water level for long time - meaning it is sever drought, land/soil cannot absorb all the rain the falls in short duration. 

If too much rain falls in short duration, most of it gets run off in drainage, or via other channels and very less quantity of water is absorbed. 

For the rain water to get absorbed, it needs to rain slowly, and consistently which is known as soaking rain. This type of showers are absorbed and provide much needed relief. 

Answer 2

Answer: It will run-off as mostly there are chances of rain coming in shirt time

Explanation:

It would come too fast and the ground would not be able to absorb everything.