Definition: In this task, you need to generate an appropriate title for the given summary of some paragraph. The generated title must be short and should include the main topic of the given text. Your summary should be less than 20 words long.
Input: Parts of the Houston region have been hammered by more than 50in of rainfall since Hurricane Harvey made landfall, setting new records for the US. But why has the city become America's flood capital?

Why is Houston so vulnerable to devastating floods?