While the oceans cover roughly 74% of the Earth’s surface and are the driving force behind the hydrologic cycle, it is the availability of freshwater that is of most concern today. Droughts and floods...While the oceans cover roughly 74% of the Earth’s surface and are the driving force behind the hydrologic cycle, it is the availability of freshwater that is of most concern today. Droughts and floods are a normal part of the hydrologic cycle, the issue is how to be prepared for them and how to best adapt to them in order to survive.