Most of the action of Swept Away takes place in the floodplain of a northern California river. Floodplains, the terrain alongside rivers that formerly became inundated during California's rainy season, are fairly prevalent in this region because of topography and climate. Rivers that overflowed to cover their floodplains have been dammed, creating reservoirs for California's long, hot, dry summers. These floodplains, now protected against water intrusion, provide both fertile land for farming and space for building new communities to Swept Away 361 house California's huge population. In Swept Away, the characters find themselves on a floodplain that is unpopulated and apparently part of a park system. A dam upriver has created a reservoir, and when the dam collapses, the floodplain reverts to its predam seasonal state—wet, marshy, muddy, and treacherous.