Storm surge
A category 1 hurricane, like Isaac, has sustained winds of at least 74 mph and no more than 95 mph. However, with increasing development in coastal areas, the more deadly effect from hurricanes has been storm surge. Storm surge is the rise in water level caused by the winds forcing the water forward. In many parts of the Gulf Coast, it does not take very strong winds to create a potentially dangerous storm surge. Isaac made landfall near the mouth of the Mississippi River with sustained winds of 70kt (81 mph). This was enough to cause flooding in large areas of south Louisiana especially in St. Bernard, Orleans, Plaquemines, and St. Tammany Parishes where water height was as much as 10 to 12 feet above sea level.